2019 239 25 October

Prompt D meson-charged particle correlations in pp, p–Pb at
$\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

ALICE Collaboration††thanks: See Appendix A for the list of collaboration
members ALICE Collaboration

The measurement of the azimuthal-correlation function of prompt D mesons with
charged particles in pp collisions at $\sqrt{s}=5.02$ TeV and p–Pb collisions
at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ALICE detector at the LHC is
reported. The $\rm D^{0}$, $\rm D^{+}$, and $\rm D^{*+}$ mesons, together with
their charge conjugates, were reconstructed at midrapidity in the transverse
momentum interval $3<p_{\rm T}<24$ GeV/$c$ and correlated with charged
particles having $p_{\rm T}>0.3$ GeV/$c$ and pseudorapidity $|\eta|<0.8$. The
properties of the correlation peaks appearing in the near- and away-side
regions (for $\Delta\varphi\approx 0$ and $\Delta\varphi\approx\pi$,
respectively) were extracted via a fit to the azimuthal correlation functions.
The shape of the correlation functions and the near- and away-side peak
features are found to be consistent in pp and p–Pb collisions, showing no
modifications due to nuclear effects within uncertainties. The results are
compared with predictions from Monte Carlo simulations performed with the
PYTHIA, POWHEG+PYTHIA, HERWIG, and EPOS 3 event generators.

##  1 Introduction

Two-particle angular correlations allow the mechanisms of particle production
to be investigated and the event properties of ultra-relativistic hadronic
collisions to be studied. In particular, the azimuthal and pseudorapidity
distribution of “associated” charged particles with respect to a “trigger” D
meson is sensitive to the charm-quark production, fragmentation, and
hadronisation processes in proton–proton (pp) collisions and to their possible
modifications in larger collision systems, like proton–nucleus (pA) or
nucleus–nucleus (AA) [1]. The typical structure of the correlation function,
featuring a “near-side” (NS) peak at $(\Delta\varphi,\Delta\eta)=(0,0)$ (with
$\Delta\varphi=\varphi_{\rm ch}-\varphi_{\rm D}$ and $\Delta\eta=\eta_{\rm
ch}-\eta_{\rm D}$) and an “away-side” (AS) peak at $\Delta\varphi=\pi$
extending over a wide pseudorapidity range, as well as its sensitivity to the
different charm-quark production mechanisms, are described in details in [2].

In this paper, results of azimuthal correlations of prompt D mesons with
charged particles at midrapidity in pp and p–Pb collisions at
$\sqrt{s_{\mathrm{NN}}}=5.02$ TeV are presented, where “prompt” refers to D
mesons produced from charm-quark fragmentation, including the decay of excited
charmed resonances. The study of the near-side correlation peak is strongly
connected to the characterisation of charm jets and of their internal
structure, in terms of their particle multiplicity, angular profile, and the
transverse-momentum distribution of the jet constituents. Probing the near-
side peak features as a function of the charged-particle transverse momentum
($p_{\rm T}$), possibly up to values of a few GeV/$c$, can provide insight
into how the jet-momentum fraction not carried by the D meson is redistributed
among the other particles produced by the parton fragmentation, as well as on
the correlation between the $p_{\rm T}$ of these particles and their radial
displacement from the jet axis, which is closely related to the width of the
near-side correlation peak. This study provides further and complementary
information with respect to the analysis of charm jets reconstructed as a
single object through a track-clustering algorithm and tagged by their charm
content [3, 4, 5].

The azimuthal-correlation function of D mesons with charged particles is
largely sensitive to the various stages of the D-meson and particle evolution,
as hard-parton scattering, parton showering, fragmentation and hadronisation
[6]. Its description by the available Monte Carlo event generators like PYTHIA
[7, 8], HERWIG [9, 10, 11], and EPOS 3 [12, 13] or pQCD calculations like
POWHEG [14, 15] coupled to event generators handling the parton shower,
depends on several features, including the order of the hard-scattering
matrix-element calculations (leading order or next-to-leading order), the
modelling of the parton shower, the algorithm used for the fragmentation and
hadronisation, and the description of the underlying event. The azimuthal-
correlation function of D mesons with charged particles in pp collisions at
$\sqrt{s}=7$ TeV measured by ALICE is described within uncertainties by
simulations produced using PYTHIA6, PYTHIA8 and POWHEG+PYTHIA6 event
generators [2]. However, more precise and differential measurements are needed
to set constraints to models and be sensitive to the differences among their
expectations.

The validation of Monte Carlo simulations for angular correlations of heavy-
flavour particles in pp collisions is also useful for interpreting the results
in nucleus–nucleus collisions, for which the measurements in pp collisions are
used as reference. The temperature and energy density reached in
nucleus–nucleus collisions at LHC energies are large enough to produce a
quark–gluon plasma (QGP), a deconfined state of strongly-interacting matter
[16, 17]. The interaction of heavy quarks (charm and beauty) with the QGP
should affect the angular-correlation function [18]. First measurements
performed at RHIC and the LHC showed modifications of the correlation function
in nucleus–nucleus collisions when the trigger was a heavy-flavour particle,
where a suppression of the away-side correlation peak and an enhancement of
the near-side correlation peak for associated particles with $p_{\rm T}<2$
GeV/$c$ was observed [19, 20]. A comparison of the results in nucleus–nucleus
collisions to those in pp collisions, along with a successful description by
models, would allow the modifications of the correlation function to be
related to the in-medium heavy-quark dynamics [18, 21, 22].

In proton–nucleus collisions, several cold-nuclear-matter effects can
influence the production, fragmentation and hadronisation of heavy-flavour
quarks. They are induced by the presence of a nucleus in the initial state of
the collision and, possibly, by the high density of particles in its final
state. Measurements of the nuclear modification factor of D mesons and of
electrons from heavy-flavour hadron decays in p–Pb collisions at
$\sqrt{s_{\mathrm{NN}}}=5.02$ TeV [23, 24] point towards a small influence of
cold-nuclear-matter effects on the heavy-flavour quark production at
midrapidity. Nevertheless, nuclear effects could still affect the
fragmentation and hadronisation of heavy quarks. These can be investigated by
measuring potential modifications of the shape of the angular correlation of
heavy-flavour particles with charged particles [25].

Additionally, the search and characterisation of collective-like effects in
high-multiplicity proton–proton and proton–nucleus collisions are a crucial
topic, due to the observation of long-range, ridge-like structures in two-
particle angular-correlation functions at RHIC [26, 27] and the LHC [28, 29,
30, 31, 32, 33], resembling those observed in Pb–Pb collisions. The mechanism
leading to these structures in small collision systems is not straightforward
to identify. Possible explanations include final-state effects due to a
hydrodynamic behaviour of the produced particles [34, 35], colour-charge
exchanges [36, 37], initial-state effects, such as gluon saturation as
described within the Color-Glass Condensate effective field theory [38, 39],
or gluon bremsstrahlung by a quark-antiquark string [40]. In addition, a
positive elliptic-flow coefficient was observed also for heavy-flavour
particles, from the analysis of their azimuthal correlations with charged
particles, by the ALICE [41, 42, 43], ATLAS [44, 45, 46], and CMS [47, 48]
Collaborations. This approach generally assumes that the jet-induced
correlation peaks do not differ in low- and high-multiplicity collisions, i.e.
nuclear effects have the same impact on the heavy-quark fragmentation and
hadronisation at different event multiplicities. This assumption can be tested
by looking for modifications of the azimuthal-correlation function.

The results presented in this paper significantly improve the precision and
extend the kinematic reach, with respect to our previous measurements [2] in
both pp (at a different energy) and p–Pb collisions. Correlations with
associated particles at higher $p_{\rm T}$ probe the angular and $p_{\rm T}$
distribution of the hardest jet fragments, which retain more closely the
imprint of the hard-scattering topology. The properties of the away-side peak
are also studied for the first time. The paper is structured as follows. In
Sec. 2, the ALICE apparatus, its main detectors and the data samples used for
the analysis are presented. In Sec. 3 the procedure adopted for building the
azimuthal-correlation functions, correcting them for experimental effects, and
extracting physical quantities is described. Section 4 describes the
systematic uncertainties associated to the measurement. The results of the
analysis are presented and discussed in Sec. 5. The paper is briefly
summarised in Sec. 6.

##  2 Experimental apparatus and data sample

The ALICE apparatus consists of a central barrel, covering the pseudorapidity
region $|\eta|<$ 0.9, a muon spectrometer with $-4<\eta<-2.5$ coverage, and
forward- and backward-pseudorapidity detectors employed for triggering,
background rejection, and event characterisation. A complete description of
the detector and an overview of its performance are presented in [49, 50]. The
central-barrel detectors used in the analysis presented in this paper,
employed for charged-particle reconstruction and identification at
midrapidity, are the Inner Tracking System (ITS), the Time Projection Chamber
(TPC), and the Time-Of-Flight detector (TOF). They are embedded in a large
solenoidal magnet that provides a magnetic field of 0.5 T, parallel to the
beams. The ITS consists of six layers of silicon detectors, with the innermost
two composed of Silicon Pixel Detectors (SPD). It is used to track charged
particles and to reconstruct primary and secondary vertices. The TPC is the
main tracking detector of the central barrel. In addition, it performs
particle identification via the measurement of the particle specific energy
loss (d$E$/d$x$) in the detector gas. Additional information for particle
identification is provided by the TOF, via the measurement of the charged-
particle flight time from the interaction point to the detector. The TOF
information is also employed to evaluate the starting time of the event [51],
together with the time information provided by the T0 detector, an array of
Cherenkov counters located along the beam line, at $+370$ cm and $-70$ cm from
the nominal interaction point.

The results reported in this paper were obtained on the data samples collected
during the 2016 LHC p–Pb run at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and the 2017
LHC pp run at $\sqrt{s}=5.02$ TeV, corresponding, after the event selection,
to integrated luminosities of $L_{\rm int}$ = (295 $\pm$ 11) $\mu$b-1 and
$L_{\rm int}$ = (19.3 $\pm$ 0.4) nb-1, respectively. The events were selected
using a minimum-bias (MB) trigger provided by the V0 detector [52], a system
of two arrays of 32 scintillators each, covering the full azimuthal angle in a
pseudorapidity range of $2.8<\eta<5.1$ (V0A) and $-3.7<\eta<-1.7$ (V0C). The
trigger condition required at least one hit in both the V0A and the V0C
scintillator arrays. This trigger is fully efficient for recording collisions
in which a D meson is produced at midrapidity. The V0 time information and the
correlation between number of hits and track segments in the SPD were used to
reject background events from the interaction of one of the beams with the
residual gas in the vacuum tube. Pile-up events, whose probability was below
1% (0.5%) in pp collisions (p–Pb collisions), were rejected using an algorithm
based on track segments, reconstructed with the SPD, to detect multiple
primary vertices. The remaining undetected pile-up events are a negligible
fraction of the analysed sample. In order to obtain a uniform acceptance of
the detectors, only events with a reconstructed primary vertex within $\pm$10
cm from the centre of the detector along the beam line were considered for
both pp and p–Pb collisions. In p–Pb collisions, the
$\sqrt{s_{\mathrm{NN}}}=5.02$ TeV energy was obtained by delivering proton and
lead beams with energies of 4 TeV and 1.58 TeV per nucleon, respectively.
Therefore, the proton–nucleus center-of-mass frame was shifted in rapidity by
$\Delta y_{\rm{NN}}$ = 0.465 in the proton direction with respect to the
laboratory frame. The azimuthal correlations between D mesons and charged
particles in p–Pb collisions were studied as a function of the collision
centrality. The centrality estimator is based on the energy deposited in the
zero-degree neutron calorimeter in the Pb-going direction (ZNA). The procedure
used to define the centrality classes and to determine the average number of
binary nucleon–nucleon collisions for each class is described in [53].

Some of the corrections for the azimuthal-correlation functions described in
Sec. 3 were evaluated by exploiting Monte Carlo simulations, which included a
detailed description of the apparatus geometry and of the detector response,
using the GEANT3 package [54], as well as the luminous region distribution
during the pp and p–Pb collision runs. For the evaluation of the charged-
particle reconstruction efficiency, pp collisions were simulated with the
PYTHIA8 event generator [8] with Perugia-2011 tune [55], while p–Pb collisions
were simulated using the HIJING 1.36 event generator [56] in order to describe
the charged-particle multiplicity and detector occupancy observed in data. For
the corrections requiring the presence of a D meson in the event, enriched
Monte Carlo samples were used, obtained by generating pp collisions containing
a ${\rm c}\overline{\rm c}$ or ${\rm b}\overline{\rm b}$ pair in the rapidity
range $[-1.5,1.5]$, employing PYTHIA 6.4.21 with Perugia-2011 tune. For p–Pb
collisions, an underlying event generated with HIJING 1.36, was superimposed
to each heavy-quark enhanced PYTHIA event.

##  3 Data analysis

The analysis largely follows the procedure described in detail in [2]. It
consists of three main parts: (i) reconstruction and selection of D mesons and
primary charged particles (see [57] for the definition of primary particle);
(ii) construction of the azimuthal-correlation function and corrections for
detector-related effects, secondary particle contamination, and beauty feed-
down contribution; (iii) extraction of correlation properties via fits to the
average D-meson azimuthal-correlation functions with charged particles.

###  3.1 Selection of D mesons and primary charged particles

The analysis procedure begins with the reconstruction of D mesons ($\rm
D^{0}$, $\rm D^{*}(2010)^{+}$, and $\rm D^{+}$ and their charge conjugates),
defined as “trigger" particles, and primary charged particles, considered as
“associated" particles. The D mesons are reconstructed from the following
hadronic decay channels: ${\rm D^{0}\to{\rm K}^{-}\pi^{+}}$ (BR = 3.89 $\pm$
0.04%), ${\rm D^{+}\to{\rm K}^{-}\pi^{+}\pi^{+}}$ (BR = 8.98 $\pm$ 0.28%), and
${\rm D^{*+}\to\rm D^{0}\pi^{+}}\to{\rm K}^{-}\pi^{+}\pi^{+}$ (BR = 2.63 $\pm$
0.03%) [58] in the transverse-momentum interval $3<p_{\rm T}<24$ GeV/$c$. The
D-meson selection strategy, described in detail in [59, 23], exploits the
displaced topology of the decay and utilises the particle identification
capabilities of the TPC and TOF to select on the D-meson decay particles. A
dedicated optimisation on the selection variables was done, where the
selections were tightened to increase the signal-to-background ratio of the
D-meson invariant mass peaks. A gain up to a factor 5 at low $p_{\rm T}^{\rm
D}$ was obtained with respect to the selection defined in [59, 23], at the
expenses of a reduction of the raw yield. This allowed reducing the impact of
the D-meson combinatorial background, whose subtraction induces the largest
source of statistical uncertainty on the correlation functions. With the
adopted candidate selection, the D-meson reconstruction efficiency is of the
order of few percent for $p_{\rm T}^{\rm D}=3$ GeV/$c$ and increases up to 35%
(50%) for $p_{\rm T}^{\rm D}=24$ GeV/$c$ in case of $\rm D^{0}$ and $\rm
D^{+}$ ($\rm D^{*+}$) both in pp and in p–Pb collisions.

The D-meson raw yields were extracted from fits applied to the invariant mass
($M$) distributions of $\rm D^{0}$ and $\rm D^{+}$ candidates, and to the
distribution of the mass difference $\Delta M=M(\rm{K}\pi\pi)-M(\rm{K}\pi)$
for $\rm D^{*+}$ candidates, for several sub-ranges in the interval 3 $<p_{\rm
T}<$ 24 GeV/$c$, as detailed in [2]. Examples of the invariant mass
distributions in pp and in p–Pb collision systems are shown in Fig. 1 for $\rm
D^{0}$, $\rm D^{+}$, and $\rm D^{*+}$ mesons in different $p_{\rm T}$
intervals.

Figure 1: Invariant mass (mass-difference) distributions of $\rm D^{0}$, $\rm
D^{+}$ ($\rm D^{*+}$), and charge conjugates, candidates in three $p_{\rm
T}^{\rm D}$ intervals for pp collisions at $\sqrt{s}$ = 5.02 TeV (top row) and
p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV (bottom row). The
curves show the fit functions applied to the distributions. For the $\rm
D^{0}$, the dashed line represents the combinatorial background including the
contribution of reflection candidates (see [59]). The values of the mean
($\mu$) and width ($\sigma$) of the signal peak, extracted from the fit, are
also reported.

Associated particles are defined as all charged primary particles with $p_{\rm
T}^{\rm assoc}>$ 0.3 GeV/$c$ and with pseudorapidity $|\eta|<$ 0.8. The
associated-particle sample does not include the decay products of the trigger
D meson. Reconstructed charged-particle tracks with at least 70 space points
out of 159 in the TPC, 2 out of 6 in the ITS, and a $\chi^{2}$/NDF of the
momentum fit in the TPC smaller than 2 were considered. The contamination of
non-primary particles was largely suppressed by requiring the distance of
closest approach (DCA) of the track to the primary vertex to be less than 1 cm
in the transverse ($xy$) plane and along the beam line ($z$-direction). This
selection identifies primary particles with a purity varying from 95% to 99%
(increasing with $p_{\rm T}^{\rm assoc}$) and rejects a negligible amount of
primary particles. In particular, less than 1% of the primary particles
originating from decays of heavy-flavour hadrons are discarded. For the $\rm
D^{0}$ mesons produced in $\rm D^{*+}\to\rm D^{0}\pi^{+}$ decays, the
low-$p_{\rm T}$ pion accompanying the $\rm D^{0}$ was removed from the sample
of associated particles by rejecting tracks that, combined with the $\rm
D^{0}$, yielded a $\Delta M$ consistent within 3$\sigma$ with the $\rm D^{*+}$
mass peak. It was verified with Monte Carlo simulations that this selection
rejects more than 99% of the pions from $\rm D^{*+}$ decays in all D-meson
$p_{\rm T}$ intervals considered and has an efficiency larger than 99% for
primary particles with $p_{\rm T}^{\rm assoc}>$ 0.3 GeV/$c$. The selection
criteria described above provided an average track reconstruction efficiency
for charged particles with $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$ of about 83%
(82%) in pp (p–Pb) collisions in the pseudorapidity interval $|\eta|<$ 0.8,
with an increasing trend as a function of $p_{\rm T}^{\rm assoc}$ up to
$\approx 1$ GeV/$c$, followed by saturation at about 90%. As the track
reconstruction efficiency has a sudden drop below $\approx 0.3$ GeV/$c$,
caused by the TPC requirements in the track selection, this transverse
momentum value was chosen as the minimum $p_{\rm T}^{\rm assoc}$ for the
analysis.

###  3.2 Evaluation and correction of the azimuthal-correlation functions

Selected D-meson candidates with an invariant mass in the range
$|M-\mu|~{}<~{}2\sigma$ (peak region), where $\mu$ and $\sigma$ denote the
mean and width of the Gaussian term of the invariant mass fit function, were
correlated to the primary charged particles selected in the same event. A two-
dimensional angular-correlation function
$C(\Delta\varphi,\Delta\eta)_{\rm{peak}}$ was evaluated by computing the
difference of the azimuthal angle and the pseudorapidity of each pair. The
azimuthal-correlation functions were studied in four D-meson $p_{\rm
T}$-intervals: $3<p_{\rm T}^{\rm D}<5$ GeV/$c$, $5<p_{\rm T}^{\rm D}<8$
GeV/$c$, $8<p_{\rm T}^{\rm D}<16$ GeV/$c$, and $16<p_{\rm T}^{\rm D}<24$
GeV/$c$ and in the following $p_{\rm T}$ ranges of the associated tracks:
$p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$, $0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$,
$1<p_{\rm T}^{\rm assoc}<2$ GeV/$c$, and $2<p_{\rm T}^{\rm assoc}<3$ GeV/$c$,
significantly extending both transverse momentum coverages with respect to the
previous measurements reported in [2].

The two-dimensional correlation functions are affected by the limited detector
acceptance and reconstruction efficiency of the associated tracks (A${}^{\rm
assoc}\times\epsilon^{\rm assoc}$), as well as the variation of those values
for prompt D mesons (A${}^{\rm trig}\times\epsilon^{\rm trig}$) inside a given
$p_{\rm T}^{\rm D}$ interval. In order to correct for these effects, a weight
equal to 1/(A${}^{\rm assoc}\times\epsilon^{\rm assoc})\times 1$/(A${}^{\rm
trig}\times\epsilon^{\rm trig}$) was assigned to each correlation pair, as
described in detail in [2]. A weight of 1/(A${}^{\rm trig}\times\epsilon^{\rm
trig}$) was applied also to the entries in the D-meson invariant mass
distributions, used for the evaluation of the amount of signal $S_{\rm{peak}}$
and background $B_{\rm{peak}}$ triggers in the peak region.

The two-dimensional correlation function
$C(\Delta\varphi,\Delta\eta)_{\rm{peak}}$ also includes correlation pairs
obtained by considering D-meson candidates from combinatorial background as
trigger particles. This contribution was subtracted by evaluating the per-
trigger correlation function obtained selecting D mesons with an invariant
mass in the sidebands, $1/B_{\rm{sidebands}}\times
C(\Delta\varphi,\Delta\eta)_{\rm{sidebands}}$, and multiplying it by
$B_{\rm{peak}}$. The term $B_{\rm{sidebands}}$ is the amount of background
candidates in the sideband region, i.e. 4$\sigma<|M-\mu|<8\sigma$
(5$\sigma<M-\mu<10\sigma$, for $\rm D^{*+}$ mesons) of the invariant mass
distributions weighted by the inverse of the prompt D-meson reconstruction
efficiency.

The event-mixing technique was used to correct the correlation functions
$C(\Delta\varphi,\Delta\eta)_{\rm{peak}}$ and
$C(\Delta\varphi,\Delta\eta)_{\rm{sidebands}}$ for the limited detector
acceptance and its spatial inhomogeneities. The peak and sideband region
event-mixing functions $\mathrm{ME}(\Delta\varphi,\Delta\eta)_{\rm{peak}}$ and
$\mathrm{ME}(\Delta\varphi,\Delta\eta)_{\rm{sidebands}}$ were evaluated as
explained in [2]. The inverse of these functions was used to weight the
functions $C(\Delta\varphi,\Delta\eta)_{\rm{peak}}$ and
$C(\Delta\varphi,\Delta\eta)_{\rm{sidebands}}$, respectively.

The per-trigger angular-correlation function was obtained by subtracting the
sideband-region correlation function from the peak-region one, as follows:

$\centering\tilde{C}_{\rm{inclusive}}(\Delta\varphi,\Delta\eta)=\frac{p_{\mathrm{prim}}(\Delta\varphi)}{S_{\mathrm{peak}}}\left(\frac{C(\Delta\varphi,\Delta\eta)}{\mathrm{ME}(\Delta\varphi,\Delta\eta)}\bigg{|}_{\mathrm{peak}}-\frac{B_{\mathrm{peak}}}{B_{\mathrm{sidebands}}}\frac{C(\Delta\varphi,\Delta\eta)}{\mathrm{ME}(\Delta\varphi,\Delta\eta)}\bigg{|}_{\mathrm{sidebands}}\right).\@add@centering$
(1)

The division by $S_{\mathrm{peak}}$ provides the normalisation to the number
of D mesons. In our notation per-trigger quantities are specified by the
$\tilde{C}$ symbol. In Eq. 1, $p_{\rm{prim}}(\Delta\varphi)$ is a correction
for the residual contamination of non-primary associated particles not
rejected by the track selection (purity correction). The correction was
applied differentially in $\Delta\varphi$, since it was verified using Monte
Carlo simulations with PYTHIA6 (Perugia-2011 tune) that this contamination
shows a $\Delta\varphi$ modulation, typically of about 1–2%. The largest value
of the contamination was found in the near-side region, for the lowest $p_{\rm
T}$ range of the associated tracks, where $p_{\rm{prim}}(\Delta\varphi)$
approaches 95%.

Statistical fluctuations prevented a ($\Delta\varphi$,$\Delta\eta$)-double-
differential study of the correlation peak properties. Therefore, the per-
trigger azimuthal-correlation function
$\tilde{C}_{\rm{inclusive}}(\Delta\varphi)$ was obtained by integrating
$\tilde{C}_{\rm{inclusive}}(\Delta\varphi,\Delta\eta)$ in the range
$|\Delta\eta|<1$.

A fraction of reconstructed D mesons originates from the decay of beauty
hadrons (feed-down D mesons). It was verified with Monte Carlo simulations
that azimuthal correlations of prompt and feed-down D mesons with charged
particles show different functions. This is a result of the different
fragmentation of beauty and charm quarks, as well as of the additional
presence of beauty-hadron decay particles in the correlation function of feed-
down D-meson triggers. The contribution of feed-down D-meson triggers to the
measured angular-correlation function was subtracted using templates of the
azimuthal-correlation function of feed-down D mesons with charged particles,
obtained with Monte Carlo simulations at generator level (i.e. without
detector effects and particle selection), as detailed in [2].

Before performing this subtraction,
$\tilde{C}_{\rm{inclusive}}(\Delta\varphi)$ has to be corrected for a bias
which distorts the shape of the near-side region of the feed-down
contribution, induced by the D-meson topological selection. For feed-down
D-meson triggers, indeed, the selection criteria are more likely to be
satisfied by decay topologies with small angular opening between the trigger D
meson and the other products of the beauty-hadron decay. This induces an
enhancement of correlation pairs from feed-down D-meson triggers at
$\Delta\varphi\approx 0$ and a depletion at larger $\Delta\varphi$ values.
This bias was accounted for as a systematic uncertainty in [2]. In this paper,
instead, a $\Delta\varphi$ dependent correction factor ($c_{\rm{FD-
bias}}(\Delta\varphi)$) was determined by comparing Monte-Carlo templates of
feed-down D mesons and associated particles at generator level and after
performing the event reconstruction and particle selection as on data. This
correction factor, ranging between 0.6 and 1.3, was applied to the feed-down
contribution to $\tilde{C}_{\rm{inclusive}}(\Delta\varphi)$ as follows, to
restore this contribution to an unbiased value:

$\tilde{C}^{\rm{corr}}_{\rm{inclusive}}(\Delta\varphi)=\tilde{C}_{\rm{inclusive}}(\Delta\varphi)\left[\frac{A^{\rm{prompt}}_{\rm
NS}(\Delta\varphi)}{A^{\rm{total}}_{\rm NS}(\Delta\varphi)}\times
f_{\rm{prompt}}+\frac{A^{\rm{feed-down}}_{\rm
NS}(\Delta\varphi)}{A^{\rm{total}}_{\rm
NS}(\Delta\varphi)}\times(1-f_{\rm{prompt}})\times c_{\rm{FD-
bias}}(\Delta\varphi)\right].$ (2)

In Eq. 2, $f_{\rm{prompt}}$ is the fraction of prompt D mesons in the raw
yields extracted from the data invariant mass distributions, typically ranging
from 90% to 95% in the studied $p_{\rm T}^{\rm D}$ intervals, and was
evaluated as detailed in [60], $A^{\rm{prompt}}_{\rm NS}(\Delta\varphi)$
($A^{\rm{feed-down}}_{\rm NS}(\Delta\varphi)$) is the value of the per-trigger
correlation function of prompt (feed-down) D-mesons with associated particles,
and the term $A^{\rm{total}}_{\rm NS}(\Delta\varphi)$ is the value of the per-
trigger correlation function considering both prompt and feed-down components.
The terms $A^{\rm{prompt}}_{\rm NS}(\Delta\varphi)$ and $A^{\rm{feed-
down}}_{\rm NS}(\Delta\varphi)$ were evaluated from an analysis on
reconstructed Monte Carlo events, where the reconstruction was performed as on
data. The maximum effect of the correction when applied on
$\tilde{C}_{\rm{inclusive}}(\Delta\varphi)$ is about 5%, at
$\Delta\varphi\approx$ 0, for the lowest D-meson $p_{\rm T}$ range and the
highest $p_{\rm T}^{\rm assoc}$ interval. The correction becomes negligible
for $p_{\rm T}^{\rm D}>8$ GeV/$c$. After performing this correction, the feed-
down contamination was subtracted as described above.

As a result, the fully-corrected, per-trigger azimuthal-correlation function
of prompt D mesons with associated particles was obtained, denoted as
$1/N_{\rm D}\times{\rm d}N^{\rm assoc}/{\rm d}\Delta\varphi$ from Fig. 2
onwards.

###  3.3 Average and fit to the correlation functions

The correlation functions obtained from $\rm D^{0}$, $\rm D^{+}$, and $\rm
D^{*+}$ mesons were averaged using, as weights, the inverse of the quadratic
sum of the statistical and D-meson uncorrelated systematic uncertainties,
discussed in Sec. 4, since the three functions were found to be consistent
within uncertainties. Since the correlation functions are symmetric around
$\Delta\varphi$ = 0 and $\Delta\varphi$ = $\pi$, they were reflected in the
range ${0<\Delta\varphi<\pi}$ to reduce statistical fluctuations. In order to
quantify the properties of the average D-meson azimuthal-correlation function,
it was fitted with the following function:

$f(\Delta\varphi)=b+\frac{Y_{\rm NS}\times\beta}{2\alpha\Gamma(1/\beta)}\times
e^{-\left(\frac{\Delta\varphi}{\alpha}\right)^{\beta}}+\frac{Y_{\rm
AS}}{\sqrt{2\pi}\sigma_{\rm AS}}\times
e^{\frac{(\Delta\varphi-\pi)^{2}}{2\sigma^{2}_{\rm AS}}}.$ (3)

The fit function is composed of a constant term $b$ describing the flat
contribution below the correlation peaks, a generalised Gaussian term
describing the NS peak, and a Gaussian reproducing the AS peak. In the
generalised Gaussian, the term $\alpha$ is related to the variance of the
function, hence to its width, while the term $\beta$ drives the shape of the
peak (the Gaussian function is obtained for $\beta=2$). The function in Eq. 3
is a generalisation of that adopted in [2], where a Gaussian function was used
for the near-side, corresponding to the case $\beta$ = 2. The new
parametrisation allowed to improve the $\chi^{2}$/ndf value in all the
kinematic ranges studied, especially in the high $p_{\rm T}$ ranges of both
the D mesons and associated particles, where the standard Gaussian fit
systematically underestimates the near-side peak yields (widths) up to 10%
(20%) with respect to the generalised Gaussian. By symmetry considerations,
the means of the Gaussian functions were fixed to $\Delta\varphi$ = 0 and
$\Delta\varphi$ = $\pi$. Figure 2 shows examples of fits to the azimuthal-
correlation functions of D mesons with associated particles, for $5<p_{\rm
T}^{\rm D}<8$ GeV/$c$ with $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$ in pp
collisions and for $8<p_{\rm T}^{\rm D}<16$ GeV/$c$ with $1<p_{\rm T}^{\rm
assoc}<2$ GeV/$c$ in p–Pb collisions.

Figure 2: Examples of the fit to the D-meson average azimuthal-correlation
function, for $5<p_{\rm T}^{\rm D}<8$ GeV/$c$, $p_{\rm T}^{\rm assoc}>0.3$
GeV/$c$ in pp collisions (left), and for $8<p_{\rm T}^{\rm D}<16$ GeV/$c$,
$1<p_{\rm T}^{\rm assoc}<2$ GeV/$c$ in p–Pb collisions (right). The
statistical uncertainties are shown as vertical error bars. The fit function
described in Eq. 3 is shown as a red solid curve. Its different terms are
shown separately: near-side generalised Gaussian function, away-side Gaussian
function, and baseline constant term. The scale uncertainty (see Sec. 4) is
also reported for completeness.

The integrals of the functions describing the near- and away-side peaks,
$Y_{\rm NS}$ and $Y_{\rm AS}$, correspond to the associated-particle yields
(i.e. the average number of associated particles contained in the peak), while
the widths of the correlation peaks are described by the square root of the
variance of their fitting terms,
$\alpha\sqrt{\Gamma(3/\beta)/\Gamma(1/\beta)}$ and $\sigma_{\rm AS}$, for the
near- and away-side, respectively. The baseline $b$ represents the physical
minimum of the $\Delta\varphi$ function, and depends on the average charged-
particle multiplicity.

To reduce the effect of statistical fluctuations on the estimate of the
associated yields, $b$ was fixed to the weighted average of the points in the
transverse region, defined as $\pi/4<|\Delta\varphi|<\pi/2$, using the inverse
of the point squared statistical uncertainties as weights.

##  4 Systematic uncertainties

The systematic uncertainty induced on the correlation function from the
evaluation of $S_{\rm{peak}}$ and $B_{\rm{peak}}$, obtained by fitting the
D-meson invariant-mass distribution, was evaluated by varying the fit
procedure. In particular, the fit was repeated modelling the background
distribution with a linear function and a second-order polynomial function
instead of an exponential function (for $\rm D^{0}$ and $\rm D^{+}$ mesons
only), varying the fit range, fixing the mean of the Gaussian term describing
the mass peak to the world-average D-meson mass [58], or fixing the Gaussian
width to the value obtained from Monte Carlo studies. A systematic uncertainty
ranging from 1 to 3% (1 to 2%), depending on the $p_{\rm T}^{\rm D}$, was
estimated from the corresponding variation of the azimuthal-correlation
function for pp (p–Pb) collisions. No dependence on $\Delta\varphi$ was
observed and the same uncertainty was estimated for all D-meson species.

An uncertainty ranging from 1 to 3%, depending on $p_{\rm T}^{\rm D}$ and on
the D-meson species, was assigned in both pp and p–Pb collisions for the
possible dependence of the shape of background correlation function on the
invariant-mass value of the trigger D meson. This source of uncertainty was
determined by evaluating
$\tilde{C}(\Delta\varphi,\Delta\eta)_{\rm{sidebands}}$, defining a different
invariant-mass sideband range, and also considering, for $\rm D^{0}$ and $\rm
D^{+}$ mesons, only the left or only the right sideband for the evaluation of
$\tilde{C}(\Delta\varphi,\Delta\eta)_{\rm{sidebands}}$. No significant
dependence on $\Delta\varphi$ was obtained for this uncertainty.

A systematic effect originating from the correction of the D-meson
reconstruction efficiency, due to possible differences of the topological
variable distributions between Monte Carlo and data, was evaluated by
repeating the analysis applying tighter and looser topological selections on
the D-meson candidates. An uncertainty up to 2.5% (2%), increasing for smaller
$p_{\rm T}^{\rm D}$ values, was assigned in pp (p–Pb) collisions. No
significant dependence on $\Delta\varphi$ was observed. The same uncertainty
was estimated for the three D-meson species.

The systematic uncertainty originating from the evaluation of the associated
track reconstruction efficiency was estimated by varying the quality selection
criteria applied to the reconstructed tracks, removing the request of at least
two associated clusters in the ITS, or requiring a hit on at least one of the
two SPD layers, or varying the request on the number of space points
reconstructed in the TPC. An uncertainty up to 4.5% (3%), was assessed for pp
(p–Pb) collisions. No significant trend in $\Delta\varphi$ was observed.

The uncertainty on the evaluation of the residual contamination from secondary
tracks was determined by repeating the analysis varying the selection on the
DCA in the $xy$ plane from 0.1 to 1 cm, and re-evaluating the purity of
associated primary particles for each variation. This resulted in a 2% (3%)
maximum systematic uncertainty on the azimuthal-correlation functions in pp
(p–Pb) collisions, decreasing with increasing $p_{\rm T}^{\rm assoc}$ and with
negligible $\Delta\varphi$ dependence.

The uncertainty on the subtraction of the beauty feed-down contribution was
quantified by generating the templates of feed-down azimuthal-correlation
functions with different event generators (PYTHIA6 with the Perugia-2010 tune,
PYTHIA8 with the 4C tune) and by varying the value of $f_{\rm{prompt}}$ within
its uncertainty band, as described in details in [59]. The resulting
uncertainty was found to be dependent on $\Delta\varphi$, with a maximum value
of 5% (3%) in pp (p–Pb) collisions, and was applied point-by-point on the
correlation functions.

As discussed in Sec. 3, Monte Carlo studies revealed the presence of a bias on
the near-side region of the correlation function for feed-down D-mesons
triggers, induced by the topological selections applied to the D mesons. The
correction applied to remove this bias relies on a proper description of the
azimuthal-correlation functions of prompt and feed-down D-meson triggers by
the Monte Carlo simulations. A $\Delta\varphi$-dependent, symmetric systematic
uncertainty of $\pm\delta\tilde{C}(\Delta\varphi)/\sqrt{12}$ was introduced to
account for under- or overestimation of the correction, where
$\delta\tilde{C}(\Delta\varphi)$ is the point-by-point shift of the
correlation function induced by the correction. The largest value of the
uncertainty was 2%, at $\Delta\varphi\approx 0$, for both pp and p–Pb
collisions.

In Tab. 1, the minimum and maximum values of the systematic uncertainties
affecting the azimuthal-correlation functions, depending on the kinematic
range, are listed for both collision systems. Only the uncertainties deriving
from the feed-down subtraction and from the correction on the bias of feed-
down D-meson correlations are $\Delta\varphi$ dependent. All the other
contributions define a $\Delta\varphi$-independent systematic uncertainty,
which acts as a scale uncertainty for the correlation function. In both pp and
p–Pb collisions the total scale uncertainty ranges from $\pm$4% to $\pm$5%.

System | pp | p–Pb
---|---|---
D-meson species |  $\rm D^{0}$, $\rm D^{*+}$, $\rm D^{+}$ |  $\rm D^{0}$, $\rm D^{*+}$, $\rm D^{+}$
Signal, background normalisation |  $\pm$1–3% |  $\pm$1–2%
Background $\Delta\varphi$ function |  $\pm$1–3% |  $\pm$1–3%
Associated-track reconstruction efficiency |  $\pm$2.5–4.5% |  $\pm$3%
Primary-particle purity |  $\pm$1–2% |  $\pm$1.5–3%
D-meson efficiency |  $\pm$1–2.5% |  $\pm$1–2%
Feed-down subtraction | up to 5%, $\Delta\varphi$-dependent | up to 3%, $\Delta\varphi$-dependent
Bias on topological selection | up to 2%, $\Delta\varphi$-dependent | up to 2%, $\Delta\varphi$-dependent
Table 1: List of systematic uncertainties for the azimuthal-correlation
functions in pp and in p–Pb collisions. If not specified, the uncertainty does
not depend on $\Delta\varphi$.

The systematic uncertainties on the near- and away-side peak yields and
widths, and on the baseline height, obtained from the fits to the azimuthal-
correlation functions, were evaluated as follows. The main source of
uncertainty arises from the definition of the $\Delta\varphi$ transverse
region used to determine the baseline height (term $b$ of Eq. 3). The impact
on the physical observables induced by the baseline value was estimated by
considering different $\Delta\varphi$ ranges for determining the baseline
position and performing the fits again using Eq. 3. Moreover, the fits were
repeated by moving the points of the correlation functions upwards and
downwards using the corresponding value of the $\Delta\varphi$-dependent
systematic uncertainty. The total systematic uncertainty was calculated by
summing in quadrature the aforementioned contributions. For the associated
yields and for the baseline, whose values depend on the normalisation of the
correlation function, also the $\Delta\varphi$-independent systematic
uncertainties affecting the correlation function (i.e. the first five
contributions listed in Table 1), which act as a scale factor, were summed in
quadrature.

In p–Pb collisions, the presence of long-range correlations among the
particles produced in the collision can have an impact on the values of the
quantities extracted from the fits, in particular for the analysis as a
function of centrality. This effect was studied by fitting the functions with
a $v_{2\Delta}$-like modulation [41], in place of a flat baseline. The $v_{2}$
values adopted for D mesons, ranging up to 8% for the lowest $p_{\rm T}^{\rm
D}$ range in 0–20% central events, were estimated employing the available
results for heavy-flavour particle $v_{2}$ in p–Pb collisions from CMS [47],
ALICE [41], and ATLAS [44, 45], while those for associated particles were
estimated based on di-hadron correlation measurements by ALICE [28]. For the
centrality-integrated analysis and for the case when $p_{\rm T}^{\rm
assoc}>0.3$ GeV/$c$, considering a $v_{2\Delta}$-like modulation reduced the
near-side peak yields by about 16% (5%) for $3<p_{\rm T}^{\rm D}<5$ GeV/$c$
($5<p_{\rm T}^{\rm D}<8$ GeV/$c$) and the away-side peak yields by about 20%
(3%) for $3<p_{\rm T}^{\rm D}<5$ GeV/$c$ ($5<p_{\rm T}^{\rm D}<8$ GeV/$c$). A
smaller variation was observed for the peak widths and for the baseline value.
For the analysis as a function of the event centrality, the largest effect was
obtained for the 0–20% centrality class, where for $p_{\rm T}^{\rm assoc}>0.3$
GeV/$c$ a decrease of 27%, 17%, and 5% was found for $3<p_{\rm T}^{\rm D}<5$
GeV/$c$, $5<p_{\rm T}^{\rm D}<8$ GeV/$c$, and ${8<p_{\rm T}^{\rm D}<16}$
GeV/$c$, respectively. Smaller variations were found for the near-side peak
width and the baseline. This systematic uncertainty was summed in quadrature
with the others to obtain the total uncertainty.

##  5 Results

###  5.1 Comparison of results in pp and p–Pb collisions

Figure 3: Average of the azimuthal-correlation functions of $\rm D^{0}$, $\rm
D^{+}$, and $\rm D^{*+}$ mesons with associated particles, after the
subtraction of the baseline, in pp collisions at ${\sqrt{s}=5.02}$ TeV and
p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, for $3<p_{\rm T}^{\rm
D}<5$ GeV/$c$, $5<p_{\rm T}^{\rm D}<8$ GeV/$c$, $8<p_{\rm T}^{\rm D}<16$
GeV/$c$, and $16<p_{\rm T}^{\rm D}<24$ GeV/$c$ (from left to right) and
$p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$, $0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$,
$1<p_{\rm T}^{\rm assoc}<2$ GeV/$c$, and $2<p_{\rm T}^{\rm assoc}<3$ GeV/$c$
(from top to bottom). Statistical and $\Delta\varphi$-dependent systematic
uncertainties are shown as vertical error bars and boxes, respectively,
$\Delta\varphi$-independent uncertainties are written as text. The
uncertainties from the subtraction of the baseline are displayed as boxes at
$\Delta\varphi>\pi$.

The averaged azimuthal-correlation functions of the $\rm D^{0}$, $\rm D^{+}$,
and $\rm D^{*+}$ mesons with associated particles in pp and p–Pb collision
systems are compared, after baseline subtraction, in Fig. 3, for four D-meson
transverse momentum ranges, ${3<p_{\rm T}^{\rm D}<5}$ GeV/$c$, ${5<p_{\rm
T}^{\rm D}<8}$ GeV/$c$, ${8<p_{\rm T}^{\rm D}<16}$ GeV/$c$, and ${16<p_{\rm
T}^{\rm D}<24}$ GeV/$c$. The functions are presented for $p_{\rm T}^{\rm
assoc}>0.3$ GeV/$c$ as well as for three sub-ranges, $0.3<p_{\rm T}^{\rm
assoc}<1$ GeV/$c$, $1<p_{\rm T}^{\rm assoc}<2$ GeV/$c$, and $2<p_{\rm T}^{\rm
assoc}<3$ GeV/$c$. The qualitative shape of the correlation function and the
evolution of the near- and away-side peaks with trigger and associated
particle $p_{\rm T}$ are consistent within uncertainties in the two collision
systems. In particular, an increase of the height of the near-side correlation
peak is observed for increasing values of the D-meson $p_{\rm T}$. This
reflects the production of a higher number of particles in the jet
accompanying the fragmenting charm quark, when the energy of the latter
increases. A similar, though milder, effect can be observed also for the away-
side peak.

A more quantitative comparison of the near- and away-side peak features and
$p_{\rm T}$ evolution in the two collision systems can be obtained by fitting
the azimuthal-correlation functions and evaluating the peak yields and widths,
as it was explained in Sec. 3. Figure 4 compares these observables for the
near-side correlation peaks in pp and p–Pb collisions, as a function of the
D-meson $p_{\rm T}$, for $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$ and in three
$p_{\rm T}^{\rm assoc}$ sub-ranges. For both yields and widths, the values
measured in the two collision systems are in agreement. The increase of
associated particle production inside the near-side peak with $p_{\rm T}^{\rm
D}$, qualitatively observed in Fig. 3, is present for all the associated
particle $p_{\rm T}^{\rm assoc}$ intervals, and is similar in the two
collision systems. A tendency for a narrowing of the near-side peak with
increasing $p_{\rm T}^{\rm D}$ is also observed in most of the $p_{\rm T}$
ranges, though a flat behaviour cannot be excluded with the current
uncertainties.

Figure 4: Near-side peak associated yields (top row) and widths (bottom row)
in pp collisions at ${\sqrt{s}=5.02}$ TeV and p–Pb collisions at
${\sqrt{s_{\mathrm{NN}}}=5.02}$ TeV, as a function of the D-meson $p_{\rm T}$,
for ${p_{\rm T}^{\rm assoc}>0.3}$ GeV/$c$, ${0.3<p_{\rm T}^{\rm assoc}<1}$
GeV/$c$, ${1<p_{\rm T}^{\rm assoc}<2}$ GeV/$c$, and ${2<p_{\rm T}^{\rm
assoc}<3}$ GeV/$c$ (from left to right). Statistical and systematic
uncertainties are shown as vertical error bars and boxes, respectively.

The away-side peak yields and widths measured in pp and p–Pb collisions are
compared in Fig. 5 as a function of the D-meson $p_{\rm T}^{\rm D}$, with the
common associated-particle $p_{\rm T}^{\rm assoc}$ ranges analysed. For pp
collisions, specific kinematic regions where the $\chi^{2}/$ndf of the fit was
much larger than unity, or where the uncertainties on the peak observables
were larger than 100%, were excluded from the results. As in the near-side
analysis, the away-side yields show an increasing trend with $p_{\rm T}^{\rm
D}$, and overall have similar values in the two collision systems. In the
intermediate D-meson transverse momentum range, there is a hint for larger
yields in p–Pb than in pp, but not a statistically significant one (about
2.2$\sigma$ for the combined range $5<p_{\rm T}^{\rm D}<16$ GeV/$c$ for all
$p_{\rm T}^{\rm assoc}$ ranges). The away-side peak widths show consistent
values in pp and p–Pb collisions in all kinematic ranges. No significant
impact from cold-nuclear-matter effects on the fragmentation of charm quarks
appears from the comparison of the results in the two collision systems,
within the current precision of the measurements.

Figure 5: Away-side peak associated yields (top row) and widths (bottom row)
in pp collisions at ${\sqrt{s}=5.02}$ TeV and p–Pb collisions at
${\sqrt{s_{\mathrm{NN}}}=5.02}$ TeV, as a function of the D-meson $p_{\rm T}$,
for ${p_{\rm T}^{\rm assoc}>0.3}$ GeV/$c$, ${0.3<p_{\rm T}^{\rm assoc}<1}$
GeV/$c$, ${1<p_{\rm T}^{\rm assoc}<2}$ GeV/$c$, and ${2<p_{\rm T}^{\rm
assoc}<3}$ GeV/$c$ (from left to right). Statistical and systematic
uncertainties are shown as vertical error bars and boxes, respectively.

###  5.2 Results in p–Pb collisions as a function of the event centrality

The correlation functions of D mesons with associated particles for p–Pb
collisions in the 0–20%, 20–60%, and 60–100% centrality classes are compared
in Fig. 6, for nine kinematic ranges with ${3<p_{\rm T}^{\rm D}<16}$ GeV/$c$
and ${p_{\rm T}^{\rm assoc}>0.3}$ GeV/$c$. No results are shown for the
60–100% centrality class, for ${3<p_{\rm T}^{\rm D}<5}$ GeV/$c$ and ${p_{\rm
T}^{\rm assoc}>1}$ GeV/$c$, because of instabilities in the fits to the
correlation functions induced by statistical fluctuations. For the comparison
of the correlation peak characteristics, the baseline values were subtracted
from the functions, since they strongly depend on the centrality interval. The
correlation functions do not show significant differences among the three
centrality intervals studied.

Figure 6: Average of the azimuthal-correlation functions of $\rm D^{0}$, $\rm
D^{+}$, and $\rm D^{*+}$ mesons with associated particles, after the
subtraction of the baseline, for p–Pb collisions in three different centrality
classes, 0–20% (blue circles), 20–60% (red squares), and 60–100% (green
diamonds). The functions are shown for $3<p_{\rm T}^{\rm D}<5$ GeV/$c$,
$5~{}<~{}p_{\rm T}^{\rm D}~{}<~{}8$ GeV/$c$, and $8<p_{\rm T}^{\rm D}<16$
GeV/$c$ (from left to right) and $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$,
$0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$, and $p_{\rm T}^{\rm assoc}>1$ GeV/$c$
(from top to bottom). Statistical and $\Delta\varphi$-dependent systematic
uncertainties are shown as vertical error bars and boxes, respectively, while
$\Delta\varphi$-independent uncertainties are written as text. The
uncertainties from the subtraction of the baseline are displayed as boxes at
$\Delta\varphi>\pi$.

Figure 7 shows the near-side yields and widths extracted by a fit to the
correlation functions, for the three centrality intervals. A similar increase
of the near-side peak yields, as a function of the D-meson $p_{\rm T}$, is
observed for the three centrality ranges, with the absolute values of the
yields also being generally in agreement. The only exception is for the
$3<p_{\rm T}^{\rm D}<5$ GeV/$c$, $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$ interval,
where the yield for the 60–100% centrality class is lower than for the 0–20%
and 20–60% centrality classes, with a statistical significance of $1.4\sigma$
and $2.1\sigma$, respectively. This effect could be due to statistical
fluctuations of the correlation function data points (see Fig. 6). The near-
side peaks also have consistent widths among the three centrality ranges, for
all the kinematic ranges studied. No centrality dependence on the correlation
peaks, which could have possibly been induced by nuclear-matter effects, is
observed within the experimental uncertainties. The limited precision of the
results does not provide a further validation of the subtraction technique of
the jet-induced correlation peaks, commonly used in analyses searching for
positive elliptic flow via two-particle correlations.

Figure 7: Comparison of near-side associated peak yields (top row) and widths
(bottom row) as a function of the D-meson $p_{\rm T}$, for p–Pb collisions in
three different centrality classes, 0–20% (blue circles), 20–60% (red
squares), and 60–100% (green diamonds). The results are presented as a
function of the D-meson $p_{\rm T}$, for $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$,
$0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$, and $p_{\rm T}^{\rm assoc}>1$ GeV/$c$
(from left to right). Statistical and systematic uncertainties are shown as
vertical error bars and boxes, respectively.

###  5.3 Comparison of ALICE results to predictions from Monte Carlo
simulations

The azimuthal-correlation functions of D mesons with associated particles, as
well as the near- and away-side peak yields and widths measured by ALICE in pp
collisions, were compared to expectations from several Monte Carlo event
generators.

The PYTHIA event generator [7, 8] allows for the generation of high-energy
collisions of leptons and/or hadrons. It employs 2 $\rightarrow$ 2 QCD matrix
elements evaluated perturbatively with leading-order precision, with the next-
to-leading order contributions taken into account during the parton showering
stage. The parton showering follows a leading-logarithmic $p_{\rm T}$
ordering, with soft-gluon emission divergences excluded by an additional veto,
and the hadronisation is handled with the Lund string-fragmentation model. Two
different versions of PYTHIA, with two different parameter tunes, were used in
this paper. The PYTHIA 6.4.25 version [7] was employed, incorporating the
Perugia 2011 tune [55], which was the first tune considering the data from pp
collisions at $\sqrt{s}=0.9$ TeV and $\sqrt{s}=7$ TeV at the LHC. With respect
to its predecessor, PYTHIA8 [8] has an improved handling of the multiple-
parton interactions and the colour reconnection processes. In this paper, it
was used with the tune 4C [61].

POWHEG [14, 15] is a pQCD generator implementing hard-scattering matrix
elements with NLO accuracy, which can be coupled to Monte Carlo generators,
like PYTHIA [7, 8] or HERWIG [9, 10], for the parton showering and
hadronisation of the produced partons. In this paper, Monte Carlo simulations
were done using the POWHEG-BOX [62] framework coupled to PYTHIA 6.4.25 with
the Perugia-2011 tune [55]. A charm-quark mass of $m_{\rm c}=1.5$ GeV/$c^{2}$
was considered, and the renormalisation and factorisation scales were set to
the transverse mass of charm quark, i.e. $\mu_{\rm R}=\mu_{\rm F}=\sqrt{p_{\rm
T}^{2}+m_{\rm c}^{2}}$. It was verified that simulation results do not change
significantly when varying the generator parameters according to the
guidelines in [63]: the variation of the charm-quark mass does not alter the
correlation function, while the variation of the renormalisation and
factorisation scales produces differences of $\pm 10\%$ ($\pm 5\%$) for the
near-side peak yields (widths) and negligible deviations for the away-side
peak yields and widths. This can be expected, since the per-trigger
correlation function of D mesons with associated particles is scarcely
sensitive to the absolute rate of production of D mesons, directly influenced
by the aforementioned parameters. An additional set of predictions from
POWHEG+PYTHIA was also evaluated (POWHEG LO+PYTHIA6 in the following), by
stopping the computation of the hard-scattering matrix elements at leading-
order accuracy, before passing the generated partons to PYTHIA for the
showering and hadronisation.

The HERWIG 7 [11, 10] event generator allows one to perform Monte Carlo
simulations at NLO accuracy for most of the Standard Model processes,
including heavy-quark production. The parton showering is performed with an
angular ordering of the fragments, which correctly takes the coherence effects
for soft-gluon emissions into account. In addition, the hadronisation is
handled via the cluster hadronisation model, differently from the Lund string
fragmentation model employed by PYTHIA.

EPOS 3 [12, 13] is a Monte Carlo generator which considers flux tube initial
conditions for the collision, generated in the Gribov-Regge multiple-
scattering framework, and applies a 3+1D viscous hydrodynamical evolution on
the dense core of the collision. Individual scatterings, referred to as
Pomerons, are identified with parton ladders, each composed of a pQCD hard
process, plus initial- and final-state radiations. The hadronisation is then
performed with a string fragmentation procedure. Non-linear effects are
considered by means of a saturation scale. An evaluation within the EPOS 3
model shows that the energy density reached in pp collisions at the LHC
energies is already sufficient for applying such a hydrodynamic evolution
[64]. In the following, due to the limited precision of the available
predictions, the comparison between EPOS 3 expectations and data results will
be restricted to the kinematic interval $3<p_{\rm T}^{\rm D}<16$ GeV/$c$, and
will not include the away-side peak observables.

Figure 8: The average of the azimuthal-correlation functions of $\rm D^{0}$,
$\rm D^{+}$, and $\rm D^{*+}$ mesons with associated particles, after the
subtraction of the baseline, in pp collisions at $\sqrt{s}=5.02$ TeV, compared
to predictions from the PYTHIA, POWHEG+PYTHIA6, POWHEG LO+PYTHIA6, HERWIG, and
EPOS 3 event generators with various configurations (see text for details).
The functions are shown for $3<p_{\rm T}^{\rm D}<5$ GeV/$c$, $5<p_{\rm T}^{\rm
D}<8$ GeV/$c$, $8<p_{\rm T}^{\rm D}<16$ GeV/$c$, and $16<p_{\rm T}^{\rm D}<24$
GeV/$c$ (from left to right) and $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$,
$0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$, $1<p_{\rm T}^{\rm assoc}<2$ GeV/$c$,
and $2<p_{\rm T}^{\rm assoc}<3$ GeV/$c$ (from top to bottom). Statistical and
$\Delta\varphi$-dependent systematic uncertainties are shown as vertical error
bars and boxes, respectively, while the $\Delta\varphi$-independent
uncertainties are written as text. The uncertainties from the subtraction of
the baseline are displayed as boxes at $\Delta\varphi>\pi$.

In Fig. 8 the azimuthal-correlation functions of D mesons with associated
particles obtained from the aforementioned event generators are compared to
the measurements from this analysis, for all the $p_{\rm T}^{\rm D}$ and
$p_{\rm T}^{\rm assoc}$ ranges studied, in pp collisions at $\sqrt{s}=5.02$
TeV, after the baseline subtraction. Most of the models provide a fair
description of the two correlation peaks in the various kinematic ranges
studied, though some tensions are visible from this qualitative comparison. In
particular, HERWIG underestimates the near-side peak height for $p_{\rm
T}^{\rm assoc}>1$ GeV/$c$, especially for low D-meson transverse momentum,
while EPOS 3 tends to overestimate the height of the near-side peak and gives
a flatter away-side peak. In addition, some systematic hierarchies among the
models appear throughout the whole $p_{\rm T}$ ranges analysed, with
POWHEG+PYTHIA6 providing the highest near-side peak, and in most of the cases
the smallest away-side peak. The overestimation of the near-side peak yield by
EPOS 3 is a relevant feature also for the understanding of the dependence of
heavy-flavour production on the charged-particle multiplicity measured in the
same rapidity window of the heavy-flavour signals [65]. Disentangling the role
of jet-biases from effects related to genuine global event properties is
fundamental for properly interpreting the measured trends, especially their
$p_{\rm T}$ dependence [66].

Figure 9: Measurements of near-side associated peak yields (top row) and
widths (third row down) in pp collisions at $\sqrt{s}=5.02$ TeV, compared to
predictions by the PYTHIA, POWHEG+PYTHIA6, POWHEG LO+PYTHIA6, HERWIG, and EPOS
3 event generators with various configurations (see text for details). The
ratios of yield (width) values with respect to the predictions by
POWHEG+PYTHIA6 are shown in the second (fourth) row down. Results are
presented as a function of the D-meson $p_{\rm T}$, for $p_{\rm T}^{\rm
assoc}>0.3$ GeV/$c$, $0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$, $1<p_{\rm T}^{\rm
assoc}<2$ GeV/$c$, and $2<p_{\rm T}^{\rm assoc}<3$ GeV/$c$ (from left to
right). Statistical and systematic uncertainties are shown as vertical error
bars and boxes, respectively.

A more detailed investigation can be performed by quantifying the peak yields
and widths extracted from the fit to the correlation functions. In Fig. 9, the
comparison of near-side peak yields and widths from data and simulation is
shown, as a function of the D-meson $p_{\rm T}$, for $p_{\rm T}^{\rm
assoc}>0.3$ GeV/$c$ and for the three $p_{\rm T}^{\rm assoc}$ sub-ranges
analysed, in pp collisions at $\sqrt{s}=5.02$ TeV. In the top row (third row
down), the absolute value of the yields (widths) are displayed, while the
second (fourth) row down reports the ratios of the yields (widths) to those
obtained with POWHEG+PYTHIA6, which reduces the visual impact of the
statistical fluctuations of the data points. As already visible from Fig. 8,
EPOS 3 predicts the largest values of the near-side yields, followed by
POWHEG+PYTHIA6, while POWHEG LO+PYTHIA6 shows about 10% lower yields with
respect to the version with NLO accuracy. The latter difference could be
explained by a different relative contribution of the NLO production
mechanisms, in particular the gluon splitting, present already at the level of
the hard scattering for POWHEG+PYTHIA6. PYTHIA8 provides near-side yield
values comparable to those of POWHEG LO+PYTHIA6, while PYTHIA6 yields are
slightly lower. HERWIG expectations for near-side yields are the lowest,
except for the $0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$ range, where they are
comparable to PYTHIA8 expectations. POWHEG+PYTHIA6 and POWHEG LO+PYTHIA6
provide the best description of the near-side yields, with data points lying
between the two predictions. PYTHIA8 also gives a good description of data,
especially for $p_{\rm T}^{\rm assoc}>1$ GeV/$c$, while PYTHIA6 predictions
are generally lower than data, though in agreement within the uncertainties.
The HERWIG expectations for near-side yield describe the data well for the
$0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$ range, while they severely underpredict
the measurements for the other $p_{\rm T}^{\rm assoc}$ ranges, especially for
the lower intervals of the D-meson $p_{\rm T}$. In particular, for the
integrated range $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$, a discrepancy of
$3.3\sigma$ ($2.9\sigma$) is found for $3<p_{\rm T}^{\rm D}<5$ GeV/$c$
($5<p_{\rm T}^{\rm D}<8$ GeV/$c$), increasing to $3.4\sigma$ ($3.6\sigma$) for
the highest associated particle transverse-momentum range $2<p_{\rm T}^{\rm
assoc}<3$ GeV/$c$. The EPOS 3 model largely overestimates the near-side
associated yields, especially at low D-meson $p_{\rm T}$. For $p_{\rm T}^{\rm
assoc}>0.3$ GeV/$c$, the discrepancy between data and predictions ranges
between $4.0\sigma$ and $5.2\sigma$. Except for EPOS 3, a similar hierarchy
among the models also characterises the near-side widths. POWHEG+PYTHIA6 give
the broadest peaks, followed by POWHEG LO+PYTHIA6, with increasing difference
between the two model expectations with increasing $p_{\rm T}^{\rm assoc}$.
PYTHIA8 gives similar widths as POWHEG LO+PYTHIA6, while PYTHIA6 widths are
generally lower. The lowest predictions are provided by EPOS 3. HERWIG
predictions are consistent with PYTHIA6 for $p_{\rm T}^{\rm assoc}<1$ GeV/$c$,
and are generally lower for $p_{\rm T}^{\rm assoc}>1$ GeV/$c$. POWHEG+PYTHIA6
provides systematically larger widths than data, though still being compatible
point-by-point. EPOS 3 predictions tend to underestimate the near-side widths,
despite being consistent with data point-by-point. All the other models
provide values of the near-side width closer to data.

The same comparison of model expectations to data is shown for the away-side
peak yields and widths in Fig. 10. POWHEG+PYTHIA6 gives the smallest away-side
yields, with about 5%–10% smaller values than POWHEG LO+PYTHIA6 predictions.
As for the near-side peak yields, this difference could be ascribed to a
different contribution from back-to-back topologies of charm-quark pair
production. PYTHIA8 and PYTHIA6 yields are rather similar, and systematically
larger than POWHEG LO+PYTHIA6 expectations. HERWIG predicts similar yields as
POWHEG LO+PYTHIA6 for the integrated $p_{\rm T}^{\rm assoc}$ range (with
larger values for $0.3<p_{\rm T}^{\rm assoc}<1$ GeV/$c$ and smaller values for
$p_{\rm T}^{\rm assoc}>1$ GeV/$c$). The best description of the away-side
yields is provided, as in the near-side peak case, by POWHEG+PYTHIA6 and
POWHEG LO+PYTHIA6 over the whole kinematic range, as well as by HERWIG for
$p_{\rm T}^{\rm assoc}>1$ GeV/$c$. As observed for the near-side peak case,
the PYTHIA8 and PYTHIA6 expectations tend to overpredict away-side yields in
the majority of the transverse-momentum intervals studied. For $p_{\rm T}^{\rm
assoc}>0.3$ GeV/$c$, about a $2\sigma$ difference with respect to the data is
present, over the whole $p_{\rm T}^{\rm D}$ interval studied. The largest
values of the away-side peak width, in particular for large values of $p_{\rm
T}^{\rm assoc}$, are given by the PYTHIA6 event generator, which tends to
systematically overpredict the data points. The predictions from the other
models, all in agreement with data, are very similar, with POWHEG+PYTHIA6
being in general the lowest of them. However, the precision of measurements
for this observable prevents from discerning the model that best describes the
data.

Figure 10: Measurements of away-side associated peak yields (top row) and
widths (third row down) in pp collisions at $\sqrt{s}=5.02$ TeV, compared to
predictions by the PYTHIA, POWHEG+PYTHIA6, POWHEG LO+PYTHIA6, and HERWIG event
generators with various configurations (see text for details). The ratios of
yield (width) values with respect to the predictions by POWHEG+PYTHIA6 are
shown in the second (fourth) row down. Results are presented as a function of
the D-meson $p_{\rm T}$, for $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$, $0.3<p_{\rm
T}^{\rm assoc}<1$ GeV/$c$, $1<p_{\rm T}^{\rm assoc}<2$ GeV/$c$, and $2<p_{\rm
T}^{\rm assoc}<3$ GeV/$c$ (from left to right). Statistical and systematic
uncertainties are shown as vertical error bars and boxes, respectively.

Figure 11 shows the baseline values of the measured azimuthal-correlation
functions and compares them to predictions from the event generators. The
measured baseline values decrease with increasing $p_{\rm T}^{\rm assoc}$ of
the associated particle, which is expected as the transverse-momentum
distribution of associated particles in pp collisions at $\sqrt{s}=5.02$ TeV
peaks at few hundred MeV/$c$ [67]. From the data it cannot be concluded
whether the baseline is flat or slightly increasing as a function of D-meson
$p_{\rm T}$. A mildly increasing trend with $p_{\rm T}^{\rm D}$ is predicted
by the event generators. However, POWHEG+PYTHIA6 and POWHEG LO+PYTHIA6 predict
a larger increase than HERWIG, EPOS 3 and PYTHIA. The same baseline values are
obtained by POWHEG+PYTHIA6 and POWHEG LO+PYTHIA6 for all the kinematic ranges.
This is not trivial, due to the different treatment of next-to-leading order
contributions to charm production, which can populate the transverse region of
the correlation function and, hence, affect the baseline value. The best
description of the results, for low values of the associated particle $p_{\rm
T}$, is provided by PYTHIA6, PYTHIA8, and EPOS, while HERWIG overestimates the
values by about 15% over the whole $p_{\rm T}^{\rm D}$ range and
POWHEG+PYTHIA6 underpredicts them by 20% at low $p_{\rm T}^{\rm D}$. For
$p_{\rm T}^{\rm assoc}>1$ GeV/$c$ HERWIG gives the closest description of the
baseline. PYTHIA6, PYTHIA8, EPOS 3, and POWHEG+PYTHIA6 tend to underpredict
data values, with the first three models catching well the $p_{\rm T}^{\rm D}$
dependence, while POWHEG+PYTHIA6 also predicting a different behaviour against
$p_{\rm T}^{\rm D}$.

Figure 11: Measurements of azimuthal-correlation function baseline height in
pp collisions at $\sqrt{s}=5.02$ TeV, compared to predictions by the PYTHIA,
POWHEG+PYTHIA6, POWHEG LO+PYTHIA6, HERWIG, and EPOS 3 event generators with
various configurations in the top row (see text for details). The ratios of
baselines with respect to predictions by POWHEG+PYTHIA6 are shown in the
bottom row. Results are presented as a function of the D-meson $p_{\rm T}$,
for $p_{\rm T}^{\rm assoc}>0.3$ GeV/$c$, $0.3<p_{\rm T}^{\rm assoc}<1$
GeV/$c$, $1<p_{\rm T}^{\rm assoc}<2$ GeV/$c$, and $2<p_{\rm T}^{\rm assoc}<3$
GeV/$c$ (from left to right). Statistical and systematic uncertainties are
shown as vertical error bars and boxes, respectively.

The baseline-subtracted azimuthal-correlation functions of D mesons with
associated particles measured in p–Pb collisions were compared to simulations
from PYTHIA6, PYTHIA8, and POWHEG+PYTHIA6 event generators. The only
modifications of the configuration of these models with respect to that used
in pp collisions consisted of a rapidity shift of the centre-of-mass system
and, for POWHEG+PYTHIA6, a nuclear correction for the parton distribution
functions [68], which induced negligible effects on the model expectations.
The comparison between these models and the results from p–Pb collision
yielded very similar conclusions as those discussed for pp collisions, not
only in terms of an overall agreement between data and models, but also for
the differences previously mentioned for specific observables and kinematic
ranges. This was expected, given the overall agreement of measurements in the
two collision systems as discussed in Sec. 5.1, where additional cold-nuclear-
matter effects, not included in the models, could also be present.

##  6 Summary

Measurements of azimuthal-correlation functions of $\rm D^{0}$, $\rm D^{*+}$,
and $\rm D^{+}$ mesons with charged particles in pp collisions at
$\sqrt{s}=5.02$ and p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV were
reported. The results obtained have statistical and systematic uncertainties
smaller by a factor of about 2-3 than those reported in our previous paper [2]
for the common $p_{\rm T}$ ranges, and extend the $p_{\rm T}$ coverage both
for the trigger and associated particles, allowing for a more differential
study of the correlation function and charm-jet properties.

After subtracting the baseline, the correlation functions, along with the
values and transverse momentum evolution of the near- and away-side peaks, are
found to be consistent in pp and p–Pb collisions, in all the kinematic ranges
addressed. This suggests that the fragmentation and hadronisation of charm
quarks is not strongly influenced by cold-nuclear-matter effects,
complementing what was observed in previous measurements [69, 24, 23] that
suggested a small impact from cold-nuclear-matter effects on D-meson
production in the $p_{\rm T}$ region covered by our measurement.

The analysis in p–Pb collisions was also performed in the 0–20%, 20–60%, and
60–100% centrality intervals, in order to study the possible modifications of
the charm fragmentation as a function of the event centrality. The same
correlation pattern, along with similar values and $p_{\rm T}$ evolution of
the near-side peak observables were found for the three centrality ranges,
within large experimental uncertainties.

The baseline-subtracted correlation functions and the near- and away-side peak
yields and widths measured by ALICE in pp collisions were compared to
predictions by several event generators, with different modelling of charm
production, parton showering, and hadronisation. In general, the models
describe well the main features of the correlation functions. POWHEG+PYTHIA6
provides the best description to experimental data of near- and away-side
yields. PYTHIA8 tends to overestimate the away-side peak yields, while
providing a good description of the near-side peak yields and of the widths of
both peaks. Overall, PYTHIA6 is more distant from data than PYTHIA8, although
in general it is consistent with the measurements. HERWIG largely
underestimates the near-side peak yields for $p_{\rm T}^{\rm assoc}>1$
GeV/$c$, while it describes reasonably well the data at lower $p_{\rm T}^{\rm
assoc}$, and provides a good description of the away-side peak features.
Finally, EPOS 3 provides a higher near-side peak and qualitatively
underestimates the away-side peak. Similar conclusions were obtained when
comparing results in p–Pb collisions to predictions from the models available
in this collision system.

The agreement between data and model expectations suggests that charm-quark
production, fragmentation and hadronisation processes, as implemented in
POWHEG+PYTHIA6 and PYTHIA8, provide an overall satisfactory description of the
measured correlation functions. Therefore, in view of future analyses in Pb–Pb
collisions, these models constitute a valid theoretical baseline for
interpreting possible modifications of charm-jet properties and thus of the
near-side correlation peak induced by the interactions of charm quarks with
the quark–gluon plasma constituents. The same argument holds for the
modifications of the whole correlation function, whose characterisation can
provide a deeper understanding of heavy-quark dynamics inside the QGP medium.
In addition, with the increased precision compared to previous measurement,
and being at the same centre-of-mass energy of the available Pb–Pb collision
samples, these results constitute the reference for measurements in that
collision system.

## Acknowledgements

The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable contributions to the construction of the experiment and the CERN accelerator teams for the outstanding performance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources and support provided by all Grid centres and the Worldwide LHC Computing Grid (WLCG) collaboration. The ALICE Collaboration acknowledges the following funding agencies for their support in building and running the ALICE detector: A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation (ANSL), State Committee of Science and World Federation of Scientists (WFS), Armenia; Austrian Academy of Sciences, Austrian Science Fund (FWF): [M 2467-N36] and Nationalstiftung für Forschung, Technologie und Entwicklung, Austria; Ministry of Communications and High Technologies, National Nuclear Research Center, Azerbaijan; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (Finep), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Universidade Federal do Rio Grande do Sul (UFRGS), Brazil; Ministry of Education of China (MOEC) , Ministry of Science & Technology of China (MSTC) and National Natural Science Foundation of China (NSFC), China; Ministry of Science and Education and Croatian Science Foundation, Croatia; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Cubaenergía, Cuba; Ministry of Education, Youth and Sports of the Czech Republic, Czech Republic; The Danish Council for Independent Research | Natural Sciences, the VILLUM FONDEN and Danish National Research Foundation (DNRF), Denmark; Helsinki Institute of Physics (HIP), Finland; Commissariat à l’Energie Atomique (CEA), Institut National de Physique Nucléaire et de Physique des Particules (IN2P3) and Centre National de la Recherche Scientifique (CNRS) and Région des Pays de la Loire, France; Bundesministerium für Bildung und Forschung (BMBF) and GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany; General Secretariat for Research and Technology, Ministry of Education, Research and Religions, Greece; National Research, Development and Innovation Office, Hungary; Department of Atomic Energy Government of India (DAE), Department of Science and Technology, Government of India (DST), University Grants Commission, Government of India (UGC) and Council of Scientific and Industrial Research (CSIR), India; Indonesian Institute of Science, Indonesia; Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi and Istituto Nazionale di Fisica Nucleare (INFN), Italy; Institute for Innovative Science and Technology , Nagasaki Institute of Applied Science (IIST), Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) and Japan Society for the Promotion of Science (JSPS) KAKENHI, Japan; Consejo Nacional de Ciencia (CONACYT) y Tecnología, through Fondo de Cooperación Internacional en Ciencia y Tecnología (FONCICYT) and Dirección General de Asuntos del Personal Academico (DGAPA), Mexico; Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Netherlands; The Research Council of Norway, Norway; Commission on Science and Technology for Sustainable Development in the South (COMSATS), Pakistan; Pontificia Universidad Católica del Perú, Peru; Ministry of Science and Higher Education and National Science Centre, Poland; Korea Institute of Science and Technology Information and National Research Foundation of Korea (NRF), Republic of Korea; Ministry of Education and Scientific Research, Institute of Atomic Physics and Ministry of Research and Innovation and Institute of Atomic Physics, Romania; Joint Institute for Nuclear Research (JINR), Ministry of Education and Science of the Russian Federation, National Research Centre Kurchatov Institute, Russian Science Foundation and Russian Foundation for Basic Research, Russia; Ministry of Education, Science, Research and Sport of the Slovak Republic, Slovakia; National Research Foundation of South Africa, South Africa; Swedish Research Council (VR) and Knut & Alice Wallenberg Foundation (KAW), Sweden; European Organization for Nuclear Research, Switzerland; Suranaree University of Technology (SUT), National Science and Technology Development Agency (NSDTA) and Office of the Higher Education Commission under NRU project of Thailand, Thailand; Turkish Atomic Energy Agency (TAEK), Turkey; National Academy of Sciences of Ukraine, Ukraine; Science and Technology Facilities Council (STFC), United Kingdom; National Science Foundation of the United States of America (NSF) and United States Department of Energy, Office of Nuclear Physics (DOE NP), United States of America.

## References

  * [1] A. Beraudo, A. De Pace, M. Monteno, M. Nardi, and F. Prino, “Heavy flavors in heavy-ion collisions: quenching, flow and correlations”, Eur. Phys. J. C75 no. 3, (2015) 121, arXiv:1410.6082 [hep-ph].
  * [2] ALICE Collaboration, J. Adam et al., “Measurement of azimuthal correlations of D mesons and charged particles in pp collisions at $\sqrt{s}=7$ TeV and p–Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV”, Eur. Phys. J. C77 no. 4, (2017) 245, arXiv:1605.06963 [nucl-ex].
  * [3] ATLAS Collaboration, G. Aad et al., “Measurement of $D^{*\pm}$ meson production in jets from pp collisions at $\sqrt{s}$ = 7 TeV with the ATLAS detector”, Phys. Rev. D85 (2012) 052005, arXiv:1112.4432 [hep-ex].
  * [4] ALICE Collaboration, S. Acharya et al., “Measurement of the production of charm jets tagged with D0 mesons in pp collisions at $\sqrt{s}=7$ TeV”, JHEP 08 (2019) 133, arXiv:1905.02510 [nucl-ex].
  * [5] CMS Collaboration, A. M. Sirunyan et al., “Measurements of the charm jet cross section and nuclear modification factor in pPb collisions at $\sqrt{{s}_{NN}}$ = 5.02 TeV”, Phys. Lett. B772 (2017) 306–329, arXiv:1612.08972 [nucl-ex].
  * [6] F. Prino and R. Rapp, “Open Heavy Flavor in QCD Matter and in Nuclear Collisions”, J. Phys. G43 no. 9, (2016) 093002, arXiv:1603.00529 [nucl-ex].
  * [7] T. Sjostrand, S. Mrenna, and P. Z. Skands, “PYTHIA 6.4 Physics and Manual”, JHEP 05 (2006) 026, arXiv:hep-ph/0603175 [hep-ph].
  * [8] T. Sjostrand, S. Mrenna, and P. Z. Skands, “A Brief Introduction to PYTHIA 8.1”, Comput. Phys. Commun. 178 (2008) 852–867, arXiv:0710.3820 [hep-ph].
  * [9] G. Corcella, I. G. Knowles, G. Marchesini, S. Moretti, K. Odagiri, P. Richardson, M. H. Seymour, and B. R. Webber, “HERWIG 6: An Event generator for hadron emission reactions with interfering gluons (including supersymmetric processes)”, JHEP 01 (2001) 010, arXiv:hep-ph/0011363 [hep-ph].
  * [10] J. Bellm et al., “Herwig 7.0/Herwig++ 3.0 release note”, Eur. Phys. J. C76 no. 4, (2016) 196, arXiv:1512.01178 [hep-ph].
  * [11] M. Bahr et al., “Herwig++ Physics and Manual”, Eur. Phys. J. C58 (2008) 639–707, arXiv:0803.0883 [hep-ph].
  * [12] K. Werner, I. Karpenko, T. Pierog, M. Bleicher, and K. Mikhailov, “Event-by-Event Simulation of the Three-Dimensional Hydrodynamic Evolution from Flux Tube Initial Conditions in Ultrarelativistic Heavy Ion Collisions”, Phys. Rev. C82 (2010) 044904, arXiv:1004.0805 [nucl-th].
  * [13] H. J. Drescher, M. Hladik, S. Ostapchenko, T. Pierog, and K. Werner, “Parton based Gribov-Regge theory”, Phys. Rept. 350 (2001) 93–289, arXiv:hep-ph/0007198 [hep-ph].
  * [14] P. Nason, “A New method for combining NLO QCD with shower Monte Carlo algorithms”, JHEP 11 (2004) 040, arXiv:hep-ph/0409146 [hep-ph].
  * [15] S. Frixione, P. Nason, and C. Oleari, “Matching NLO QCD computations with Parton Shower simulations: the POWHEG method”, JHEP 11 (2007) 070, arXiv:0709.2092 [hep-ph].
  * [16] P. Braun-Munzinger, V. Koch, T. Schäfer, and J. Stachel, “Properties of hot and dense matter from relativistic heavy ion collisions”, Phys. Rept. 621 (2016) 76–126, arXiv:1510.00442 [nucl-th].
  * [17] HotQCD Collaboration, A. Bazavov et al., “Equation of state in ( 2+1 )-flavor QCD”, Phys. Rev. D90 (2014) 094503, arXiv:1407.6387 [hep-lat].
  * [18] M. Nahrgang, J. Aichelin, P. B. Gossiaux, and K. Werner, “Azimuthal correlations of heavy quarks in Pb + Pb collisions at $\sqrt{s}=2.76$ TeV at the CERN Large Hadron Collider”, Phys. Rev. C90 no. 2, (2014) 024907, arXiv:1305.3823 [hep-ph].
  * [19] PHENIX Collaboration, A. Adare et al., “Azimuthal correlations of electrons from heavy-flavor decay with hadrons in p+p and Au+Au collisions at $\sqrt{s_{\rm{NN}}}=200$ GeV”, Phys. Rev. C83 (2011) 044912, arXiv:1011.1477 [nucl-ex].
  * [20] STAR Collaboration, A. Jentsch, “Studies of Heavy Flavor Jets Using $D^{0}$-Hadron Correlations in Azimuth and Pseudorapidity in Au $+$ Au Collisons at 200 GeV at the STAR Experiment”, MDPI Proc. 10 no. 1, (2019) 34.
  * [21] S. Cao, G.-Y. Qin, and S. A. Bass, “Modeling of heavy-flavor pair correlations in Au-Au collisions at 200A GeV at the BNL Relativistic Heavy Ion Collider”, Phys. Rev. C92 no. 5, (2015) 054909, arXiv:1505.01869 [nucl-th].
  * [22] S. Cao, G.-Y. Qin, and S. A. Bass, “Suppression and Two-Particle Correlations of Heavy Mesons in Heavy-Ion Collisions”, Nucl. Phys. A956 (2016) 505–508.
  * [23] ALICE Collaboration, S. Acharya et al., “Measurement of prompt D0, D+, D∗+, and D${}^{+}_{s}$ production in p$-$Pb collisions at $\mathbf{\sqrt{{\textit{s}}_{\rm NN}}~{}=~{}5.02~{}TeV}$”, arXiv:1906.03425 [nucl-ex].
  * [24] ALICE Collaboration, J. Adam et al., “Measurement of electrons from heavy-flavour hadron decays in p–Pb collisions at $\sqrt{s_{\rm NN}}=$ 5.02 TeV”, Phys. Lett. B754 (2016) 81–93, arXiv:1509.07491 [nucl-ex].
  * [25] H. Fujii and K. Watanabe, “Heavy quark pair production in high energy pA collisions: Open heavy flavors”, Nucl. Phys. A920 (2013) 78–93, arXiv:1308.1258 [hep-ph].
  * [26] PHENIX Collaboration, A. Adare et al., “Quadrupole Anisotropy in Dihadron Azimuthal Correlations in Central $d$+Au Collisions at $\sqrt{s_{\rm{NN}}}$ = 200 GeV”, Phys. Rev. Lett. 111 no. 21, (2013) 212301, arXiv:1303.1794 [nucl-ex].
  * [27] STAR Collaboration, L. Adamczyk et al., “Long-range pseudorapidity dihadron correlations in $d$+Au collisions at $\sqrt{s_{\rm NN}}=200$ GeV”, Phys. Lett. B747 (2015) 265–271, arXiv:1502.07652 [nucl-ex].
  * [28] ALICE Collaboration, B. Abelev et al., “Long-range angular correlations on the near and away side in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV”, Phys. Lett. B719 (2013) 29–41, arXiv:1212.2001 [nucl-ex].
  * [29] ALICE Collaboration, B. Abelev et al., “Long-range angular correlations of $\rm\pi$, K and p in p–Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV”, Phys. Lett. B726 (2013) 164–177, arXiv:1307.3237 [nucl-ex].
  * [30] ATLAS Collaboration, M. Aaboud et al., “Measurements of long-range azimuthal anisotropies and associated Fourier coefficients for $pp$ collisions at $\sqrt{s}=5.02$ and $13$ TeV and $p$+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector”, Phys. Rev. C96 no. 2, (2017) 024908, arXiv:1609.06213 [nucl-ex].
  * [31] CMS Collaboration, S. Chatrchyan et al., “Multiplicity and transverse momentum dependence of two- and four-particle correlations in pPb and PbPb collisions”, Phys. Lett. B724 (2013) 213–240, arXiv:1305.0609 [nucl-ex].
  * [32] CMS Collaboration, V. Khachatryan et al., “Observation of Long-Range Near-Side Angular Correlations in Proton-Proton Collisions at the LHC”, JHEP 09 (2010) 091, arXiv:1009.4122 [hep-ex].
  * [33] CMS Collaboration, V. Khachatryan et al., “Long-range two-particle correlations of strange hadrons with charged particles in pPb and PbPb collisions at LHC energies”, Phys. Lett. B742 (2015) 200–224, arXiv:1409.3392 [nucl-ex].
  * [34] K. Werner, I. Karpenko, and T. Pierog, “The ’Ridge’ in Proton-Proton Scattering at 7 TeV”, Phys. Rev. Lett. 106 (2011) 122004, arXiv:1011.0375 [hep-ph].
  * [35] W.-T. Deng, Z. Xu, and C. Greiner, “Elliptic and Triangular Flow and their Correlation in Ultrarelativistic High Multiplicity Proton Proton Collisions at 14 TeV”, Phys. Lett. B711 (2012) 301–306, arXiv:1112.0470 [hep-ph].
  * [36] C.-Y. Wong, “Momentum Kick Model Description of the Ridge in $\Delta\phi$-$\Delta\eta$ Correlation in pp Collisions at 7 TeV”, Phys. Rev. C84 (2011) 024901, arXiv:1105.5871 [hep-ph].
  * [37] A. Dumitru, T. Lappi, and L. McLerran, “Are the angular correlations in $pA$ collisions due to a Glasmion or Bose condensation?”, Nucl. Phys. A922 (2014) 140–149, arXiv:1310.7136 [hep-ph].
  * [38] A. Bzdak, B. Schenke, P. Tribedy, and R. Venugopalan, “Initial state geometry and the role of hydrodynamics in proton-proton, proton-nucleus and deuteron-nucleus collisions”, Phys. Rev. C87 no. 6, (2013) 064906, arXiv:1304.3403 [nucl-th].
  * [39] K. Dusling and R. Venugopalan, “Comparison of the color glass condensate to dihadron correlations in proton-proton and proton-nucleus collisions”, Phys. Rev. D87 no. 9, (2013) 094034, arXiv:1302.7018 [hep-ph].
  * [40] B. A. Arbuzov, E. E. Boos, and V. I. Savrin, “CMS ridge effect at LHC as a manifestation of bremstralung of gluons due to the quark-anti-quark string formation”, Eur. Phys. J. C71 (2011) 1730, arXiv:1104.1283 [hep-ph].
  * [41] ALICE Collaboration, S. Acharya et al., “Azimuthal Anisotropy of Heavy-Flavor Decay Electrons in $p$-Pb Collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV”, Phys. Rev. Lett. 122 no. 7, (2019) 072301, arXiv:1805.04367 [nucl-ex].
  * [42] ALICE Collaboration, S. Acharya et al., “Search for collectivity with azimuthal J/$\psi$-hadron correlations in high multiplicity p–Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 and 8.16 TeV”, Phys. Lett. B780 (2018) 7–20, arXiv:1709.06807 [nucl-ex].
  * [43] ALICE Collaboration, J. Adam et al., “Forward-central two-particle correlations in p–Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV”, Phys. Lett. B753 (2016) 126–139, arXiv:1506.08032 [nucl-ex].
  * [44] ATLAS Collaboration, “$D$ meson production and long-range azimuthal correlation in $8.16~{}\mathrm{TeV}$ $p$+Pb collisions with ATLAS”, Tech. Rep. ATLAS-CONF-2017-073, CERN, Geneva, Sep, 2017.  http://cds.cern.ch/record/2285811.
  * [45] ATLAS Collaboration, “Measurement of the long-range pseudorapidity correlations between muons and charged-particles in $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV proton-lead collisions with the ATLAS detector”, Tech. Rep. ATLAS-CONF-2017-006, CERN, Geneva, Feb, 2017.  https://cds.cern.ch/record/2244808.
  * [46] ATLAS Collaboration, G. Aad et al., “Measurement of azimuthal anisotropy of muons from charm and bottom hadrons in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector”, arXiv:1909.01650 [nucl-ex].
  * [47] CMS Collaboration, A. M. Sirunyan et al., “Elliptic flow of charm and strange hadrons in high-multiplicity pPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 8.16 TeV”, Phys. Rev. Lett. 121 no. 8, (2018) 082301, arXiv:1804.09767 [hep-ex].
  * [48] CMS Collaboration, A. M. Sirunyan et al., “Observation of prompt J/$\psi$ meson elliptic flow in high-multiplicity pPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 8.16 TeV”, Phys. Lett. B791 (2019) 172–194, arXiv:1810.01473 [hep-ex].
  * [49] ALICE Collaboration, K. Aamodt et al., “The ALICE experiment at the CERN LHC”, JINST 3 (2008) S08002.
  * [50] ALICE Collaboration, B. Abelev et al., “Performance of the ALICE Experiment at the CERN LHC”, Int. J. Mod. Phys. A29 (2014) 1430044, arXiv:1402.4476 [nucl-ex].
  * [51] ALICE Collaboration, J. Adam et al., “Determination of the event collision time with the ALICE detector at the LHC”, Eur. Phys. J. Plus 132 no. 2, (2017) 99, arXiv:1610.03055 [physics.ins-det].
  * [52] ALICE Collaboration, E. Abbas et al., “Performance of the ALICE VZERO system”, JINST 8 (2013) P10016, arXiv:1306.3130 [nucl-ex].
  * [53] ALICE Collaboration, J. Adam et al., “Centrality dependence of particle production in p–Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV”, Phys. Rev. C91 no. 6, (2015) 064905, arXiv:1412.6828 [nucl-ex].
  * [54] R. Brun, F. Bruyant, F. Carminati, S. Giani, M. Maire, A. McPherson, G. Patrick, and L. Urban, “GEANT: Detector Description and Simulation Tool”,. http://cds.cern.ch/record/1082634.
  * [55] P. Z. Skands, “Tuning Monte Carlo Generators: The Perugia Tunes”, Phys. Rev. D82 (2010) 074018, arXiv:1005.3457 [hep-ph].
  * [56] X.-N. Wang and M. Gyulassy, “HIJING: A Monte Carlo model for multiple jet production in $\mathrm{pp}$, $\mathrm{pA}$, and $\mathrm{AA}$ collisions”, Phys. Rev. D 44 (Dec, 1991) 3501–3516.
  * [57] ALICE Collaboration, “The ALICE definition of primary particles”, Tech. Rep. ALICE-PUBLIC-2017-005, Jun, 2017.  https://cds.cern.ch/record/2270008.
  * [58] Particle Data Group Collaboration, M. Tanabashi et al., “Review of Particle Physics”, Phys. Rev. D98 no. 3, (2018) 030001.
  * [59] ALICE Collaboration, S. Acharya et al., “Measurement of ${{\mathrm{D}}^{0}}$ , ${{\mathrm{D}}^{+}}$ , ${{\mathrm{D}}^{*+}}$ and ${{\mathrm{D}}^{+}_{\mathrm{s}}}$ production in pp collisions at ${\sqrt{{\textit{s}}}~{}=~{}5.02~{}{\text{TeV}}}$ with ALICE”, Eur. Phys. J. C79 no. 5, (2019) 388, arXiv:1901.07979 [nucl-ex].
  * [60] ALICE Collaboration, S. Acharya et al., “Measurement of D-meson production at mid-rapidity in pp collisions at ${\sqrt{s}=7}$ TeV”, Eur. Phys. J. C77 no. 8, (2017) 550, arXiv:1702.00766 [hep-ex].
  * [61] R. Corke and T. Sjostrand, “Interleaved Parton Showers and Tuning Prospects”, JHEP 03 (2011) 032, arXiv:1011.1759 [hep-ph].
  * [62] S. Alioli, P. Nason, C. Oleari, and E. Re, “A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX”, JHEP 06 (2010) 043, arXiv:1002.2581 [hep-ph].
  * [63] M. Cacciari, S. Frixione, N. Houdeau, M. L. Mangano, P. Nason, and G. Ridolfi, “Theoretical predictions for charm and bottom production at the LHC”, JHEP 10 (2012) 137, arXiv:1205.6344 [hep-ph].
  * [64] K. Werner, B. Guiot, I. Karpenko, and T. Pierog, “Analysing radial flow features in p-Pb and p-p collisions at several TeV by studying identified particle production in EPOS3”, Phys. Rev. C89 no. 6, (2014) 064903, arXiv:1312.1233 [nucl-th].
  * [65] ALICE Collaboration, J. Adam et al., “Measurement of charm and beauty production at central rapidity versus charged-particle multiplicity in proton-proton collisions at $\sqrt{s}=7$ TeV”, JHEP 09 (2015) 148, arXiv:1505.00664 [nucl-ex].
  * [66] S. G. Weber, A. Dubla, A. Andronic, and A. Morsch, “Elucidating the multiplicity dependence of $\mathrm{J}/\psi$ production in proton–proton collisions with PYTHIA8”, Eur. Phys. J. C79 no. 1, (2019) 36, arXiv:1811.07744 [nucl-th].
  * [67] ALICE Collaboration, S. Acharya et al., “Transverse momentum spectra and nuclear modification factors of charged particles in pp, p–Pb and Pb–Pb collisions at the LHC”, JHEP 11 (2018) 013, arXiv:1802.09145 [nucl-ex].
  * [68] K. J. Eskola, H. Paukkunen, and C. A. Salgado, “EPS09: A New Generation of NLO and LO Nuclear Parton Distribution Functions”, JHEP 04 (2009) 065, arXiv:0902.4154 [hep-ph].
  * [69] ALICE Collaboration, J. Adam et al., “Measurement of D-meson production versus multiplicity in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV”, JHEP 08 (2016) 078, arXiv:1602.07240 [nucl-ex].

##  Appendix A The ALICE Collaboration

S. Acharyaorg141&D. Adamováorg94&A. Adlerorg74&J. Adolfssonorg80&M.M.
Aggarwalorg99&G. Aglieri Rinellaorg33&M. Agnelloorg30&N. Agrawalorg10,org53&Z.
Ahammedorg141&S. Ahmadorg16&S.U. Ahnorg76&A. Akindinovorg91&M. Al-
Turanyorg106&S.N. Alamorg141&D.S.D. Albuquerqueorg122&D. Aleksandrovorg87&B.
Alessandroorg58&H.M. Alfandaorg6&R. Alfaro Molinaorg71&B. Aliorg16&Y.
Aliorg14&A. Aliciorg10,org26,org53&A. Alkinorg2&J. Almeorg21&T. Altorg68&L.
Altenkamperorg21&I. Altsybeevorg112&M.N. Anaamorg6&C. Andreiorg47&D.
Andreouorg33&H.A. Andrewsorg110&A. Andronicorg144&M. Angelettiorg33&V.
Anguelovorg103&C. Ansonorg15&T. Antičićorg107&F. Antinoriorg56&P.
Antonioliorg53&R. Anwarorg125&N. Apadulaorg79&L. Aphecetcheorg114&H.
Appelshäuserorg68&S. Arcelliorg26&R. Arnaldiorg58&M. Arratiaorg79&I.C.
Arseneorg20&M. Arslandokorg103&A. Augustinusorg33&R. Averbeckorg106&S.
Azizorg61&M.D. Azmiorg16&A. Badalàorg55&Y.W. Baekorg40&S. Bagnascoorg58&X.
Baiorg106&R. Bailhacheorg68&R. Balaorg100&A. Baldisseriorg137&M. Ballorg42&S.
Balouzaorg104&R. Barberaorg27&L. Barioglioorg25&G.G. Barnaföldiorg145&L.S.
Barnbyorg93&V. Barretorg134&P. Bartaliniorg6&K. Barthorg33&E. Bartschorg68&F.
Baruffaldiorg28&N. Bastidorg134&S. Basuorg143&G. Batigneorg114&B.
Batyunyaorg75&D. Bauriorg48&J.L. Bazo Albaorg111&I.G. Beardenorg88&C.
Beddaorg63&N.K. Beheraorg60&I. Belikovorg136&A.D.C. Bell Hechavarriaorg144&F.
Belliniorg33&R. Bellwiedorg125&V. Belyaevorg92&G. Bencediorg145&S.
Beoleorg25&A. Bercuciorg47&Y. Berdnikovorg97&D. Berenyiorg145&R.A.
Bertensorg130&D. Berzanoorg58&M.G. Besoiuorg67&L. Betevorg33&A.
Bhasinorg100&I.R. Bhatorg100&M.A. Bhatorg3&H. Bhattorg48&B.
Bhattacharjeeorg41&A. Bianchiorg25&L. Bianchiorg25&N. Bianchiorg51&J.
Bielčíkorg36&J. Bielčíkováorg94&A. Bilandzicorg104,org117&G. Biroorg145&R.
Biswasorg3&S. Biswasorg3&J.T. Blairorg119&D. Blauorg87&C. Blumeorg68&G.
Bocaorg139&F. Bockorg33,org95&A. Bogdanovorg92&S. Boiorg23&L.
Boldizsárorg145&A. Bolozdynyaorg92&M. Bombaraorg37&G. Bonomiorg140&H.
Borelorg137&A. Borissovorg92,org144&H. Bossiorg146&E. Bottaorg25&L.
Bratrudorg68&P. Braun-Munzingerorg106&M. Bregantorg121&M. Brozorg36&E.J.
Bruckenorg43&E. Brunaorg58&G.E. Brunoorg105&M.D. Bucklandorg127&D.
Budnikovorg108&H. Bueschingorg68&S. Bufalinoorg30&O. Bugnonorg114&P.
Buhlerorg113&P. Buncicorg33&Z. Butheleziorg72,org131&J.B. Buttorg14&J.T.
Buxtonorg96&S.A. Bysiakorg118&D. Caffarriorg89&A. Calivaorg106&E. Calvo
Villarorg111&R.S. Camachoorg44&P. Cameriniorg24&A.A. Caponorg113&F.
Carnesecchiorg10,org26&R. Caronorg137&J. Castillo Castellanosorg137&A.J.
Castroorg130&E.A.R. Casulaorg54&F. Catalanoorg30&C. Ceballos Sanchezorg52&P.
Chakrabortyorg48&S. Chandraorg141&W. Changorg6&S. Chapelandorg33&M.
Chartierorg127&S. Chattopadhyayorg141&S. Chattopadhyayorg109&A.
Chauvinorg23&C. Cheshkovorg135&B. Cheynisorg135&V. Chibante Barrosoorg33&D.D.
Chinellatoorg122&S. Choorg60&P. Chochulaorg33&T. Chowdhuryorg134&P.
Christakoglouorg89&C.H. Christensenorg88&P. Christiansenorg80&T.
Chujoorg133&C. Cicaloorg54&L. Cifarelliorg10,org26&F. Cindoloorg53&J.
Cleymansorg124&F. Colamariaorg52&D. Colellaorg52&A. Colluorg79&M.
Colocciorg26&M. Concasorg58orgI&G. Conesa Balbastreorg78&Z. Conesa del
Valleorg61&G. Continorg24,org127&J.G. Contrerasorg36&T.M. Cormierorg95&Y.
Corrales Moralesorg25&P. Corteseorg31&M.R. Cosentinoorg123&F. Costaorg33&S.
Costanzaorg139&P. Crochetorg134&E. Cuautleorg69&P. Cuiorg6&L.
Cunqueiroorg95&D. Dabrowskiorg142&T. Dahmsorg104,org117&A. Daineseorg56&F.P.A.
Damasorg114,org137&M.C. Danischorg103&A. Danuorg67&D. Dasorg109&I.
Dasorg109&P. Dasorg85&P. Dasorg3&S. Dasorg3&A. Dashorg85&S. Dashorg48&S.
Deorg85&A. De Caroorg29&G. de Cataldoorg52&J. de Cuvelandorg38&A. De
Falcoorg23&D. De Gruttolaorg10&N. De Marcoorg58&S. De Pasqualeorg29&S.
Deborg49&B. Debjaniorg3&H.F. Degenhardtorg121&K.R. Dejaorg142&A.
Delofforg84&S. Delsantoorg25,org131&D. Devetakorg106&P. Dhankherorg48&D. Di
Bariorg32&A. Di Mauroorg33&R.A. Diazorg8&T. Dietelorg124&P.
Dillensegerorg68&Y. Dingorg6&R. Diviàorg33&D.U. Dixitorg19&Ø.
Djuvslandorg21&U. Dmitrievaorg62&A. Dobrinorg33,org67&B. Dönigusorg68&O.
Dordicorg20&A.K. Dubeyorg141&A. Dublaorg106&S. Dudiorg99&M. Dukhishyamorg85&P.
Dupieuxorg134&R.J. Ehlersorg146&V.N. Eikelandorg21&D. Eliaorg52&H.
Engelorg74&E. Eppleorg146&B. Erazmusorg114&F. Erhardtorg98&A.
Erokhinorg112&M.R. Ersdalorg21&B. Espagnonorg61&G. Eulisseorg33&D.
Evansorg110&S. Evdokimovorg90&L. Fabbiettiorg104,org117&M. Fagginorg28&J.
Faivreorg78&F. Fanorg6&A. Fantoniorg51&M. Faselorg95&P. Fecchioorg30&A.
Felicielloorg58&G. Feofilovorg112&A. Fernández Téllezorg44&A. Ferreroorg137&A.
Ferrettiorg25&A. Festantiorg33&V.J.G. Feuillardorg103&J. Figielorg118&S.
Filchaginorg108&D. Finogeevorg62&F.M. Fiondaorg21&G. Fiorenzaorg52&F.
Flororg125&S. Foertschorg72&P. Fokaorg106&S. Fokinorg87&E. Fragiacomoorg59&U.
Frankenfeldorg106&U. Fuchsorg33&C. Furgetorg78&A. Fursorg62&M. Fusco
Girardorg29&J.J. Gaardhøjeorg88&M. Gagliardiorg25&A.M. Gagoorg111&A.
Galorg136&C.D. Galvanorg120&P. Ganotiorg83&C. Garabatosorg106&E. Garcia-
Solisorg11&K. Gargorg27&C. Gargiuloorg33&A. Garibliorg86&K. Garnerorg144&P.
Gasikorg104,org117&E.F. Gaugerorg119&M.B. Gay Ducatiorg70&M. Germainorg114&J.
Ghoshorg109&P. Ghoshorg141&S.K. Ghoshorg3&P. Gianottiorg51&P.
Giubellinoorg58,org106&P. Giubilatoorg28&P. Glässelorg103&D.M. Goméz
Coralorg71&A. Gomez Ramirezorg74&V. Gonzalezorg106&P. González-Zamoraorg44&S.
Gorbunovorg38&L. Görlichorg118&S. Gotovacorg34&V. Grabskiorg71&L.K.
Graczykowskiorg142&K.L. Grahamorg110&L. Greinerorg79&A. Grelliorg63&C.
Grigorasorg33&V. Grigorievorg92&A. Grigoryanorg1&S. Grigoryanorg75&O.S.
Groettvikorg21&F. Grosaorg30&J.F. Grosse-Oetringhausorg33&R. Grossoorg106&R.
Guernaneorg78&M. Guittiereorg114&K. Gulbrandsenorg88&T. Gunjiorg132&A.
Guptaorg100&R. Guptaorg100&I.B. Guzmanorg44&R. Haakeorg146&M.K. Habiborg106&C.
Hadjidakisorg61&H. Hamagakiorg81&G. Hamarorg145&M. Hamidorg6&R.
Hanniganorg119&M.R. Haqueorg63,org85&A. Harlenderovaorg106&J.W.
Harrisorg146&A. Hartonorg11&J.A. Hasenbichlerorg33&H. Hassanorg95&D.
Hatzifotiadouorg10,org53&P. Hauerorg42&S. Hayashiorg132&S.T.
Heckelorg68,org104&E. Hellbärorg68&H. Helstruporg35&A. Herghelegiuorg47&T.
Hermanorg36&E.G. Hernandezorg44&G. Herrera Corralorg9&F. Herrmannorg144&K.F.
Hetlandorg35&T.E. Hildenorg43&H. Hillemannsorg33&C. Hillsorg127&B.
Hippolyteorg136&B. Hohlwegerorg104&D. Horakorg36&A. Hornungorg68&S.
Hornungorg106&R. Hosokawaorg15,org133&P. Hristovorg33&C. Huangorg61&C.
Hughesorg130&P. Huhnorg68&T.J. Humanicorg96&H. Hushnudorg109&L.A.
Husovaorg144&N. Hussainorg41&S.A. Hussainorg14&D. Hutterorg38&J.P.
Iddonorg33,org127&R. Ilkaevorg108&M. Inabaorg133&G.M. Innocentiorg33&M.
Ippolitovorg87&A. Isakovorg94&M.S. Islamorg109&M. Ivanovorg106&V.
Ivanovorg97&V. Izucheevorg90&B. Jacakorg79&N. Jacazioorg53&P.M. Jacobsorg79&S.
Jadlovskaorg116&J. Jadlovskyorg116&S. Jaelaniorg63&C. Jahnkeorg121&M.J.
Jakubowskaorg142&M.A. Janikorg142&T. Jansonorg74&M. Jercicorg98&O.
Jevonsorg110&M. Jinorg125&F. Jonasorg95,org144&P.G. Jonesorg110&J.
Jungorg68&M. Jungorg68&A. Juskoorg110&P. Kalinakorg64&A. Kalweitorg33&V.
Kaplinorg92&S. Karorg6&A. Karasu Uysalorg77&O. Karavichevorg62&T.
Karavichevaorg62&P. Karczmarczykorg33&E. Karpechevorg62&A. Kazantsevorg87&U.
Kebschullorg74&R. Keidelorg46&M. Keilorg33&B. Ketzerorg42&Z.
Khabanovaorg89&A.M. Khanorg6&S. Khanorg16&S.A. Khanorg141&A.
Khanzadeevorg97&Y. Kharlovorg90&A. Khatunorg16&A. Khuntiaorg118&B.
Kilengorg35&B. Kimorg60&B. Kimorg133&D. Kimorg147&D.J. Kimorg126&E.J.
Kimorg73&H. Kimorg17,org147&J. Kimorg147&J.S. Kimorg40&J. Kimorg103&J.
Kimorg147&J. Kimorg73&M. Kimorg103&S. Kimorg18&T. Kimorg147&T. Kimorg147&S.
Kirschorg38,org68&I. Kiselorg38&S. Kiselevorg91&A. Kisielorg142&J.L.
Klayorg5&C. Kleinorg68&J. Kleinorg58&S. Kleinorg79&C. Klein-Bösingorg144&M.
Kleinerorg68&A. Klugeorg33&M.L. Knichelorg33&A.G. Knospeorg125&C.
Kobdajorg115&M.K. Köhlerorg103&T. Kolleggerorg106&A. Kondratyevorg75&N.
Kondratyevaorg92&E. Kondratyukorg90&J. Konigorg68&P.J. Konopkaorg33&L.
Koskaorg116&O. Kovalenkoorg84&V. Kovalenkoorg112&M. Kowalskiorg118&I.
Králikorg64&A. Kravčákováorg37&L. Kreisorg106&M. Krivdaorg64,org110&F.
Krizekorg94&K. Krizkova Gajdosovaorg36&M. Krügerorg68&E. Kryshenorg97&M.
Krzewickiorg38&A.M. Kuberaorg96&V. Kučeraorg60&C. Kuhnorg136&P.G.
Kuijerorg89&L. Kumarorg99&S. Kumarorg48&S. Kunduorg85&P. Kurashviliorg84&A.
Kurepinorg62&A.B. Kurepinorg62&A. Kuryakinorg108&S. Kushpilorg94&J.
Kvapilorg110&M.J. Kweonorg60&J.Y. Kwonorg60&Y. Kwonorg147&S.L. La
Pointeorg38&P. La Roccaorg27&Y.S. Laiorg79&R. Langoyorg129&K. Lapidusorg33&A.
Lardeuxorg20&P. Larionovorg51&E. Laudiorg33&R. Lavickaorg36&T.
Lazarevaorg112&R. Leaorg24&L. Leardiniorg103&J. Leeorg133&S. Leeorg147&F.
Lehasorg89&S. Lehnerorg113&J. Lehrbachorg38&R.C. Lemmonorg93&I. León
Monzónorg120&E.D. Lesserorg19&M. Lettrichorg33&P. Lévaiorg145&X. Liorg12&X.L.
Liorg6&J. Lienorg129&R. Lietavaorg110&B. Limorg17&V. Lindenstruthorg38&S.W.
Lindsayorg127&C. Lippmannorg106&M.A. Lisaorg96&V. Litichevskyiorg43&A.
Liuorg19&S. Liuorg96&W.J. Llopeorg143&I.M. Lofnesorg21&V. Loginovorg92&C.
Loizidesorg95&P. Loncarorg34&X. Lopezorg134&E. López Torresorg8&J.R.
Luhderorg144&M. Lunardonorg28&G. Luparelloorg59&Y. Maorg39&A.
Maevskayaorg62&M. Magerorg33&S.M. Mahmoodorg20&T. Mahmoudorg42&A.
Maireorg136&R.D. Majkaorg146&M. Malaevorg97&Q.W. Malikorg20&L.
Malininaorg75orgII&D. Mal’Kevichorg91&P. Malzacherorg106&G. Mandaglioorg55&V.
Mankoorg87&F. Mansoorg134&V. Manzariorg52&Y. Maoorg6&M. Marchisoneorg135&J.
Marešorg66&G.V. Margagliottiorg24&A. Margottiorg53&J. Marguttiorg63&A.
Marínorg106&C. Markertorg119&M. Marquardorg68&N.A. Martinorg103&P.
Martinengoorg33&J.L. Martinezorg125&M.I. Martínezorg44&G. Martínez
Garcíaorg114&M. Martinez Pedreiraorg33&S. Masciocchiorg106&M. Maseraorg25&A.
Masoniorg54&L. Massacrierorg61&E. Massonorg114&A. Mastroserioorg52,org138&A.M.
Mathisorg104,org117&O. Matonohaorg80&P.F.T. Matuokaorg121&A. Matyjaorg118&C.
Mayerorg118&M. Mazzilliorg52&M.A. Mazzoniorg57&A.F. Mechlerorg68&F.
Meddiorg22&Y. Melikyanorg62,org92&A. Menchaca-Rochaorg71&C. Mengkeorg6&E.
Meninnoorg29,org113&M. Meresorg13&S. Mhlangaorg124&Y. Miakeorg133&L.
Michelettiorg25&D.L. Mihaylovorg104&K. Mikhaylovorg75,org91&A.
Mischkeorg63org*&A.N. Mishraorg69&D. Miśkowiecorg106&A. Modakorg3&N.
Mohammadiorg33&A.P. Mohantyorg63&B. Mohantyorg85&M. Mohisin Khanorg16orgIII&C.
Mordasiniorg104&D.A. Moreira De Godoyorg144&L.A.P. Morenoorg44&I.
Morozovorg62&A. Morschorg33&T. Mrnjavacorg33&V. Mucciforaorg51&E.
Mudnicorg34&D. Mühlheimorg144&S. Muhuriorg141&J.D. Mulliganorg79&M.G.
Munhozorg121&R.H. Munzerorg68&H. Murakamiorg132&S. Murrayorg124&L.
Musaorg33&J. Musinskyorg64&C.J. Myersorg125&J.W. Myrchaorg142&B. Naikorg48&R.
Nairorg84&B.K. Nandiorg48&R. Naniaorg10,org53&E. Nappiorg52&M.U.
Naruorg14&A.F. Nassirpourorg80&C. Nattrassorg130&R. Nayakorg48&T.K.
Nayakorg85&S. Nazarenkoorg108&A. Neaguorg20&R.A. Negrao De Oliveiraorg68&L.
Nellenorg69&S.V. Nesboorg35&G. Neskovicorg38&D. Nesterovorg112&L.T.
Neumannorg142&B.S. Nielsenorg88&S. Nikolaevorg87&S. Nikulinorg87&V.
Nikulinorg97&F. Noferiniorg10,org53&P. Nomokonovorg75&J. Normanorg78,org127&N.
Novitzkyorg133&P. Nowakowskiorg142&A. Nyaninorg87&J. Nystrandorg21&M.
Oginoorg81&A. Ohlsonorg80,org103&J. Oleniaczorg142&A.C. Oliveira Da
Silvaorg121,org130&M.H. Oliverorg146&C. Oppedisanoorg58&R. Oravaorg43&A. Ortiz
Velasquezorg69&A. Oskarssonorg80&J. Otwinowskiorg118&K. Oyamaorg81&Y.
Pachmayerorg103&V. Pacikorg88&D. Paganoorg140&G. Paićorg69&J. Panorg143&A.K.
Pandeyorg48&S. Panebiancoorg137&P. Pareekorg49,org141&J. Parkorg60&J.E.
Parkkilaorg126&S. Parmarorg99&S.P. Pathakorg125&R.N. Patraorg141&B.
Paulorg23,org58&H. Peiorg6&T. Peitzmannorg63&X. Pengorg6&L.G. Pereiraorg70&H.
Pereira Da Costaorg137&D. Peresunkoorg87&G.M. Perezorg8&E. Perez
Lezamaorg68&V. Peskovorg68&Y. Pestovorg4&V. Petráčekorg36&M.
Petroviciorg47&R.P. Pezziorg70&S. Pianoorg59&M. Piknaorg13&P. Pillotorg114&O.
Pinazzaorg33,org53&L. Pinskyorg125&C. Pintoorg27&S. Pisanoorg10,org51&D.
Pistoneorg55&M. Płoskońorg79&M. Planinicorg98&F. Pliquettorg68&J.
Plutaorg142&S. Pochybovaorg145org*&M.G. Poghosyanorg95&B. Polichtchoukorg90&N.
Poljakorg98&A. Poporg47&H. Poppenborgorg144&S. Porteboeuf-Houssaisorg134&V.
Pozdniakovorg75&S.K. Prasadorg3&R. Preghenellaorg53&F. Prinoorg58&C.A.
Pruneauorg143&I. Pshenichnovorg62&M. Puccioorg25,org33&J. Putschkeorg143&R.E.
Quishpeorg125&S. Ragoniorg110&S. Rahaorg3&S. Rajputorg100&J. Rakorg126&A.
Rakotozafindrabeorg137&L. Ramelloorg31&F. Ramiorg136&R. Raniwalaorg101&S.
Raniwalaorg101&S.S. Räsänenorg43&R. Rathorg49&V. Ratzaorg42&I.
Ravasengaorg30,org89&K.F. Readorg95,org130&K. Redlichorg84orgIV&A.
Rehmanorg21&P. Reicheltorg68&F. Reidtorg33&X. Renorg6&R. Renfordtorg68&Z.
Rescakovaorg37&J.-P. Revolorg10&K. Reygersorg103&V. Riabovorg97&T.
Richertorg80,org88&M. Richterorg20&P. Riedlerorg33&W. Rieglerorg33&F.
Riggiorg27&C. Risteaorg67&S.P. Rodeorg49&M. Rodríguez Cahuantziorg44&K.
Røedorg20&R. Rogalevorg90&E. Rogochayaorg75&D. Rohrorg33&D. Röhrichorg21&P.S.
Rokitaorg142&F. Ronchettiorg51&E.D. Rosasorg69&K. Roslonorg142&A.
Rossiorg28,org56&A. Rotondiorg139&A. Royorg49&P. Royorg109&O.V. Ruedaorg80&R.
Ruiorg24&B. Rumyantsevorg75&A. Rustamovorg86&E. Ryabinkinorg87&Y.
Ryabovorg97&A. Rybickiorg118&H. Rytkonenorg126&O.A.M. Saarimakiorg43&S.
Sadhuorg141&S. Sadovskyorg90&K. Šafaříkorg36&S.K. Sahaorg141&B. Sahooorg48&P.
Sahooorg48,org49&R. Sahooorg49&S. Sahooorg65&P.K. Sahuorg65&J. Sainiorg141&S.
Sakaiorg133&S. Sambyalorg100&V. Samsonovorg92,org97&D. Sarkarorg143&N.
Sarkarorg141&P. Sarmaorg41&V.M. Sartiorg104&M.H.P. Sasorg63&E.
Scapparoneorg53&B. Schaeferorg95&J. Schambachorg119&H.S. Scheidorg68&C.
Schiauaorg47&R. Schickerorg103&A. Schmahorg103&C. Schmidtorg106&H.R.
Schmidtorg102&M.O. Schmidtorg103&M. Schmidtorg102&N.V. Schmidtorg68,org95&A.R.
Schmierorg130&J. Schukraftorg88&Y. Schutzorg33,org136&K. Schwarzorg106&K.
Schwedaorg106&G. Scioliorg26&E. Scomparinorg58&M. Šefčíkorg37&J.E.
Segerorg15&Y. Sekiguchiorg132&D. Sekihataorg132&I. Selyuzhenkovorg92,org106&S.
Senyukovorg136&D. Serebryakovorg62&E. Serradillaorg71&A. Sevcencoorg67&A.
Shabanovorg62&A. Shabetaiorg114&R. Shahoyanorg33&W. Shaikhorg109&A.
Shangaraevorg90&A. Sharmaorg99&A. Sharmaorg100&H. Sharmaorg118&M.
Sharmaorg100&N. Sharmaorg99&A.I. Sheikhorg141&K. Shigakiorg45&M.
Shimomuraorg82&S. Shirinkinorg91&Q. Shouorg39&Y. Sibiriakorg87&S.
Siddhantaorg54&T. Siemiarczukorg84&D. Silvermyrorg80&G. Simatovicorg89&G.
Simonettiorg33,org104&R. Singhorg85&R. Singhorg100&R. Singhorg49&V.K.
Singhorg141&V. Singhalorg141&T. Sinhaorg109&B. Sitarorg13&M. Sittaorg31&T.B.
Skaaliorg20&M. Slupeckiorg126&N. Smirnovorg146&R.J.M. Snellingsorg63&T.W.
Snellmanorg43,org126&C. Sonccoorg111&J. Songorg60,org125&A.
Songmoolnakorg115&F. Soramelorg28&S. Sorensenorg130&I. Sputowskaorg118&J.
Stachelorg103&I. Stanorg67&P. Stankusorg95&P.J. Steffanicorg130&E.
Stenlundorg80&D. Stoccoorg114&M.M. Storetvedtorg35&L.D. Strittoorg29&A.A.P.
Suaideorg121&T. Sugitateorg45&C. Suireorg61&M. Suleymanovorg14&M.
Suljicorg33&R. Sultanovorg91&M. Šumberaorg94&S. Sumowidagdoorg50&S.
Swainorg65&A. Szaboorg13&I. Szarkaorg13&U. Tabassamorg14&G.
Taillepiedorg134&J. Takahashiorg122&G.J. Tambaveorg21&S. Tangorg6,org134&M.
Tarhiniorg114&M.G. Tarzilaorg47&A. Tauroorg33&G. Tejeda Muñozorg44&A.
Telescaorg33&C. Terrevoliorg125&D. Thakurorg49&S. Thakurorg141&D.
Thomasorg119&F. Thoresenorg88&R. Tieulentorg135&A. Tikhonovorg62&A.R.
Timminsorg125&A. Toiaorg68&N. Topilskayaorg62&M. Toppiorg51&F. Torales-
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Tripathyorg48&S. Trogoloorg28&G. Trombettaorg32&L. Tropporg37&V.
Trubnikovorg2&W.H. Trzaskaorg126&T.P. Trzcinskiorg142&B.A. Trzeciakorg63&T.
Tsujiorg132&A. Tumkinorg108&R. Turrisiorg56&T.S. Tveterorg20&K.
Ullalandorg21&E.N. Umakaorg125&A. Urasorg135&G.L. Usaiorg23&A.
Utrobicicorg98&M. Valaorg37&N. Valleorg139&S. Valleroorg58&N. van der
Kolkorg63&L.V.R. van Doremalenorg63&M. van Leeuwenorg63&P. Vande Vyvreorg33&D.
Vargaorg145&Z. Vargaorg145&M. Varga-Kofaragoorg145&A. Vargasorg44&M.
Vasileiouorg83&A. Vasilievorg87&O. Vázquez Doceorg104,org117&V.
Vecherninorg112&A.M. Veenorg63&E. Vercellinorg25&S. Vergara Limónorg44&L.
Vermuntorg63&R. Vernetorg7&R. Vértesiorg145&L. Vickovicorg34&Z.
Vilakaziorg131&O. Villalobos Baillieorg110&A. Villatoro Telloorg44&G.
Vinoorg52&A. Vinogradovorg87&T. Virgiliorg29&V. Vislaviciusorg88&A.
Vodopyanovorg75&B. Volkelorg33&M.A. Völklorg102&K. Voloshinorg91&S.A.
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Zaviyalovorg108&H. Zbroszczykorg142&M. Zhalovorg97&S. Zhangorg39&X.
Zhangorg6&Z. Zhangorg6&V. Zherebchevskiiorg112&D. Zhouorg6&Y. Zhouorg88&Z.
Zhouorg21&J. Zhuorg6,org106&Y. Zhuorg6&A. Zichichiorg10,org26&M.B.
Zimmermannorg33&G. Zinovjevorg2&N. Zurloorg140&

## Affiliation notes

org*Deceased

orgIDipartimento DET del Politecnico di Torino, Turin, Italy

orgIIM.V. Lomonosov Moscow State University, D.V. Skobeltsyn Institute of
Nuclear, Physics, Moscow, Russia

orgIIIDepartment of Applied Physics, Aligarh Muslim University, Aligarh, India

orgIVInstitute of Theoretical Physics, University of Wroclaw, Poland

## Collaboration Institutes

org1A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute)
Foundation, Yerevan, Armenia

org2Bogolyubov Institute for Theoretical Physics, National Academy of Sciences
of Ukraine, Kiev, Ukraine

org3Bose Institute, Department of Physics and Centre for Astroparticle Physics
and Space Science (CAPSS), Kolkata, India

org4Budker Institute for Nuclear Physics, Novosibirsk, Russia

org5California Polytechnic State University, San Luis Obispo, California,
United States

org6Central China Normal University, Wuhan, China

org7Centre de Calcul de l’IN2P3, Villeurbanne, Lyon, France

org8Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana,
Cuba

org9Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City
and Mérida, Mexico

org10Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche
“Enrico Fermi’, Rome, Italy

org11Chicago State University, Chicago, Illinois, United States

org12China Institute of Atomic Energy, Beijing, China

org13Comenius University Bratislava, Faculty of Mathematics, Physics and
Informatics, Bratislava, Slovakia

org14COMSATS University Islamabad, Islamabad, Pakistan

org15Creighton University, Omaha, Nebraska, United States

org16Department of Physics, Aligarh Muslim University, Aligarh, India

org17Department of Physics, Pusan National University, Pusan, Republic of
Korea

org18Department of Physics, Sejong University, Seoul, Republic of Korea

org19Department of Physics, University of California, Berkeley, California,
United States

org20Department of Physics, University of Oslo, Oslo, Norway

org21Department of Physics and Technology, University of Bergen, Bergen,
Norway

org22Dipartimento di Fisica dell’Università ’La Sapienza’ and Sezione INFN,
Rome, Italy

org23Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy

org24Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy

org25Dipartimento di Fisica dell’Università and Sezione INFN, Turin, Italy

org26Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN,
Bologna, Italy

org27Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN,
Catania, Italy

org28Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN,
Padova, Italy

org29Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Gruppo
Collegato INFN, Salerno, Italy

org30Dipartimento DISAT del Politecnico and Sezione INFN, Turin, Italy

org31Dipartimento di Scienze e Innovazione Tecnologica dell’Università del
Piemonte Orientale and INFN Sezione di Torino, Alessandria, Italy

org32Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari,
Italy

org33European Organization for Nuclear Research (CERN), Geneva, Switzerland

org34Faculty of Electrical Engineering, Mechanical Engineering and Naval
Architecture, University of Split, Split, Croatia

org35Faculty of Engineering and Science, Western Norway University of Applied
Sciences, Bergen, Norway

org36Faculty of Nuclear Sciences and Physical Engineering, Czech Technical
University in Prague, Prague, Czech Republic

org37Faculty of Science, P.J. Šafárik University, Košice, Slovakia

org38Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-
Universität Frankfurt, Frankfurt, Germany

org39Fudan University, Shanghai, China

org40Gangneung-Wonju National University, Gangneung, Republic of Korea

org41Gauhati University, Department of Physics, Guwahati, India

org42Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-
Wilhelms-Universität Bonn, Bonn, Germany

org43Helsinki Institute of Physics (HIP), Helsinki, Finland

org44High Energy Physics Group, Universidad Autónoma de Puebla, Puebla, Mexico

org45Hiroshima University, Hiroshima, Japan

org46Hochschule Worms, Zentrum für Technologietransfer und Telekommunikation
(ZTT), Worms, Germany

org47Horia Hulubei National Institute of Physics and Nuclear Engineering,
Bucharest, Romania

org48Indian Institute of Technology Bombay (IIT), Mumbai, India

org49Indian Institute of Technology Indore, Indore, India

org50Indonesian Institute of Sciences, Jakarta, Indonesia

org51INFN, Laboratori Nazionali di Frascati, Frascati, Italy

org52INFN, Sezione di Bari, Bari, Italy

org53INFN, Sezione di Bologna, Bologna, Italy

org54INFN, Sezione di Cagliari, Cagliari, Italy

org55INFN, Sezione di Catania, Catania, Italy

org56INFN, Sezione di Padova, Padova, Italy

org57INFN, Sezione di Roma, Rome, Italy

org58INFN, Sezione di Torino, Turin, Italy

org59INFN, Sezione di Trieste, Trieste, Italy

org60Inha University, Incheon, Republic of Korea

org61Institut de Physique Nucléaire d’Orsay (IPNO), Institut National de
Physique Nucléaire et de Physique des Particules (IN2P3/CNRS), Université de
Paris-Sud, Université Paris-Saclay, Orsay, France

org62Institute for Nuclear Research, Academy of Sciences, Moscow, Russia

org63Institute for Subatomic Physics, Utrecht University/Nikhef, Utrecht,
Netherlands

org64Institute of Experimental Physics, Slovak Academy of Sciences, Košice,
Slovakia

org65Institute of Physics, Homi Bhabha National Institute, Bhubaneswar, India

org66Institute of Physics of the Czech Academy of Sciences, Prague, Czech
Republic

org67Institute of Space Science (ISS), Bucharest, Romania

org68Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt,
Frankfurt, Germany

org69Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México,
Mexico City, Mexico

org70Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS),
Porto Alegre, Brazil

org71Instituto de Física, Universidad Nacional Autónoma de México, Mexico
City, Mexico

org72iThemba LABS, National Research Foundation, Somerset West, South Africa

org73Jeonbuk National University, Jeonju, Republic of Korea

org74Johann-Wolfgang-Goethe Universität Frankfurt Institut für Informatik,
Fachbereich Informatik und Mathematik, Frankfurt, Germany

org75Joint Institute for Nuclear Research (JINR), Dubna, Russia

org76Korea Institute of Science and Technology Information, Daejeon, Republic
of Korea

org77KTO Karatay University, Konya, Turkey

org78Laboratoire de Physique Subatomique et de Cosmologie, Université
Grenoble-Alpes, CNRS-IN2P3, Grenoble, France

org79Lawrence Berkeley National Laboratory, Berkeley, California, United
States

org80Lund University Department of Physics, Division of Particle Physics,
Lund, Sweden

org81Nagasaki Institute of Applied Science, Nagasaki, Japan

org82Nara Women’s University (NWU), Nara, Japan

org83National and Kapodistrian University of Athens, School of Science,
Department of Physics , Athens, Greece

org84National Centre for Nuclear Research, Warsaw, Poland

org85National Institute of Science Education and Research, Homi Bhabha
National Institute, Jatni, India

org86National Nuclear Research Center, Baku, Azerbaijan

org87National Research Centre Kurchatov Institute, Moscow, Russia

org88Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark

org89Nikhef, National institute for subatomic physics, Amsterdam, Netherlands

org90NRC Kurchatov Institute IHEP, Protvino, Russia

org91NRC «Kurchatov Institute» - ITEP, Moscow, Russia

org92NRNU Moscow Engineering Physics Institute, Moscow, Russia

org93Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, United
Kingdom

org94Nuclear Physics Institute of the Czech Academy of Sciences, Řež u Prahy,
Czech Republic

org95Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

org96Ohio State University, Columbus, Ohio, United States

org97Petersburg Nuclear Physics Institute, Gatchina, Russia

org98Physics department, Faculty of science, University of Zagreb, Zagreb,
Croatia

org99Physics Department, Panjab University, Chandigarh, India

org100Physics Department, University of Jammu, Jammu, India

org101Physics Department, University of Rajasthan, Jaipur, India

org102Physikalisches Institut, Eberhard-Karls-Universität Tübingen, Tübingen,
Germany

org103Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg,
Heidelberg, Germany

org104Physik Department, Technische Universität München, Munich, Germany

org105Politecnico di Bari, Bari, Italy

org106Research Division and ExtreMe Matter Institute EMMI, GSI
Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany

org107Rudjer Bošković Institute, Zagreb, Croatia

org108Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

org109Saha Institute of Nuclear Physics, Homi Bhabha National Institute,
Kolkata, India

org110School of Physics and Astronomy, University of Birmingham, Birmingham,
United Kingdom

org111Sección Física, Departamento de Ciencias, Pontificia Universidad
Católica del Perú, Lima, Peru

org112St. Petersburg State University, St. Petersburg, Russia

org113Stefan Meyer Institut für Subatomare Physik (SMI), Vienna, Austria

org114SUBATECH, IMT Atlantique, Université de Nantes, CNRS-IN2P3, Nantes,
France

org115Suranaree University of Technology, Nakhon Ratchasima, Thailand

org116Technical University of Košice, Košice, Slovakia

org117Technische Universität München, Excellence Cluster ’Universe’, Munich,
Germany

org118The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy
of Sciences, Cracow, Poland

org119The University of Texas at Austin, Austin, Texas, United States

org120Universidad Autónoma de Sinaloa, Culiacán, Mexico

org121Universidade de São Paulo (USP), São Paulo, Brazil

org122Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil

org123Universidade Federal do ABC, Santo Andre, Brazil

org124University of Cape Town, Cape Town, South Africa

org125University of Houston, Houston, Texas, United States

org126University of Jyväskylä, Jyväskylä, Finland

org127University of Liverpool, Liverpool, United Kingdom

org128University of Science and Techonology of China, Hefei, China

org129University of South-Eastern Norway, Tonsberg, Norway

org130University of Tennessee, Knoxville, Tennessee, United States

org131University of the Witwatersrand, Johannesburg, South Africa

org132University of Tokyo, Tokyo, Japan

org133University of Tsukuba, Tsukuba, Japan

org134Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France

org135Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon,
Villeurbanne, Lyon, France

org136Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg,
France, Strasbourg, France

org137Université Paris-Saclay Centre d’Etudes de Saclay (CEA), IRFU,
Départment de Physique Nucléaire (DPhN), Saclay, France

org138Università degli Studi di Foggia, Foggia, Italy

org139Università degli Studi di Pavia, Pavia, Italy

org140Università di Brescia, Brescia, Italy

org141Variable Energy Cyclotron Centre, Homi Bhabha National Institute,
Kolkata, India

org142Warsaw University of Technology, Warsaw, Poland

org143Wayne State University, Detroit, Michigan, United States

org144Westfälische Wilhelms-Universität Münster, Institut für Kernphysik,
Münster, Germany

org145Wigner Research Centre for Physics, Budapest, Hungary

org146Yale University, New Haven, Connecticut, United States

org147Yonsei University, Seoul, Republic of Korea