2015 155 22 June

Forward-central two-particle correlations in p–Pb collisions ALICE
Collaboration††thanks: See Appendix A for the list of collaboration members
ALICE Collaboration

Two-particle angular correlations between trigger particles in the forward
pseudorapidity range ($2.5<|\eta|<4.0$) and associated particles in the
central range ($|\eta|<1.0$) are measured with the ALICE detector in p–Pb
collisions at a nucleon–nucleon centre-of-mass energy of 5.02 TeV. The trigger
particles are reconstructed using the muon spectrometer, and the associated
particles by the central barrel tracking detectors. In high-multiplicity
events, the double-ridge structure, previously discovered in two-particle
angular correlations at midrapidity, is found to persist to the pseudorapidity
ranges studied in this Letter. The second-order Fourier coefficients for muons
in high-multiplicity events are extracted after jet-like correlations from
low-multiplicity events have been subtracted. The coefficients are found to
have a similar transverse momentum ($p_{\mathrm{T}}$) dependence in p-going
(p–Pb) and Pb-going (Pb–p) configurations, with the Pb-going coefficients
larger by about $16\pm 6$%, rather independent of $p_{\mathrm{T}}$ within the
uncertainties of the measurement. The data are compared with calculations
using the AMPT model, which predicts a different $p_{\mathrm{T}}$ and $\eta$
dependence than observed in the data. The results are sensitive to the parent
particle $v_{2}$ and composition of reconstructed muon tracks, where the
contribution from heavy flavour decays is expected to dominate at
$p_{\mathrm{T}}>2$ GeV/$c$.

##  1 Introduction

Measurements of correlations in $\Delta\varphi$ and $\Delta\eta$, where
$\Delta\varphi$ and $\Delta\eta$ are the differences in azimuthal angle
($\varphi$) and pseudorapidity ($\eta$) between two particles, respectively,
provide insight on the underlying mechanism of particle production in
collisions of hadrons and nuclei at high energy.

For such measurements in proton–proton (pp) collisions, jet production leads
to a characteristic peak-like structure on the “near side” (at
$\Delta\varphi\approx 0$, $\Delta\eta\approx 0$) and an elongated structure in
$\Delta\eta$ on the “away side” (at $\Delta\varphi\approx\pi$) [1]. In
nucleus–nucleus (A–A) collisions, ridge-like structures extending over a long
range along the $\Delta\eta$ axis emerge on the near and away sides, in
addition to the jet-related correlations [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14]. The Fourier decomposition of the correlation in $\Delta\varphi$ at
large $\Delta\eta$ is dominated by the second- and third-order harmonic
coefficients $v_{2}$ and $v_{3}$, but significant harmonics have been measured
up to $v_{6}$ [11, 12, 7, 6, 9, 13, 14, 10, 15, 16]. In A–A collisions, the
$v_{n}$ coefficients are interpreted as the collective response of the created
matter to the collision geometry and fluctuations in the initial state [17,
18], and are used to extract its transport properties in hydrodynamic models
[19, 20, 21].

Long-range ridge structures on the near side ($\Delta\varphi\approx 0$) were
also observed in high-multiplicity pp collisions at a centre-of-mass energy
$\sqrt{s}=$ 7 TeV [22] and in proton–lead (p–Pb) collisions at a
nucleon–nucleon centre-of-mass energy $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV [23].
Shortly after, measurements in which the contributions from jet fragmentation
were suppressed by subtracting the correlations extracted from low-
multiplicity events, revealed the presence of essentially the same long-range
structures on the away side as on the near side in high-multiplicity events
[24, 25]. Evidence of long-range double-ridge structures in high-multiplicity
deuteron–gold (d–Au) collisions at $\sqrt{s_{\mathrm{NN}}}=$ 0.2 TeV was also
reported [26]. By now, the existence of long-range correlations in p–Pb
collisions is firmly established by measurements [27, 28, 29, 30, 31]
involving four, six or more particle correlations, with the lower-order
correlations removed [32], demonstrating that the long-range ridges originate
from genuine multi-particle correlations. Intriguingly, the transverse
momentum dependence of the extracted $v_{n}$ [27, 28, 30], and the particle-
mass dependence of $v_{n}$ [33, 34, 35] are found to be qualitatively similar
to those measured in A–A collisions.

The similarity of the ridges in the pp, p–Pb, d–Au and A–A systems suggests
the possibility of a common hydrodynamical origin [36, 37, 38, 39, 40, 41, 42,
43]. However, whether hydrodynamical models can indeed be reliably applied to
such small systems is under intense debate [44]. Other proposed mechanisms
involve initial-state effects, such as gluon saturation and extended color
connections forming along the longitudinal direction [45, 46, 47, 48, 49] or
final-state parton–parton induced interactions [50, 51, 52, 53, 54].

Further insight into the production mechanism of these long-range correlation
structures may be gained by studying their $\eta$-dependence. A preliminary
result [55] indicates a mild $\eta$ dependence, but the measurement is limited
to $|\eta|<2$. A similar magnitude of the two-particle correlation amplitudes
in the Au-going and d-going directions at $2.8<|\eta|<3.8$ has also been
reported in d–Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 0.2 TeV [56].
Calculations for $v_{2}$ at large $\eta$ ($2.5<|\eta|<4$) in p–Pb collisions
at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV from a 3+1 dimensional, viscous
hydrodynamical model and a multi-phase transport model (AMPT) predict a
stronger $\eta$ dependence, with about 50% and 30% larger $v_{2}$ values on
the lead nucleus side for the hydrodynamical and AMPT model, respectively
[57].

In this Letter, we report a measurement of angular correlations between
trigger particles in the pseudorapidity range $2.5<|\eta|<4.0$ and associated
particles in the central range $|\eta|<1.0$ in p–Pb collisions at
$\sqrt{s_{\mathrm{NN}}}=$5.02 TeV at the Large Hadron Collider (LHC). The
trigger particles are inclusive muons, reconstructed using the ALICE muon
spectrometer, and the associated particles are charged particles,
reconstructed by the ALICE central barrel tracking detectors. As in previous
measurements [24, 33], the double ridge is extracted by subtracting the
correlations obtained in low-multiplicity events from those in high-
multiplicity events. Results for the second order Fourier coefficient for
muons, $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$, and the ratio of
$v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ coefficients111Here, and in the following,
“2PC” stands for “two-particle correlation” and “sub” for “subtraction”, and
indicates the analysis technique with which the coefficients are measured. in
the Pb-going (Pb–p) and p-going (p–Pb) directions are reported for high-
multiplicity events, and compared to model predictions. The remainder of the
Letter is structured as follows: We describe the experimental setup in Sec. 2,
the event and track selection in Sec. 3, the analysis method in Sec. 4 and the
evaluation of the systematic uncertainties in Sec. 5. Finally, in Sec. 6 we
report the results, and compare them with model predictions. In Sec. 7 we
conclude with a summary.

##  2 Experimental setup

In 2013, the LHC provided collisions between protons with a beam energy of 4
TeV and lead ions with a beam energy of 1.58 TeV per nucleon, resulting in a
centre-of-mass energy of $\sqrt{s_{\mathrm{NN}}}=5.02\,\mathrm{TeV}$. The
beams were set up in two configurations: a period with the proton momentum in
the direction of negative $\eta$ in the ALICE coordinate system, denoted as
p–Pb, followed by a period with reversed beams, denoted as Pb–p. Due to the
asymmetric beam energies, the nucleon-nucleon centre-of-mass reference system
moves with a rapidity of 0.465 in the direction of the proton beam with
respect to the ALICE laboratory system. Pseudorapidity, denoted by $\eta$, is
given in the laboratory frame throughout this Letter.

Details on ALICE and its subdetectors can be found in Refs. [58, 59]. In the
following, we give a brief summary of the components needed for the
measurement reported in the Letter.

Trigger tracks used in this analysis are detected in the muon spectrometer
with an acceptance of $-4.0<\eta<-2.5$. The muon spectrometer consists of a
thick absorber of about ten interaction lengths ($\lambda_{\rm I}$), which
filters muons in front of five tracking stations made of two planes of Cathode
Pad Chambers each. The third station is placed inside a dipole magnet with a 3
Tm integrated field. The tracking apparatus is completed by a trigger system
made of four layers of Resistive Plate Chambers placed behind a second
absorber of 7.2 $\lambda_{\rm I}$ thickness. This setup ensures that most of
the hadrons in the acceptance are stopped in one of the absorber layers,
providing a muon purity above 99% for the tracks used in this analysis. In
p–Pb collisions, the trigger particle travels in the same direction as the p
beam (p-going case), while in Pb–p collisions in the same direction as the Pb
nucleus (Pb-going case).

Associated particles in $|\eta|<1.0$ are reconstructed using the combined
information from the Inner Tracking System (ITS) and the Time Projection
Chamber (TPC), which are located inside the ALICE solenoid with a field of 0.5
T. The ITS consists of six layers of silicon detectors: two layers of Silicon
Pixel Detector (SPD), surrounded by two layers of Silicon Drift Detector (SDD)
and two layers of Silicon Strip Detector (SSD). SPD tracklets, short track
segments reconstructed in the two SPD layers alone, are also used as
associated particles.

The V0 detector, consisting of two arrays with 32 scintillator tiles arranged
in four rings each, is used to generate the minimum-bias trigger and offline
for multiplicity selection [60]. The detector covers the full azimuth within
$2.8<\eta<5.1$ (V0-A) and $-3.7<\eta<-1.7$ (V0-C). The timing information of
the V0 is also used for offline rejection of interactions of the beam with
residual gas. In addition, two neutron Zero Degree Calorimeters (ZDCs) located
at $+112.5$ m (ZNA) and $-112.5$ m (ZNC) from the interaction point are used
in the offline event selection and as an alternative approach to define event-
multiplicity classes.

##  3 Event and track selection

The online event selection used in this analysis is based on a combination of
minimum-bias ($\mathrm{MB}$) and muon trigger inputs. The $\mathrm{MB}$
selection uses the coincidence between hits in the V0-A and V0-C detectors and
covers 99.2% of the non-single-diffractive cross section as described in [61].
Only approximately 5% of the MB events contain one or more tracks
reconstructed in the muon spectrometer. In order to increase the number of
recorded events, the presence of at least one muon above a $p_{\mathrm{T}}$
threshold was required in addition to the $\mathrm{MB}$ trigger condition. Two
different thresholds were used: a low-$p_{\mathrm{T}}$ threshold corresponding
to about $0.5$ $\mathrm{GeV}/c$ ($\mu$-low-$p_{\mathrm{T}}$) and a higher
$p_{\mathrm{T}}$ threshold corresponding to about $4.2$ $\mathrm{GeV}/c$
($\mu$-high-$p_{\mathrm{T}}$). These thresholds are not sharp and the reported
values correspond to a 50% trigger probability for a muon candidate. The
integrated luminosity collected with $\mu$-high-$p_{\mathrm{T}}$ triggers is
$5.0\ {\rm nb}^{-1}$ in the p–Pb and $5.8\ {\rm nb}^{-1}$ in the Pb–p periods.
The $\mu$-low-$p_{\mathrm{T}}$ trigger class was downscaled by a factor
$10$–$35$ depending on the data taking conditions, resulting in an integrated
luminosity of $0.28\ {\rm nb}^{-1}$ in the p–Pb and $0.26\ {\rm nb}^{-1}$ in
the Pb–p periods.

The TPC and SDD detectors have longer deadtime compared to the muon
spectrometer, the SPD and the V0. Therefore, they were read out only in a
fraction of $\mu$-low-$p_{\mathrm{T}}$ events (about 25% in p–Pb and below 10%
in Pb–p collisions). Both muon-track and muon-tracklet correlation results
were measured in the p–Pb configuration. For Pb–p collisions, only muon-
tracklet correlations could be studied due to the significantly lower number
of triggers with the TPC in the readout.

The primary-vertex position is determined using reconstructed clusters in the
SPD detector as described in LABEL:Abelev:2014ffa. Only events with a
reconstructed vertex coordinate along the beam direction ($z_{\mathrm{vtx}}$)
within 7 cm from the nominal interaction point are selected. The probability
of multiple interactions in the same bunch crossing (pileup) was dependent on
the beam conditions and always below 3%. Pileup events are removed by
rejecting triggers with more than one reconstructed vertex.

Event | $\left\langle\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta\right\rangle|_{|\eta|<0.5}$
---|---
class |  $p_{\mathrm{T}}>$ 0 $\mathrm{GeV}/c$
00–20% | $35.8\pm 0.8$
20–40% | $23.2\pm 0.5$
40–60% | $15.8\pm 0.4$
60–100% | $6.8\pm 0.2$
Table 1:  V0S multiplicity classes as fractions of the analyzed event sample
and the corresponding
$\left\langle\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta\right\rangle|_{|\eta|<0.5}$.
The $\left\langle\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta\right\rangle$ values
are not corrected for trigger and vertex-reconstruction inefficiencies, which
are about 4% for non-single-diffractive events [61], mainly affecting the
80-100% lowest mulitiplicity events [62]. Only systematic uncertainties are
listed, since the statistical uncertainties are negligible.

All events were characterized by their event activity, and sorted into event
classes. As in previous studies [24, 33], the event characterization was based
on the signal in the V0 detectors. However, unlike before, both beam
orientations were investigated in this Letter. Therefore, the signals from
only two out the four rings of V0-A and V0-C detectors were combined to
guarantee a more symmetric acceptance. On the V0-A side, the two outermost
rings with an acceptance of $2.8<\eta<3.9$, while on the V0-C side the two
innermost rings with an acceptance of $-3.7<\eta<-2.7$ were used. This
combination is called V0S in the following. The definition of the event
classes as fractions of the analyzed event sample and their corresponding
average number of particles at midrapidity
($\left\langle\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta\right\rangle|_{|\eta|<0.5}$),
measured using tracklets as explained below, is given in Tab. 1.

Muon tracks are reconstructed in the geometrical acceptance of the muon
spectrometer ($-4<\eta<-2.5$). The tracks are required to exit the front
absorber at a radial distance from the beam axis, $R_{\rm abs}$, in the range
$17.6<R_{\rm abs}<89.5$ cm in order to avoid regions with large material
density. The muon identification is performed by matching the tracks
reconstructed in the tracking chambers with the corresponding track segments
in the trigger chambers. Beam-gas tracks, which do not point to the
interaction vertex, are removed by a selection on the product of the total
momentum of a given track and its distance to the interaction vertex in the
transverse plane. In the analysis, muons in the transverse momentum range
$0.5<p_{\mathrm{T}}<4$ $\mathrm{GeV}/c$ were considered.

Figure 1:  Parent particle composition of reconstructed muon tracks (left
panel) and reconstruction efficiency for muons from pion and kaon decays
relative to that for heavy flavor (HF) decay muons (right panel) from a
detector simulation of the ALICE muon spectrometer.

Reconstructed muons mainly originate from weak decays of $\mathrm{\pi}$,
$\mathrm{K}$ 222Here, and in the following, pions and kaons refer to the sum
of both charge states. Neutral particles are also considered in the case of
kaons. and mesons from heavy flavor (HF) decays. Because of the different
$p_{\mathrm{T}}$ distribution of the various sources and the absorber in front
of the spectrometer, which suppresses by design weak decays from light
hadrons, the parent particle composition for the reconstructed muon tracks
changes as a function of $p_{\mathrm{T}}$. The composition shown as a function
of the reconstructed $p_{\mathrm{T}}$ in the left panel of Fig. 1 was
evaluated using full detector simulations based on the DPMJET Monte Carlo (MC)
event generator [63]. The detector response was simulated using GEANT3 for
particle transport [64]. The composition of parent particles in the simulation
differs by less than 10% for the two beam configurations. The reconstructed
muons are dominated by light-hadron decays below 1.5 $\mathrm{GeV}/c$, and by
heavy flavor decays above 2 $\mathrm{GeV}/c$. No significant multiplicity
dependence was found. Similar conclusions are obtained using simulations with
the AMPT generator [65].

Without strong model assumptions, one cannot deduce the composition of parent
particles from the measured muon distribution, and correct the data for muon
decay and absorber effects. For comparison of the $v_{2}$ data with
calculations, however, only relative contributions of the parent species
matter. In order to ease future model calculations, the reconstruction
efficiencies for muons from pion and kaon decays relative to those for muons
from heavy flavor decays are provided in the right panel of Fig. 1 as a
function of the generated decay muon $p_{\mathrm{T}}$ in different
pseudorapidity intervals. Contributions from muon decays of other particles
are significantly smaller than those for pions and can be ignored. The
systematic uncertainty on the relative efficiencies was estimated to be less
than $5$%.

Tracks reconstructed in the ITS and the TPC are selected in the fiducial
region $|\eta|<1$ and $0.5<p_{\mathrm{T}}<4~{}\mathrm{GeV}/c$. The track
selection used in this Letter is the same as in LABEL:Abelev:2012ola.

Tracklet candidates are formed using information on the position of the
primary vertex and the two hits on the SPD layers [66], located at a distance
of 3.9 and 7.6 cm from the detector centre. The differences of the azimuthal
($\Delta\varphi_{\,\rm h}$, bending plane) and polar ($\Delta\theta_{\,\rm
h}$, non-bending direction) angles of the hits with respect to the primary
vertex are used to select particles, typically with $p_{\mathrm{T}}>50$
$\mathrm{MeV}/c$. Particles below 50 $\mathrm{MeV}/c$ are mostly absorbed by
material. Compared to previous analyses [66, 61] a tighter cut in
$\Delta\varphi_{\,\rm h}$ is applied ($\Delta\varphi_{\,\rm h}$ < 5 mrad) to
select particles with larger $p_{\mathrm{T}}$ and to minimize contributions of
fake and secondary tracks to below 2.5%. The corresponding mean
$p_{\mathrm{T}}$ of selected particles, estimated from the DPMJET MC, is about
0.75 $\mathrm{GeV}/c$.

##  4 Analysis

The associated yield of tracks or tracklets per trigger particle in the muon
spectrometer is measured as a function of the difference in azimuthal angle
($\Delta\varphi$) and pseudorapidity ($\Delta\eta$). As in previous analyses
[24, 33], it is defined as

$Y=\frac{1}{N_{\mathrm{trig}}}\frac{\mathrm{d}^{2}N_{\mathrm{assoc}}}{\mathrm{d}\Delta\eta\mathrm{d}\Delta\varphi}=\frac{S(\Delta\eta,\Delta\varphi)}{B(\Delta\eta,\Delta\varphi)},$
(1)

in intervals of event multiplicity and trigger particle transverse momentum,
$p_{\mathrm{T}}^{\mathrm{t}}$. The variable $N_{\mathrm{trig}}$ denotes the
total number of trigger particles in the event class and
$p_{\mathrm{T}}^{\mathrm{t}}$ interval, not corrected for single-muon
efficiency. The signal distribution
$S(\Delta\eta,\Delta\varphi)=1/N_{\mathrm{trig}}\mathrm{d}^{2}N_{\rm
same}/\mathrm{d}\Delta\eta\mathrm{d}\Delta\varphi$ is the associated yield per
trigger particle for particle pairs from the same event, obtained in 1 cm-wide
intervals of $z_{\mathrm{vtx}}$. A correction for pair acceptance and pair
efficiency is obtained by dividing by the background distribution
$B(\Delta\eta,\Delta\varphi)=\alpha\ \mathrm{d}^{2}N_{\rm
mixed}/\mathrm{d}\Delta\eta\mathrm{d}\Delta\varphi$. The background
distribution is constructed by correlating trigger particles from one event
with the associated particles from other events within the same event
multiplicity class and 1 cm-wide $z_{\rm vtx}$ intervals. The factor $\alpha$
is used to normalize the background distribution to unity in the $\Delta\eta$
region of maximal pair acceptance. The final per-trigger yield is obtained by
calculating the average over the $z_{\rm vtx}$ intervals weighted by
$N_{\mathrm{trig}}$.

Figure 2:  Associated yield per trigger particle as a function of $\Delta\eta$
and $\Delta\varphi$ for muon-track correlations in p–Pb (left) and muon-
tracklet correlations in p–Pb (middle) and Pb–p (right panels), measured in
60–100% (top row) and 0–20% (bottom row) event classes. The trigger particle
(muon) range is $0.5<p_{\mathrm{T}}^{\mathrm{t}}<1$ $\mathrm{GeV}/c$, the
associated particle intervals are $0.5<p_{\mathrm{T}}^{\mathrm{a}}<4.0$
$\mathrm{GeV}/c$ for tracks and $0<\Delta\varphi_{\,\rm h}<5$ mrad for
tracklets. Statistical uncertainties are not shown.

In Fig. 2, the associated yield per trigger particle as a function of
$\Delta\varphi$ and $\Delta\eta$ for muon-track correlations in p–Pb (left)
and muon-tracklet correlations in p–Pb (middle) and Pb–p (right panels),
measured in 60–100% (top row) and 0–20% (bottom row) event classes is shown.
In the low-multiplicity class (60–100%), the dominant feature is the recoil
jet on the away side ($\pi/2<\Delta\varphi<3\pi/2$). While in previous two-
particle correlation studies at midrapidity [24, 33] the away-side jet
structure was mostly flat in $\Delta\eta$, from $\Delta\eta=-1.5$ to
$\Delta\eta=-5.0$ it decreases, as expected considering the kinematics of
dijets at large $\Delta\eta$. The near side ($|\Delta\varphi|<\pi/2$) shows
almost no structure in $\Delta\varphi$ and $\Delta\eta$, since it is
sufficiently separated from the near-side jet peak at
$(\Delta\varphi,\Delta\eta)=(0,0)$, so that no contribution from jets is
expected. In the high-multiplicity (0–20%) class, the away-side jet structure
is also visible, and the associated yields are considerably higher than for
the low-multiplicity (60–100%) class. Moreover, in contrast to the low-
multiplicity class, a near-side structure emerges, similar to that previously
observed at lower pseudorapidities, revealing that the near-side ridge extends
up to pseudorapidity ranges of $2.5<|\eta|<4$.

Figure 3:  Top panels: Associated yield per trigger particle as a function of
$\Delta\varphi$ and $\Delta\eta$ for muon-track correlations in p–Pb (left)
and muon-tracklet correlations in p–Pb (centre) and Pb–p (right) collisions
for the 0–20% event class, where the corresponding correlation from the
60–100% event class has been subtracted. Statistical uncertainties are not
shown. The trigger particle (muon) range is
$0.5<p_{\mathrm{T}}^{\mathrm{t}}<1$ $\mathrm{GeV}/c$, the associated particle
intervals are $0.5<p_{\mathrm{T}}^{\mathrm{a}}<4.0$ $\mathrm{GeV}/c$ for
tracks and $0<\Delta\varphi_{\,\rm h}<5$ mrad for tracklets. Bottom panels:
The same as above projected onto $\Delta\varphi$. The lines indicate the fit
to the data and the first harmonic contributions as explained in the text.

In order to isolate long-range correlations, we apply the same subtraction
method as in previous measurements [24, 33]. Jet-associated yields have only a
weak multiplicity dependence [67], thus the subtraction of the low-
multiplicity event class removes most of the jet-like correlations. The per-
trigger yield of the 60–100% event class is subtracted from that in the 0–20%
event class, and the result is presented (labelled as $Y_{\rm sub}$) in the
top panels of Fig. 3. After subtraction, two similar ridges on the near and on
the away side are clearly visible.

The magnitude of the contributing long-range amplitudes is quantified by
extracting the Fourier coefficients from the $\Delta\varphi$ projection of the
per-trigger yield distribution, after the subtraction of the low-multiplicity
class, as shown in the lower panels of Fig. 3. In order to reduce the
statistical fluctuations at the edges of the per-trigger yield distribution,
the $\Delta\varphi$ projection is obtained from a first-order polynomial fit
along $\Delta\eta$ for each $\Delta\varphi$ interval. In the p–Pb cases, the
near- and away-side amplitudes are quite different, while in the Pb–p case the
amplitudes on the near and away side are similar. The difference in the
amplitudes of the near- and away-side ridge, which may be due to a residual
jet contribution in the subtracted distribution, is taken into account in the
systematic error evaluation, as explained in Sec. 5.

The Fourier coefficients are then obtained by fitting $Y_{\rm sub}$ with

$a_{0}+2\,a_{1}\cos(\Delta\varphi)+2\,a_{2}\cos(2\Delta\varphi)+2\,a_{3}\cos(3\Delta\varphi)\,,$
(2)

leading to $\chi^{2}/{\rm NDF}$ values typically below $1.5$. The relative
modulation is given by $V_{n\Delta}\\{{\rm 2PC,sub}\\}=\frac{a_{n}}{a_{0}+b}$,
where $b$ is the baseline of the low-multiplicity class (60–100%) estimated
from the integral of the per-trigger yield around the minimum. Assuming that
the two-particle Fourier coefficient factorizes into a product of trigger and
associate single-particle $v_{2}$ [30], the $v_{n}\\{\mathrm{2PC,sub}\\}$
coefficients for particles reconstructed in the muon spectrometer are then
obtained as

$\displaystyle v_{n}\\{\mathrm{2PC,sub}\\}=V_{n\Delta}\\{{\rm
2PC,sub}\\}/\sqrt{V_{n\Delta}^{\rm c}\\{{\rm 2PC,sub}\\}},$ (3)

where $V_{n\Delta}^{\rm c}\\{{\rm 2PC,sub}\\}$ is measured by correlating only
central barrel tracks (or tracklets) with each other (essentially repeating
the analysis as in LABEL:Abelev:2012ola).

In this Letter, $v_{2}\\{\mathrm{2PC,sub}\\}$ values for muons in the
acceptance of the muon spectrometer are reported. Weak decays and scattering
in the absorber of the muon spectrometer can cause the kinematics of
reconstructed muons to deviate from those of their parent particles, and can
influence the reconstructed $v_{2}$, especially in case $v_{2,\text{parent}}$
has a strong $p_{\mathrm{T}}$ dependence. Since we cannot correct the measured
$v_{2}$ for the species-dependent inefficiencies induced by the absorber, we
denote the resulting coefficients by $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ to
indicate that the result holds for decay muons measured in the muon
spectrometer.

##  5 Systematic uncertainties

The systematic uncertainty on $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ was
estimated by varying the analysis procedure as described in this section. The
uncertainty on the ratio between the $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ in
Pb–p and p–Pb collisions was obtained on the ratio itself, in order to
properly treat the (anti-) correlated systematics between the p–Pb and Pb–p
data samples. A summary is given in Tab. 2.

| Assoc. tracks | Assoc. tracklets
---|---|---
Systematic effect | p–Pb | p–Pb | Pb–p | Ratio
Acceptance ($z_{\mathrm{vtx}}$ dependence) | 3$-$4% | 0$-$5% | 0$-$3% | 0$-$1%
Remaining jet after subtraction | 4$-$10% | 5$-$14% | 1$-$2% | 3$-$15%
Remaining ridge in low-multiplicity class | 1$-$4% | 1$-$6% | 0$-$2% | 2$-$8%
Calculation of $v_{2}$ | 0$-$1% | 0$-$1% | 1% | 0$-$2%
Resolution correction | 1% | 0$-$1% | 0$-$1% | 0$-$2%
Sum (added in quadrature) | 7$-$11% | 6$-$14% | 2$-$4% | 5$-$17%
Table 2: Summary of main systematic uncertainties. The uncertainties usually
depend on $p_{\mathrm{T}}$ and vary within the given ranges.

The acceptance of the ALICE central barrel depends on the position of
$z_{\mathrm{vtx}}$. To study its influence on
$v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$, the analysis was repeated using only
events with a reconstructed primary vertex within $\pm$5 cm instead of $\pm$7
cm from the nominal interaction point. The yield per trigger particle was not
corrected for single track acceptance and efficiency of associated particles.
Since $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ is a relative quantity, it is not
expected to depend on the normalization. This was verified in the case of the
muon-track analysis, where good agreement was found between the second-order
Fourier coefficients obtained with and without single-track acceptance and
efficiency corrections. Hence, no additional uncertainty was considered.

As observed in previous analyses [24, 33], the subtraction of the low-
multiplicity class leads to a residual peak around
$(\Delta\eta,\Delta\varphi)\approx(0,0)$, possibly due to a bias of the event
selection on the jet fragmentation in low-multiplicity events [67]. The
pseudorapidity gap [24, 25] used to calculate $V_{n\Delta}^{c}$ was varied
from $1.2$ to $1.0$ and to $0.8$ in order to estimate the contribution of the
residual near-side short-range correlations. Due to the large gap in
pseudorapidity between the ALICE central barrel and the muon spectrometer,
this contribution does not affect the forward-central correlation. The effect
of the bias introduced by the multiplicity selection was addressed on the away
side by scaling the $60$–$100$% multiplicity class. The scaling factor ($f$)
is determined as the ratio between away-side yields in high- and low-
multiplicity classes after the subtraction of the second-order Fourier
component [67]. This procedure was applied in the calculation of both
$V_{n\Delta}$ and $V_{n\Delta}^{\rm c}$. The scaling factors were found to be
larger in the case of p–Pb collisions ($f\leq 1.40$), compared to Pb–p ($f\leq
1.26$), and tend to be lower for increasing $p_{\mathrm{T}}$. The difference
with respect to the baseline results, for which no scaling ($f=1$) is applied,
was taken as the systematic uncertainty.

As previously reported [67], the contribution of the long-range correlations
to the measured yields is not significant in low-multiplicity events. Still,
their potential influence was addressed by changing the multiplicity range
from $60$–$100$% to $70$–$100$% for the low-multiplicity class.

To test the stability of the fit, the $v_{2}$ coefficient was calculated using
a fit with only the first and the second Fourier components in Eq. 2. As
another variation, the baseline $b$ was calculated from a fit of the per-
trigger yield in the low-multiplicity class using a Gaussian to model the
shape of the away-side ridge and a constant to estimate $b$. An equivalent
approach, which makes use of the baseline of the high-multiplicity class $B$
in $V_{n\Delta}\\{{\rm 2PC,sub}\\}=a_{n}/B$, was also used, where $B$ was
estimated from the integral or from a parabolic fit of the correlation
function around the minimum. Finally, the $\Delta\varphi$ projection was
obtained from a weighted average instead of a first-order polynomial fit along
$\Delta\eta$ for each $\Delta\varphi$ interval.

The effect from the finite angular and momentum resolution of the muon
spectrometer on $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ was evaluated from a
dedicated MC study with the measured $v_{2}$ as input distribution, and
resulted in a small correction of below $2$%. The associated uncertainty was
evaluated by varying the input $v_{2}$ by $50$% at the lowest and highest
measured points.

##  6 Results

The $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ coefficients were measured for muon
tracks in the p-going direction (p–Pb period) using both tracks and tracklets
as associated central barrel particles, as described in Sec. 4. The
$v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ coefficients obtained from the per-trigger
yields of associated central barrel tracks agree well with those of associated
tracklets, as shown in Fig. 4 as a function of muon $p_{\mathrm{T}}$. Since
the two measurements probe different ranges in associated particle
$p_{\mathrm{T}}$, the agreement is a consequence of trigger and associate
$v_{2}$ factorization [30]. In addition, good agreement was found between the
$v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ obtained with different cuts on
$\Delta\varphi_{\,\rm h}$ of associated tracklets (inducing a change of
average $p_{\mathrm{T}}$ by about $20$%).

The p-going and Pb-going $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ coefficients
obtained using muon-tracklet correlations for the two different beam
configurations (p–Pb and Pb–p) are reported in the left panel of Fig. 5 as a
function of muon $p_{\mathrm{T}}$. The Pb-going
$v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ (i.e. when the muon trigger particle
travels in the same direction as the Pb nucleus) is observed to be larger than
the p-going $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ over the measured
$p_{\mathrm{T}}$ range, but the two have a similar
$p_{\mathrm{T}}$-dependence. To quantify the asymmetry, the Pb-going over
p-going ratio for the $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ coefficients is
reported in the right panel of Fig. 5 as a function of muon $p_{\mathrm{T}}$.
The ratio is found to be rather independent of $p_{\mathrm{T}}$ given the
statistical and systematic uncertainties of the measurement. A constant fit to
the ratio adding statistical and systematic uncertainties in quadrature gives
$1.16\pm 0.06$ with a $\chi^{2}/{\rm NDF}=0.4$. The analysis was also repeated
using the energy deposited in the neutron ZDCs on the Pb-going side instead of
the V0S amplitude for the event class definition. As discussed in detail in
[62], the correlation between forward energy measured in the ZDCs and particle
density at central rapidities is weak in p–Pb collisions. Therefore, event
classes defined as fixed fractions of the signal distribution in the ZDCs
select different events, with different mean particle multiplicity at
midrapidity, than the samples selected with the same fractions in the V0
detector. Still, the $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ values were measured
to be similar, within 25% of those extracted with V0S estimator. In addition,
the asymmetry between Pb- and p-going $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ was
found to persist with similar shape and magnitude. The observed asymmetry may
result from decorrelations of event planes at different rapidity [68].

Figure 4:  Comparison of $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ for
$-4<\eta<-2.5$ extracted from muon-track and muon-tracklet correlations in
p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.

Figure 5:  The $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ coefficients from muon-
tracklet correlations in p-going and Pb-going directions (left) and their
ratio (right) for $-4<\eta<-2.5$ in p–Pb collisions at
$\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The data are compared to model calculations
from AMPT.

The data in Fig. 5 can not be readily compared with existing predictions [57]
for a 3+1 dimensional, viscous hydrodynamical model [39] and the AMPT model
with the string-melting mechanism enabled [65]. The model calculations were
performed without taking into account the effect of the muon absorber, and
represent the $v_{2}$ of primary particles, while as discussed in Sec. 3 the
measured $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ coefficients are reported for
decay muons. Depending on particle composition and on the
$p_{\mathrm{T}}$-dependence of the parent particle $v_{2}$ distribution, the
difference between primary particle $v_{2}$ and decay muon $v_{2}$ can be
quite large. For example, at $1$ $\mathrm{GeV}/c$, assuming the $v_{2}$ of the
parent particles rises with $p_{\mathrm{T}}$ like at mid-rapidity [33], the
measured $v_{2}^{\mu}\\{\mathrm{2PC,sub}\\}$ for muons originating from decays
of pions (kaons) would be $\approx$20 (40)% larger than that of the parent
pions (kaons).

Instead, in Fig. 5 we show a comparison of the data with AMPT model
calculations performed with the same parameters as in [57]. These calculations
were performed at generator level, decaying primary particles into muons using
the PYTHIA decayer [69]. The effects of the muon absorber were included by
applying the $p_{\mathrm{T}}$ and $\eta$ dependent relative efficiencies
provided in the right panel of Fig. 1. Event characterization was done by
mimicking the V0S criteria at particle level, i.e. by counting charged
particles in $2.8<\eta<3.9$ and $-3.7<\eta<-2.7$. The $v_{2}$ values were
obtained separately for muons decaying from pions, kaons and heavy-flavor
hadrons, and otherwise performing the analysis in the same way as in data. We
found the $v_{2}$ for HF muons to be consistent with zero within the generated
statistics (5M events with a HF muon in the acceptance of the muon
spectrometer for each period). Hence, for the inclusive $v_{2}$, which is
obtained by weighting the calculated $v_{2}$ with the relative yields in each
decay channel, the $v_{2}$ for HF muons has been set to zero to reduce
statistical fluctuations. In AMPT the factor $f$ used to scale low-
multiplicity class to eliminate the remaining jet contribution after
subtraction, reaches values much larger than in the data, up to $f=2$.
Applying the scaling reduces the extracted $v_{2}$ and consequently this
choice constitutes the lower (upper) bound of the shaded area in Fig. 5 left
(right), while the opposite bounds correspond to $f=1$ (as used for the
baseline result in the data).

As shown in the left panel of Fig. 5, below $p_{\mathrm{T}}<1.5$
$\mathrm{GeV}/c$, where the inclusive muon yield is expected to be dominated
by weak decays of pions and kaons, the calculation produces qualitatively
similar trends as observed in the data. However, quantitatively a different
$p_{\mathrm{T}}$ and $\eta$ dependence is found, visible in particular in the
right panel of Fig. 5. At $p_{\mathrm{T}}>2$ $\mathrm{GeV}/c$, where the
inclusive muon yield is dominated by heavy-flavor decays, the data may support
a finite value for the $v_{2}$ of HF muons, or a drastically different
composition of the parent distribution or their $v_{2}$ values in AMPT
compared to data. Indeed, comparing predictions of AMPT to pion, kaon and
D-meson yields measured at midrapidity [70, 71], muons from heavy-flavor
decays would be underestimated by a factor $3$–$5$ relative to pion and kaon
decays assuming the same discrepancy between model and data at forward
rapidity. A finite value for HF muon $v_{2}$ would be consistent with the
emergence of radial flow in heavy-flavor meson spectra as predicted in [72],
and has been recently measured in Pb–Pb collisions at
$\sqrt{s_{\mathrm{NN}}}=2.76$ TeV [73].

##  7 Summary

Two-particle angular correlations between trigger particles in the forward
pseudorapidity range $2.5<|\eta|<4.0$ and associated particles in the central
range $|\eta|<1.0$ measured by ALICE are reported in p–Pb collisions at a
nucleon–nucleon centre-of-mass energy of 5.02 TeV. The trigger particles are
inclusive muons and the associated particles are charged particles,
reconstructed by the muon spectrometer and central barrel tracking detectors,
respectively. The composition of parent particles for the measured muons is
expected to vary as a function of $p_{\mathrm{T}}$ (Fig. 1). A near-side ridge
is observed in high-multiplicity events (Fig. 2). After subtraction of jet-
like correlations measured in low-multiplicity events, the double-ridge
structure, previously discovered in two-particle angular correlations at
midrapidity, is found to persist even in the pseudorapidity ranges studied
here (Fig. 3). The second-order Fourier coefficients for muon tracks are
determined assuming factorization of the Fourier coefficients at central and
forward rapidity. The measurement in p–Pb collisions was performed in two
different ways, using tracks or tracklets for particles at $|\eta|<1.0$,
yielding consistent results (Fig. 4). The second-order Fourier coefficients
for muons in high-multiplicity events were found to have a similar transverse
momentum dependence in the p-going (p–Pb) and Pb-going (Pb–p) configurations,
with the Pb-going coefficients larger by $16\pm 6$%, rather independent of
$p_{\mathrm{T}}$ within the uncertainties of the measurement (Fig. 5). The
results were compared with calculations using the AMPT model incorporating the
effects of the muon absorber, showing a different $p_{\mathrm{T}}$ and $\eta$
dependence than observed in the data. Above $2$ $\mathrm{GeV}/c$, the results
are sensitive to the $v_{2}$ of heavy-flavor decay muons. Forthcoming model
calculations should apply the relative efficiencies for muon decays from pion
and kaons (provided in Fig. 1) at generator level for detailed comparison with
our data. Further measurements (e.g. of heavy-flavor muon yields or charged-
particle $v_{2}$ at forward rapidity) will be needed to reduce the ambiguity
between between muon parent particle composition and their $v_{2}$.

## Acknowledgements

We thank P. Bozek, A. Bzdak, and G.-L. Ma for fruitful discussions concerning
their calculations [57].

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: State
Committee of Science, World Federation of Scientists (WFS) and Swiss Fonds
Kidagan, Armenia, 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); National Natural Science
Foundation of China (NSFC), the Chinese Ministry of Education (CMOE) and the
Ministry of Science and Technology of China (MSTC); Ministry of Education and
Youth of the Czech Republic; Danish Natural Science Research Council, the
Carlsberg Foundation and the Danish National Research Foundation; The European
Research Council under the European Community’s Seventh Framework Programme;
Helsinki Institute of Physics and the Academy of Finland; French CNRS-IN2P3,
the ‘Region Pays de Loire’, ‘Region Alsace’, ‘Region Auvergne’ and CEA,
France; German Bundesministerium fur Bildung, Wissenschaft, Forschung und
Technologie (BMBF) and the Helmholtz Association; General Secretariat for
Research and Technology, Ministry of Development, Greece; Hungarian Orszagos
Tudomanyos Kutatasi Alappgrammok (OTKA) and National Office for Research and
Technology (NKTH); Department of Atomic Energy and Department of Science and
Technology of the Government of India; Istituto Nazionale di Fisica Nucleare
(INFN) and Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche
"Enrico Fermi", Italy; MEXT Grant-in-Aid for Specially Promoted Research,
Japan; Joint Institute for Nuclear Research, Dubna; National Research
Foundation of Korea (NRF); Consejo Nacional de Cienca y Tecnologia (CONACYT),
Direccion General de Asuntos del Personal Academico(DGAPA), México, Amerique
Latine Formation academique - European Commission (ALFA-EC) and the EPLANET
Program (European Particle Physics Latin American Network); Stichting voor
Fundamenteel Onderzoek der Materie (FOM) and the Nederlandse Organisatie voor
Wetenschappelijk Onderzoek (NWO), Netherlands; Research Council of Norway
(NFR); National Science Centre, Poland; Ministry of National
Education/Institute for Atomic Physics and National Council of Scientific
Research in Higher Education (CNCSI-UEFISCDI), Romania; Ministry of Education
and Science of Russian Federation, Russian Academy of Sciences, Russian
Federal Agency of Atomic Energy, Russian Federal Agency for Science and
Innovations and The Russian Foundation for Basic Research; Ministry of
Education of Slovakia; Department of Science and Technology, South Africa;
Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas
(CIEMAT), E-Infrastructure shared between Europe and Latin America (EELA),
Ministerio de Economía y Competitividad (MINECO) of Spain, Xunta de Galicia
(Consellería de Educación), Centro de Aplicaciones Tecnológicas y Desarrollo
Nuclear (CEADEN), Cubaenergía, Cuba, and IAEA (International Atomic Energy
Agency); Swedish Research Council (VR) and Knut $\&$ Alice Wallenberg
Foundation (KAW); Ukraine Ministry of Education and Science; United Kingdom
Science and Technology Facilities Council (STFC); The United States Department
of Energy, the United States National Science Foundation, the State of Texas,
and the State of Ohio; Ministry of Science, Education and Sports of Croatia
and Unity through Knowledge Fund, Croatia. Council of Scientific and
Industrial Research (CSIR), New Delhi, India

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##  Appendix A The ALICE Collaboration

J. Adamorg40&D. Adamováorg83&M.M. Aggarwalorg87&G. Aglieri Rinellaorg36&M.
Agnelloorg111&N. Agrawalorg48&Z. Ahammedorg132&S.U. Ahnorg68&I.
Aimoorg94,org111&S. Aiolaorg136&M. Ajazorg16&A. Akindinovorg58&S.N.
Alamorg132&D. Aleksandrovorg100&B. Alessandroorg111&D. Alexandreorg102&R.
Alfaro Molinaorg64&A. Aliciorg105,org12&A. Alkinorg3&J.R.M. Almarazorg119&J.
Almeorg38&T. Altorg43&S. Altinpinarorg18&I. Altsybeevorg131&C. Alves Garcia
Pradoorg120&C. Andreiorg78&A. Andronicorg97&V. Anguelovorg93&J.
Anielskiorg54&T. Antičićorg98&F. Antinoriorg108&P. Antonioliorg105&L.
Aphecetcheorg113&H. Appelshäuserorg53&S. Arcelliorg28&N. Armestoorg17&R.
Arnaldiorg111&I.C. Arseneorg22&M. Arslandokorg53&B. Audurierorg113&A.
Augustinusorg36&R. Averbeckorg97&M.D. Azmiorg19&M. Bachorg43&A.
Badalàorg107&Y.W. Baekorg44&S. Bagnascoorg111&R. Bailhacheorg53&R.
Balaorg90&A. Baldisseriorg15&F. Baltasar Dos Santos Pedrosaorg36&R.C.
Baralorg61&A.M. Barbanoorg111&R. Barberaorg29&F. Barileorg33&G.G.
Barnaföldiorg135&L.S. Barnbyorg102&V. Barretorg70&P. Bartaliniorg7&K.
Barthorg36&J. Bartkeorg117&E. Bartschorg53&M. Basileorg28&N. Bastidorg70&S.
Basuorg132&B. Bathenorg54&G. Batigneorg113&A. Batista Camejoorg70&B.
Batyunyaorg66&P.C. Batzingorg22&I.G. Beardenorg80&H. Beckorg53&C.
Beddaorg111&N.K. Beheraorg48,org49&I. Belikovorg55&F. Belliniorg28&H. Bello
Martinezorg2&R. Bellwiedorg122&R. Belmontorg134&E. Belmont-Morenoorg64&V.
Belyaevorg76&G. Bencediorg135&S. Beoleorg27&I. Berceanuorg78&A.
Bercuciorg78&Y. Berdnikovorg85&D. Berenyiorg135&R.A. Bertensorg57&D.
Berzanoorg36,org27&L. Betevorg36&A. Bhasinorg90&I.R. Bhatorg90&A.K.
Bhatiorg87&B. Bhattacharjeeorg45&J. Bhomorg128&L. Bianchiorg122&N.
Bianchiorg72&C. Bianchinorg134,org57&J. Bielčíkorg40&J. Bielčíkováorg83&A.
Bilandzicorg80&R. Biswasorg4&S. Biswasorg79&S. Bjelogrlicorg57&J.T.
Blairorg118&F. Blancoorg10&D. Blauorg100&C. Blumeorg53&F. Bockorg93,org74&A.
Bogdanovorg76&H. Bøggildorg80&L. Boldizsárorg135&M. Bombaraorg41&J.
Bookorg53&H. Borelorg15&A. Borissovorg96&M. Borriorg82&F. Bossúorg65&E.
Bottaorg27&S. Böttgerorg52&P. Braun-Munzingerorg97&M. Bregantorg120&T.
Breitnerorg52&T.A. Brokerorg53&T.A. Browningorg95&M. Brozorg40&E.J.
Bruckenorg46&E. Brunaorg111&G.E. Brunoorg33&D. Budnikovorg99&H.
Bueschingorg53&S. Bufalinoorg27,org111&P. Buncicorg36&O. Buschorg128,org93&Z.
Butheleziorg65&J.B. Buttorg16&J.T. Buxtonorg20&D. Caffarriorg36&X. Caiorg7&H.
Cainesorg136&L. Calero Diazorg72&A. Calivaorg57&E. Calvo Villarorg103&P.
Cameriniorg26&F. Carenaorg36&W. Carenaorg36&F. Carnesecchiorg28&J. Castillo
Castellanosorg15&A.J. Castroorg125&E.A.R. Casulaorg25&C. Cavicchioliorg36&C.
Ceballos Sanchezorg9&J. Cepilaorg40&P. Cerelloorg111&J. Cerkalaorg115&B.
Changorg123&S. Chapelandorg36&M. Chartierorg124&J.L. Charvetorg15&S.
Chattopadhyayorg132&S. Chattopadhyayorg101&V. Chelnokovorg3&M. Cherneyorg86&C.
Cheshkovorg130&B. Cheynisorg130&V. Chibante Barrosoorg36&D.D.
Chinellatoorg121&P. Chochulaorg36&K. Choiorg96&M. Chojnackiorg80&S.
Choudhuryorg132&P. Christakoglouorg81&C.H. Christensenorg80&P.
Christiansenorg34&T. Chujoorg128&S.U. Chungorg96&Z. Chunhuiorg57&C.
Cicaloorg106&L. Cifarelliorg12,org28&F. Cindoloorg105&J. Cleymansorg89&F.
Colamariaorg33&D. Colellaorg36,org33,org59&A. Colluorg25&M. Colocciorg28&G.
Conesa Balbastreorg71&Z. Conesa del Valleorg51&M.E. Connorsorg136&J.G.
Contrerasorg11,org40&T.M. Cormierorg84&Y. Corrales Moralesorg27&I. Cortés
Maldonadoorg2&P. Corteseorg32&M.R. Cosentinoorg120&F. Costaorg36&P.
Crochetorg70&R. Cruz Albinoorg11&E. Cuautleorg63&L. Cunqueiroorg36&T.
Dahmsorg92,org37&A. Daineseorg108&A. Danuorg62&D. Dasorg101&I.
Dasorg101,org51&S. Dasorg4&A. Dashorg121&S. Dashorg48&S. Deorg120&A. De
Caroorg31,org12&G. de Cataldoorg104&J. de Cuvelandorg43&A. De Falcoorg25&D. De
Gruttolaorg12,org31&N. De Marcoorg111&S. De Pasqualeorg31&A.
Deistingorg97,org93&A. Delofforg77&E. Dénesorg1350&G. D’Erasmoorg33&D. Di
Bariorg33&A. Di Mauroorg36&P. Di Nezzaorg72&M.A. Diaz Corcheroorg10&T.
Dietelorg89&P. Dillensegerorg53&R. Diviàorg36&Ø. Djuvslandorg18&A.
Dobrinorg57,org81&T. Dobrowolskiorg770&D. Domenicis Gimenezorg120&B.
Dönigusorg53&O. Dordicorg22&T. Drozhzhovaorg53&A.K. Dubeyorg132&A.
Dublaorg57&L. Ducrouxorg130&P. Dupieuxorg70&R.J. Ehlersorg136&D. Eliaorg104&H.
Engelorg52&B. Erazmusorg36,org113&I. Erdemirorg53&F. Erhardtorg129&D.
Eschweilerorg43&B. Espagnonorg51&M. Estienneorg113&S. Esumiorg128&J.
Eumorg96&D. Evansorg102&S. Evdokimovorg112&G. Eyyubovaorg40&L.
Fabbiettiorg37,org92&D. Fabrisorg108&J. Faivreorg71&A. Fantoniorg72&M.
Faselorg74&L. Feldkamporg54&D. Feleaorg62&A. Felicielloorg111&G.
Feofilovorg131&J. Ferenceiorg83&A. Fernández Téllezorg2&E.G. Ferreiroorg17&A.
Ferrettiorg27&A. Festantiorg30&V.J.G. Feuillardorg15,org70&J.
Figielorg117&M.A.S. Figueredoorg124,org120&S. Filchaginorg99&D.
Finogeevorg56&F.M. Fiondaorg25&E.M. Fioreorg33&M.G. Fleckorg93&M.
Florisorg36&S. Foertschorg65&P. Fokaorg97&S. Fokinorg100&E.
Fragiacomoorg110&A. Francesconorg36,org30&U. Frankenfeldorg97&U. Fuchsorg36&C.
Furgetorg71&A. Fursorg56&M. Fusco Girardorg31&J.J. Gaardhøjeorg80&M.
Gagliardiorg27&A.M. Gagoorg103&M. Gallioorg27&D.R. Gangadharanorg74&P.
Ganotiorg88&C. Gaoorg7&C. Garabatosorg97&E. Garcia-Solisorg13&C.
Gargiuloorg36&P. Gasikorg92,org37&M. Germainorg113&A. Gheataorg36&M.
Gheataorg62,org36&P. Ghoshorg132&S.K. Ghoshorg4&P. Gianottiorg72&P.
Giubellinoorg36,org111&P. Giubilatoorg30&E. Gladysz-Dziadusorg117&P.
Glässelorg93&D.M. Goméz Coralorg64&A. Gomez Ramirezorg52&P. González-
Zamoraorg10&S. Gorbunovorg43&L. Görlichorg117&S. Gotovacorg116&V.
Grabskiorg64&L.K. Graczykowskiorg133&K.L. Grahamorg102&A. Grelliorg57&A.
Grigorasorg36&C. Grigorasorg36&V. Grigorievorg76&A. Grigoryanorg1&S.
Grigoryanorg66&B. Grinyovorg3&N. Grionorg110&J.F. Grosse-
Oetringhausorg36&J.-Y. Grossiordorg130&R. Grossoorg36&F. Guberorg56&R.
Guernaneorg71&B. Guerzoniorg28&K. Gulbrandsenorg80&H. Gulkanyanorg1&T.
Gunjiorg127&A. Guptaorg90&R. Guptaorg90&R. Haakeorg54&Ø. Haalandorg18&C.
Hadjidakisorg51&M. Haiducorg62&H. Hamagakiorg127&G. Hamarorg135&A.
Hansenorg80&J.W. Harrisorg136&H. Hartmannorg43&A. Hartonorg13&D.
Hatzifotiadouorg105&S. Hayashiorg127&S.T. Heckelorg53&M. Heideorg54&H.
Helstruporg38&A. Herghelegiuorg78&G. Herrera Corralorg11&B.A. Hessorg35&K.F.
Hetlandorg38&T.E. Hildenorg46&H. Hillemannsorg36&B. Hippolyteorg55&R.
Hosokawaorg128&P. Hristovorg36&M. Huangorg18&T.J. Humanicorg20&N.
Hussainorg45&T. Hussainorg19&D. Hutterorg43&D.S. Hwangorg21&R. Ilkaevorg99&I.
Ilkivorg77&M. Inabaorg128&M. Ippolitovorg76,org100&M. Irfanorg19&M.
Ivanovorg97&V. Ivanovorg85&V. Izucheevorg112&P.M. Jacobsorg74&S.
Jadlovskaorg115&C. Jahnkeorg120&H.J. Jangorg68&M.A. Janikorg133&P.H.S.Y.
Jayarathnaorg122&C. Jenaorg30&S. Jenaorg122&R.T. Jimenez Bustamanteorg97&P.G.
Jonesorg102&H. Jungorg44&A. Juskoorg102&P. Kalinakorg59&A. Kalweitorg36&J.
Kaminorg53&J.H. Kangorg137&V. Kaplinorg76&S. Karorg132&A. Karasu Uysalorg69&O.
Karavichevorg56&T. Karavichevaorg56&L. Karayanorg93,org97&E. Karpechevorg56&U.
Kebschullorg52&R. Keidelorg138&D.L.D. Keijdenerorg57&M. Keilorg36&K.H.
Khanorg16&M.M. Khanorg19&P. Khanorg101&S.A. Khanorg132&A. Khanzadeevorg85&Y.
Kharlovorg112&B. Kilengorg38&B. Kimorg137&D.W. Kimorg44,org68&D.J.
Kimorg123&H. Kimorg137&J.S. Kimorg44&M. Kimorg44&M. Kimorg137&S. Kimorg21&T.
Kimorg137&S. Kirschorg43&I. Kiselorg43&S. Kiselevorg58&A. Kisielorg133&G.
Kissorg135&J.L. Klayorg6&C. Kleinorg53&J. Kleinorg36,org93&C. Klein-
Bösingorg54&A. Klugeorg36&M.L. Knichelorg93&A.G. Knospeorg118&T.
Kobayashiorg128&C. Kobdajorg114&M. Kofaragoorg36&T. Kolleggerorg97,org43&A.
Kolojvariorg131&V. Kondratievorg131&N. Kondratyevaorg76&E. Kondratyukorg112&A.
Konevskikhorg56&M. Kopcikorg115&M. Kourorg90&C. Kouzinopoulosorg36&O.
Kovalenkoorg77&V. Kovalenkoorg131&M. Kowalskiorg117&G. Koyithatta
Meethaleveeduorg48&J. Kralorg123&I. Králikorg59&A. Kravčákováorg41&M.
Kretzorg43&M. Krivdaorg102,org59&F. Krizekorg83&E. Kryshenorg36&M.
Krzewickiorg43&A.M. Kuberaorg20&V. Kučeraorg83&T. Kugathasanorg36&C.
Kuhnorg55&P.G. Kuijerorg81&A. Kumarorg90&J. Kumarorg48&L. Kumarorg87,org79&P.
Kurashviliorg77&A. Kurepinorg56&A.B. Kurepinorg56&A. Kuryakinorg99&S.
Kushpilorg83&M.J. Kweonorg50&Y. Kwonorg137&S.L. La Pointeorg111&P. La
Roccaorg29&C. Lagana Fernandesorg120&I. Lakomovorg36&R. Langoyorg42&C.
Laraorg52&A. Lardeuxorg15&A. Lattucaorg27&E. Laudiorg36&R. Leaorg26&L.
Leardiniorg93&G.R. Leeorg102&S. Leeorg137&I. Legrandorg36&F. Lehasorg81&R.C.
Lemmonorg82&V. Lentiorg104&E. Leograndeorg57&I. León Monzónorg119&M.
Leoncinoorg27&P. Lévaiorg135&S. Liorg7,org70&X. Liorg14&J. Lienorg42&R.
Lietavaorg102&S. Lindalorg22&V. Lindenstruthorg43&C. Lippmannorg97&M.A.
Lisaorg20&H.M. Ljunggrenorg34&D.F. Lodatoorg57&P.I. Loenneorg18&V.
Loginovorg76&C. Loizidesorg74&X. Lopezorg70&E. López Torresorg9&A.
Loweorg135&P. Luettigorg53&M. Lunardonorg30&G. Luparelloorg26&P.H.F.N.D.
Luzorg120&A. Maevskayaorg56&M. Magerorg36&S. Mahajanorg90&S.M. Mahmoodorg22&A.
Maireorg55&R.D. Majkaorg136&M. Malaevorg85&I. Maldonado Cervantesorg63&L.
Malininaidp3813520,org66&D. Mal’Kevichorg58&P. Malzacherorg97&A.
Mamonovorg99&V. Mankoorg100&F. Mansoorg70&V. Manzariorg36,org104&M.
Marchisoneorg27&J. Marešorg60&G.V. Margagliottiorg26&A. Margottiorg105&J.
Marguttiorg57&A. Marínorg97&C. Markertorg118&M. Marquardorg53&N.A.
Martinorg97&J. Martin Blancoorg113&P. Martinengoorg36&M.I. Martínezorg2&G.
Martínez Garcíaorg113&M. Martinez Pedreiraorg36&Y. Martynovorg3&A.
Masorg120&S. Masciocchiorg97&M. Maseraorg27&A. Masoniorg106&L.
Massacrierorg113&A. Mastroserioorg33&H. Masuiorg128&A. Matyjaorg117&C.
Mayerorg117&J. Mazerorg125&M.A. Mazzoniorg109&D. Mcdonaldorg122&F.
Meddiorg24&Y. Melikyanorg76&A. Menchaca-Rochaorg64&E. Meninnoorg31&J. Mercado
Pérezorg93&M. Meresorg39&Y. Miakeorg128&M.M. Mieskolainenorg46&K.
Mikhaylovorg66,org58&L. Milanoorg36&J. Milosevicorg22&L.M.
Minerviniorg104,org23&A. Mischkeorg57&A.N. Mishraorg49&D. Miśkowiecorg97&J.
Mitraorg132&C.M. Mituorg62&N. Mohammadiorg57&B. Mohantyorg132,org79&L.
Molnarorg55&L. Montaño Zetinaorg11&E. Montesorg10&M. Morandoorg30&D.A. Moreira
De Godoyorg113,org54&S. Morettoorg30&A. Morrealeorg113&A. Morschorg36&V.
Mucciforaorg72&E. Mudnicorg116&D. Mühlheimorg54&S. Muhuriorg132&M.
Mukherjeeorg132&J.D. Mulliganorg136&M.G. Munhozorg120&S. Murrayorg65&L.
Musaorg36&J. Musinskyorg59&B.K. Nandiorg48&R. Naniaorg105&E. Nappiorg104&M.U.
Naruorg16&C. Nattrassorg125&K. Nayakorg79&T.K. Nayakorg132&S.
Nazarenkoorg99&A. Nedosekinorg58&L. Nellenorg63&F. Ngorg122&M.
Nicassioorg97&M. Niculescuorg62,org36&J. Niedzielaorg36&B.S. Nielsenorg80&S.
Nikolaevorg100&S. Nikulinorg100&V. Nikulinorg85&F. Noferiniorg105,org12&P.
Nomokonovorg66&G. Noorenorg57&J.C.C. Norisorg2&J. Normanorg124&A.
Nyaninorg100&J. Nystrandorg18&H. Oeschlerorg93&S. Ohorg136&S.K. Ohorg67&A.
Ohlsonorg36&A. Okatanorg69&T. Okuboorg47&L. Olahorg135&J. Oleniaczorg133&A.C.
Oliveira Da Silvaorg120&M.H. Oliverorg136&J. Onderwaaterorg97&C.
Oppedisanoorg111&R. Oravaorg46&A. Ortiz Velasquezorg63&A. Oskarssonorg34&J.
Otwinowskiorg117&K. Oyamaorg93&M. Ozdemirorg53&Y. Pachmayerorg93&P.
Paganoorg31&G. Paićorg63&C. Pajaresorg17&S.K. Palorg132&J. Panorg134&A.K.
Pandeyorg48&D. Pantorg48&P. Papcunorg115&V. Papikyanorg1&G.S.
Pappalardoorg107&P. Pareekorg49&W.J. Parkorg97&S. Parmarorg87&A.
Passfeldorg54&V. Paticchioorg104&R.N. Patraorg132&B. Paulorg101&T.
Peitzmannorg57&H. Pereira Da Costaorg15&E. Pereira De Oliveira Filhoorg120&D.
Peresunkoorg100,org76&C.E. Pérez Laraorg81&E. Perez Lezamaorg53&V.
Peskovorg53&Y. Pestovorg5&V. Petráčekorg40&V. Petrovorg112&M.
Petroviciorg78&C. Pettaorg29&S. Pianoorg110&M. Piknaorg39&P. Pillotorg113&O.
Pinazzaorg105,org36&L. Pinskyorg122&D.B. Piyarathnaorg122&M. Płoskońorg74&M.
Planinicorg129&J. Plutaorg133&S. Pochybovaorg135&P.L.M. Podesta-
Lermaorg119&M.G. Poghosyanorg86,org84&B. Polichtchoukorg112&N. Poljakorg129&W.
Poonsawatorg114&A. Poporg78&S. Porteboeuf-Houssaisorg70&J. Porterorg74&J.
Pospisilorg83&S.K. Prasadorg4&R. Preghenellaorg36,org105&F. Prinoorg111&C.A.
Pruneauorg134&I. Pshenichnovorg56&M. Puccioorg111&G. Pudduorg25&P.
Pujahariorg134&V. Puninorg99&J. Putschkeorg134&H. Qvigstadorg22&A.
Rachevskiorg110&S. Rahaorg4&S. Rajputorg90&J. Rakorg123&A.
Rakotozafindrabeorg15&L. Ramelloorg32&F. Ramiorg55&R. Raniwalaorg91&S.
Raniwalaorg91&S.S. Räsänenorg46&B.T. Rascanuorg53&D. Ratheeorg87&K.F.
Readorg125&J.S. Realorg71&K. Redlichorg77&R.J. Reedorg134&A. Rehmanorg18&P.
Reicheltorg53&F. Reidtorg93,org36&X. Renorg7&R. Renfordtorg53&A.R.
Reolonorg72&A. Reshetinorg56&F. Rettigorg43&J.-P. Revolorg12&K.
Reygersorg93&V. Riabovorg85&R.A. Ricciorg73&T. Richertorg34&M. Richterorg22&P.
Riedlerorg36&W. Rieglerorg36&F. Riggiorg29&C. Risteaorg62&A. Rivettiorg111&E.
Roccoorg57&M. Rodríguez Cahuantziorg2&A. Rodriguez Mansoorg81&K. Røedorg22&E.
Rogochayaorg66&D. Rohrorg43&D. Röhrichorg18&R. Romitaorg124&F.
Ronchettiorg72&L. Ronfletteorg113&P. Rosnetorg70&A. Rossiorg30,org36&F.
Roukoutakisorg88&A. Royorg49&C. Royorg55&P. Royorg101&A.J. Rubio
Monteroorg10&R. Ruiorg26&R. Russoorg27&E. Ryabinkinorg100&Y. Ryabovorg85&A.
Rybickiorg117&S. Sadovskyorg112&K. Šafaříkorg36&B. Sahlmullerorg53&P.
Sahooorg49&R. Sahooorg49&S. Sahooorg61&P.K. Sahuorg61&J. Sainiorg132&S.
Sakaiorg72&M.A. Salehorg134&C.A. Salgadoorg17&J. Salzwedelorg20&S.
Sambyalorg90&V. Samsonovorg85&X. Sanchez Castroorg55&L. Šándororg59&A.
Sandovalorg64&M. Sanoorg128&D. Sarkarorg132&E. Scapparoneorg105&F.
Scarlassaraorg30&R.P. Scharenbergorg95&C. Schiauaorg78&R. Schickerorg93&C.
Schmidtorg97&H.R. Schmidtorg35&S. Schuchmannorg53&J. Schukraftorg36&M.
Schulcorg40&T. Schusterorg136&Y. Schutzorg113,org36&K. Schwarzorg97&K.
Schwedaorg97&G. Scioliorg28&E. Scomparinorg111&R. Scottorg125&J.E.
Segerorg86&Y. Sekiguchiorg127&D. Sekihataorg47&I. Selyuzhenkovorg97&K.
Senosiorg65&J. Seoorg96,org67&E. Serradillaorg64,org10&A. Sevcencoorg62&A.
Shabanovorg56&A. Shabetaiorg113&O. Shaduraorg3&R. Shahoyanorg36&A.
Shangaraevorg112&A. Sharmaorg90&M. Sharmaorg90&M. Sharmaorg90&N.
Sharmaorg125,org61&K. Shigakiorg47&K. Shtejerorg9,org27&Y. Sibiriakorg100&S.
Siddhantaorg106&K.M. Sielewiczorg36&T. Siemiarczukorg77&D.
Silvermyrorg84,org34&C. Silvestreorg71&G. Simatovicorg129&G. Simonettiorg36&R.
Singarajuorg132&R. Singhorg79&S. Singhaorg132,org79&V. Singhalorg132&B.C.
Sinhaorg132&T. Sinhaorg101&B. Sitarorg39&M. Sittaorg32&T.B. Skaaliorg22&M.
Slupeckiorg123&N. Smirnovorg136&R.J.M. Snellingsorg57&T.W. Snellmanorg123&C.
Søgaardorg34&R. Soltzorg75&J. Songorg96&M. Songorg137&Z. Songorg7&F.
Soramelorg30&S. Sorensenorg125&M. Spacekorg40&E. Spiritiorg72&I.
Sputowskaorg117&M. Spyropoulou-Stassinakiorg88&B.K. Srivastavaorg95&J.
Stachelorg93&I. Stanorg62&G. Stefanekorg77&M. Steinpreisorg20&E.
Stenlundorg34&G. Steynorg65&J.H. Stillerorg93&D. Stoccoorg113&P.
Strmenorg39&A.A.P. Suaideorg120&T. Sugitateorg47&C. Suireorg51&M.
Suleymanovorg16&R. Sultanovorg58&M. Šumberaorg83&T.J.M. Symonsorg74&A.
Szaboorg39&A. Szanto de Toledoorg1200&I. Szarkaorg39&A.
Szczepankiewiczorg36&M. Szymanskiorg133&J. Takahashiorg121&G.J.
Tambaveorg18&N. Tanakaorg128&M.A. Tangaroorg33&J.D. Tapia
Takakiidp5954704,org51&A. Tarantola Peloniorg53&M. Tarhiniorg51&M.
Tariqorg19&M.G. Tarzilaorg78&A. Tauroorg36&G. Tejeda Muñozorg2&A.
Telescaorg36&K. Terasakiorg127&C. Terrevoliorg30,org25&B. Teyssierorg130&J.
Thäderorg74,org97&D. Thomasorg118&R. Tieulentorg130&A.R. Timminsorg122&A.
Toiaorg53&S. Trogoloorg111&V. Trubnikovorg3&W.H. Trzaskaorg123&T.
Tsujiorg127&A. Tumkinorg99&R. Turrisiorg108&T.S. Tveterorg22&K.
Ullalandorg18&A. Urasorg130&G.L. Usaiorg25&A. Utrobicicorg129&M.
Vajzerorg83&M. Valaorg59&L. Valencia Palomoorg70&S. Valleroorg27&J. Van Der
Maarelorg57&J.W. Van Hoorneorg36&M. van Leeuwenorg57&T. Vanatorg83&P. Vande
Vyvreorg36&D. Vargaorg135&A. Vargasorg2&M. Vargyasorg123&R. Varmaorg48&M.
Vasileiouorg88&A. Vasilievorg100&A. Vauthierorg71&V. Vecherninorg131&A.M.
Veenorg57&M. Veldhoenorg57&A. Velureorg18&M. Venaruzzoorg73&E.
Vercellinorg27&S. Vergara Limónorg2&R. Vernetorg8&M. Verweijorg134,org36&L.
Vickovicorg116&G. Viestiorg300&J. Viinikainenorg123&Z. Vilakaziorg126&O.
Villalobos Baillieorg102&A. Vinogradovorg100&L. Vinogradovorg131&Y.
Vinogradovorg990&T. Virgiliorg31&V. Vislaviciusorg34&Y.P. Viyogiorg132&A.
Vodopyanovorg66&M.A. Völklorg93&K. Voloshinorg58&S.A. Voloshinorg134&G.
Volpeorg135,org36&B. von Hallerorg36&I. Vorobyevorg37,org92&D.
Vranicorg36,org97&J. Vrlákováorg41&B. Vulpescuorg70&A. Vyushinorg99&B.
Wagnerorg18&J. Wagnerorg97&H. Wangorg57&M. Wangorg7,org113&Y. Wangorg93&D.
Watanabeorg128&Y. Watanabeorg127&M. Weberorg36&S.G. Weberorg97&J.P.
Wesselsorg54&U. Westerhofforg54&J. Wiechulaorg35&J. Wikneorg22&M.
Wildeorg54&G. Wilkorg77&J. Wilkinsonorg93&M.C.S. Williamsorg105&B.
Windelbandorg93&M. Winnorg93&C.G. Yaldoorg134&H. Yangorg57&P. Yangorg7&S.
Yanoorg47&Z. Yinorg7&H. Yokoyamaorg128&I.-K. Yooorg96&V. Yurchenkoorg3&I.
Yushmanovorg100&A. Zaborowskaorg133&V. Zaccoloorg80&A. Zamanorg16&C.
Zampolliorg105&H.J.C. Zanoliorg120&S. Zaporozhetsorg66&N. Zardoshtiorg102&A.
Zarochentsevorg131&P. Závadaorg60&N. Zaviyalovorg99&H. Zbroszczykorg133&I.S.
Zguraorg62&M. Zhalovorg85&H. Zhangorg18,org7&X. Zhangorg74&Y. Zhangorg7&C.
Zhaoorg22&N. Zhigarevaorg58&D. Zhouorg7&Y. Zhouorg80,org57&Z. Zhouorg18&H.
Zhuorg18,org7&J. Zhuorg113,org7&X. Zhuorg7&A. Zichichiorg12,org28&A.
Zimmermannorg93&M.B. Zimmermannorg54,org36&G. Zinovjevorg3&M. Zyzakorg43

## Affiliation notes

0Deceased

idp3813520Also at: M.V. Lomonosov Moscow State University, D.V. Skobeltsyn
Institute of Nuclear, Physics, Moscow, Russia

idp5954704Also at: University of Kansas, Lawrence, Kansas, United States

## Collaboration Institutes

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

org2Benemérita Universidad Autónoma de Puebla, Puebla, Mexico

org3Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine

org4Bose Institute, Department of Physics and Centre for Astroparticle Physics
and Space Science (CAPSS), Kolkata, India

org5Budker Institute for Nuclear Physics, Novosibirsk, Russia

org6California Polytechnic State University, San Luis Obispo, California,
United States

org7Central China Normal University, Wuhan, China

org8Centre de Calcul de l’IN2P3, Villeurbanne, France

org9Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana,
Cuba

org10Centro de Investigaciones Energéticas Medioambientales y Tecnológicas
(CIEMAT), Madrid, Spain

org11Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City
and Mérida, Mexico

org12Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche
“Enrico Fermi”, Rome, Italy

org13Chicago State University, Chicago, Illinois, USA

org14China Institute of Atomic Energy, Beijing, China

org15Commissariat à l’Energie Atomique, IRFU, Saclay, France

org16COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan

org17Departamento de Física de Partículas and IGFAE, Universidad de Santiago
de Compostela, Santiago de Compostela, Spain

org18Department of Physics and Technology, University of Bergen, Bergen,
Norway

org19Department of Physics, Aligarh Muslim University, Aligarh, India

org20Department of Physics, Ohio State University, Columbus, Ohio, United
States

org21Department of Physics, Sejong University, Seoul, South Korea

org22Department of Physics, University of Oslo, Oslo, Norway

org23Dipartimento di Elettrotecnica ed Elettronica del Politecnico, Bari,
Italy

org24Dipartimento di Fisica dell’Università ’La Sapienza’ and Sezione INFN
Rome, Italy

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

org26Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy

org27Dipartimento di Fisica dell’Università and Sezione INFN, Turin, Italy

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

org29Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN,
Catania, Italy

org30Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN,
Padova, Italy

org31Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Gruppo
Collegato INFN, Salerno, Italy

org32Dipartimento di Scienze e Innovazione Tecnologica dell’Università del
Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy

org33Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari,
Italy

org34Division of Experimental High Energy Physics, University of Lund, Lund,
Sweden

org35Eberhard Karls Universität Tübingen, Tübingen, Germany

org36European Organization for Nuclear Research (CERN), Geneva, Switzerland

org37Excellence Cluster Universe, Technische Universität München, Munich,
Germany

org38Faculty of Engineering, Bergen University College, Bergen, Norway

org39Faculty of Mathematics, Physics and Informatics, Comenius University,
Bratislava, Slovakia

org40Faculty of Nuclear Sciences and Physical Engineering, Czech Technical
University in Prague, Prague, Czech Republic

org41Faculty of Science, P.J. Šafárik University, Košice, Slovakia

org42Faculty of Technology, Buskerud and Vestfold University College,
Vestfold, Norway

org43Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-
Universität Frankfurt, Frankfurt, Germany

org44Gangneung-Wonju National University, Gangneung, South Korea

org45Gauhati University, Department of Physics, Guwahati, India

org46Helsinki Institute of Physics (HIP), Helsinki, Finland

org47Hiroshima University, Hiroshima, Japan

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

org49Indian Institute of Technology Indore, Indore (IITI), India

org50Inha University, Incheon, South Korea

org51Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud,
CNRS-IN2P3, Orsay, France

org52Institut für Informatik, Johann Wolfgang Goethe-Universität Frankfurt,
Frankfurt, Germany

org53Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt,
Frankfurt, Germany

org54Institut für Kernphysik, Westfälische Wilhelms-Universität Münster,
Münster, Germany

org55Institut Pluridisciplinaire Hubert Curien (IPHC), Université de
Strasbourg, CNRS-IN2P3, Strasbourg, France

org56Institute for Nuclear Research, Academy of Sciences, Moscow, Russia

org57Institute for Subatomic Physics of Utrecht University, Utrecht,
Netherlands

org58Institute for Theoretical and Experimental Physics, Moscow, Russia

org59Institute of Experimental Physics, Slovak Academy of Sciences, Košice,
Slovakia

org60Institute of Physics, Academy of Sciences of the Czech Republic, Prague,
Czech Republic

org61Institute of Physics, Bhubaneswar, India

org62Institute of Space Science (ISS), Bucharest, Romania

org63Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México,
Mexico City, Mexico

org64Instituto de Física, Universidad Nacional Autónoma de México, Mexico
City, Mexico

org65iThemba LABS, National Research Foundation, Somerset West, South Africa

org66Joint Institute for Nuclear Research (JINR), Dubna, Russia

org67Konkuk University, Seoul, South Korea

org68Korea Institute of Science and Technology Information, Daejeon, South
Korea

org69KTO Karatay University, Konya, Turkey

org70Laboratoire de Physique Corpusculaire (LPC), Clermont Université,
Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France

org71Laboratoire de Physique Subatomique et de Cosmologie, Université
Grenoble-Alpes, CNRS-IN2P3, Grenoble, France

org72Laboratori Nazionali di Frascati, INFN, Frascati, Italy

org73Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy

org74Lawrence Berkeley National Laboratory, Berkeley, California, United
States

org75Lawrence Livermore National Laboratory, Livermore, California, United
States

org76Moscow Engineering Physics Institute, Moscow, Russia

org77National Centre for Nuclear Studies, Warsaw, Poland

org78National Institute for Physics and Nuclear Engineering, Bucharest,
Romania

org79National Institute of Science Education and Research, Bhubaneswar, India

org80Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark

org81Nikhef, Nationaal instituut voor subatomaire fysica, Amsterdam,
Netherlands

org82Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, United
Kingdom

org83Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež
u Prahy, Czech Republic

org84Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

org85Petersburg Nuclear Physics Institute, Gatchina, Russia

org86Physics Department, Creighton University, Omaha, Nebraska, United States

org87Physics Department, Panjab University, Chandigarh, India

org88Physics Department, University of Athens, Athens, Greece

org89Physics Department, University of Cape Town, Cape Town, South Africa

org90Physics Department, University of Jammu, Jammu, India

org91Physics Department, University of Rajasthan, Jaipur, India

org92Physik Department, Technische Universität München, Munich, Germany

org93Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg,
Heidelberg, Germany

org94Politecnico di Torino, Turin, Italy

org95Purdue University, West Lafayette, Indiana, United States

org96Pusan National University, Pusan, South Korea

org97Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum
für Schwerionenforschung, Darmstadt, Germany

org98Rudjer Bošković Institute, Zagreb, Croatia

org99Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

org100Russian Research Centre Kurchatov Institute, Moscow, Russia

org101Saha Institute of Nuclear Physics, Kolkata, India

org102School of Physics and Astronomy, University of Birmingham, Birmingham,
United Kingdom

org103Sección Física, Departamento de Ciencias, Pontificia Universidad
Católica del Perú, Lima, Peru

org104Sezione INFN, Bari, Italy

org105Sezione INFN, Bologna, Italy

org106Sezione INFN, Cagliari, Italy

org107Sezione INFN, Catania, Italy

org108Sezione INFN, Padova, Italy

org109Sezione INFN, Rome, Italy

org110Sezione INFN, Trieste, Italy

org111Sezione INFN, Turin, Italy

org112SSC IHEP of NRC Kurchatov institute, Protvino, Russia

org113SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3,
Nantes, France

org114Suranaree University of Technology, Nakhon Ratchasima, Thailand

org115Technical University of Košice, Košice, Slovakia

org116Technical University of Split FESB, Split, Croatia

org117The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy
of Sciences, Cracow, Poland

org118The University of Texas at Austin, Physics Department, Austin, Texas,
USA

org119Universidad Autónoma de Sinaloa, Culiacán, Mexico

org120Universidade de São Paulo (USP), São Paulo, Brazil

org121Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil

org122University of Houston, Houston, Texas, United States

org123University of Jyväskylä, Jyväskylä, Finland

org124University of Liverpool, Liverpool, United Kingdom

org125University of Tennessee, Knoxville, Tennessee, United States

org126University of the Witwatersrand, Johannesburg, South Africa

org127University of Tokyo, Tokyo, Japan

org128University of Tsukuba, Tsukuba, Japan

org129University of Zagreb, Zagreb, Croatia

org130Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon,
Villeurbanne, France

org131V. Fock Institute for Physics, St. Petersburg State University, St.
Petersburg, Russia

org132Variable Energy Cyclotron Centre, Kolkata, India

org133Warsaw University of Technology, Warsaw, Poland

org134Wayne State University, Detroit, Michigan, United States

org135Wigner Research Centre for Physics, Hungarian Academy of Sciences,
Budapest, Hungary

org136Yale University, New Haven, Connecticut, United States

org137Yonsei University, Seoul, South Korea

org138Zentrum für Technologietransfer und Telekommunikation (ZTT),
Fachhochschule Worms, Worms, Germany