Incompatibilities between numerical simulations, theoretical predictions and cosmological observations at small and large scales suggest that the Dark Matter (DM) could strongly self-interact. It has been shown that introducing a light mediator would greatly help in accounting for large DM self-interactions. This mediator can allow portal interactions between the "hidden sector" containing the DM and the mediator and the "visible sector" containing the ordinary SM particles we know. However, more and more of the parameter space is excluded due to strong tensions between cosmological and astrophysical observations, on the one hand, and the fact that there is, until now, still no hint of DM in particle physics experiments, on the other hand.

In this thesis, we start by reviewing all constraints applying on self-interacting DM with a light mediator considering well-known Higgs portal and Kinetic Mixing portal models as concrete examples. Then, we elaborate on the Sommerfeld effect, and we study its many implications on self-interacting DM models with light mediator. Next, we investigate how to account for the DM relic abundance in such portal models which present a generic structure with three populations (Standard Model, DM and mediator particles) connected to each other through three interactions resulting from two coupling strengths. It appears that this can be done through five different dynamical ways which give rise to nine regimes among which four are new. Those new production regimes are relevant for a situation where the hidden sector particles are not thermally connected to the visible vector particles.

We further study the possibility of a thermally disconnected Hidden Sector and establish the general allowed parameter space for DM thermal candidates in the hidden-to-visible temperature ratio versus DM mass plane. We show that, in this framework, simple portal models such as the two we consider can alleviate tensions at small scale while offering suitable DM candidates. Other minimal self-interacting DM with light mediator frameworks which consistently fulfil all constraints are also proposed and explored.

KEYWORDS: Dark matter, hidden sector, self-interactions, light mediator, production mechanism, portal.

Les incompatibilités entre les simulations numériques, les prédictions théori-ques et les observations cosmologiques à courtes et larges échelles suggèrent que la Matière Noire (MN) auto-interagit fortement. Il a été démontré qu’introduire un médiateur léger peut permettre de rendre compte de telles auto-interactions pour la MN. Un tel médiateur permet, de plus, des interactions "portails" entre le "secteur caché" (contenant la MN et le médiateur léger) et le "secteur visible" (contenant les particules que l'on connaît déjà, c'est-à-dire du Modèle Standard). Toutefois, l’espace des paramètres se voit de plus en plus exclu aux vues d’une tension entre, d’une part, les observations cosmologiques et astrophysiques et, d’autre part, le fait que l'on ait à ce jour toujours pas mis en évidence des traces de MN dans aucune expérience de physique des particules.

Nous commençons par détailler toutes les contraintes qui s’appliquent aux modèles pour lesquels la MN auto-interagit au moyen d’un médiateur léger. Pour cela, nous considérons les deux exemples de modèles connus du portail de Higgs et du portail de mélange cinétique. Nous discutons ensuite l’effet Sommerfeld et étudions ses nombreuses implications sur de tels modèles. Nous poursuivons en établissant comment rendre compte de la densité relique de MN observée aujourd’hui dans l'Univers dans de tels modèles, c'est-à-dire dans des modèles qui présentent une structure générique composée de trois populations de particules (le Modèle Standard, la MN et le médiateur) connectées les unes aux autres au travers de trois interactions résultantes de deux couplages fondamentaux entre particules. Il apparaît que cela peut être fait selon cinq manières dynamiques différentes qui donnent lieu à neuf régimes de production de la MN dont quatre sont nouveaux. Ces nouveaux régimes de production sont pertinents pour la situation où les particules du secteur caché ne sont pas en équilibre thermique avec les particules du secteur visible.

Nous étudions ensuite plus en détail la possibilité d’un secteur caché qui n’est pas thermiquement connecté au secteur visible, en déterminant en particulier l’espace des paramètres autorisé pour des candidats de MN thermaux en termes du ratio des températures des deux secteurs et de la masse de la MN. Nous montrons ensuite que si les deux secteurs ne sont pas thermalement connectés, les deux modèles simples de portails que nous considérons permettent de diminuer les tensions à courtes échelles tout en offrant des candidats de MN viables. Enfin, nous proposons et explorons d’autres modèles minimaux de MN auto-interagissante qui satisfont aux nombreuses contraintes de manière consistante.

MOTS-CLÉS: Matière noire, secteur caché, auto-interactions, médiateur léger, mécanisme de production, portail.

Au travers de ces quelques lignes, je souhaiterais remercier chaque personne qui aura directement ou indirectement contribué à ce travail, en commençant, bien sur, par mon promoteur Thomas Hambye. Durant ces cinq dernières années, il m'aura énormément appris, tant d'un point de vue professionnel que personnel. Depuis le premier jour, il a pris son rôle à coeur en m'enseignant tout ce qu'il pouvait, en me guidant dans ce monde qui m'était alors totalement inconnu, sans jamais s'impatienter. Il m'a fait découvrir le monde de la recherche, ses obligations, ses opportunités, ses voyages et les incroyables rencontres qui y sont liées. Grâce à lui, j'ai le sentiment d'avoir vécu mes années de thèse à fond et n'ai aucun regret. I also warmly thank Laura Lopez-Honorez, Riccardo Argurio, Michele Redi and Kai Schmidt-Hoberg, the members of my jury for agreeing to read my manuscript and for the useful remarks and comments they have made during the private defense.

Je tiens également à remercier l'ensemble des membres du Service de Physique Théorique qui m'a accueilli durant toute la durée de mon mémoire de fin d'étude et de mon doctorat. Je pense notamment à Michel Tytgat avec qui j'ai eu le plaisir de collaborer plusieurs fois, à Petr Tyniakov grâce à qui j'ai pu participer à l'encadre-ment du cours de relativité restreinte, à Laura Lopez-Honorez pour avoir apporté tant de bonne humeur et de dynamisme au quotidien et enfin à Jean-Marie Frère qui aura contribué à mon apprentissage. Je n'oublie évidement pas Isabelle Renders et Sarah Bouzerda qui m'ont aidées à maintes reprises au sujet de tâches administratives qui m'étaient parfois obscures. I thank everybody I met during my thesis in the group: Iason, Aritra, Deanna, Marco, Mikhail, Xunjie, Quentin, Sam, Baptiste, Raghuveer, Yoann, Mikaël, Daniele, Julian and many more. Let thank also Camillo, Chaïma, Rupert, Matteo and Jérôme, my collaborators, which all helped me to be the physicist I became.

Durant ma thèse et mes années passées à l'ULB, j'ai eu la chance de rencontrer et côtoyer bon nombre de personnes qui ont permis de transformer un quotidien parfois répétitif en des instants inoubliables. Je pense à toutes ces VUB et interminables pauses cafés passées avec notamment Martin, Adrien, Béa, Pawel, Louis, Daniel, Romain, Colin, Quentin, ... . Je retiendrai tout particulièrement Bilal, Antoine, Jérôme et Tanguy sans qui ces années à l'ULB n'auraient jamais pu être aussi extraordinaires. Je ne compte plus les heures passées aux salles d'étude, salles de repos, cafés, restaurants, billards à discuter de tout et de rien, à divaguer mais surtout à nous soutenir les uns les autres. Leur amitié durant mes études et ensuite durant ma thèse restera inoubliable.

Ma passion pour la physique est née bien avant d'entrer à l'université, grâce notamment à ma rencontre avec Salahdin, lorsque nous avions dix ans environ. Nous nous sommes tout de suite parfaitement entendus et n'avons jamais cessé depuis de parler de physique et de sciences en général. Bien que nos chemins se soient quelques peu éloignés, il a toujours su éveiller ma curiosité et entretenir ma passion pour la physique, pour ça et pour notre longue amitié, je lui serai éternellement reconnaissant.

Sans aucun doute, ma famille a joué un rôle primordial dans l'accomplissement de cette thèse. Que ce soit Bruno, Isabelle, Catherine, Papa ou Maman, vous avez tous toujours cru en moi. Jamais vous n'avez douté et ce même lorsque j'ai pu traverser des moments plus difficiles. Tantôt tour à tour, tantôt à l'unissons, vous avez tous su me remotiver et me montrer comment grandir, comment passer au-dessus des épreuves. Vous avez et êtes toujours des exemples pour moi, c'est donc pour moi une immense fierté de pouvoir enfin vous présenter ma thèse, mon travail. Le "petit" ne l'est peut-être plus tant que ça finalement ...

Enfin, je finirai ces lignes en remerciant ma compagne (et presque épouse!) Élise qui, sans le moindre doute, m'aura été et m'est toujours d'un grand soutien. Depuis notre rencontre, tu es derrière moi, me motives, me forces à me dépasser et ce comme nul autre n'a pu le faire. Tout en suivant ton propre chemin, en menant de longues et passionnantes études, tu as su m'épauler en y mettant du coeur et de l'énergie. Il est certain que sans toi à mes côtés, je ne serais jamais arrivé là où j'en suis aujourd'hui. Grâce à toi, j'ai également rencontré ta famille, Alain, Evelyne et Christophe qui eux aussi m'auront soutenu et motivé, notamment en s'intéressant à ma thèse malgré le sujet plus qu'abstrait mais aussi en suivant mon parcours de près et en me conseillant. Pour ça, encore merci.

BBN     Big Bang Nucleosynthesis

CDM     Cold Dark Matter

CMB     Cosmic Microwave Background

DG     Dwarf Galaxy

DM     Dark Matter

FLRW     Fridemann - Lemaître Robertson Walker

FI     Freeze-In

FO     Freeze-Out

FS     Free-Streaming

HP     Higgs Portal

HS     Hidden Sector

IR     Infrared

KM     Kinetic Mixing

LHC     Large Hadron Collider

MW     Milky Way

MR     Matter-Radiation

NFW     Navarro-Frenk-White

NR     Non-Relativistic

QCD     Quantum ChromoDynamics

SIDM     Self Interacting Dark Matter

SM     Standard Model

VEV     Vacuum Expectation Value

VS     Visible Sector

The Self-Interacting Dark Matter with light mediator problematic

DM production and Hidden Sector

Self-Interacting Dark Matter ways-out

Missing 'biblatex' package
The bibliography requires the 'biblatex' package.

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We report the first dark matter search results from XENON1T, a
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Phase Transition
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It is estimated that demands for experimental observation of recently
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titleCold collapse and the core catastrophe
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We review theories of dark matter (DM) beyond the collisionless paradigm,
known as self-interacting dark matter (SIDM), and their observable
implications for astrophysical structure in the Universe. Self-interactions
are motivated, in part, due to the potential to explain long-standing (and
more recent) small scale structure observations that are in tension with
collisionless cold DM (CDM) predictions. Simple particle physics models for
SIDM can provide a universal explanation for these observations across a wide
range of mass scales spanning dwarf galaxies, low and high surface brightness
spiral galaxies, and clusters of galaxies. At the same time, SIDM leaves
intact the success of $\Lambda$CDM cosmology on large scales. This report
covers the following topics: (1) small scale structure issues, including the
core–cusp problem, the diversity problem for rotation curves, the missing
satellites problem, and the too-big-to-fail problem, as well as recent
progress in hydrodynamical simulations of galaxy formation; (2) N-body
simulations for SIDM, including implications for density profiles, halo
shapes, substructure, and the interplay between baryons and
self-interactions; (3) semi-analytic Jeans-based methods that provide a
complementary approach for connecting particle models with observations; (4)
merging systems, such as cluster mergers (e.g., the Bullet Cluster) and minor
infalls, along with recent simulation results for mergers; (5) particle
physics models, including light mediator models and composite DM models; and
(6) complementary probes for SIDM, including indirect and direct detection
experiments, particle collider searches, and cosmological observations. We
provide a summary and critical look for all current constraints on DM
self-interactions and an outline for future directions.

titleDark matter self-interactions and small scale structure
journaltitlePhysics Reports

Astrophysical observations spanning dwarf galaxies to galaxy clusters
indicate that dark matter (DM) halos are less dense in their central regions
compared to expectations from collisionless DM N-body simulations. Using
detailed fits to DM halos of galaxies and clusters, we show that
self-interacting DM (SIDM) may provide a consistent solution to the DM
deficit problem across all scales, even though individual systems exhibit a
wide diversity in halo properties. Since the characteristic velocity of DM
particles varies across these systems, we are able to measure the
self-interaction cross section as a function of kinetic energy and thereby
deduce the SIDM particle physics model parameters. Our results prefer a
mildly velocity-dependent cross section, from $\sigma$/m≈2 cm2/g on galaxy
scales to $\sigma$/m≈0.1 cm2/g on cluster scales, consistent with the upper
limits from merging clusters. Our results dramatically improve the
constraints on SIDM models and may allow the masses of both DM and dark
mediator particles to be measured even if the dark sector is completely
hidden from the standard model, which we illustrate for the dark photon

titleDark Matter Halos as Particle Colliders: Unified Solution to
Small-Scale Structure Puzzles from Dwarfs to Clusters
journaltitlePhysical Review Letters

The rotation curves of spiral galaxies exhibit a diversity that has been
difficult to understand in the cold dark matter (CDM) paradigm. We show that
the self-interacting dark matter (SIDM) model provides excellent fits to the
rotation curves of a sample of galaxies with asymptotic velocities in the
25-300 km/s range that exemplify the full range of diversity. We assume only
the halo concentration-mass relation predicted by the CDM model and a fixed
value of the self-interaction cross section. In dark-matter-dominated
galaxies, thermalization due to self-interactions creates large cores and
reduces dark matter densities. In contrast, thermalization leads to denser
and smaller cores in more luminous galaxies and naturally explains the
flatness of rotation curves of the highly luminous galaxies at small radii.
Our results demonstrate that the impact of the baryons on the SIDM halo
profile and the scatter from the assembly history of halos as encoded in the
concentration-mass relation can explain the diverse rotation curves of spiral

titleSelf-Interacting Dark Matter Can Explain Diverse Galactic
Rotation Curves
journaltitlePhysical Review Letters

titleThe Structure of dark matter halos in dwarf galaxies
journaltitleIAU Symp.

titleTesting the dark matter hypothesis with low surface
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titleDwarf galaxy rotation curves and the core problem of dark
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titleThe Dark matter distribution in disk galaxies
journaltitleMon. Not. Roy. Astron. Soc.

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titleHigh-Resolution Rotation Curves of Low Surface Brightness
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titleHalpha rotation curves: the soft core question
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titleThe dwarf galaxy DDO 47 as a dark matter laboratory: testing
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titleNGC 3741: Dark halo profile from the most extended rotation
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titleHigh Resolution Optical Velocity Fields of 11 Low Surface
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titleMass Models for Low Surface Brightness Galaxies with High
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titleThe Universal Rotation Curve of Spiral Galaxies. 2. The Dark
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titleHigh-resolution mass models of dwarf galaxies from LITTLE
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titleProfiles of dark haloes. Evolution, scatter, and
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Dark matter (DM) may belong to a hidden sector (HS) that is only feebly
interacting with the standard model (SM) and may have never been in thermal
equilibrium in the early Universe. In this case, the observed abundance of
dark matter particles could have built up through a process known as
freeze-in. We show that, for the first time, direct detection experiments are
testing this DM production mechanism. This applies to scenarios where SM and
HS communicate through a light mediator of mass less than a few MeV. Through
the exchange of such a light mediator, the very same feebly interacting
massive particles can have self-interactions that are in the range required
to address the small scale structure issues of collisionless cold DM.

titleDark matter direct detection is testing freeze-in
journaltitlePhysical Review D

IOP Publishing

The light mediator scenario of self-interacting dark matter is strongly
constrained in many ways. After summarizing the various constraints, we
discuss minimal options and models which allow to nevertheless satisfy all
these constraints. One straightforward possibility emerges if the dark matter
and light mediator particles have a temperature sizably smaller than the SM
particles. Another simple possibility arises if dark matter doesn't
annihilate dominantly into a pair of light mediators but into heavier
particles. Both possibilities are discussed with scalar as well as vector
boson light mediators. Further possibilities, such as with a hierarchy of
quartic scalar couplings, are also identified.

titleMinimal self-interacting dark matter models with light
journaltitleJournal of Cosmology and Astroparticle Physics

* Invalid format of field 'month'

Galactic Mass, Galactic Rotation, Mass To Light Ratios, Spiral
Galaxies, Dwarf Galaxies, Galactic Structure, Halos, Astrophysics
titleExtended rotation curves of spiral galaxies : dark haloes
and modified dynamics.

titleExistence and Nature of Dark Matter in the Universe
journaltitleAnn. Rev. Astron. Astrophys.

titleDark matter halos around galaxies
journaltitleASP Conf. Ser.

titleChandra sample of nearby relaxed galaxy clusters: Mass, gas
fraction, and mass-temperature relation
journaltitleAstrophys. J.

titleA direct empirical proof of the existence of dark matter
journaltitleAstrophys. J. Lett.

noteAccessed: 2021-01-15
titleESA - Planck Collaboration

American Physical Society

titleGeneralized Laguerre representation: Application to
relativistic two-photon decay rates
journaltitlePhys. Rev. A

* Invalid format of field 'month'

titleFirst year Wilkinson Microwave Anisotropy Probe (WMAP)
observations: Preliminary maps and basic results
journaltitleAstrophys. J. Suppl.

titlePlanck 2018 results. VI. Cosmological parameters

Most embeddings of the Standard Model into a more unified theory, in
particular the ones based on supergravity or superstrings, predict the
existence of a hidden sector of particles which have only very weak
interactions with the visible sector Standard Model particles. Some of these
exotic particle candidates (such as e.g. "axions", "axion-like particles" and
"hidden U(1) gauge bosons") may be very light, with masses in the sub-eV
range, and have very weak interactions with photons. Correspondingly, these
very weakly interacting sub-eV particles (WISPs) may lead to observable
effects in experiments (as well as in astrophysical and cosmological
observations) searching for light shining through a wall, for changes in
laser polarisation, for non-linear processes in large electromagnetic fields
and for deviations from Coulomb's law. We present the physics case and a
status report of this emerging low-energy frontier of fundamental physics.

titleThe Low-Energy Frontier of Particle Physics
journaltitleAnnual Review of Nuclear and Particle Science

Dark sectors, consisting of new, light, weakly-coupled particles that do
not interact with the known strong, weak, or electromagnetic forces, are a
particularly compelling possibility for new physics. Nature may contain
numerous dark sectors, each with their own beautiful structure, distinct
particles, and forces. This review summarizes the physics motivation for dark
sectors and the exciting opportunities for experimental exploration. It is
the summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled
Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions,
which solve the strong CP problem and are an excellent dark matter candidate,
and their generalization to axion-like particles. We also review dark photons
and other dark-sector particles, including sub-GeV dark matter, which are
theoretically natural, provide for dark matter candidates or new dark matter
interactions, and could resolve outstanding puzzles in particle and
astro-particle physics. In many cases, the exploration of dark sectors can
proceed with existing facilities and comparatively modest experiments. A
rich, diverse, and low-cost experimental program has been identified that has
the potential for one or more game-changing discoveries. These physics
opportunities should be vigorously pursued in the US and elsewhere.

booktitleProceedings, 2013 Community Summer Study on the Future of
U.S. Particle Physics: Snowmass on the Mississippi (CSS2013): Minneapolis,
MN, USA, July 29-August 6, 2013
titleWorking Group Report: New Light Weakly Coupled Particles

titleDark Sectors 2016 Workshop: Community Report

A simple way of explaining dark matter without modifying known Standard
Model physics is to require the existence of a hidden (dark) sector, which
interacts with the visible one predominantly via gravity. We consider a
hidden sector containing two stable particles charged under an unbroken
U(1)′ gauge symmetry, hence featuring dissipative interactions. The
massless gauge field associated with this symmetry, the dark photon, can
interact via kinetic mixing with the ordinary photon. In fact, such an
interaction of strength $\epsilon$∼10-9 appears to be necessary in order to
explain galactic structure. We calculate the effect of this new physics on
big bang nucleosynthesis and its contribution to the relativistic energy
density at hydrogen recombination. We then examine the process of dark
recombination, during which neutral dark states are formed, which is
important for large-scale structure formation. Galactic structure is
considered next, focusing on spiral and irregular galaxies. For these
galaxies we modeled the dark matter halo (at the current epoch) as a
dissipative plasma of dark matter particles, where the energy lost due to
dissipation is compensated by the energy produced from ordinary supernovae
(the core-collapse energy is transferred to the hidden sector via kinetic
mixing induced processes in the supernova core). We find that such a
dynamical halo model can reproduce several observed features of disk
galaxies, including the cored density profile and the Tully-Fisher relation.
We also discuss how elliptical and dwarf spheroidal galaxies could fit into
this picture. Finally, these analyses are combined to set bounds on the
parameter space of our model, which can serve as a guideline for future
experimental searches.

titleDissipative hidden sector dark matter
journaltitlePhysical Review D - Particles, Fields, Gravitation and

Dark matter,Dark radiation,Effective number of neutrinos
Light (M ≤ 20 MeV) dark-matter particles freeze out after neutrino
decoupling. If the dark-matter particle couples to a neutrino or an
electromagnetic plasma, the late time entropy production from dark-matter
annihilation can change the neutrino-to-photon temperature ratio, and equally
the effective number of neutrinos Neff. We study the non-equilibrium effects
of dark-matter annihilation on the Neff and the effects by using a thermal
equilibrium approximation. Both results are constrained with Planck
observations. We demonstrate that the lower bounds of the dark-matter mass
and the possibilities of the existence of additional radiation particles are
more strongly constrained for dark-matter annihilation process in

titleLight dark matter and dark radiation
journaltitleJournal of the Korean Physical Society

Cosmology of theories beyond the SM,Dark matter
Dark matter may be hidden, with no standard model gauge interactions. At
the same time, in WIMPless models (WIMP: weakly interacting massive
particles) with hidden matter masses proportional to hidden gauge couplings
squared, the hidden dark matter's thermal relic density may naturally be in
the right range, preserving the key quantitative virtue of WIMPs. We consider
this possibility in detail. We first determine model-independent constraints
on hidden sectors from big bang nucleosynthesis and the cosmic microwave
background. Contrary to conventional wisdom, large hidden sectors are easily
accommodated. A flavour-free version of the standard model is allowed if the
hidden sector is just 30% colder than the observable sector after
reheating. Alternatively, if the hidden sector contains a one-generation
version of the standard model with characteristic mass scale below 1MeV, even
identical reheating temperatures are allowed. We then analyse hidden sector
freeze-out in detail for a concrete model, solving the Boltzmann equation
numerically and explaining the results from both observable and hidden sector
points of view. We find that WIMPless dark matter does indeed obtain the
correct relic density for masses in the range . The upper bound results from
the requirement of perturbativity, and the lower bound assumes that the
observable and hidden sectors reheat to the same temperature, and is raised
to the MeV scale if the hidden sector is ten times colder. WIMPless dark
matter therefore generalizes the WIMP paradigm to the largest mass range
possible for viable thermal relics and provides a unified framework for
exploring dark matter signals across nine orders of magnitude in dark matter
mass. © 2008 IOP Publishing Ltd.

titleThermal relics in hidden sectors
journaltitleJournal of Cosmology and Astroparticle Physics

Cosmological perturbation theory,Dark matter theory,Galaxy
Can dark matter be stabilized by charge conservation, just as the electron
is in the standard model? We examine the possibility that dark matter is
hidden, that is, neutral under all standard model gauge interactions, but
charged under an exact U(1) gauge symmetry of the hidden sector. Such
candidates are predicted in WIMPless models, supersymmetric models in which
hidden dark matter has the desired thermal relic density for a wide range of
masses. Hidden charged dark matter has many novel properties not shared by
neutral dark matter: (1) bound state formation and Sommerfeld-enhanced
annihilation after chemical freeze out may reduce its relic density, (2)
similar effects greatly enhance dark matter annihilation in protohalos at
redshifts of z ∼ 30, (3) Compton scattering off hidden photons delays
kinetic decoupling, suppressing small scale structure, and (4) Rutherford
scattering makes such dark matter self-interacting and collisional,
potentially impacting properties of the Bullet Cluster and the observed
morphology of galactic halos. We analyze all of these effects in a WIMPless
model in which the hidden sector is a simplified version of the minimal
supersymmetric standard model and the dark matter is a hidden sector stau. We
find that charged hidden dark matter is viable and consistent with the
correct relic density for reasonable model parameters and dark matter masses
in the range 1GeVm ≲ m X ≲ 10 TeV. At the same time, in the preferred
range of parameters, this model predicts cores in the dark matter halos of
small galaxies and other halo properties that may be within the reach of
future observations. These models therefore provide a viable and
well-motivated framework for collisional dark matter with Sommerfeld
enhancement, with novel implications for astrophysics and dark matter
searches. © 2009 IOP Publishing Ltd and SISSA.

titleHidden charged dark matter
journaltitleJournal of Cosmology and Astroparticle Physics

From the particle physics point of view, the most peculiar property of the
dark matter particle is its stability on cosmological time scales. We briefly
review the possible origins of this stability for candidates whose relic
density results from the thermal freeze-out of its annihilation. We emphasize
that each stabilization mechanism implies an all specific phenomenology. The
models reviewed include supersymmetric and non-supersymmetric models where
the stability is a consequence of grand-unification, models where stability
is due to an unbroken gauge group and models where the DM stability is
accidental. The latter possibility includes minimal dark matter, hidden
vector dark matter and composite DM models. © Copyright owned
by the author(s) under the terms of the Creative Commons
Attribution-NonCommercial-ShareAlike Licence.

titleOn the stability of particle dark matter
journaltitleProceedings of Science

Translated from "Die Wechselwirkungskraefte in der Elektrodynamik und in
der Feldtheorie der Kernkraefte (Teil II and III)".

titleInteraction forces in electrodynamics and in the field
theory of nuclear forces

titleBroken symmetry and the mass of gauge vector mesons
journaltitlePhysical Review Letters

titleBroken symmetries and the masses of gauge bosons
journaltitlePhysical Review Letters

Axions,Solar and atmospheric neutrinos
The flux of hypothetical 'hidden photons' from the Sun is computed under
the assumption that they interact with normal matter only through kinetic
mixing with the ordinary standard model photon. Requiring that the exotic
luminosity is smaller than the standard photon luminosity provides limits for
the mixing parameter down to , depending on the hidden photon mass.
Furthermore, it is pointed out that helioscopes looking for solar axions are
also very sensitive to hidden photons. The recent results of the CAST
collaboration are used to further constrain the mixing parameter $\chi$ at
low masses (m $\gamma$′1eV) where the luminosity bound is
weaker. In this regime the solar hidden photon flux has a sizable
contribution of longitudinally polarized hidden photons of low energy which
are invisible for current helioscopes. © 2008 IOP Publishing
Ltd and SISSA.

titleHelioscope bounds on hidden sector photons
journaltitleJournal of Cosmology and Astroparticle Physics

If there is a light Abelian gauge boson $\gamma$′ in the hidden sector
its kinetic mixing with the photon can produce a hidden cosmic microwave
background (HCMB). For meV masses, resonant oscillations $\gamma$ $\gamma$′
happen after big bang nucleosynthesis (BBN) but before CMB decoupling,
increasing the effective number of neutrinos N$\nu$eff and the baryon to
photon ratio, and distorting the CMB blackbody spectrum. The agreement
between BBN and CMB data provides new constraints. However, including
Lyman-$\alpha$ data, N$\nu$eff3 is preferred. It is tempting to
attribute this effect to the HCMB. The interesting parameter range will be
tested in upcoming laboratory experiments. © 2008 The American
Physical Society.

titleSignatures of a hidden cosmic microwave background
journaltitlePhysical Review Letters

Cosmology of theories beyond the SM,Dark matter
We study the possibility that a keV-MeV mass hidden photon (HP), i.e. a
hidden sector U(1) gauge boson, accounts for the observed amount of dark
matter. We focus on the case where the HP interacts with the standard model
sector only through kinetic mixing with the photon. The relic abundance is
computed including all relevant plasma effects into the photon's self-energy,
which leads to a resonant yield almost independent of the HP mass. The HP can
decay into three photons. Moreover, if light enough it can be copiously
produced in stars. Including bounds from cosmic photon backgrounds and
stellar evolution, we find that the hidden photon can only give a subdominant
contribution to the dark matter. This negative conclusion may be avoided if
another production mechanism besides kinetic mixing is operative.
© 2009 IOP Publishing Ltd and SISSA.

titleMassive hidden photons as lukewarm dark matter
journaltitleJournal of Cosmology and Astroparticle Physics

We consider the stellar production of vector states V within the minimal
model of "dark photons". We show that when the Stückelberg mass of the
dark vector becomes smaller than plasma frequency, the emission rate is
dominated by the production of the longitudinal modes of V, and scales as
$\kappa$2mV2, where $\kappa$ and mV are the mixing angle with the photon and
the mass of the dark state. This is in contrast with widespread assertions in
the literature that the emission rate decouples as the forth power of the
mass. We derive ensuing constraints on the ($\kappa$, mV) parameter space by
calculating the cooling rates for the Sun and horizontal branch stars. We
find that stellar bounds for mV10eV are significantly
strengthened, to the extent that all current "light-shining-through-wall"
experiments find themselves within deeply excluded regions. ©
2013 Elsevier B.V.

titleNew stellar constraints on dark photons
journaltitlePhysics Letters, Section B: Nuclear, Elementary
Particle and High-Energy Physics

axions,solar and atmospheric neutrinos,solar physics
We re-examine solar emission of hidden photons $\gamma$′ (mass m) caused
by kinetic $\gamma$-$\gamma$′ mixing. We calculate the emission rate with
thermal field theory methods and with a kinetic equation that includes
$\gamma$-$\gamma$′ "flavor oscillations" and $\gamma$ absorption and
emission by the thermal medium. In the resonant case both methods yield
identical emission rates which, in the longitudinal channel, are enhanced by
a factor $\omega$P2/m2 (plasma frequency $\omega$P) in agreement with An,
Pospelov and Pradler (2013). The Sun must not emit more energy in a "dark
channel" than allowed by solar neutrino measurements, i.e., not more than
10% of its photon luminosity. Together with the revised emission rate,
this conservative requirement implies $\chi$  4 × 10-12(eV/m) for
the kinetic mixing parameter. This is the most restrictive stellar limit
below m ∼ 3eV, whereas for larger masses the transverse channel dominates
together with limits from other stars. A recent analysis of XENON10 data
marginally improves the solar limit, leaving open the opportunity to detect
solar hidden photons with future large-scale dark matter experiments.
Detecting low-mass hidden photons with the ALPS-II photon-regeneration
experiment also remains possible. © 2013 IOP Publishing Ltd
and Sissa Medialab srl.

titleSolar constraints on hidden photons re-visited
journaltitleJournal of Cosmology and Astroparticle Physics

We explore the cosmological consequences of kinetically mixed dark photons
with a mass between 1 MeV and 10 GeV and an effective electromagnetic fine
structure constant as small as 10-38. We calculate the freeze-in abundance of
these dark photons in the early universe and explore the impact of late
decays on big bang nucleosynthesis and the cosmic microwave background. This
leads to new constraints on the parameter space of mass mV vs kinetic mixing
parameter $\kappa$. © 2014 American Physical Society.

titleCosmological constraints on very dark photons
journaltitlePhysical Review D - Particles, Fields, Gravitation and

Dark matter,Methods: numerical
We present N-body simulations of a new class of self-interacting dark
matter models, which do not violate any astrophysical constraints due to a
non-power-law velocity dependence of the transfer cross-section which is
motivated by a Yukawa-like new gauge boson interaction. Specifically, we
focus on the formation of a Milky-Way-like dark matter halo taken from the
Aquarius project and resimulate it for a couple of representative cases in
the allowed parameter space of this new model. We find that for these cases,
the main halo only develops a small core (1kpc) followed by a density
profile identical to that of the standard cold dark matter scenario outside
of that radius. Neither the subhalo mass function nor the radial number
density of subhaloes is altered in these models but there is a significant
change in the inner density structure of subhaloes resulting in the formation
of a large density core. As a consequence, the inner circular velocity
profiles of the most massive subhaloes differ significantly from the cold
dark matter predictions and we demonstrate that they are compatible with the
observational data of the brightest Milky Way dwarf spheroidals (dSphs) in
such a velocity-dependent self-interacting dark matter scenario.
Specifically, and contrary to the cold dark matter case, there are no
subhaloes that are more concentrated than what is inferred from the
kinematics of the Milky Way dSphs. We conclude that these models offer an
interesting alternative to the cold dark matter model that can reduce the
recently reported tension between the brightest Milky Way satellites and the
dense subhaloes found in cold dark matter simulations. © 2012
The Authors Monthly Notices of the Royal Astronomical Society
© 2012 RAS.

titleSubhaloes in self-interacting galactic dark matter haloes
journaltitleMonthly Notices of the Royal Astronomical Society

Dark matter,Galaxies: haloes,Methods: numerical
We use cosmological simulations to study the effects of self-interacting
dark matter (SIDM) on the density profiles and substructure counts of
dark-matter haloes from the scales of spiral galaxies to galaxy clusters,
focusing explicitly on models with cross-sections over dark-matter particle
mass $\sigma$/m = 1 and 0.1 cm2 g-1. Our simulations rely on a new SIDM
N-body algorithm that is derived self-consistently from the Boltzmann
equation and that reproduces analytic expectations in controlled numerical
experiments. We find that well-resolved SIDM haloes have constant-density
cores, with significantly lower central densities than their cold dark matter
(CDM) counterparts. In contrast, the subhalo content of SIDM haloes is only
modestly reduced compared to CDM, with the suppression greatest for large
hosts and small halo-centric distances. Moreover, the large-scale clustering
and halo circular velocity functions in SIDM are effectively identical to
CDM, meaning that all of the large-scale successes of CDM are equally well
matched by SIDM. From our largest cross-section runs, we are able to extract
scaling relations for core sizes and central densities over a range of halo
sizes and find a strong correlation between the core radius of an SIDM halo
and the NFW scale radius of its CDM counterpart. We construct a simple
analytic model, based on CDM scaling relations, that captures all aspects of
the scaling relations for SIDM haloes. Our results show that halo core
densities in $\sigma$/m = 1 cm2 g-1 models are too low to match observations
of galaxy clusters, low surface brightness spirals (LSBs) and dwarf
spheroidal galaxies. However, SIDM with $\sigma$/m ≃ 0.1 cm2 g-1 appears
capable of reproducing reported core sizes and central densities of dwarfs,
LSBs and galaxy clusters without the need for velocity dependence. Higher
resolution simulations over a wider range of masses will be required to
confirm this expectation. We discuss constraints arising from the Bullet
cluster observations, measurements of dark-matter density on small scales and
subhalo survival requirements, and show that SIDM models with $\sigma$/m ≃
0.1 cm2 g-1 ≃ 0.2 barn GeV-1 are consistent with all observational
constraints. © 2013 The Authors. Published by Oxford
University Press on behalf of the Royal Astronomical Society.

titleCosmological simulations with self-interacting dark matter -
I. Constant-density cores and substructure
journaltitleMonthly Notices of the Royal Astronomical Society

Dark matter,Galaxies: haloes,Methods: Numerical
Self-interacting dark matter is an attractive alternative to the cold dark
matter paradigm only if it is able to substantially reduce the central
densities of dwarf-size haloes while keeping the densities and shapes of
cluster-size haloes within current constraints. Given the seemingly stringent
nature of the latter, it was thought for nearly a decade that
self-interacting dark matter would be viable only if the cross-section for
self-scattering was strongly velocity dependent. However, it has recently
been suggested that a constant cross-section per unit mass of $\sigma$T/m
0.1 cm2 g-1 is sufficient to accomplish the desired effect. We
explicitly investigate this claim using high-resolution cosmological
simulations of a Milky Way-size halo and find that, similarly to the cold
dark matter case, such cross-section produces a population of massive
subhaloes that is inconsistent with the kinematics of the classical dwarf
spheroidals, in particular with the inferred slopes of the mass profiles of
Fornax and Sculptor. This problem is resolved if $\sigma$T/m  1 cm2 g-1
at the dwarf spheroidal scales. Since this value is likely inconsistent with
the halo shapes of several clusters, our results leave only a small window
open for a velocity-independent self-interacting dark matter model to work as
a distinct alternative to cold dark matter. © 2013 The Authors
Published by Oxford University Press on behalf of the Royal Astronomical

titleConstraining self-interacting dark matter with the milky
way's dwarf spheroidals
journaltitleMonthly Notices of the Royal Astronomical Society:

Dark matter,Galaxies: haloes,Methods: numerical
If dark matter has a large self-interaction scattering cross-section, then
interactions among dark-matter particles will drive galaxy and cluster haloes
to become spherical in their centres. Work in the past has used this effect
to rule out velocity-independent, elastic cross-sections larger than
$\sigma$/m ≃ 0.02 cm2 g-1 based on comparisons to the shapes of galaxy
cluster lensing potentials and X-ray isophotes. In this paper, we use
cosmological simulations to show that these constraints were off by more than
an order of magnitude because (a) they did not properly account for the fact
that the observed ellipticity gets contributions from the triaxial mass
distribution outside the core set by scatterings, (b) the scatter in axis
ratios is large and (c) the core region retains more of its triaxial nature
than estimated before. Including these effects properly shows that the same
observations now allow dark matter self-interaction cross-sections at least
as large as $\sigma$/m = 0.1 cm2 g-1. We show that constraints on
self-interacting dark matter from strong-lensing clusters are likely to
improve significantly in the near future, but possibly more via central
densities and core sizes than halo shapes. © 2013 The Authors.
Published by Oxford University Press on behalf of the Royal Astronomical

titleCosmological simulations with self-interacting dark matter -
II. Halo shapes versus observations
journaltitleMonthly Notices of the Royal Astronomical Society

titleWeak lensing mass reconstruction of the interacting cluster
1E0657-558: Direct evidence for the existence of dark matter
journaltitleAstrophys. J.

titleDirect constraints on the dark matter self-interaction
cross-section from the merging galaxy cluster 1E0657-56
journaltitleAstrophys. J.

titleConstraints on the Self-Interaction Cross-Section of Dark
Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-56
journaltitleAstrophys. J.

Collisions between galaxy clusters provide a test of the nongravitational
forces acting on dark matter. Dark matter's lack of deceleration in the
"bullet cluster" collision constrained its self-interaction cross section
$\sigma$DM/m  1.25 square centimeters per gram (cm2/g) [68%
confidence limit (CL)] ($\sigma$DM, self-interaction cross section; m, unit
mass of dark matter) for long-ranged forces. Using the Chandra and Hubble
Space Telescopes, we have now observed 72 collisions, including both major
and minor mergers. Combining these measurements statistically, we detect the
existence of dark mass at 7.6s significance. The position of the dark mass
has remained closely aligned within 5.8 T 8.2 kiloparsecs of associated
stars, implying a self-interaction cross section $\sigma$DM/m
0.47 cm2/g (95% CL) and disfavoring some proposed extensions to the
standard model.

titleThe nongravitational interactions of dark matter in
colliding galaxy clusters

{IOP} Publishing

dark matter experiments,dark matter theory
The observed surface densities of dark matter halos are known to follow a
simple scaling law, ranging from dwarf galaxies to galaxy clusters, with a
weak dependence on their virial mass. Here we point out that this can not
only be used to provide a method to determine the standard relation between
halo mass and concentration, but also to use large samples of objects in
order to place constraints on dark matter self-interactions that can be more
robust than constraints derived from individual objects. We demonstrate our
method by considering a sample of about 50 objects distributed across the
whole halo mass range, and by modelling the effect of self-interactions in a
way similar to what has been previously done in the literature. Using
additional input from simulations then results in a constraint on the
self-interaction cross section per unit dark matter mass of about
$\sigma$/m$\chi$≲ 0.3 cm2/g. We expect that these constraints can be
significantly improved in the future, and made more robust, by i) an improved
modelling of the effect of self-interactions, both theoretical and by
comparison with simulations, ii) taking into account a larger sample of
objects and iii) by reducing the currently still relatively large
uncertainties that we conservatively assign to the surface densities of
individual objects. The latter can be achieved in particular by using
kinematic observations to directly constrain the average halo mass inside a
given radius, rather than fitting the data to a pre-selected profile and then
reconstruct the mass. For a velocity-independent cross-section, our current
result is formally already somewhat smaller than the range 0.5-5 cm2/g that
has been invoked to explain potential inconsistencies between small-scale
observations and expectations in the standard collisionless cold dark matter

titleConstraining self-interacting dark matter with scaling laws
of observed halo surface densities
journaltitleJournal of Cosmology and Astroparticle Physics

Dark matter (DM) self-interactions have important implications for the
formation and evolution of structure, from dwarf galaxies to clusters of
galaxies. We study the dynamics of self-interacting DM via a light mediator,
focusing on the quantum resonant regime where the scattering cross section
has a nontrivial velocity dependence. While there are long-standing
indications that observations of small scale structure in the Universe are
not in accord with the predictions of collisionless DM, theoretical study and
simulations of DM self-interactions have focused on parameter regimes with
simple analytic solutions for the scattering cross section, with constant or
classical velocity (and no angular) dependence. We devise a method that
allows us to explore the velocity and angular dependence of self-scattering
more broadly, in the strongly coupled resonant and classical regimes where
many partial modes are necessary for achieving the result. We map out the
entire parameter space of DM self-interactions - and implications for
structure observations - as a function of the coupling and the DM and
mediator masses. We derive a new analytic formula for describing resonant
s-wave scattering. Finally, we show that DM self-interactions can be
correlated with observations of Sommerfeld enhancements in DM annihilation
through indirect detection experiments. © 2013 American
Physical Society.

titleBeyond collisionless dark matter: Particle physics dynamics
for dark matter halo structure
journaltitlePhysical Review D - Particles, Fields, Gravitation and

Recent measurements of the cosmic microwave background (CMB) anisotropies
by Planck provide a sensitive probe of dark matter annihilation during the
cosmic dark ages, and specifically constrain the annihilation parameter feff
v/m$\chi$. Using new results (paper II) for the ionization produced by
particles injected at arbitrary energies, we calculate and provide feff
values for photons and e+e- pairs injected at keV-TeV energies; the feff
value for any dark matter model can be obtained straightforwardly by
weighting these results by the spectrum of annihilation products. This result
allows the sensitive and robust constraints on dark matter annihilation
presented by the Planck collaboration to be applied to arbitrary dark matter
models with s-wave annihilation. We demonstrate the validity of this approach
using principal component analysis. As an example, we integrate over the
spectrum of annihilation products for a range of Standard Model final states
to determine the CMB bounds on these models as a function of dark matter
mass, and demonstrate that the new limits generically exclude models proposed
to explain the observed high-energy rise in the cosmic ray positron fraction.
We make our results publicly available at

titleIndirect dark matter signatures in the cosmic dark ages. I.
Generalizing the bound on s -wave dark matter annihilation from Planck
journaltitlePhysical Review D

Coupling dark matter to light new particles is an attractive way to combine
thermal production with strong velocity-dependent self-interactions. Here we
point out that in such models the dark matter annihilation rate is
generically enhanced by the Sommerfeld effect, and we derive the resulting
constraints from the cosmic microwave background and other indirect detection
probes. For the frequently studied case of s-wave annihilation, these
constraints exclude the entire parameter space where the self-interactions
are large enough to address the small-scale problems of structure formation.

titleStrong Constraints on Self-Interacting Dark Matter with
Light Mediators
journaltitlePhysical Review Letters

,Absorption and radiation processes,Cosmology of theories beyond the
SM,Dark matter experiments,Dark matter theory
Dark matter (DM) charged under a dark U(1) force appears in many extensions
of the Standard Model, and has been invoked to explain anomalies in
cosmic-ray data, as well as a self-interacting DM candidate. In this paper,
we perform a comprehensive phenomenological analysis of such a model,
assuming that the DM abundance arises from the thermal freeze-out of the dark
interactions. We include, for the first time, bound-state effects both in the
DM production and in the indirect detection signals, and quantify their
importance for Fermi, Ams-02, and CMB experiments. We find that DM in the
mass range 1 GeV to 100TeV, annihilating into dark photons of MeV to GeV
mass, is in conict with observations. Instead, DM annihilation into heavier
dark photons is viable. We point out that the late decays of multi-GeV dark
photons can produce significant entropy and thus dilute the DM density. This
can lower considerably the dark coupling needed to obtain the DM abundance,
and in turn relax the existing constraints.

titleDark Matter's secret liaisons: Phenomenology of a dark U(1)
sector with bound states
journaltitleJournal of Cosmology and Astroparticle Physics

cosmology connection, recombination, reionization, dark
mattertheory,particle physics
We compute cosmic microwave background (CMB) anisotropy constraints on
exotic forms of energy injection in electromagnetic (e.m.) channels over a
large range of timescales. We show that these constraints are very powerful
around or just after recombination, although CMB keeps some sensitivity e.g.
to decaying species with lifetimes as long as 1025 s. These bounds are
complementary to CMB spectral distortions and primordial nucleosynthesis
ones, which dominate at earlier timescales, as we also review here. For the
first time, we describe the effects of the e.m. energy injection on the CMB
power spectra as a function of the injection epoch, using the lifetime of a
decaying particle as proxy. We also identify a suitable on-the-spot
approximation, that can be used to derive accurate constraints, and describe
its differences with the most up-to-date treatment. Our results are of
interest not only for early universe relics constituting (a fraction of) the
dark matter, but also for other exotic injection of e.m. radiation. For
illustration, we apply our formalism to: i) Primordial black holes of mass
1013.5 g ≲ M ≲ 1016.8 g, showing that the constraints are comparable to
the ones obtained from gamma-ray background studies and even dominate below
∼ 1014 g. ii) To a peculiar mass-mixing range in the sterile neutrino
parameter space, complementary to other astrophysical and laboratory probes.
iii) Finally, we provide a first estimate of the room for improvement left
for forthcoming 21 cm experiments, comparing it with the reach of proposed
CMB spectral distortion (PiXiE) and CMB angular power spectrum (CORE)
missions. We show that the best and most realistic opportunity to look for
this signal (or to improve over current constraints) in the 21 cm probe is to
focus on the Cosmic Dawn epoch, 15 ≲ z ≲ 30, where the qualitatively
unambiguous signature of a spectrum in emission can be expected for models
that evade all current constraints.

titleCosmological constraints on exotic injection of
electromagnetic energy
journaltitleJournal of Cosmology and Astroparticle Physics

Dark matter annihilation or deexcitation, decay of metastable species, or
other new physics may inject energetic electrons and photons into the
photon-baryon fluid during and after recombination. As such particles cool,
they partition their energy into a large number of efficiently ionizing
electrons and photons, which in turn modify the ionization history. Recent
work has provided a simple method for constraining arbitrary
energy-deposition histories using the cosmic microwave background (CMB); in
this note, we present results describing the energy-deposition histories for
photons and electrons as a function of initial energy and injection redshift.
With these results, the CMB bounds on any process injecting some arbitrary
spectrum of electrons, positrons and/or photons with arbitrary redshift
dependence can be immediately computed. © 2013 American
Physical Society.

titleEnergy injection and absorption in the cosmic dark ages
journaltitlePhysical Review D - Particles, Fields, Gravitation and

Cosmology of theories beyond the SM,Supersymmetric effective
theories,Supersymmetry breaking
We present constraints on decaying and annihilating dark matter (DM) in the
4 keV to 10 GeV mass range, using published results from the satellites
HEAO-1, INTEGRAL, COMPTEL, EGRET, and the Fermi Gamma-ray Space Telescope. We
derive analytic expressions for the gamma-ray spectra from various DM decay
modes, and find lifetime constraints in the range 1024 - 1028 sec, depending
on the DM mass and decay mode. We map these constraints onto the parameter
space for a variety of models, including a hidden photino that is part of a
kinetically mixed hidden sector, a gravitino with R-parity violating decays,
a sterile neutrino, DM with a dipole moment, and a dark pion. The indirect
constraints on sterile-neutrino and hidden-photino DM are found to be more
powerful than other experimental or astrophysical probes in some parts of
parameter space. While our focus is on decaying DM, we also present
constraints on DM annihilation to electron-positron pairs. We find that if
the annihilation is p-wave suppressed, the galactic diffuse constraints are,
depending on the DM mass and velocity at recombination, more powerful than
the constraints from the Cosmic Microwave Background.

titleConstraining light dark matter with diffuse X-ray and
gamma-ray observations
journaltitleJournal of High Energy Physics

The astrophysics community is considering plans for a variety of gamma-ray
telescopes (including ACT, GRIPS, and AdEPT) in the energy range 1-100 MeV,
which can fill in the so-called "MeV gap" in current sensitivity. We
investigate the utility of such detectors for the study of low-mass dark
matter annihilation or decay. For annihilating (decaying) dark matter with a
mass below about 140 MeV (280 MeV) and couplings to first generation quarks,
the final states will be dominated by photons or neutral pions, producing
striking signals in gamma-ray telescopes. We determine the sensitivity of
future detectors to the kinematically allowed final states. In particular, we
find that planned detectors can improve on current sensitivity to this class
of models by up to a few orders of magnitude.

titleIndirect detection of dark matter using MeV-range gamma-ray
journaltitlePhysical Review D - Particles, Fields, Gravitation and

Dark matter,Line: identification,X-rays: galaxies: clusters
Some dark matter candidates, e.g., sterile neutrinos, provide observable
signatures in the form of mono-energetic line emission. We present the first
search for dark matter line emission in the 3-80 keV range in a pointed
observation of the Bullet Cluster with NuSTAR. We do not detect any
significant line emission and instead we derive upper limits (95% CL) on
the flux, and interpret these constraints in the context of sterile neutrinos
and more generic dark matter candidates. NuSTAR does not have the sensitivity
to constrain the recently claimed line detection at 3.5 keV, but improves on
the constraints for energies of 10-25 keV.

titleDark matter line emission constraints from NuSTAR
observations of the bullet cluster
journaltitleAstrophysical Journal

big bang nucleosynthesis,cosmology of theories beyond the SM,dark
matter theory,particle physics - cosmology connection
Meta-stable dark sector particles decaying into electrons or photons may
non-trivially change the Hubble rate, lead to entropy injection into the
thermal bath of Standard Model particles and may also photodisintegrate light
nuclei formed in the early universe. We study generic constraints from Big
Bang Nucleosynthesis on such a setup, with a particular emphasis on MeV-scale
particles which are neither fully relativistic nor non-relativistic during
all times relevant for Big Bang Nucleosynthesis. We apply our results to a
simple model of self-interacting dark matter with a light scalar mediator.
This setup turns out to be severely constrained by these considerations in
combination with direct dark matter searches and will be fully tested with
the next generation of low-threshold direct detection experiments.

titleBBN constraints on MeV-scale dark sectors. Part II:
Electromagnetic decays
journaltitleJournal of Cosmology and Astroparticle Physics

titleBig Bang Nucleosynthesis as a Probe of New Physics
journaltitleAnn. Rev. Nucl. Part. Sci.

booktitle2nd International Heidelberg Conference on Dark Matter
in Astro and Particle Physics
titleBig bang nucleosynthesis: Reprise

titleThe Cosmological baryon density from the deuterium to
hydrogen ratio towards QSO absorption systems: D/H towards Q1243+3047
journaltitleAstrophys. J. Suppl.

The hypothetical massive dark photon ($\gamma$') which has kinetic mixing
with the SM photon can decay electromagnetically to e+e- pairs if its mass m
exceeds 2me, and otherwise into three SM photons. These decays yield
cosmological and supernovae associated signatures. We briefly discuss these
signatures, particularly in connection with the supernova SN1987A, and
delineate the extra constraints that arise on the mass and mixing parameter
of the dark photon. In particular, we find that for dark photon mass
m$\gamma$' in the 5-20 MeV range arguments based on supernova 1987A
observations lead to a bound on $\epsilon$ which is about 300 times stronger
than the presently existing bounds based on energy loss arguments.

titleSupernova bounds on the dark photon using its
electromagnetic decay
journaltitleNuclear Physics B

Beyond Standard Model,Thermal Field Theory
We revisit constraints on dark photons with masses below ∼ 100 MeV from
the observations of Supernova 1987A. If dark photons are produced in
sufficient quantity, they reduce the amount of energy emitted in the form of
neutrinos, in conflict with observations. For the first time, we include the
effects of finite temperature and density on the kinetic-mixing parameter,
ϵ, in this environment. This causes the constraints on ϵ to weaken with the
dark-photon mass below ∼ 15 MeV. For large-enough values of ϵ, it is well
known that dark photons can be reabsorbed within the supernova. Since the
rates of reabsorption processes decrease as the dark-photon energy increases,
we point out that dark photons with energies above the Wien peak can escape
without scattering, contributing more to energy loss than is possible
assuming a blackbody spectrum. Furthermore, we estimate the systematic
uncertainties on the cooling bounds by deriving constraints assuming one
analytic and four different simulated temperature and density profiles of the
proto-neutron star. Finally, we estimate also the systematic uncertainty on
the bound by varying the distance across which dark photons must propagate
from their point of production to be able to affect the star. This work
clarifies the bounds from SN1987A on the dark-photon parameter space.

titleRevisiting Supernova 1987A constraints on dark photons
journaltitleJournal of High Energy Physics

We revisit SN1987A constraints on light, hidden sector gauge bosons ("dark
photons") that are coupled to the standard model through kinetic mixing with
the photon. These constraints are realized because excessive bremsstrahlung
radiation of the dark photon can lead to rapid cooling of the SN1987A
progenitor core, in contradiction to the observed neutrinos from that event.
The models we consider are of interest as phenomenological models of strongly
self-interacting dark matter. We clarify several possible ambiguities in the
literature and identify errors in prior analyses. We find constraints on the
dark photon mixing parameter that are in rough agreement with the early
estimates of Dent et al. [arXiv:1201.2683.], but only because significant
errors in their analyses fortuitously canceled. Our constraints are in good
agreement with subsequent analyses by Rrapaj & Reddy [Phys. Rev. C 94,
045805 (2016).PRVCAN2469-998510.1103/PhysRevC.94.045805] and Hardy &
Lasenby [J. High Energy Phys. 02 (2017)
33.JHEPFG1029-847910.1007/JHEP02(2017)033]. We estimate the dark photon
bremsstrahlung rate using one-pion exchange (OPE), while Rrapaj & Reddy
use a soft radiation approximation (SRA) to exploit measured nuclear
scattering cross sections. We find that the differences between mixing
parameter constraints obtained through the OPE approximation or the SRA
approximation are roughly a factor of ∼2-3. Hardy & Laseby [J. High
Energy Phys. 02 (2017) 33.JHEPFG1029-847910.1007/JHEP02(2017)033] include
plasma effects in their calculations finding significantly weaker constraints
on dark photon mixing for dark photon masses below ∼10 MeV. We do not
consider plasma effects. Lastly, we point out that the properties of the
SN1987A progenitor core remain somewhat uncertain and that this uncertainty
alone causes uncertainty of at least a factor of ∼2-3 in the excluded
values of the dark photon mixing parameter. Further refinement of these
estimates is unwarranted until either the interior of the SN1987A progenitor
is more well understood or additional, large, and heretofore neglected
effects, such as the plasma interactions studied by Hardy & Lasenby [J.
High Energy Phys. 02 (2017) 33.JHEPFG1029-847910.1007/JHEP02(2017)033], are

titleUpdated constraints on self-interacting dark matter from
Supernova 1987A
journaltitlePhysical Review D

,Beyond Standard Model,Thermal Field Theory
We consider the constraints from Supernova 1987A on particles with small
couplings to the Standard Model. We discuss a model with a fermion coupled to
a dark photon, with various mass relations in the dark sector; millicharged
particles; dark-sector fermions with inelastic transitions; the hadronic QCD
axion; and an axion-like particle that couples to Standard Model fermions
with couplings proportional to their mass. In the fermion cases, we develop a
new diagnostic for assessing when such a particle is trapped at large mixing
angles. Our bounds for a fermion coupled to a dark photon constrain small
couplings and masses ≲ 200 MeV, and do not decouple for low fermion masses.
They exclude parameter space that is otherwise unconstrained by existing
accelerator-based and direct-detection searches. In addition, our bounds are
complementary to proposed laboratory searches for sub-GeV dark matter, and do
not constrain several benchmark-model targets in parameter space for which
the dark matter obtains the correct relic abundance from interactions with
the Standard Model. For a millicharged particle, we exclude charges between
10−9–few×10−6 in units of the electron charge, also for masses ≲ 200
MeV; this excludes parameter space to higher millicharges and masses than
previous bounds. For the QCD axion and an axion-like particle, we apply
several updated nuclear physics calculations and include the energy
dependence of the optical depth to accurately account for energy loss at
large couplings. These corrections allow us to rule out a hadronic axion of
mass between 0.1 and a few hundred eV, or equivalently to put a bound on the
scale of Peccei-Quinn symmetry breaking between a few×104 and 108 GeV,
closing the hadronic axion window. For an axion-like particle, our bounds
disfavor decay constants between a few×105 GeV up to a few×108 GeV, for a
mass ≲ 200 MeV. In all cases, our bounds differ from previous work by more
than an order of magnitude across the entire parameter space. We also provide
estimated systematic errors due to the uncertainties of the progenitor.

titleSupernova 1987A constraints on sub-GeV dark sectors,
millicharged particles, the QCD axion, and an axion-like particle
journaltitleJournal of High Energy Physics

American Physical Society

titleAxions and stars
journaltitlePhys. Rev. D

* Invalid format of field 'month'

American Physical Society

titleAxions from SN1987A
journaltitlePhys. Rev. Lett.

* Invalid format of field 'month'

American Physical Society

titleAxions and SN 1987A
journaltitlePhys. Rev. D

* Invalid format of field 'month'

titleDiscovering New Light States at Neutrino Experiments
journaltitlePhys. Rev. D

family=St Denis,

We present measurements of the B+ meson total cross section and
differential cross section dsigma/dp(T). The measurements use a 98+/-4 pb(-1)
sample of p (p) over bar collisions at roots = 1.8 TeV collected by the CDF
detector. Charged B meson candidates are reconstructed through the decay B+/-
– J/psiK(+/-) with J/psi – mu(+)mu(-). The
total cross section, measured in the central rapidity region
$\backslash$y$\backslash$  1.0 for p(T)(B)  6.0
GeV/c, is 3.6+/-0.6(stat + syst) mub. The measured differential cross section
is substantially larger than typical QCD predictions calculated to
next-to-leading order.

titleMeasurement of the B+ total cross section and B+
differential cross section d sigma/dp(T) in p(p)over-bar collisions at root
s=1.8 TeV
journaltitlePhysical Review D
[Erratum: Phys. Rev.D92,no.3,039906(2015)]

We systematically study light (few GeV) dark matter (DM) models
that thermalize with visible matter through the Higgs portal and identify the
remaining gaps in the viable parameter space. Such models require a
comparably light scalar mediator that mixes with the Higgs to avoid DM
overproduction and can be classified according to whether this mediator
decays (in)visibly. In a representative benchmark model with Dirac fermion
DM, we find that, even with conservative assumptions about the DM-mediator
coupling and mass ratio, the regime in which the mediator is heavier than the
DM is fully ruled out by a combination of collider, rare meson decay, and
direct detection limits; future and planned experiments including NA62 can
further improve sensitivity to scenarios in which the Higgs portal
interaction does not determine the DM abundance. The opposite regime in which
the mediator is lighter than the DM and the latter annihilates to pairs of
visibly decaying mediators is still viable, but much of the parameter space
is covered by rare meson decay, supernova cooling, beam dump, and direct
detection constraints. Nearly all of these conclusions apply broadly to the
simplest variations (e.g., scalar or asymmetric DM). Future experiments
including SHiP, NEWS, and Super-CDMS SNOLAB can greatly improve coverage to
this class of models.

titleProbing light thermal dark matter with a Higgs portal
journaltitlePhysical Review D

dark matter experiments,dark matter theory,particle physics -
cosmology connection
We explore the potential of future cryogenic direct detection experiments
to determine the properties of the mediator that communicates the
interactions between dark matter and nuclei. Due to their low thresholds and
large exposures, experiments like CRESST-III, SuperCDMS SNOLAB and
EDELWEISS-III will have excellent capability to reconstruct mediator masses
in the MeV range for a large class of models. Combining the information from
several experiments further improves the parameter reconstruction, even when
taking into account additional nuisance parameters related to background
uncertainties and the dark matter velocity distribution. These observations
may offer the intriguing possibility of studying dark matter
self-interactions with direct detection experiments.

titleExploring light mediators with low-threshold direct
detection experiments
journaltitleJournal of Cosmology and Astroparticle Physics

family=De Perio,

family=Di Gangi,

family=Di Giovanni,

family=Gallo Rosso,

family=Marrodán Undagoitia,

family=Ramírez García,

family=Dos Santos,

family=Scotto Lavina,

We report on a search for weakly interacting massive particles (WIMPs)
using 278.8 days of data collected with the XENON1T experiment at LNGS.
XENON1T utilizes a liquid xenon time projection chamber with a fiducial mass
of (1.30±0.01) ton, resulting in a 1.0 ton yr exposure. The energy region of
interest, [1.4,10.6] keVee ([4.9,40.9] keVnr), exhibits an ultralow electron
recoil background rate of [82-3+5(syst)±3(stat)] events/(ton yr keVee). No
significant excess over background is found, and a profile likelihood
analysis parametrized in spatial and energy dimensions excludes new parameter
space for the WIMP-nucleon spin-independent elastic scatter cross section for
WIMP masses above 6 GeV/c2, with a minimum of 4.1×10-47 cm2 at 30 GeV/c2 and
a 90% confidence level.

titleDark Matter Search Results from a One Ton-Year Exposure of
journaltitlePhysical Review Letters

We discuss the positive indications of a possible dark matter signal in
direct detection experiments in terms of a mechanism of interaction between
the dark matter particle and the nuclei occurring via the exchange of a light
mediator, resulting in a long-range interaction. We analyze the annual
modulation results observed by the DAMA and CoGeNT experiments and the
observed excess of events of CRESST. In our analysis, we discuss the
relevance of uncertainties related to the velocity distribution of galactic
dark matter and to the channeling effect in NaI. We find that a long-range
force is a viable mechanism, which can provide full agreement between the
reconstructed dark matter properties from the various experimental data sets,
especially for masses of the light mediator in the 10-30MeV range and a light
dark matter with a mass around 10GeV. The relevant bounds on the light
mediator mass and scattering cross section are then derived, should the
annual modulation effects be due to this class of long-range forces.
© 2011 American Physical Society.

titleLong-range forces in direct dark matter searches
journaltitlePhysical Review D - Particles, Fields, Gravitation and

American Physical Society

titleInelastic and Elastic Scattering of 187-Mev Electrons from
Selected Even-Even Nuclei
journaltitlePhys. Rev.

* Invalid format of field 'month'

We point out a selection rule for enhancement (suppression) of odd (even)
partial waves of dark matter coannihilation or annihilation using the
Sommerfeld effect. Using this, the usually velocity-suppressed p-wave
annihilation can dominate the annihilation signals in the present Universe.
The selection mechanism is a manifestation of the exchange symmetry of
identical incoming particles, and generic for multistate DM with off-diagonal
long-range interactions. As a consequence, the relic and late-time
annihilation rates are parametrically different and a distinctive
phenomenology, with large but strongly velocity-dependent annihilation rates,
is predicted.

titleSelection Rule for Enhanced Dark Matter Annihilation
journaltitlePhysical Review Letters

family=De Palma,

family=Do Couto E Silva,

family=Llena Garde,

American Physical Society (APS)

Dark matter particle annihilation or decay can produce monochromatic
gamma-ray lines and contribute to the diffuse gamma-ray background. Flux
upper limits are presented for gamma-ray spectral lines from 7 to 200GeV and
for the diffuse gamma-ray background from 4.8GeV to 264GeV obtained from two
years of Fermi Large Area Telescope data integrated over most of the sky. We
give cross-section upper limits and decay lifetime lower limits for dark
matter models that produce gamma-ray lines or contribute to the diffuse
spectrum, including models proposed as explanations of the PAMELA and Fermi
cosmic-ray data. © 2012 American Physical Society.

titleFermi LAT search for dark matter in gamma-ray lines and the
inclusive photon spectrum
journaltitlePhysical Review D - Particles, Fields, Gravitation and

family=Becker Tjus,

family=De Naurois,

family=De Oña Wilhelmi,

family=Paz Arribas,

family=De Los Reyes,

family=Van Eldik,

American Physical Society (APS)

Gamma-ray line signatures can be expected in the very-high-energy (E
$\gamma$100 GeV) domain due to self-annihilation or decay of
dark matter (DM) particles in space. Such a signal would be readily
distinguishable from astrophysical $\gamma$-ray sources that in most cases
produce continuous spectra that span over several orders of magnitude in
energy. Using data collected with the H.E.S.S. $\gamma$-ray instrument, upper
limits on linelike emission are obtained in the energy range between ∼500
GeV and ∼25 TeV for the central part of the Milky Way halo and for
extragalactic observations, complementing recent limits obtained with the
Fermi-LAT instrument at lower energies. No statistically significant signal
could be found. For monochromatic $\gamma$-ray line emission, flux limits of
(2×10-7- 2×10-5) m-2 s-1 sr-1 and (1×10-8-2×10-6) m-2 s-1 sr-1 are
obtained for the central part of the Milky Way halo and extragalactic
observations, respectively. For a DM particle mass of 1 TeV, limits on the
velocity-averaged DM annihilation cross section
âŸ̈$\sigma$vâŸ© $\chi$$\chi$→$\gamma$$\gamma$
reach ∼10-27 cm3 s -1, based on the Einasto parametrization of the Galactic
DM halo density profile. © 2013 American Physical Society.

titleSearch for photon-linelike signatures from dark matter
annihilations with H.E.S.S.
journaltitlePhysical Review Letters

* Invalid format of field 'month'

family=De Angelis,

family=De Palma,

family=Di Venere,

American Physical Society (APS)

Dark matter in the Milky Way may annihilate directly into $\gamma$ rays,
producing a monoenergetic spectral line. Therefore, detecting such a
signature would be strong evidence for dark matter annihilation or decay. We
search for spectral lines in the Fermi Large Area Telescope observations of
the Milky Way halo in the energy range 200 MeV-500 GeV using analysis methods
from our most recent line searches. The main improvements relative to
previous works are our use of 5.8 years of data reprocessed with the Pass 8
event-level analysis and the additional data resulting from the modified
observing strategy designed to increase exposure of the Galactic center
region. We search in five sky regions selected to optimize sensitivity to
different theoretically motivated dark matter scenarios and find no
significant detections. In addition to presenting the results from our search
for lines, we also investigate the previously reported tentative detection of
a line at 133 GeV using the new Pass 8 data.

titleUpdated search for spectral lines from Galactic dark matter
interactions with pass 8 data from the Fermi Large Area Telescope
journaltitlePhysical Review D - Particles, Fields, Gravitation and

family=Ait Benkhali,

family=Becker Tjus,

family=De Naurois,

family=Paz Arribas,

family=De Los Reyes,

family=Van Der Walt,

family=Van Eldik,

family=Van Soelen,

American Physical Society (APS)

The inner region of the Milky Way halo harbors a large amount of dark
matter (DM). Given its proximity, it is one of the most promising targets to
look for DM. We report on a search for the annihilations of DM particles
using $\gamma$-ray observations towards the inner 300 pc of the Milky Way,
with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is
based on a 2D maximum likelihood method using Galactic Center (GC) data
accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show
any significant $\gamma$-ray signal above background. Assuming Einasto and
Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on
the annihilation cross section v. These constraints are the strongest
obtained so far in the TeV DM mass range and improve upon previous limits by
a factor 5. For the Einasto profile, the constraints reach v values of
6×10-26 cm3 s-1 in the W+W- channel for a DM particle mass of 1.5 TeV, and
2×10-26 cm3 s-1 in the $\tau$+$\tau$- channel for a 1 TeV mass. For the
first time, ground-based $\gamma$-ray observations have reached sufficient
sensitivity to probe v values expected from the thermal relic density for TeV
DM particles.

titleSearch for Dark Matter Annihilations towards the Inner
Galactic Halo from 10 Years of Observations with H.E.S.S.
journaltitlePhysical Review Letters

* Invalid format of field 'month'

note[Erratum: Phys.Lett.B 796, 253–255 (2019)]
titleResults from the search for dark matter in the Milky Way
with 9 years of data of the ANTARES neutrino telescope
journaltitlePhys. Lett. B

family=MAGIC Collaboration,

family=Barres De Almeida,

family=Becerra González,

family=Da Vela,

family=De Angelis,

family=De Lotto,

family=De Oña Wilhelmi,

family=Delgado Mendez,

family=Di Pierro,

family=Dominis Prester,

family=Eisenacher Glawion,

family=García López,

family=Garrido Terrats,

family=González Muñoz,

family=La Barbera,

family=Nievas Rosillo,

family=Prada Moroni,

family=Rodriguez Garcia,

IOP Publishing

dark matter experiments,dwarfs galaxies,gamma ray
experiments,neutrino experiments
We present the first joint analysis of gamma-ray data from the MAGIC
Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for
gamma-ray signals from dark matter annihilation in dwarf satellite galaxies.
We combine 158 hours of Segue 1 observations with MAGIC with 6-year
observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain
limits on the annihilation cross-section for dark matter particle masses
between 10 GeV and 100 TeV - the widest mass range ever explored by a single
gamma-ray analysis. These limits improve on previously published Fermi-LAT
and MAGIC results by up to a factor of two at certain masses. Our new
inclusive analysis approach is completely generic and can be used to perform
a global, sensitivity-optimized dark matter search by combining data from
present and future gamma-ray and neutrino detectors.

titleLimits to dark matter annihilation cross-section from a
combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite
journaltitleJournal of Cosmology and Astroparticle Physics

titleSearch for invisible decays of a Higgs boson produced
through vector boson fusion in proton-proton collisions at $\sqrt{s} =$ 13
journaltitlePhys. Lett. B

titleDirect detection and complementary constraints for sub-GeV
dark matter

titleSearch for $A'\to\mu^+\mu^-$ Decays
journaltitlePhys. Rev. Lett.

There can exist a parallel 'mirror' world which has the same particle
physics as the observable world and couples the latter only gravitationally.
The nucleosynthesis bounds demand that the mirror sector should have a
smaller temperature than the ordinary one. By this reason its evolution
should be substantially deviated from the standard cosmology as far as the
crucial epochs like baryogenesis, nucleosynthesis etc. are concerned.
Starting from an inflationary scenario which could explain the different
initial temperatures of the two sectors, we study the time history of the
early mirror universe. In particular, we show that in the context of the GUT
or electroweak baryogenesis scenarios, the baryon asymmetry in the mirror
world should be larger than in the observable one and in fact the mirror
baryons could provide the dominant dark matter component of the universe. In
addition, analyzing the nucleosynthesis epoch, we show that the mirror helium
abundance should be much larger than that of ordinary helium. The
implications of the mirror baryons representing a kind of self-interacting
dark matter for the large scale structure formation, the CMB anysotropy, the
galactic halo structures, microlensing, etc. are briefly discussed.
© 2001 Elsevier Science B.V. All rights reserved.

titleThe early mirror universe: Inflation, baryogenesis,
nucleosynthesis and dark matter
journaltitlePhysics Letters, Section B: Nuclear, Elementary
Particle and High-Energy Physics

Strings and branes phenomenology,Supersymmetry phenomenology
Extra "hidden" U(1) gauge factors are a generic feature of string theory
that is of particular phenomenological interest. They can kinetically mix
with the Standard Model photon and are thereby accessible to a wide variety
of astrophysical and cosmological observations and laboratory experiments. In
this paper we investigate the masses and the kinetic mixing of hidden U(1)s
in LARGE volume compactifications of string theory. We find that in these
scenarios the hidden photons can be naturally light and that their kinetic
mixing with the ordinary electromagnetic photon can be of a size interesting
for near future experiments and observations. © 2009 SISSA.

titleNaturally light hidden photons in LARGE volume string
journaltitleJournal of High Energy Physics

Mirror world, a parallel hidden sector with microphysics identical to
ordinary particle physics, can have several interesting phenomenological and
astrophysical implications and mirror matter can be a natural candidate for
dark matter in the universe. If the ordinary and the mirror photons have a
kinetic mixing due to the Lagrangian term ($\epsilon${lunate} / 2)
F$\mu$ $\nu$ F′ $\mu$ $\nu$, then mirror particles effectively acquire the
electric charges ∼$\epsilon${lunate} with respect to the ordinary
photon, so that they become a sort of particles historically coined as
"millicharged" though nowadays they must be called more appropriately as
"nanocharged". In this Letter we revise the cosmological bounds on the
kinetic mixing parameter and in the case of exact mirror parity set an upper
limit $\epsilon${lunate}  3 × 10- 10. Much weaker limit can
be obtained in the case of asymmetric mirror sector, with an electroweak
symmetry breaking scale larger than the ordinary electroweak scale.
© 2009 Elsevier B.V. All rights reserved.

titleCosmological bounds on the "millicharges" of mirror
journaltitlePhysics Letters, Section B: Nuclear, Elementary
Particle and High-Energy Physics

We consider current observational constraints on the electromagnetic charge
of dark matter. The velocity dependence of the scattering cross section
through the photon gives rise to qualitatively different constraints than
standard dark matter scattering through massive force carriers. In
particular, recombination epoch observations of dark matter density
perturbations require that $\epsilon$, the ratio of the dark matter to
electronic charge, is less than 10-6 for mX=1GeV, rising to
$\epsilon$10-4 for m X=10TeV. Though naively one would expect that
dark matter carrying a charge well below this constraint could still give
rise to large scattering in current direct detection experiments, we show
that charged dark matter particles that could be detected with upcoming
experiments are expected to be evacuated from the Galactic disk by the
Galactic magnetic fields and supernova shock waves and hence will not give
rise to a signal. Thus dark matter with a small charge is likely not a source
of a signal in current or upcoming dark matter direct detection experiments.
© 2011 American Physical Society.

titleTurning off the lights: How dark is dark matter?
journaltitlePhysical Review D - Particles, Fields, Gravitation and

WILEY-VCH Verlag

Übersicht: Der I. Teil bildet eine systematische Einleitung zu der
Behandlung des kontinuierlichen Röntgenspektrums im II. Teil. Der I.
Teil geht nur in der Methode, nicht in den Resultaten über die Arbeiten
von Gordon, Mott, Temple hinaus. Der II. Teil setzt, im Gegensatz zu Arbeiten
von Oppenheimer und Sugiura den Endzustand des gebremsten Elektrons als
ebene, durch Beugung modifizierte Welle an. Polarisation und Intensität
im kontinuierlichen Spektrum werden nach der Methode der Matrixelemente
berechnet. Um die azimutale Verteilung der Intensität, insbesondere die
Voreilung des Maximums zu erhalten, muß die Rechenmethode verfeinert
werden durch Berücksichtigung der Retardierung. Die Resultate werden
mit Messungen von Kulenkampff verglichen. Copyright © 1931
WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

titleÜber die Beugung und Bremsung der Elektronen
journaltitleAnnalen der Physik

American Physical Society

titleConsistent definitions for, and relationships among, cross
sections for elastic scattering of hydrogen ions, atoms, and molecules
journaltitlePhys. Rev. A

* Invalid format of field 'month'

seriesCollection Enseignement des sciences, 16
titleMecanique Quantique, vol.II

An exact relativistic single-integral formula for the thermal average of
the annihilation cross section times velocity, the key quantity in the
determination of the cosmic relic abundance of a species, is obtained. Since
it does not require expansion of the cross section at low relative velocity,
it can also be used when the cross section varies rapidly with energy, e.g.
near the formation of a resonance or the opening of a new annihilation
channel. We discuss approximate formulas in these cases, and we find that
dips in the relic density near resonances are significantly broader and
shallower than previously thought and that spurious reductions near
thresholds disappear. © 1991.

titleCosmic abundances of stable particles: Improved analysis
journaltitleNuclear Physics, Section B

In the past few years one of the most exciting areas of research in physics
has been the interdisciplinary field of cosmology and particle physics. The
NSF's Institute for Theoretical Physics in Santa Barbara devoted a 6-month
program and an intensive 1-week workshop to the subject. A brief review is
given of both the workshop and this field which is attracting attention, in
part, because the early Universe seems to be the only laboratory in which to
study grand unification. © 1981 Nature Publishing Group.

titleThe early Universe
Frontiers in Physics, 69

Dark matter with Sommerfeld-enhanced annihilation has been proposed to
explain observed cosmic ray positron excesses in the 10 GeV to TeV energy
range. We show that the required enhancement implies thermal relic densities
that are too small to be all of dark matter. We also show that the dark
matter is sufficiently self-interacting that observations of elliptical
galactic dark matter halos exclude large Sommerfeld enhancement for light
force carriers. Resonant Sommerfeld enhancement does not modify these
conclusions, and the astrophysical boosts required to resolve these
discrepancies are disfavored, especially when significant self-interactions
suppress halo substructure. © 2010 The American Physical

titleHalo-shape and relic-density exclusions of
sommerfeld-enhanced dark matter explanations of cosmic ray excesses
journaltitlePhysical Review Letters

titleDistinguishing Dark Matter Annihilation Enhancement
Scenarios via Halo Shapes
journaltitlePhys. Lett. B

We show that cold dark matter particles interacting through a Yukawa
potential could naturally explain the recently observed cores in dwarf
galaxies without affecting the dynamics of objects with a much larger
velocity dispersion, such as clusters of galaxies. The velocity dependence of
the associated cross section as well as the possible exothermic nature of the
interaction alleviates earlier concerns about strongly interacting dark
matter. Dark matter evaporation in low-mass objects might explain the
observed deficit of satellite galaxies in the Milky Way halo and have
important implications for the first galaxies and reionization.
© 2011 American Physical Society.

titleCores in dwarf galaxies from dark matter with a Yukawa
journaltitlePhysical Review Letters

A dark force can impact the cosmological history of dark matter (DM), both
explaining observed cores in dwarf galaxies and setting the DM relic density
through annihilation to dark force bosons. For GeV-TeV DM mass, DM
self-scattering in dwarf galaxy halos exhibits quantum mechanical resonances,
analogous to a Sommerfeld enhancement for annihilation. We show that a simple
model of DM with a dark force can accommodate all astrophysical bounds on
self-interactions in halos and explain the observed relic density, through a
single coupling constant. © 2013 American Physical Society.

titleResonant dark forces and small-scale structure
journaltitlePhysical Review Letters

IOP Publishing

The Sommerfeld factor for arbitrary partial wave processes is derived in
the non-relativistic limit. The s-wave and p-wave numerical results are
presented for the case of Yukawa interactions. An approximate analytic
expression is also found for the Sommerfeld factor of Yukawa interactions
with arbitrary partial waves, which is exact in the Coulomb limit. It is
demonstrated that this result is accurate to within 10
scenarios. The non-s-wave Sommerfeld effect is determined to be significant,
and can allow higher partial waves to dominate cross sections.

titleSommerfeld factor for arbitrary partial wave processes
journaltitleJournal of Physics G: Nuclear and Particle Physics

* Invalid format of field 'month'

American Physical Society

titleScattering in the Attractive Yukawa Potential in the Limit of
Strong Interaction
journaltitlePhys. Rev. Lett.

* Invalid format of field 'month'

American Physical Society

titleMomentum transfer in complex plasmas
journaltitlePhys. Rev. E

* Invalid format of field 'month'

IOP Publishing

We present an analysis of the Sommerfeld enhancement to dark matter
annihilation in the presence of an excited state, where the interaction
inducing the enhancement is purely off-diagonal, such as in models of
exciting or inelastic dark matter. We derive a simple and accurate
semi-analytic approximation for the s-wave enhancement, which is valid
provided the mass splitting between the ground and excited states is not too
large, and discuss the cutoff of the enhancement for large mass splittings.
We reproduce previously derived results in the appropriate limits, and
demonstrate excellent agreement with numerical calculations of the
enhancement. We show that the presence of an excited state leads to
generically larger values of the Sommerfeld enhancement, larger resonances,
and shifting of the resonances to lower mediator masses. Furthermore, in the
presence of a mass splitting the enhancement is no longer a monotonic
function of velocity: the enhancement where the kinetic energy is close to
that required to excite the higher state can be up to twice as large as the
enhancement at zero velocity.

titleThe Sommerfeld enhancement for dark matter with an excited
journaltitleJournal of Cosmology and Astroparticle Physics

* Invalid format of field 'month'

given=Michel H.G.,

We analyse how dark matter (DM) can be produced in the early universe,
working in the framework of a hidden sector charged under a U(1)' gauge
symmetry and interacting with the Standard Model through kinetic mixing.
Depending on the masses of the dark matter particle and of the dark photon,
as well as on the hidden U(1)' gauge coupling and the kinetic mixing
parameter, we classify all the distinct regimes along which the observed dark
matter relic density can be accounted for. We find that 9 regimes are
potentially operative to produce the DM particles and this along 5 distinct
dynamical mechanisms. Among these, 4 regimes are new and correspond to
regimes in which the DM particles are produced by on-shell dark photons. One
of them proceeds along a new dynamical mechanism, which we dub sequential
freeze-in. We argue that such regimes and the associated dynamical mechanisms
are characteristic of DM models for which, on top of the Standard Model and
the dark sector, there are other massive, but relatively light particles –
akin to the dark photon – that interact both with the SM and the DM

titleDark matter from dark photons: a taxonomy of dark matter
journaltitlePhys. Rev.

titleDark matter from dark photons

dark matter theory,particle physics - cosmology connection
We consider the possibility that along the thermal history of the Universe,
dark matter (DM) would have been created from Standard Model particles,
either through a kinetic mixing portal to an extra U(1) gauge field, or
through the Higgs portal. Depending solely on the DM particle mass, on the
portal and on the DM hidden sector interaction, we show how the observed DM
relic density can be obtained. There are four possible
freeze-in/reannihilation/freeze-out regimes, which together result in a
simple characteristic relic density phase diagram, with the shape of a
”Mesa”. In the case of the kinetic mixing portal, we show that, unlike
other freeze-in scenarios discussed in the literature, the freeze-in regime
can be probed by forthcoming DM direct detection experiments. These results
are well representative of any scenario where a DM hidden sector would be
created out of the Standard Model sector. © 2012 IOP
Publishing Ltd and Sissa Medialab srl.

titleThe four basic ways of creating dark matter through a
journaltitleJournal of Cosmology and Astroparticle Physics

We perform a comprehensive study of models of dark matter (DM) in a
Universe with a nonthermal cosmological history, i.e. with a phase of
pressureless matter domination before the onset of big-bang nucleosynthesis
(BBN). Such cosmological histories are generically predicted by UV
completions that contain gravitationally coupled scalar fields (moduli). We
classify the different production mechanisms for DM in this framework,
generalizing previous works by considering a wide range of DM
masses/couplings and allowing for DM to be in equilibrium with a "dark"
sector. We identify four distinct parametric regimes for the production of
relic DM, and derive accurate semianalytic approximations for the DM relic
abundance. Our results are particularly relevant for supersymmetric theories,
in which the standard nonthermally produced DM candidates are disfavored by
indirect-detection constraints. We also comment on experimental signals in
this framework, focusing on novel effects involving the power spectrum of DM
density perturbations. In particular, we identify a class of models where the
spectrum of DM density perturbations is sensitive to the pressureless
matter-dominated era before BBN, giving rise to interesting astrophysical
signatures to be looked for in the future. A worthwhile future direction
would be to study well-motivated theoretical models within this framework and
carry out detailed studies of the pattern of expected experimental signals.

dark matter theory,particle physics - cosmology connection
The freeze-in mechanism of dark matter production provides a simple and
intriguing alternative to the WIMP paradigm. In this paper, we analyze
whether freeze-in can be used to account for the dark matter in the so-called
singlet fermionic model. In it, the SM is extended with only two additional
fields, a singlet scalar that mixes with the Higgs boson, and the dark matter
particle, a fermion assumed to be odd under a Z2 symmetry. After numerically
studying the generation of dark matter, we analyze the dependence of the
relic density with respect to all the free parameters of the model. These
results are then used to obtain the regions of the parameter space that are
compatible with the dark matter constraint. We demonstrate that the observed
dark matter abundance can be explained via freeze-in over a wide range of
masses extending down to the keV range. As a result, warm and cold dark
matter can be obtained in this model. It is also possible to have dark matter
masses well above the unitarity bound for WIMPs. © 2013 IOP
Publishing Ltd and Sissa Medialab srl.

titleWarm and cold fermionic dark matter via freeze-in
journaltitleJournal of Cosmology and Astroparticle Physics

New gauge bosons at the MeV scale with tiny gauge couplings (so-called dark
photons) can be responsible for the freeze-in production of dark matter and
provide a clear target for present and future experiments. We study the
effects of thermal mixing between dark photons and Standard Model gauge
bosons and of the resulting plasmon decays on dark matter production before
and after the electroweak phase transition. In the parameter regions
preferred by the observed dark matter relic abundance, the dark photon is
sufficiently long-lived to be probed with fixed-target experiments and light
enough to induce direct detection signals. Indeed, current limits from
XENON1T already constrain Dirac fermion dark matter in the GeV to TeV range
produced via the freeze-in mechanism. We illustrate our findings for the case
of a $U(1)_{B-L}$ gauge extension and discuss possible

titleProbing the freeze-in mechanism in dark matter models with
U(1)' gauge extensions

The discontinuity, or imaginary part, of the self-energy function at T =0
is found to be of the form =di for bosons and fermions, respectively. The
generalized decay rate d and inverse decay rate i are recognizable as
integrals over phase space of amplitudes squared, weighted with certain
statistical factors that account for the possibility of particle absorption
from the medium or particle emission into the medium. Nonequilibrium
statistical mechanics shows that gives precisely the rate at which the
single-particle distribution function approaches the equilibrium form.
© 1983 The American Physical Society.

titleSimple rules for discontinuities in finite-temperature field
journaltitlePhysical Review D

family=Le Bellac,

Cambridge University Press

1. Introduction – 2. Quantum statistical mechanics – 3. The scalar
field at finite temperature – 4. Simple applications of perturbation theory
– 5. Dirac and gauge fields at finite temperature – 6. Collective
excitations in a plasma – 7. Hard thermal loops and resummation – 8.
Dynamical screening – 9. Neutrino emission from stars – 10. Infrared
problems at finite temperature – A Formulary – B Operator formalism Now
in paperback, this text introduces the theoretical framework for describing
the quark-gluon plasma, an important new state of matter. The first part of
this book is a self-contained introduction to relativistic thermal field
theory. Topics include the path integral approach, the real and the imaginary
time formalisms, fermion fields and gauge fields at finite temperature.
Useful techniques such as the evaluation of frequency sums or the use of
cutting rules are illustrated on various examples. The second part of the
book is devoted to recent developments, giving a detailed account of
collective excitations (bosonic and fermionic), and showing how they give
rise to energy scales which imply a reorganization of perturbation theory.
The relation with kinetic theory is also explained. Applications to processes
which occur in heavy ion collisions and in astrophysics are worked out in
detail. Each chapter ends with exercises and a guide to the literature

booktitleThermal Field Theory
isbn9780511885068, 9780521654777
seriesCambridge Monographs on Mathematical Physics
titleThermal Field Theory

We present a unified approach which is accurate at all temperatures and
densities for calculating the energy loss from a stellar plasma due to the
plasma process-the decay of photons and plasmons into neutrino pairs. To
allow efficient numerical calculations, an analytic approximation to the
dispersion equations for photons and plasmons is developed. It is correct to
order $\alpha$ in the classical, degenerate, and relativistic limits for all
momenta k and is correct at small k for all temperatures and electron
densities. Within the same approximations, concise expressions are derived
for the transverse, longitudinal, and axial-vector components of the neutrino
emissivity. © 1993 The American Physical Society.

titleNeutrino energy loss from the plasma process at all
temperatures and densities
journaltitlePhysical Review D

given=Michel H.G.,

titleThe domain of thermal dark matter candidates

titleAn Upper Limit on the Neutrino Rest Mass
journaltitlePhys. Rev. Lett.

titleHidden Hot Dark Matter as Cold Dark Matter

Using partial-wave unitarity and the observed density of the Universe, we
show that a stable elementary particle which was once in thermal equilibrium
cannot have a mass greater than 340 TeV. An extended object which was once in
thermal equilibrium cannot have a radius less than 7.5×10-7 fm. A lower
limit to the relic abundance of such particles is also found.
© 1990 The American Physical Society.

titleUnitarity limits on the mass and radius of dark-matter
journaltitlePhysical Review Letters

note[Erratum: JCAP 11, E02 (2020)]
titleBig-Bang Nucleosynthesis after Planck

titleTowards a precision calculation of the effective number of
neutrinos $N_{\rm eff}$ in the Standard Model I: The QED equation of state

CMBR theory,big bang nucleosynthesis,cosmology of theories beyond the
SM,particle physics-cosmology connection
Any neutral boson such as a dark photon or dark Higgs that is part of a
non-standard sector of particles can mix with its standard model counterpart.
When very weakly mixed with the Standard Model, these particles are produced
in the early Universe via the freeze-in mechanism and subsequently decay back
to standard model particles. In this work, we place constraints on such
mediator decays by considering bounds from Big Bang nucleosynthesis and the
cosmic microwave background radiation. We find both nucleosynthesis and CMB
can constrain dark photons with a kinetic mixing parameter between log ∼-10
to-17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing
angle with the Standard Model Higgs is constrained between log ∼-6 to-15.
Dramatic improvement on the bounds from CMB spectral distortions can be
achieved with proposed experiments such as PIXIE.

titleCosmological constraints on decoupled dark photons and dark
journaltitleJournal of Cosmology and Astroparticle Physics

titleBBN constraints on MeV-scale dark sectors. Part I. Sterile

titleNew Constraints on the free-streaming of warm dark matter
from intermediate and small scale Lyman-$\alpha$ forest data
journaltitlePhys. Rev. D

Beyond Standard Model,Cosmology of Theories beyond the SM
Motivated by the hypothesis that dark matter self-interactions provide a
solution to the small-scale structure formation problems, we investigate the
possibilities that the relic density of a self-interacting dark matter
candidate can proceed from the thermal freeze-out of annihilations into
Standard Model particles. We find that scalar and Majorana dark matter in the
mass range of 10-500 MeV, coupled to a slightly heavier massive gauge boson,
are the only possible candidates in agreement with multiple current
experimental constraints. Here dark matter annihilations take place at a much
slower rate than the self-interactions simply because the interaction
connecting the Standard Model and the dark matter sectors is small. We also
discuss prospects of establishing or excluding these two scenarios in future

titleCan the relic density of self-interacting dark matter be due
to annihilations into Standard Model particles?
journaltitleJournal of High Energy Physics

titleSolving the small-scale structure puzzles with dissipative
dark matter

big bang nucleosynthesis,cosmology of theories beyond the SM,dark
matter theory,particle physics - cosmology connection
Light vector mediators can naturally induce velocity-dependent dark matter
self-interactions while at the same time allowing for the correct dark matter
relic abundance via thermal freeze-out. If these mediators subsequently decay
into Standard Model states such as electrons or photons however, this is
robustly excluded by constraints from the Cosmic Microwave Background. We
study to what extent this conclusion can be circumvented if the vector
mediator is stable and hence contributes to the dark matter density while
annihilating into lighter degrees of freedom. We find viable parts of
parameter space which lead to the desired self-interaction cross section of
dark matter to address the small-scale problems of the collisionless cold
dark matter paradigm while being compatible with bounds from the Cosmic
Microwave Background and Big Bang Nucleosynthesis observations.

titleSelf-interacting dark matter with a stable vector mediator
journaltitleJournal of Cosmology and Astroparticle Physics

titleNEW Z-prime PHENOMENOLOGY
journaltitlePhys. Rev. D

titleNew Physics From Electric Charge Quantization?
journaltitleMod. Phys. Lett. A

titleSimplest Z-prime model
journaltitlePhys. Rev. D

titleGauged  $L_\mu - L_\tau$  Symmetry  at  the  Electroweak
journaltitlePhys. Rev. D

titleThe Muon anomalous magnetic moment and a new light gauge
journaltitlePhys. Lett. B

titleMuon anomalous g-2 and gauged L(muon) - L(tau) models
journaltitlePhys. Rev. D

titleFlavor-Nonuniversal Dark Gauge Bosons and the Muon g-2
journaltitlePhys. Lett. B

titleNeutrino Trident Production: A Powerful Probe of New Physics
with Neutrino Beams
journaltitlePhys. Rev. Lett.

note[Addendum: Nucl.Phys.B 873, 530–533 (2013)]
titleModel-independent implications of the e+-, anti-proton
cosmic ray spectra on properties of Dark Matter
journaltitleNucl. Phys. B

titlePhenomenology of U(1)(L(mu)-L(tau)) charged dark matter at
PAMELA and colliders

titleDark matter interactions with muons in neutron stars
journaltitlePhys. Rev. D

titleSelf-interacting dark matter and muon $g-2$ in a gauged
U$(1)_{L_{\mu} - L_{\tau}}$ model

titleAsymmetric dark matter: residual annihilations and
journaltitleSciPost Phys.

Departures from thermal equilibrium which are likely to occur in an
expanding universe allow the production of an appreciable net baryon density
by processes which violate baryon-number conservation. It is shown that the
resulting baryon to entropy ratio can be calculated in terms of purely
microscopic quantities. © 1979 The American Physical Society.

titleCosmological production of baryons
journaltitlePhysical Review Letters

titleRate of dark photon emission from electron positron
annihilation in massive stars
journaltitlePhysical Review D

Missing 'biblatex' package
The bibliography requires the 'biblatex' package.

titleThe force exerted by the stellar system in the direction
perpendicular to the galactic plane and some related problems
journaltitleBull. Ast. Inst. Neth

titleDie Rotverschiebung von extragalaktischen Nebeln
journaltitleHelv. Phys. Acta

titleRotation of the Andromeda Nebula from a Spectroscopic Survey
of Emission Regions

family=De Perio,

family=Di Gangi,

family=Di Giovanni,

family=Gallo Rosso,

family=Marrodán Undagoitia,

family=Dos Santos,

family=Scotto Lavina,

We report the first dark matter search results from XENON1T, a
∼2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber
in operation at the Laboratori Nazionali del Gran Sasso in Italy and the
first ton-scale detector of this kind. The blinded search used 34.2 live days
of data acquired between November 2016 and January 2017. Inside the
(1042±12)-kg fiducial mass and in the [5,40] keVnr energy range of interest
for weakly interacting massive particle (WIMP) dark matter searches, the
electronic recoil background was (1.93±0.25)×10-4 events/(kg×day×keVee),
the lowest ever achieved in such a dark matter detector. A profile likelihood
analysis shows that the data are consistent with the background-only
hypothesis. We derive the most stringent exclusion limits on the
spin-independent WIMP-nucleon interaction cross section for WIMP masses above
10 GeV/c2, with a minimum of 7.7×10-47 cm2 for 35-GeV/c2 WIMPs at 90%

titleFirst Dark Matter Search Results from the XENON1T
journaltitlePhysical Review Letters

titleResults from a search for dark matter in the complete LUX
journaltitlePhys. Rev. Lett.

We report a new search for weakly interacting massive particles (WIMPs)
using the combined low background data sets acquired in 2016 and 2017 from
the PandaX-II experiment in China. The latest data set contains a new
exposure of 77.1 live days, with the background reduced to a level of
0.8×10-3 evt/kg/day, improved by a factor of 2.5 in comparison to the
previous run in 2016. No excess events are found above the expected
background. With a total exposure of 5.4×104 kg day, the most stringent
upper limit on the spin-independent WIMP-nucleon cross section is set for a
WIMP with mass larger than 100 GeV/c2, with the lowest 90% C.L. exclusion
at 8.6×10-47 cm2 at 40 GeV/c2.

titleDark Matter Results from 54-Ton-Day Exposure of PandaX-II
journaltitlePhysical Review Letters

titleSearch for dark matter particles produced in association
with a top quark pair at $\sqrt{s} =$ 13 TeV
journaltitlePhys. Rev. Lett.

titleSearch for narrow and broad dijet resonances in
proton-proton collisions at $ \sqrt{s}=13 $ TeV and constraints on dark
matter mediators and other new particles

titleSearch for dark matter produced in association with a Higgs
boson decaying to $\gamma\gamma$ or $\tau^+\tau^-$ at $\sqrt{s} =$ 13 TeV

3 TeV and constraints on
dark matter and other models
journaltitleEur. Phys. J. C

titleSearch for dark matter in events with energetic,
hadronically decaying top quarks and missing transverse momentum at $
\sqrt{s}=13 $ TeV

titleSearch for dark matter in events with a hadronically
decaying vector boson and missing transverse momentum in $pp$ collisions at
$\sqrt{s} = 13$ TeV with the ATLAS detector

titleSearch for top squarks and dark matter particles in
opposite-charge dilepton final states at $\sqrt{s}=$ 13 TeV
journaltitlePhys. Rev. D

titleSearch for dark matter and other new phenomena in events
with an energetic jet and large missing transverse momentum using the ATLAS

titleSearch for dark matter produced in association with bottom
or top quarks in $\sqrt{s}=13$ TeV pp collisions with the ATLAS detector
journaltitleEur. Phys. J. C

titleSearch for an invisibly decaying Higgs boson or dark matter
candidates produced in association with a $Z$ boson in $pp$ collisions at
$\sqrt{s} =$ 13 TeV with the ATLAS detector
journaltitlePhys. Lett. B

titleA systematic study of hidden sector dark matter:application
to the gamma-ray and antiproton excesses

given=Daniel J.H.,

titleSuperheavy dark matter
journaltitlePhys. Rev.

given=Daniel J.H.,

booktitleTrends in theoretical physics II. Proceedings, 2nd La
Plata Meeting, Buenos Aires, Argentina, November 29-December 4, 1998
journaltitleAIP Conf. Proc.

titleFlooded Dark Matter and S Level Rise

titlePeV-Scale Dark Matter as a Thermal Relic of a Decoupled
journaltitlePhys. Lett.

titleThermal Dark Matter From A Highly Decoupled Sector
journaltitlePhys. Rev.

titleThermal Relic Dark Matter Beyond the Unitarity Limit

titleReheating the Standard Model from a hidden sector
journaltitlePhys. Rev.

titleWIMPs with GUTs: Dark Matter Coannihilation with a Lighter
journaltitlePhys. Rev. Lett.

titleSuperheavy Thermal Dark Matter and Primordial Asymmetries

titleSuperheavy dark matter through Higgs portal operators
journaltitlePhys. Rev.

titleNovel Gamma-Ray Signatures of PeV-Scale Dark Matter

titleHomeopathic Dark Matter, or how diluted heavy substances
produce high energy cosmic rays

titleGetting a THUMP from a WIMP

titleSuperheavy Thermal Dark Matter
journaltitlePhys. Rev. Lett.

titleInflaton portal to a highly decoupled EeV dark matter
journaltitlePhys. Rev.

titleFiltered Dark Matter at a First Order Phase Transition

titleDark matter filtering-out effect during a first-order phase

titleSpontaneous Freeze Out of Dark Matter From an Early Thermal
Phase Transition
journaltitlePhys. Rev.

It is estimated that demands for experimental observation of recently
investigated theoretically hard Vavilov-Čerenkov radiation at moderate
energies are realisable. © 1968.

titleOn the possibility of experimental observation of Hard
Vavilov-Čerenkov radiation
journaltitlePhysics Letters A
[Yad. Fiz.3,1154(1966)]

titleON POSSIBLE EFFECTS OF 'MIRROR' PARTICLES
journaltitleSov. J. Nucl. Phys.

titleA Model with fundamental improper space-time symmetries
journaltitlePhys. Lett. B

titleMirror baryons as the dark matter
journaltitlePhys. Rev. D

titleAsymmetric inflationary reheating and the nature of mirror
journaltitlePhys. Lett. B

titlePredictive landscapes and new physics at a TeV

titleEchoes of a hidden valley at hadron colliders
journaltitlePhys. Lett. B

titleA Natural Supersymmetric Model with MeV Dark Matter
journaltitlePhys. Rev. D

titleThe WIMPless Miracle: Dark-Matter Particles without
Weak-Scale Masses or Weak Interactions
journaltitlePhys. Rev. Lett.

titleStringy Hidden Valleys

journaltitleRev. Mod. Phys.

titleHiggs discovery: the beginning or the end of natural EWSB?

titleHiggs After the Discovery: A Status Report

titleThe Composite Twin Higgs scenario

titleThe Formation and Evolution of Galaxies Within Merging Dark
Matter Haloes
journaltitleMon. Not. Roy. Astron. Soc.

titleThe velocity function in the local environment from LCDM and
LWDM constrained simulations
journaltitleAstrophys. J.

journaltitleMon. Not. Roy. Astron. Soc.

titleDark matter substructure within galactic halos
journaltitleAstrophys. J. Lett.

titleWhere are the missing Galactic satellites?
journaltitleAstrophys. J.

titleToo big to fail? The puzzling darkness of massive Milky Way
journaltitleMon. Not. Roy. Astron. Soc.

titleThe Milky Way's bright satellites as an apparent failure of
journaltitleMon. Not. Roy. Astron. Soc.

titleM31 Satellite Masses Compared to LCDM Subhaloes
journaltitleMon. Not. Roy. Astron. Soc.

titleToo Big to Fail in the Local Group
journaltitleMon. Not. Roy. Astron. Soc.

titleThe Structure of cold dark matter halos
journaltitleAstrophys. J.

titleThe Structure of cold dark matter halos
journaltitleAstrophys. J.

titleA Universal density profile from hierarchical clustering
journaltitleAstrophys. J.

titleObservational and theoretical constraints on singular dark
matter halos
journaltitleAstrophys. J. Lett.

titleEvidence against dissipationless dark matter from
observations of galaxy haloes

titleCold collapse and the core catastrophe
journaltitleMon. Not. Roy. Astron. Soc.

We review theories of dark matter (DM) beyond the collisionless paradigm,
known as self-interacting dark matter (SIDM), and their observable
implications for astrophysical structure in the Universe. Self-interactions
are motivated, in part, due to the potential to explain long-standing (and
more recent) small scale structure observations that are in tension with
collisionless cold DM (CDM) predictions. Simple particle physics models for
SIDM can provide a universal explanation for these observations across a wide
range of mass scales spanning dwarf galaxies, low and high surface brightness
spiral galaxies, and clusters of galaxies. At the same time, SIDM leaves
intact the success of $\Lambda$CDM cosmology on large scales. This report
covers the following topics: (1) small scale structure issues, including the
core–cusp problem, the diversity problem for rotation curves, the missing
satellites problem, and the too-big-to-fail problem, as well as recent
progress in hydrodynamical simulations of galaxy formation; (2) N-body
simulations for SIDM, including implications for density profiles, halo
shapes, substructure, and the interplay between baryons and
self-interactions; (3) semi-analytic Jeans-based methods that provide a
complementary approach for connecting particle models with observations; (4)
merging systems, such as cluster mergers (e.g., the Bullet Cluster) and minor
infalls, along with recent simulation results for mergers; (5) particle
physics models, including light mediator models and composite DM models; and
(6) complementary probes for SIDM, including indirect and direct detection
experiments, particle collider searches, and cosmological observations. We
provide a summary and critical look for all current constraints on DM
self-interactions and an outline for future directions.

titleDark matter self-interactions and small scale structure
journaltitlePhysics Reports

Astrophysical observations spanning dwarf galaxies to galaxy clusters
indicate that dark matter (DM) halos are less dense in their central regions
compared to expectations from collisionless DM N-body simulations. Using
detailed fits to DM halos of galaxies and clusters, we show that
self-interacting DM (SIDM) may provide a consistent solution to the DM
deficit problem across all scales, even though individual systems exhibit a
wide diversity in halo properties. Since the characteristic velocity of DM
particles varies across these systems, we are able to measure the
self-interaction cross section as a function of kinetic energy and thereby
deduce the SIDM particle physics model parameters. Our results prefer a
mildly velocity-dependent cross section, from $\sigma$/m≈2 cm2/g on galaxy
scales to $\sigma$/m≈0.1 cm2/g on cluster scales, consistent with the upper
limits from merging clusters. Our results dramatically improve the
constraints on SIDM models and may allow the masses of both DM and dark
mediator particles to be measured even if the dark sector is completely
hidden from the standard model, which we illustrate for the dark photon

titleDark Matter Halos as Particle Colliders: Unified Solution to
Small-Scale Structure Puzzles from Dwarfs to Clusters
journaltitlePhysical Review Letters

The rotation curves of spiral galaxies exhibit a diversity that has been
difficult to understand in the cold dark matter (CDM) paradigm. We show that