Production of pions, kaons, (anti-)protons and φ mesons in Xe-Xe collisions at \sqrt{s_{\rm NN}} = 5.44 TeV
aa r X i v : . [ nu c l - e x ] J a n EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
CERN-EP-2020-24922 December 2020© 2020 CERN for the benefit of the ALICE Collaboration.Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license.
Production of pions, kaons, (anti-)protons and φ mesons in Xe–Xecollisions at √ s NN = 5.44 TeV ALICE Collaboration * The first measurement of the production of pions, kaons, (anti-)protons and φ mesons at midrapidityin Xe–Xe collisions at √ s NN = .
44 TeV is presented. Transverse momentum ( p T ) spectra and p T -integrated yields are extracted in several centrality intervals bridging from p–Pb to mid-central Pb–Pbcollisions in terms of final-state multiplicity. The study of Xe–Xe and Pb–Pb collisions allows systemsat similar charged-particle multiplicities but with different initial geometrical eccentricities to be inves-tigated. A detailed comparison of the spectral shapes in the two systems reveals an opposite behaviourfor radial and elliptic flow. In particular, this study shows that the radial flow does not depend on thecolliding system when compared at similar charged-particle multiplicity. In terms of hadron chemistry,the previously observed smooth evolution of particle ratios with multiplicity from small to large collisionsystems is also found to hold in Xe–Xe. In addition, our results confirm that two remarkable featuresof particle production at LHC energies are also valid in the collision of medium-sized nuclei: the lowerproton-to-pion ratio with respect to the thermal model expectations and the increase of the φ -to-pionratio with increasing final-state multiplicity. * See Appendix A for the list of collaboration members roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration In recent years, the production of hadrons consisting of light flavour quarks ( u , d , and s ) has been ex-tensively studied in pp, p–Pb and Pb–Pb collisions at LHC energies [1–11] with the aim to explore thestrongly interacting Quark-Gluon Plasma (QGP) produced in heavy-ion collisions. After the formation,the QGP expands hydrodynamically reaching first a chemical freeze-out, where hadron abundances arefixed [12, 13], and then a kinetic freeze-out, where the hadron momenta are fixed.Remarkably, a smooth evolution of the hadron chemistry, i.e. of the relative abundance of hadron species,was observed across different collision systems as a function of the final-state multiplicity [9]. This be-haviour was also found to be independent of collision energy [10]. In particular, the relative abundanceof strange particles with respect to the non-strange ones increases continuously from small to large multi-plicities until a saturation is observed for systems in which about 100 charged particles are produced perunit of pseudorapidity [8]. This observation suggests a gradual approach to a chemical equilibrium thatis assumed to originate from the same underlying physical mechanisms across different collision sys-tems [14–16]. The study of the pion, kaon, (anti-)proton, and φ production in the collisions of medium-sized nuclei such as Xe provides the ultimate test for validating this picture by bridging the gap betweenp–Pb and Pb–Pb multiplicities.In this context, two remarkable features of particle production are of particular interest to be verifiedin Xe–Xe collisions: (i) the low value of the p / π ratio with respect to statistical-thermal model esti-mates [17] and (ii) the rising trend of the φ / π ratio from low to high multiplicities [9]. The first ob-servation has led to several speculations ranging from the incomplete treatment of resonance feed-downto a potential difference in chemical freeze-out temperatures among different quark flavours [18–20]but found its most likely explanation in the inclusion of pion-nucleon phase shifts within the statistical-thermal model framework [21]. The second effect provides strict constraints for both the canonicalstatistical-thermal approach in which no rise is predicted [9, 22, 23] as well as for models with onlypartial strangeness equilibration in which a steeper rise is expected similarly to the Ξ baryon [22].Moreover, the detailed comparison of spectral shapes in Xe–Xe and Pb–Pb collisions at similar multi-plicities provides the unique opportunity to investigate the hydrodynamic expansion in systems of similarfinal state charged particle multiplicity and different geometrical eccentricity. Already existing data onthe elliptic flow coefficient v [24] show a large difference in central collisions between the two systems,as expected from the Glauber and hydrodynamical models. In contrast, the radial flow and consequentlythe mean transverse momenta are expected to be comparable between Xe–Xe and Pb–Pb at similar mul-tiplicities [25]. The test of this hypothesis is one of the subjects of this manuscript. In addition, thedata used in this article were collected with a lower magnetic field, thus allowing us to extend the mea-surement of pions to lower transverse momenta with respect to previous studies [26]. For this reason,these data may also be of great relevance for future studies of potential condensation phenomena at lowtransverse momenta [27].This article is organised as follows. Section 2 describes the experimental setup and data analysis aswell as the systematic uncertainties. Results and comparisons with model calculations are discussed inSection 3. The summary and conclusions are given in Section 4. The measurements reported in this article are obtained with the ALICE central barrel which has fullazimuthal coverage around midrapidity in | η | < . × minimum bias (MB) events passing the event selection described below. The MB interactiontrigger is provided by two arrays of forward scintillators, named V0 detectors, with a pseudorapiditycoverage of 2 . < η < . − . < η < − . π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaborationcharged-particle multiplicity and is used to divide the Xe–Xe sample in centrality classes defined in per-centiles of the hadronic cross section [31–33]. The analysis is carried out in the centrality classes 0 − − − − − − − − − φ measurements are obtained in wider centrality classes 0 − − − − − − − − ≈ ± p < / c ) via the measurement of their specific energy loss (d E / d x ). An ITS-only analysis can beperformed by using a dedicated algorithm to treat the ITS as a standalone tracker, enabling the recon-struction and identification of low-momentum particles that do not reach the TPC. The TPC, a cylindricalgas detector equipped with Multi-Wire Proportional Chambers (MWPC), constitutes the main central-barrel tracking detector and is also used for PID through the d E / d x measurements in the gas. Thetime-of-flight measured with the TOF, a large area cylindrical detector based on Multigap Resistive PlateChamber (MRPC) technology, combined with the momentum information measured in the TPC, is em-ployed to identify particles at low and intermediate momenta ( . / c ).The events analysed in this article are chosen according to the selection criteria described in [26]. Theprimary vertex is determined from tracks, including the track segments reconstructed in the SPD. Theposition along the beam axis ( z ) of the vertex reconstructed with the SPD segments and of the onereconstructed from tracks are required to be compatible within 0.5 cm with a resolution of the SPD onebetter than 0.25 cm. The position of the primary vertex along z is required to be within 10 cm fromthe nominal interaction point. These criteria ensure a uniform acceptance in the pseudorapidity region | η | < . τ > / c that are either produced directly in the interaction or from decays of particles with τ < / c , restricted to decay chains leading to the interaction point [38]. To reduce the contaminationfrom secondary particles from weak decays and interactions in the detector material, as well as trackswith wrongly associated hits, similar selection criteria as described in [26, 34] are used and are sum-marised below. Tracks reconstructed with both the TPC and the ITS are required to cross at least 70 TPCreadout rows out of a maximum of 159 with a χ normalised to the number of TPC space points (“clus-ters”), χ / cluster, lower than 4. The ratio between the number of clusters and the number of crossedrows in the TPC has to be larger than 0.8. An additional cut on the track geometrical length in the TPCfiducial volume is used as in [34]. Tracks are also required to have at least two hits in the ITS detector3roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaborationout of which at least one has to be in the SPD. In addition, for the ITS-only analysis, the tracks must haveat least three hits in the SDD + SSD layers. The χ / cluster is also recalculated constraining the trackto pass by the primary vertex and it is required to be lower than 36. The same selection is also appliedon the ITS points of the track: χ / N hitsITS <
36. For the ITS-only analysis, this selection is restricted to χ / N hitsITS < .
5. Finally, the tracks are required to have a distance of closest approach (DCA) to theprimary vertex along the beam axis lower than 2 cm. A p T -dependent selection is then applied to theDCA in the transverse plane (DCA xy ): | DCA xy | < σ DCA xy where σ DCA xy is the resolution on the DCA xy in each p T interval. Furthermore, the tracks associated with decay products of weakly decaying kaons(“kinks”) are rejected. This selection is not applied for kaons studied via their kink decay topology. Thetrack selection criteria for kaons and pions from kinks will be described in the next paragraph.The Xe–Xe data were collected by operating the detector in its low B field configuration (B = . p T . This allowed for the measurementof pions down to 50 MeV / c for the first time at the LHC with respect to past publications [2, 26] wherethe lowest p T reach was to 100 MeV / c . While increasing the particle detection efficiencies at lowmomenta with respect to the standard field of 0.5 T, this configuration leads to a p T resolution for ITS-only tracks that is worse by almost a factor 2 for π ± , K ± , p and p in their lowest p T bin. As a consequence,to achieve a reliable PID, an unfolding technique is used for ITS-only tracks to account for the resolutioneffects as it will be described in the next section. On the contrary, the time-of-flight resolution andhence the performance of the TOF detector in terms of PID separation power is unaffected by the lowermagnetic field. Overall, the time-of-flight resolution is about 60 ps in central collisions. The particle identification for π ± , K ± , p and p relies on the signals measured in the ITS, TPC andTOF detectors. This provides a separation between different particle hypotheses using track-by-trackor statistical techniques. In addition, π and K are measured by reconstructing their weak decay (kink)topology [29]. Each of these identification techniques is best performing in a given p T region, as reportedin Table 1, and all together cover a wide p T interval of up to 5 GeV / c . The final spectra of each particlespecies are obtained by combining the single analyses. The identification of π ± , K ± , p and p with ITS,TPC and TOF proceeds by evaluating the difference between the measured and expected signal (e.g.d E / d x , time-of-flight) for a given species i in terms of number-of-sigmas ( N σ ): N σ ( i ) = Signal
MEAS − Signal
EXP ( i ) σ ( i ) (1)where Signal
EXP ( i ) is the expected signal and σ ( i ) its expected standard deviation obtained under eachparticle mass hypothesis, as described in [29, 36]. A detailed description of such techniques and themeasured separation power between the different particle species is shown for Pb–Pb collisions in [26]and it is unchanged for this data set. Table 1:
Transverse momentum intervals and the corresponding PID methods for pions, kaons and (anti-)protons.
Technique π ± (GeV / c ) K ± (GeV / c ) p and p (GeV / c )ITS 0.05 − − − − − − − − − − − − ITS analysis.
The ITS can be used as a standalone low- p T PID detector thanks to the particle energyloss (d E / d x ) measured in its four outermost layers [39]. To correct for the detector resolution effects on4roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaborationthe particle identification for p . / c , a Bayesian unfolding technique is employed with the RooUn-fold package [40]. The unfolding of the momentum distribution in d E / d x slices (1.1 keV/300 µ m each)is performed with a four-iteration procedure where the initial prior probability is taken from the gen-erated momentum distribution in the Monte Carlo (MC) simulated events with HIJING [41]. A propercorrection for detector inefficiencies and particle contamination is applied following the prescriptionin [40]. The unfolded momentum ( p TRUE ) corresponding to the maximum of the conditional probabilityP( p TRUE | p MEAS ) for a given measured momentum p MEAS is considered for the evaluation of the ex-pected signal in the N σ approach (see Eq. 1). Based on this, the plane ( p TRUE ; d E / d x ) is divided intoidentification regions where each point is assigned a unique particle identity. The identity of a track isassigned based on the difference between the measured d E / d x and the one computed under each masshypothesis. The hypothesis which gives the smallest distance is used, thereby removing the sensitivityto the parameterisation of the d E / d x resolution. A further selection | N πσ | < p T distributions (vs p TRUET ), the Bayesian unfolding is also applied to the raw p MEAST distributions of each species. In this case, the initial prior probability for the unfolding is takenfrom the generated p T distributions of each species in the MC and the number of iterations is kept tofour so as to minimize the statistical fluctuations (different numbers are considered for the systematicuncertainty evaluation).With this method it is possible to identify π ± , K ± , p and p in the following p T ranges, respectively:0 . − . / c , 0 . − . / c and 0 . − . / c . This also allows for the reduction of the con-tamination due to other particle species. For the first time at the LHC, thanks to the low magnetic fieldconfiguration the p T reach of the pion spectra is extended down to 50 MeV / c with a contamination fromelectrons of about 30%. To this purpose, a detailed study in the low momentum region was carriedout in different rapidity intervals to verify the stability of the measurement (as it will be explained insection 2.3). TPC and TOF analyses.
The identification with the TPC and TOF detectors mostly follows the pro-cedure developed in [26] with some adaptations. In both cases, the response of the PID signal was tunedfor the lower magnetic field configuration. The raw yield of particles is extracted in each p T interval viaa statistical unfolding. In particular, for the TOF analysis templates obtained with a data-driven approachare used. An additional template is used to take into account the signal component due to the TPC-TOF track mismatch. The excellent PID performance achieved with both detectors allowed a continuousseparation of pions from kaons and kaons from (anti-)protons in a wide interval of p T as reported inTable 1. Kink analysis.
Charged kaons and pions can also be identified by reconstructing their weak decaytopology (kink topology) defined as secondary vertices with two tracks (mother and daughter) havingthe same charge. The kink topology is analysed inside the TPC volume within a radius of 110–220 cm.Details about the kaon identification algorithm based on the kink topology can be found in [5, 26, 29, 42].In this article, the identification of pions via their kink decay topology is reported for the first time at theLHC.The identification of kaons from kink topology and their separation from pion decays is based on the two-body decay kinematics. The method allows for the extraction of kaon and pion spectra on a track-by-trackbasis. Both particles decay into µ + ν µ with branching ratios (B.R.) of 63.55% (K) and 99.99% ( π ) [43].For this decay channel, the transverse momentum of the charged daughter particle with respect to thedirection of the mother track ( q T ), has an upper limit of 236 MeV / c for kaons and 30 MeV / c for pions.Taking into account that the upper limit of q T for the decay K ± → π ± + π (with B . R . = .
66% [43])is 205 MeV / c , an effective separation of kaons from pions can be achieved by selecting kinks with q T >
40 MeV / c . Further selections are applied to reach a purity of kaons higher than 95%: ( i ) q T > π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE CollaborationMeV / c in order to discard pion and 3-body kaon decays, ( ii ) a kink radius in the transverse plane between110 and 205 cm, ( iii ) at least 20 TPC clusters for the mother track, ( iv ) a decay angle greater than 2 o inorder to remove fake kinks from particles that are wrongly reconstructed as two separate tracks, and ( v )a kink decay angle, at a given mother momentum, between the maximum decay angle for pion to muon( µ + ν µ decay) and the maximum decay angle of kaon to muon ( µ + ν µ decay). Finally, identified kaonsfrom kinks are accepted if the mother track is found to have a d E / d x within 3 . σ around the expectedBethe-Bloch value for kaons.The charged pions that are identified via their kink decay topology show a purity higher than 97%.Similar selection criteria as for kaons are used except for 10 < q T <
40 MeV / c (the most effective cut)and with the requirement of a decay angle smaller than the maximum decay angle of π → µ + ν µ . Thedifference in the q T selection for kaon and pion identification is due to their different decay angles to amuon at equal mother momentum. The maximum decay angle of a kink mother track with momentum p = . / c is 2 o for the pion to muon decay while 50 o for the kaon to muon decay, because ofthe mass difference of the mother particles. This feature restricts the pion identification below p = . / c . The p T distributions of π ± , K ± , p and p are obtained by correcting the raw spectra for PID efficiency,misidentification probability, acceptance and tracking efficiencies as performed in [26] for the ITS, TPC,TOF and kink analyses. The efficiencies are obtained from Monte Carlo simulated events generated withHIJING. The propagation of particles through the detector is simulated with the GEANT3 transportcode [44] where the detector characteristics and data-taking conditions are precisely reproduced. Thanksto the lower magnetic field of the Xe–Xe data sample, a tracking efficiency of about 2% (2.4%) is reachedat the lowest p T point ( p T = 50 MeV / c ) for pions in the most central (peripheral) bin compared to anefficiency lower than 1‰ at full field. It is known [2, 26, 45] that the energy loss of low- p T p in thedetector material and the cross section of low- p T K − are not well reproduced in GEANT3. For thisreason, a correction of the efficiency is estimated using GEANT4 [46] and FLUKA [47], respectively, inwhich these processes are reproduced more accurately. The corrections amount to about 10% and 4% forp and K − , respectively, in the lowest p T bin (see Table 1). The PID efficiency and the misidentificationprobability are estimated in the simulation by requiring the simulated data to reproduce the real PIDresponse for each detector included in this analysis.The raw distributions are further corrected for the contribution of secondary particles mainly due to weakdecays of K (affecting π ± ), Λ and Σ + (affecting p and p). Secondary protons coming from the detectormaterial are also subtracted from the raw spectrum. The estimation of this correction factor is data-driven since the event generators underestimate the strangeness production and, as already mentioned,the transport codes do not provide a precise description of the interaction of low- p T particles with thedetector material. For each analysis, the reconstructed DCA xy distributions for each particle speciesare fitted in each p T interval with three contributions (as templates) extracted from the Monte Carlosimulation: primary particles, secondary particles from weak decays of strange hadrons and secondaryparticles produced in the interaction with the detector material. Finally, the spectra are normalized tothe total number of events analysed in each centrality class. The spectra in the extended p T range areobtained by combining those obtained with the single identification techniques. In the p T intervals wheremore analyses overlap, the combination is carried out by performing an averaged mean using the singlesystematic uncertainties as weights. φ meson analysis The φ meson signal is reconstructed via invariant mass analysis by exploiting the decay channel intocharged kaons, φ → K + K − (B.R. = 0.492 ± π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaborationdescribed extensively in [6, 7, 11]. Candidate kaons are identified based on the variable defined byEq. 1 for the d E / d x sampled in the TPC ( N TPC σ ) or the time-of-flight measured by the TOF ( N TOF σ ).More precisely, a track associated with a hit in the TOF detector is identified as a K if | N TOF σ | < | N TPC σ | <
5. If a track does not reach the TOF detector and no time-of-flight measurement is available,only the information of the TPC is used by requiring that | N TPC σ | < p T > . / c , | N TPC σ | < . < p T < . / c , and | N TPC σ | < p T < . / c . Within each event, identified kaons arecombined in oppositely-charged pairs (“unlike-sign”) to extract the invariant mass ( M KK ) distribution ofthe signal. To estimate the background from uncorrelated pairs, an event mixing technique is used, whichconsists in building the invariant mass distribution of K + K − pairs from five different events with similarcentrality (within 5%) and a similar vertex position along the beam axis (within 1 cm). Only same-eventand mixed-event pairs with rapidity | y | < . . ≤ M KK ≤ . / c and then subtracted. The resulting distribution exhibits a clear peak centered at the nominal mass of φ [43], on top of a low residual background. The φ signal peak is fitted with a Voigtian function (asin [48]), which is the convolution of a Breit–Wigner, describing the characteristic shape of the resonancestate, and a Gaussian, taking into account the detector resolution. The resonance width is fixed to thenominal value of Γ φ = .
26 MeV / c [43], whereas the mass and the mass resolution σ φ are left as free fitparameters. The mass resulting from the fit is consistent with the nominal value of the φ mass reportedin [43]. The σ φ parameter ranges from ≈ / c at p T = . − / c to ≈ / c at p T = 10 GeV / c , and it is consistent with the mass resolution extracted from Monte Carlo simulations ofthe full detector setup and reconstruction chain. The residual background is parameterised with a linearfunction. The fit is performed in the range 0 . < M KK < .
07 GeV / c . This procedure is repeated foreach p T and centrality interval.The p T -differential yields obtained with the described procedure are corrected for efficiency and accep-tance, as described in [11]. The corrections are obtained from a Monte Carlo simulation where eventsare generated with HIJING [41] and particles are transported through a detailed simulation of the ALICEdetector with the GEANT3 transport code [44]. The selection criteria for φ candidates are the same inMonte Carlo and data. The calculation of the systematic uncertainties follows the procedure performed already for previousanalyses [2, 7, 26, 42, 48]. The main sources of systematic uncertainties for each particle species aresummarised in Table 2 ( π ± , K ± , p and p) and in Table 3 ( φ ).The main sources of systematic uncertainty affecting this analysis are: PID, feed-down correction,the imperfect description of the material budget in the Monte Carlo simulation, the knowledge of thehadronic interaction cross section in the detector material [26], the ITS-TPC [34] (accounted twice forthe decay daughters of the φ ) and TPC-TOF matching efficiencies, the track selection, the unfoldingiterations and the rapidity selection for the ITS. The uncertainties for track selection refer to the qual-ity requirements based on the number of crossed rows in the TPC, the number of clusters in the ITS,the DCA xy and DCA z , and the χ / NDF of the reconstructed tracks. To estimate these uncertainties, avariation of the standard selection criteria is performed and the ratio between the corrected spectra withmodified selection criteria and the ones with standard requirements is calculated, as performed in [26].For the uncertainty related to the number of iterations in the Bayesian unfolding for the ITS analysis, asimilar approach is followed where the number of iterations is changed from 4 (default) to 3, 5, 7 and 9.The uncertainties related to PID are evaluated by comparing different techniques (e.g. statistical unfold-ing versus track-by-track N σ selection). In addition, for the φ , a detailed study of the yield extractionprocedure was carried out by investigating the effect of variations in the signal shape parameters, thebackground shape and the fit range, as performed in [48]. The uncertainties of the detector material bud-get are estimated by changing the material budget in the simulation with the GEANT3 transport code by7roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration Table 2:
Main sources and values of the relative systematic uncertainties (expressed in %) of the p T -differentialyields of π ± , K ± , p and p obtained in the analysis of Xe–Xe collisions. The first section is common to all theanalyses, the analysis specific uncertainties are listed separately. When two values are reported, they correspondto the lowest and highest p T bin respectively, considering the maximum contribution among the various centralityclasses. If only one value is reported, the systematic uncertainty is not p T -dependent. For certain sources, thecentrality is specified when a larger dependence on centrality is observed. The maximum total systematic uncer-tainties (among all centrality classes) are shown. The total uncertainty refers to the uncertainty of the combinedresults (see text). Effect π ± (%) K ± (%) p and p (%)ITS − TPC matching efficiency (0 − − − − − TPC matching efficiency (40 − − − − − TPC matching efficiency (70 − − − − − − − − − − − − − − − E × B − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − PID + reconstruction efficiency (40 − − − PID + reconstruction efficiency (70 − − − Contamination (0 − − − − Contamination (40 − − − − Contamination (80 − − − − Total 11.1 − − − π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration ±
7% as in [26, 49]. The uncertainty of the hadronic interaction cross section is calculated by comparingthe efficiencies in different transport codes (GEANT3, GEANT4, FLUKA) following the prescriptiongiven in [50]. Finally, the uncertainties on the feed-down are determined by varying the range of thetemplate fit to the DCA xy distributions.For the ITS analysis, a systematic uncertainty is introduced to take into account the shift of the clusterpositions caused by the Lorentz force ( E × B effect), as described in [26]. For the kink analysis, thesystematic uncertainties are estimated by comparing the standard spectra with the ones obtained byvarying the selection criteria on the decay product transverse momentum, the minimum number of TPCclusters and the kink radius.Finally, the systematic uncertainties on the very low p T region of the spectra are higher compared toprevious analyses [2, 26] because of the lower momentum resolution in the reduced magnetic field.Nonetheless, the uncertainty on the pion measurement below 100 MeV / c is below 12%. In addition,the limited statistics of the Xe–Xe data sample restricts the detectors and techniques that can contributeto the PID at higher momenta, excluding the HMPID detector and the TPC energy loss measurementin the relativistic rise region. This yields overall larger uncertainties with respect to previous ALICEmeasurements in other collision systems. At 3 GeV / c the uncertainties are approximately twice as largewith respect to [26] for π ± , K ± , p and p. Table 3:
Main sources and values of the relative systematic uncertainties (expressed in %) of the p T -differentialyields of φ obtained in the analysis of Xe–Xe collisions. When two values are reported, they correspond to thelowest and highest p T bin respectively, considering the maximum contribution among the various centrality classes.If only one value is reported, the systematic uncertainty is not p T -dependent. The maximum total systematicuncertainties (among all centrality classes) are shown. Effect φ (%)B.R. 1ITS − TPC matching efficiency 6 . − . − − . − . − − − The π ± , K ± , p, p and φ p T spectra obtained after all corrections are shown for central and peripheralcollisions in Fig. 1. Each spectrum is individually fitted with a Blast-wave function [51], shown withdashed lines. The integrated yield h d N / d y i and the mean transverse momenta h p T i are calculated fromthe measured spectra and the extrapolation of the Blast-wave functions in the unmeasured regions. Asperformed in previous analyses [2, 26], the systematic uncertainties for both h d N / d y i and h p T i are eval-uated by shifting the data points up and down within their systematic uncertainty to obtain the softest andhardest spectra. An additional contribution is given by the extrapolation to p T = 0 GeV / c where differentfunctions ( m T -exponential, Fermi-Dirac, Bose-Einstein, Boltzmann) were used for the calculation. Theuncertainty on the extrapolation for the most central collisions is found to be ∼
1% for pions and kaons, ∼
5% for protons and ∼
2% for φ . 9roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration c (GeV/ T p − − − − − −
10 110 - ) c ) ( G e V / y d T p / ( d N d e v N / = 5.44 TeV NN s Xe − Xe ALICE − × ( - π + + π ) -1 × ( - + K + K ) -2 × (pp + 10% − -3 × ( φ c (GeV/ T p −
70 ) × ( - π + + π ) × ( - + K + K ) -1 × (pp + ) -2 × ( φ Individual blast-wave fit
Figure 1: p T distributions of π ± , K ± , p, p, φ as measured in central (left) and peripheral (right) Xe–Xe collisionsat √ s NN = .
44 TeV. The statistical and systematic uncertainties are shown as error bars and boxes around thedata points.
As already observed in Pb–Pb and also in small collision systems [1, 9, 26], the h p T i rises with increasingcentrality and multiplicity ( h d N ch / d η i ). This hardening is significantly more pronounced for heavierparticles. For instance, the maximum of the p spectrum shifts from p T ≈ . / c in peripheral to p T ≈ . / c in central collisions, while for pions the shift is much smaller. This feature is generallyconsidered as a consequence of the radial expansion of the system. The comparison of h p T i as a functionof charged-particle multiplicity for Pb–Pb and Xe–Xe collisions, shown in Fig. 2, clearly demonstratesthat this effect is entirely driven by the multiplicity and not by the collision geometry. Most notably, the h p T i values of protons and φ differ in peripheral Xe–Xe and Pb–Pb collisions, but reach similar values insemi-central and central collisions. This behaviour is expected due to the small mass difference of thesetwo particles if the spectral shape is more and more dominated by radial flow with increasing centrality.The mass-dependent radial flow naturally explains in central collisions the so-called baryon-to-mesonenhancement at low to intermediate p T ( . / c ) observed in the light-flavour sector [26]. Thiseffect is seen in Fig. 3 where the p / π ratio shows a maximum at around 3 − / c . Consideringthe most central Xe–Xe collisions, which have a multiplicity similar to 10 −
20% Pb–Pb collisions at √ s NN = .
02 TeV [26], the p / π ratio at the peak is enhanced by a factor of about 3 with respect to ppcollisions at the same energy. Instead, in peripheral Pb–Pb collisions the effect of the radial flow is lessevident and a behaviour similar to the one found in pp is observed. Therefore, the measurements shownin Fig. 3 for peripheral collisions suggest that this consideration might hold true also in Xe–Xe collisions.Another explanation for the baryon-to-meson enhancement advocates quark recombination [52, 53] asthe dominant production mechanism for baryons at intermediate momenta. In this picture, the productionof baryons is enhanced at intermediate momenta as it is more likely to combine three soft quarks (with p T , q = p T /
3) into a baryon in order to reach a given momentum p T than to produce a meson via quark-antiquark pair (each with p T , q = p T / / φ ratio displayed in Fig. 3 is rather independent10roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration | < 0.5 η | 〉η /d ch N d 〈 ) c ( G e V / 〉 T p 〈 - π + + π - +K + K pp+ φ ALICE = 5.02 TeV (open symbols) NN sPb − Pb = 5.44 TeV (solid symbols) NN sXe − Xe Figure 2:
Mean p T of pions, kaons, (anti-)protons and φ as a function of the charged-particle multiplicity densityin Xe–Xe collisions at √ s NN = .
44 TeV and Pb–Pb collisions at √ s NN = .
02 TeV [11, 26]. The statistical andsystematic uncertainties are shown as error bars and boxes around the data points. of p T as expected in the radial flow picture. Although their quark content is different, p and φ have similarmasses, indicating that this is the main variable in the determination of the spectral shape. Nevertheless,as discussed in [54], the same model including radial flow and coalescence plus fragmentation is able todescribe both p / π and p / φ in central Pb–Pb collisions showing that both radial flow and recombinationplay a role.A direct comparison of the Xe–Xe with Pb–Pb collisions allows the study of systems with the samecharged particle density and different initial eccentricity: semi central Pb–Pb collisions have the samemultiplicity as central Xe–Xe collisions, however, the overlap region and thus the initial eccentricity isformer in the latter case. A difference in the initial eccentricity affects the hydrodynamic expansion,eventually leading to a different elliptic flow of the charged particles. This is best illustrated in Fig. 4which compares the elliptic flow coefficient v { , | ∆η | > } of charged particles (for details on thedefinition, see [24, 55]) with the p / π ratio. Due to the large mass difference between protons andpions this ratio is very sensitive to radial flow effects. Consequently, a depletion of this ratio at lowtransverse momenta and an enhancement at intermediate transverse momenta with increasing particledensity is observed. The magnitude of this effect is not only qualitatively, but also quantitatively, withinuncertainties the same in Xe–Xe and Pb–Pb collisions for similar charged particle densities. In contrast,the v coefficient shows large differences between the two collision systems at similar particle densities,because it is dominantly influenced by the initial eccentricity. To investigate the particle chemistry, the p T -integrated particle yields are determined in each centralitybin with the procedure described above for the h p T i . The resulting h d N / d y i values are summarised inTable 4. The ratios of kaons, (anti-)protons, and φ to pions are shown in Fig. 5 and compared with resultsfrom Pb–Pb collisions. Similarly to the spectral shapes, also the particle yield ratios are comparablebetween Xe–Xe and Pb–Pb collisions at similar charged-particle multiplicities. The results reinforce two11roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration ) c (GeV/ T p R a t i o ALICE ± = 1180 〉η /d ch N d 〈 = 5.02 TeV, 10-20% (open symbols) NN s Pb − Pb 25 ± = 1053 〉η /d ch N d 〈 = 5.44 TeV, 0-10% (full symbols) NN s Xe − Xe × φ )/p(p+ ) - π + + π )/(p(p+ ) c (GeV/ T p ± = 96 〉η /d ch N d 〈 = 5.02 TeV, 60-70% (open symbols) NN s Pb − Pb 3 ± = 91 〉η /d ch N d 〈 = 5.44 TeV, 50-70% (full symbols) NN s Xe − Xe Figure 3:
Left: Proton-to-phi and proton-to-pion p T -differential ratios in 0 −
10% central Xe–Xe collisions at √ s NN = .
44 TeV and 10 −
20% central Pb–Pb collisions at √ s NN = .
02 TeV [26]. Right: proton-to-phi andproton-to-pion p T -differential ratios in 50 −
70% Xe–Xe collisions at √ s NN = .
44 TeV and 60 −
70% Pb–Pbcollisions at √ s NN = .
02 TeV [11, 26]. The two selected groups of centrality bins have similar h d N ch / d η i (seetext for details). The statistical and systematic uncertainties are shown as error bars and boxes around the datapoints. π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration ) - π + + π ) / ( p ( p + (full symbols) c < 1.1 GeV/ T p c < 3.4 GeV/ T p |<0.5 η | 〉η /d ch N d 〈 | > } η ∆ { , | v c < 3.0 GeV/ T p ALICE = 5.44 TeV NN s Xe − Xe = 5.02 TeV NN s Pb − Pb Figure 4:
Proton-to-pion ratio as a function of charged particle multiplicity density in two p T intervals for Xe–Xeand Pb–Pb collisions at √ s NN = 5.44 and 5.02 TeV. In the bottom panel, the flow coefficient v { , | ∆η | > } isplotted for the same collision systems [24, 55] as a function of charged particle multiplicity density. The statisticaland systematic uncertainties are shown as error bars and boxes around the data points. π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration Table 4: h d N / d y i of pions, kaons, (anti-)protons and φ for different centrality classes as measured at midrapidityin Xe–Xe collisions at √ s NN = .
44 TeV. The uncertainties are reported in the order ± (stat) ± (syst.). Centrality Class h d N / d y i π + + π − h d N / d y i K + + K − h d N / d y i p + p h d N / d y i φ −
5% 1002.67 ± ± ± ± ± ± ± ± −
10% 808.76 ± ± ± ± ± ± −
20% 620.47 ± ± ± ± ± ± ± ± −
30% 426.77 ± ± ± ± ± ± −
40% 287.20 ± ± ± ± ± ± ± ± −
50% 182.89 ± ± ± ± ± ± −
60% 1111.05 ± ± ± ± ± ± ± ± −
70% 61.23 ± ± ± ± ± ± −
90% 21.43 ± ± ± ± ± ± ± ± of the surprising features that were first observed in Pb–Pb collisions at the LHC energies and are nowconfirmed in a new heavy-ion collision system. First, the p / π -ratio values are around 0.05, significantlylower than those predicted before the LHC era [17]. While the overall magnitude is understood as aconsequence of the pion-nucleon phase-shift [21, 56] the decreasing trend with increasing centrality canbe interpreted as a consequence of the antibaryon-baryon annihilation [57]. The results presented in thisarticle add constraints to the particle production mechanisms proposed to explain this observation. Thedata reported in this work suggests that at LHC energies, particle production is not only independentof collision energy but also of the collision system when studied as a function of multiplicity. Second,the φ / π ratio shows an increasing trend from peripheral to central collisions with a hint of a decreaseat higher multiplicities. Notably, this increase appears to be slightly stronger for φ / π with respect toK / π . As shown in Fig. 5, this is not expected in canonical statistical hadronisation models [22, 56],which predict a constant or slightly decreasing trend since the net strangeness content S of the φ is zero.This feature is predicted from both models reported in Fig. 5, independent of the fact that the correlationvolume over which the strangeness conservation is imposed is kept fixed in [22] and has a multiplicitydependence in [56]. Future studies including the measurement of double-strange ( S = Ξ baryons inXe–Xe collisions can determine across all available collision systems whether the increase for the φ iscloser to S = S = Ξ ). The measurements of φ production inPb–Pb collisions [58] indicate that the increase lies in between these two extremes. In this article, results on the π ± , K ± , p, p and φ production measured as a function of centrality in Xe–Xecollisions at √ s NN = .
44 TeV are presented. For the first time at the LHC, it was possible to disentanglewith AA collisions the role of the collision region “shape” (eccentricity) and “size” (charged-particlemultiplicity) on the aspects of the particle production. The results show a mass dependent enhancementof the particle production at intermediate p T and a depletion at low p T . This feature is more prominentin central collisions and is typically associated with the presence of radial flow. The effect of the radialflow is reflected in a mass dependent increase of the average momentum for more central collisions.In light of this interpretation scheme, particles with similar masses receive a similar increase in theiraverage momentum. This behaviour is confirmed in the comparison of the h p T i of p and φ as a functionof h d N ch / d η i . The effect of the radial flow on the production of particles with different masses isinvestigated by comparing the baryon-to-meson (p / π and p / φ ) ratios. A sizable depletion of the low- p T part of the spectrum is only observed when comparing particles with large mass differences, in agreement14roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration |<0.5 η | 〉η /d ch N d 〈 ) - π + + π R a t i o o f y i e l d s t o ( ALICE - +K + K pp+ 5) × ( φ = 5.44 TeV NN s Xe − Xe = 5.02 TeV NN s Pb − Pb = 2.76 TeV NN s Pb − PbCSM PRC 100 (2019) 5, 054906arXiv:2009.04844
Figure 5:
Ratio of kaon, proton and φ integrated yields to pion integrated yield as a function of the charged-particle multiplicity density for Xe–Xe collisions at √ s NN = .
44 TeV and Pb–Pb collisions at √ s NN =2.76 TeV [2, 48] and 5.02 TeV [11, 26]. The statistical and systematic uncertainties are shown as error barsand boxes around the data points. Predictions from the canonical statistical model (CSM) are shown as bandsconsidering different correlation volumes [22] and chemical freeze-out temperatures [56]. The correlation volumeindicates the volume over which the strangeness conservation is imposed. π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaborationwith the expectations from the radial flow. The comparison of particles with similar mass (such as p and φ ) hints to the fact that the effect is mostly driven by the hadron mass and not by the quark content as onecould expect from the recombination of quarks into baryons and mesons. However, models includingrecombination of quarks and radial flow are able to reproduce both p / π and p / φ at intermediate p T in central Pb–Pb collisions suggesting the importance of both mechanisms [54]. Moreover, it is foundthat the results in Xe–Xe and Pb–Pb collisions are in agreement, indicating that radial flow has a similarmagnitude in the two collision systems at LHC energies. The magnitude of the radial flow is compared inthe two systems by using the p / π ratio in the depletion (1 GeV / c ) and enhancement (3 GeV / c ) regions.It is found that the amount of depletion and enhancement is similar in both cases, while the v exhibitsa clear deviation. This observation corroborates the intuition that the radial flow depends exclusively onthe h d N ch / d η i , while anisotropic flow (e.g. v ) depends also on the initial eccentricities of the collisionregion.The hadrochemistry is investigated by studying the integrated particle yield ratios of kaons, (anti-)protons,and φ to the most abundantly produced pions. Also, in this case, a behaviour that is mostly driven by h d N ch / d η i is observed and thus the intriguing observations from Pb–Pb collisions related to the p / π ratio and the φ / π ratio are now confirmed in a smaller heavy-ion collision system at LHC energies.As an outlook, these results also pave the way for the future programme of light nuclei collisions at theLHC (in particular the proposed extended future programme with nuclear beams lighter than Pb [59])which is attractive since higher parton luminosities are achievable. Our results suggest that particlechemistry and radial flow will be driven also in these systems by the final-state charged particle densities.While Pb–Pb collisions offer the largest dynamic range in this context, it is also clear from our findingsthat collisions of small and intermediate nuclei provide an excellent tool to study the hot and strongly-interacting matter in the range of moderate multiplicities. Acknowledgements
The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable con-tributions to the construction of the experiment and the CERN accelerator teams for the outstandingperformance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources andsupport 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 andrunning 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 fürForschung, Technologie und Entwicklung, Austria; Ministry of Communications and High Technolo-gies, National Nuclear Research Center, Azerbaijan; Conselho Nacional de Desenvolvimento Científicoe Tecnológico (CNPq), Financiadora de Estudos e Projetos (Finep), Fundação de Amparo à Pesquisa doEstado de São Paulo (FAPESP) and Universidade Federal do Rio Grande do Sul (UFRGS), Brazil; Min-istry of Education of China (MOEC) , Ministry of Science & Technology of China (MSTC) and NationalNatural Science Foundation of China (NSFC), China; Ministry of Science and Education and CroatianScience 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 DanishNational Research Foundation (DNRF), Denmark; Helsinki Institute of Physics (HIP), Finland; Commis-sariat à l’Energie Atomique (CEA) and Institut National de Physique Nucléaire et de Physique des Par-ticules (IN2P3) and Centre National de la Recherche Scientifique (CNRS), France; Bundesministeriumfür Bildung und Forschung (BMBF) and GSI Helmholtzzentrum für Schwerionenforschung GmbH, Ger-many; General Secretariat for Research and Technology, Ministry of Education, Research and Religions,Greece; National Research, Development and Innovation Office, Hungary; Department of Atomic En-16roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaborationergy 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 IndustrialResearch (CSIR), India; Indonesian Institute of Science, Indonesia; 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 So-ciety 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) andDirección General de Asuntos del Personal Academico (DGAPA), Mexico; Nederlandse Organisatievoor Wetenschappelijk Onderzoek (NWO), Netherlands; The Research Council of Norway, Norway;Commission on Science and Technology for Sustainable Development in the South (COMSATS) andPakistan Atomic Energy Commission, Pakistan; Pontificia Universidad Católica del Perú, Peru; Ministryof Science and Higher Education, National Science Centre and WUT ID-UB, Poland; Korea Instituteof Science and Technology Information and National Research Foundation of Korea (NRF), Republicof Korea; Ministry of Education and Scientific Research, Institute of Atomic Physics and Ministry ofResearch 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 Kur-chatov Institute, Russian Science Foundation and Russian Foundation for Basic Research, Russia; Min-istry of Education, Science, Research and Sport of the Slovak Republic, Slovakia; National ResearchFoundation of South Africa, South Africa; Swedish Research Council (VR) and Knut & Alice Wallen-berg Foundation (KAW), Sweden; European Organization for Nuclear Research, Switzerland; SuranareeUniversity of Technology (SUT), National Science and Technology Development Agency (NSDTA) andOffice of the Higher Education Commission under NRU project of Thailand, Thailand; Turkish AtomicEnergy Agency (TAEK), Turkey; National Academy of Sciences of Ukraine, Ukraine; Science and Tech-nology Facilities Council (STFC), United Kingdom; National Science Foundation of the United States ofAmerica (NSF) and United States Department of Energy, Office of Nuclear Physics (DOE NP), UnitedStates of America. References [1]
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Collaboration, S. Acharya et al. , “Multiplicity dependence of K*(892) and φ (1020)production in pp collisions at √ s =13 TeV”, Phys. Lett. B (2020) , arXiv:1910.14397 [nucl-ex] .[59] A. Dainese, M. Mangano, A. B. Meyer, A. Nisati, G. Salam, and M. A. Vesterinen,“Report on the Physics at the HL-LHC, and Perspectives for the HE-LHC”, Tech. Rep.CERN-2019-007, Geneva, Switzerland, 2019. http://cds.cern.ch/record/2703572 .21roduction of π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration A The ALICE Collaboration
S. Acharya , D. Adamová , A. Adler , J. Adolfsson , G. Aglieri Rinella , M. Agnello , N. Agrawal ,Z. Ahammed , S. Ahmad , S.U. Ahn , Z. Akbar , A. Akindinov , M. Al-Turany ,D.S.D. Albuquerque , D. Aleksandrov , B. Alessandro , H.M. Alfanda , R. Alfaro Molina , B. Ali ,Y. Ali , A. Alici , N. Alizadehvandchali , A. Alkin , J. Alme , T. Alt , L. Altenkamper , I. Altsybeev ,M.N. Anaam , C. Andrei , D. Andreou , A. Andronic , V. Anguelov , T. Antiˇci´c , F. Antinori ,P. Antonioli , C. Anuj , N. Apadula , L. Aphecetche , H. Appelshäuser , S. Arcelli , R. Arnaldi ,M. Arratia , I.C. Arsene , M. Arslandok , , A. Augustinus , R. Averbeck , S. Aziz , M.D. Azmi ,A. Badalà , Y.W. Baek , X. Bai , R. Bailhache , R. Bala , A. Balbino , A. Baldisseri , M. Ball ,D. Banerjee , R. Barbera , L. Barioglio , M. Barlou , G.G. Barnaföldi , L.S. Barnby , V. Barret ,C. Bartels , K. Barth , E. Bartsch , F. Baruffaldi , N. Bastid , S. Basu , , G. Batigne , B. Batyunya ,D. Bauri , J.L. Bazo Alba , I.G. Bearden , C. Beattie , I. Belikov , A.D.C. Bell Hechavarria ,F. Bellini , R. Bellwied , S. Belokurova , V. Belyaev , G. Bencedi , , S. Beole , A. Bercuci ,Y. Berdnikov , A. Berdnikova , D. Berenyi , L. Bergmann , M.G. Besoiu , L. Betev , P.P. Bhaduri ,A. Bhasin , I.R. Bhat , M.A. Bhat , B. Bhattacharjee , P. Bhattacharya , A. Bianchi , L. Bianchi ,N. Bianchi , J. Bielˇcík , J. Bielˇcíková , A. Bilandzic , G. Biro , S. Biswas , J.T. Blair , D. Blau ,M.B. Blidaru , C. Blume , G. Boca , F. Bock , A. Bogdanov , S. Boi , J. Bok , L. Boldizsár ,A. Bolozdynya , M. Bombara , P.M. Bond , G. Bonomi , H. Borel , A. Borissov , , H. Bossi ,E. Botta , L. Bratrud , P. Braun-Munzinger , M. Bregant , M. Broz , G.E. Bruno , , M.D. Buckland ,D. Budnikov , H. Buesching , S. Bufalino , O. Bugnon , P. Buhler , P. Buncic , Z. Buthelezi , ,J.B. Butt , S.A. Bysiak , D. Caffarri , A. Caliva , E. Calvo Villar , J.M.M. Camacho , R.S. Camacho ,P. Camerini , F.D.M. Canedo , A.A. Capon , F. Carnesecchi , R. Caron , J. Castillo Castellanos ,E.A.R. Casula , F. Catalano , C. Ceballos Sanchez , P. Chakraborty , S. Chandra , W. Chang ,S. Chapeland , M. Chartier , S. Chattopadhyay , S. Chattopadhyay , A. Chauvin , T.G. Chavez ,C. Cheshkov , B. Cheynis , V. Chibante Barroso , D.D. Chinellato , S. Cho , P. Chochula ,P. Christakoglou , C.H. Christensen , P. Christiansen , T. Chujo , C. Cicalo , L. Cifarelli , F. Cindolo ,M.R. Ciupek , G. Clai II , , J. Cleymans , F. Colamaria , J.S. Colburn , D. Colella , , A. Collu ,M. Colocci , , M. Concas III , , G. Conesa Balbastre , Z. Conesa del Valle , G. Contin , J.G. Contreras ,T.M. Cormier , P. Cortese , M.R. Cosentino , F. Costa , S. Costanza , P. Crochet , E. Cuautle , P. Cui ,L. Cunqueiro , A. Dainese , F.P.A. Damas , , M.C. Danisch , A. Danu , I. Das , P. Das , P. Das ,S. Das , S. Dash , S. De , A. De Caro , G. de Cataldo , L. De Cilladi , J. de Cuveland , A. De Falco ,D. De Gruttola , N. De Marco , C. De Martin , S. De Pasquale , S. Deb , H.F. Degenhardt , K.R. Deja ,L. Dello Stritto , S. Delsanto , W. Deng , P. Dhankher , D. Di Bari , A. Di Mauro , R.A. Diaz , T. Dietel ,Y. Ding , R. Divià , D.U. Dixit , Ø. Djuvsland , U. Dmitrieva , J. Do , A. Dobrin , B. Dönigus ,O. Dordic , A.K. Dubey , A. Dubla , , S. Dudi , M. Dukhishyam , P. Dupieux , T.M. Eder ,R.J. Ehlers , V.N. Eikeland , D. Elia , B. Erazmus , F. Ercolessi , F. Erhardt , A. Erokhin ,M.R. Ersdal , B. Espagnon , G. Eulisse , D. Evans , S. Evdokimov , L. Fabbietti , M. Faggin ,J. Faivre , F. Fan , A. Fantoni , M. Fasel , P. Fecchio , A. Feliciello , G. Feofilov , A. Fernández Téllez ,A. Ferrero , A. Ferretti , A. Festanti , V.J.G. Feuillard , J. Figiel , S. Filchagin , D. Finogeev ,F.M. Fionda , G. Fiorenza , F. Flor , A.N. Flores , S. Foertsch , P. Foka , S. Fokin , E. Fragiacomo ,U. Fuchs , N. Funicello , C. Furget , A. Furs , M. Fusco Girard , J.J. Gaardhøje , M. Gagliardi ,A.M. Gago , A. Gal , C.D. Galvan , P. Ganoti , C. Garabatos , J.R.A. Garcia , E. Garcia-Solis ,K. Garg , C. Gargiulo , A. Garibli , K. Garner , P. Gasik , E.F. Gauger , M.B. Gay Ducati ,M. Germain , J. Ghosh , P. Ghosh , S.K. Ghosh , M. Giacalone , P. Gianotti , P. Giubellino , ,P. Giubilato , A.M.C. Glaenzer , P. Glässel , V. Gonzalez , L.H. González-Trueba , S. Gorbunov ,L. Görlich , S. Gotovac , V. Grabski , L.K. Graczykowski , K.L. Graham , L. Greiner , A. Grelli ,C. Grigoras , V. Grigoriev , A. Grigoryan I , , S. Grigoryan , , O.S. Groettvik , F. Grosa ,J.F. Grosse-Oetringhaus , R. Grosso , R. Guernane , M. Guilbaud , M. Guittiere , K. Gulbrandsen ,T. Gunji , A. Gupta , R. Gupta , I.B. Guzman , R. Haake , M.K. Habib , C. Hadjidakis ,H. Hamagaki , G. Hamar , M. Hamid , R. Hannigan , M.R. Haque , , A. Harlenderova , J.W. Harris ,A. Harton , J.A. Hasenbichler , H. Hassan , D. Hatzifotiadou , P. Hauer , L.B. Havener , S. Hayashi ,S.T. Heckel , E. Hellbär , H. Helstrup , T. Herman , E.G. Hernandez , G. Herrera Corral , F. Herrmann ,K.F. Hetland , H. Hillemanns , C. Hills , B. Hippolyte , B. Hohlweger , J. Honermann , G.H. Hong ,D. Horak , S. Hornung , R. Hosokawa , P. Hristov , C. Huang , C. Hughes , P. Huhn , T.J. Humanic ,H. Hushnud , L.A. Husova , N. Hussain , D. Hutter , J.P. Iddon , , R. Ilkaev , H. Ilyas , M. Inaba ,G.M. Innocenti , M. Ippolitov , A. Isakov , , M.S. Islam , M. Ivanov , V. Ivanov , V. Izucheev , π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration B. Jacak , N. Jacazio , , P.M. Jacobs , S. Jadlovska , J. Jadlovsky , S. Jaelani , C. Jahnke ,M.J. Jakubowska , M.A. Janik , T. Janson , M. Jercic , O. Jevons , M. Jin , F. Jonas , ,P.G. Jones , J. Jung , M. Jung , A. Junique , A. Jusko , P. Kalinak , A. Kalweit , V. Kaplin , S. Kar ,A. Karasu Uysal , D. Karatovic , O. Karavichev , T. Karavicheva , P. Karczmarczyk , E. Karpechev ,A. Kazantsev , U. Kebschull , R. Keidel , M. Keil , B. Ketzer , Z. Khabanova , A.M. Khan , S. Khan ,A. Khanzadeev , Y. Kharlov , A. Khatun , A. Khuntia , B. Kileng , B. Kim , D. Kim , D.J. Kim ,E.J. Kim , H. Kim , J. Kim , J.S. Kim , J. Kim , J. Kim , J. Kim , M. Kim , S. Kim , T. Kim ,T. Kim , S. Kirsch , I. Kisel , S. Kiselev , A. Kisiel , J.L. Klay , J. Klein , , S. Klein ,C. Klein-Bösing , M. Kleiner , T. Klemenz , A. Kluge , A.G. Knospe , C. Kobdaj , M.K. Köhler ,T. Kollegger , A. Kondratyev , N. Kondratyeva , E. Kondratyuk , J. Konig , S.A. Konigstorfer ,P.J. Konopka , , G. Kornakov , S.D. Koryciak , L. Koska , O. Kovalenko , V. Kovalenko ,M. Kowalski , I. Králik , A. Kravˇcáková , L. Kreis , M. Krivda , , F. Krizek ,K. Krizkova Gajdosova , M. Kroesen , M. Krüger , E. Kryshen , M. Krzewicki , V. Kuˇcera , C. Kuhn ,P.G. Kuijer , T. Kumaoka , L. Kumar , S. Kundu , P. Kurashvili , A. Kurepin , A.B. Kurepin ,A. Kuryakin , S. Kushpil , J. Kvapil , M.J. Kweon , J.Y. Kwon , Y. Kwon , S.L. La Pointe , P. LaRocca , Y.S. Lai , A. Lakrathok , M. Lamanna , R. Langoy , K. Lapidus , P. Larionov , E. Laudi ,L. Lautner , R. Lavicka , T. Lazareva , R. Lea , J. Lee , S. Lee , J. Lehrbach , R.C. Lemmon , I. LeónMonzón , E.D. Lesser , M. Lettrich , P. Lévai , X. Li , X.L. Li , J. Lien , R. Lietava , B. Lim ,S.H. Lim , V. Lindenstruth , A. Lindner , C. Lippmann , A. Liu , J. Liu , I.M. Lofnes , V. Loginov ,C. Loizides , P. Loncar , J.A. Lopez , X. Lopez , E. López Torres , J.R. Luhder , M. Lunardon ,G. Luparello , Y.G. Ma , A. Maevskaya , M. Mager , S.M. Mahmood , T. Mahmoud , A. Maire ,R.D. Majka I , , M. Malaev , Q.W. Malik , L. Malinina IV , , D. Mal’Kevich , N. Mallick , P. Malzacher ,G. Mandaglio , , V. Manko , F. Manso , V. Manzari , Y. Mao , J. Mareš , G.V. Margagliotti ,A. Margotti , A. Marín , S. Marium , C. Markert , M. Marquard , N.A. Martin , P. Martinengo ,J.L. Martinez , M.I. Martínez , G. Martínez García , S. Masciocchi , M. Masera , A. Masoni ,L. Massacrier , A. Mastroserio , , A.M. Mathis , O. Matonoha , P.F.T. Matuoka , A. Matyja ,C. Mayer , A.L. Mazuecos , F. Mazzaschi , M. Mazzilli , , M.A. Mazzoni , A.F. Mechler , F. Meddi ,Y. Melikyan , A. Menchaca-Rocha , C. Mengke , , E. Meninno , , A.S. Menon , M. Meres ,S. Mhlanga , Y. Miake , L. Micheletti , L.C. Migliorin , D.L. Mihaylov , K. Mikhaylov , ,A.N. Mishra , , D. Mi´skowiec , A. Modak , N. Mohammadi , A.P. Mohanty , B. Mohanty , M. MohisinKhan , Z. Moravcova , C. Mordasini , D.A. Moreira De Godoy , L.A.P. Moreno , I. Morozov ,A. Morsch , T. Mrnjavac , V. Muccifora , E. Mudnic , D. Mühlheim , S. Muhuri , J.D. Mulligan ,A. Mulliri , M.G. Munhoz , R.H. Munzer , H. Murakami , S. Murray , L. Musa , J. Musinsky ,C.J. Myers , J.W. Myrcha , B. Naik , R. Nair , B.K. Nandi , R. Nania , E. Nappi , M.U. Naru ,A.F. Nassirpour , C. Nattrass , S. Nazarenko , A. Neagu , L. Nellen , S.V. Nesbo , G. Neskovic ,D. Nesterov , B.S. Nielsen , S. Nikolaev , S. Nikulin , V. Nikulin , F. Noferini , S. Noh ,P. Nomokonov , J. Norman , N. Novitzky , P. Nowakowski , A. Nyanin , J. Nystrand , M. Ogino ,A. Ohlson , J. Oleniacz , A.C. Oliveira Da Silva , M.H. Oliver , A. Onnerstad , C. Oppedisano ,A. Ortiz Velasquez , T. Osako , A. Oskarsson , J. Otwinowski , K. Oyama , Y. Pachmayer , S. Padhan ,D. Pagano , G. Pai´c , A. Palasciano , J. Pan , S. Panebianco , P. Pareek , J. Park , J.E. Parkkila ,S. Parmar , S.P. Pathak , B. Paul , J. Pazzini , H. Pei , T. Peitzmann , X. Peng , L.G. Pereira ,H. Pereira Da Costa , D. Peresunko , G.M. Perez , S. Perrin , Y. Pestov , V. Petráˇcek , M. Petrovici ,R.P. Pezzi , S. Piano , M. Pikna , P. Pillot , O. Pinazza , , L. Pinsky , C. Pinto , S. Pisano ,M. Płosko´n , M. Planinic , F. Pliquett , M.G. Poghosyan , B. Polichtchouk , N. Poljak , A. Pop ,S. Porteboeuf-Houssais , J. Porter , V. Pozdniakov , S.K. Prasad , R. Preghenella , F. Prino ,C.A. Pruneau , I. Pshenichnov , M. Puccio , S. Qiu , L. Quaglia , R.E. Quishpe , S. Ragoni ,A. Rakotozafindrabe , L. Ramello , F. Rami , S.A.R. Ramirez , A.G.T. Ramos , R. Raniwala ,S. Raniwala , S.S. Räsänen , R. Rath , I. Ravasenga , K.F. Read , , A.R. Redelbach , K. Redlich V , ,A. Rehman , P. Reichelt , F. Reidt , R. Renfordt , Z. Rescakova , K. Reygers , A. Riabov ,V. Riabov , T. Richert , , M. Richter , P. Riedler , W. Riegler , F. Riggi , C. Ristea , S.P. Rode ,M. Rodríguez Cahuantzi , K. Røed , R. Rogalev , E. Rogochaya , T.S. Rogoschinski , D. Rohr ,D. Röhrich , P.F. Rojas , P.S. Rokita , F. Ronchetti , A. Rosano , , E.D. Rosas , A. Rossi , A. Rotondi ,A. Roy , P. Roy , N. Rubini , O.V. Rueda , R. Rui , B. Rumyantsev , A. Rustamov , E. Ryabinkin ,Y. Ryabov , A. Rybicki , H. Rytkonen , W. Rzesa , O.A.M. Saarimaki , R. Sadek , S. Sadovsky ,J. Saetre , K. Šafaˇrík , S.K. Saha , S. Saha , B. Sahoo , P. Sahoo , R. Sahoo , S. Sahoo , D. Sahu ,P.K. Sahu , J. Saini , S. Sakai , S. Sambyal , V. Samsonov I , , , D. Sarkar , N. Sarkar , P. Sarma , π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration V.M. Sarti , M.H.P. Sas , , J. Schambach , , H.S. Scheid , C. Schiaua , R. Schicker , A. Schmah ,C. Schmidt , H.R. Schmidt , M.O. Schmidt , M. Schmidt , N.V. Schmidt , , A.R. Schmier ,R. Schotter , J. Schukraft , Y. Schutz , K. Schwarz , K. Schweda , G. Scioli , E. Scomparin ,J.E. Seger , Y. Sekiguchi , D. Sekihata , I. Selyuzhenkov , , S. Senyukov , J.J. Seo , D. Serebryakov ,L. Šerkšnyt˙e , A. Sevcenco , A. Shabanov , A. Shabetai , R. Shahoyan , W. Shaikh , A. Shangaraev ,A. Sharma , H. Sharma , M. Sharma , N. Sharma , S. Sharma , O. Sheibani , A.I. Sheikh ,K. Shigaki , M. Shimomura , S. Shirinkin , Q. Shou , Y. Sibiriak , S. Siddhanta , T. Siemiarczuk ,T.F.D. Silva , D. Silvermyr , G. Simatovic , G. Simonetti , B. Singh , R. Singh , R. Singh , R. Singh ,V.K. Singh , V. Singhal , T. Sinha , B. Sitar , M. Sitta , T.B. Skaali , G. Skorodumovs ,M. Slupecki , N. Smirnov , R.J.M. Snellings , C. Soncco , J. Song , A. Songmoolnak , F. Soramel ,S. Sorensen , I. Sputowska , M. Spyropoulou-Stassinaki , J. Stachel , I. Stan , P.J. Steffanic ,S.F. Stiefelmaier , D. Stocco , M.M. Storetvedt , C.P. Stylianidis , A.A.P. Suaide , T. Sugitate ,C. Suire , M. Suljic , R. Sultanov , M. Šumbera , V. Sumberia , S. Sumowidagdo , S. Swain ,A. Szabo , I. Szarka , U. Tabassam , S.F. Taghavi , G. Taillepied , J. Takahashi , G.J. Tambave ,S. Tang , , Z. Tang , M. Tarhini , M.G. Tarzila , A. Tauro , G. Tejeda Muñoz , A. Telesca ,L. Terlizzi , C. Terrevoli , G. Tersimonov , S. Thakur , D. Thomas , R. Tieulent , A. Tikhonov ,A.R. Timmins , M. Tkacik , A. Toia , N. Topilskaya , M. Toppi , F. Torales-Acosta , S.R. Torres ,A. Trifiró , , S. Tripathy , T. Tripathy , S. Trogolo , G. Trombetta , L. Tropp , V. Trubnikov ,W.H. Trzaska , T.P. Trzcinski , B.A. Trzeciak , A. Tumkin , R. Turrisi , T.S. Tveter , K. Ullaland ,E.N. Umaka , A. Uras , M. Urioni , G.L. Usai , M. Vala , N. Valle , S. Vallero , N. van der Kolk ,L.V.R. van Doremalen , M. van Leeuwen , P. Vande Vyvre , D. Varga , Z. Varga , M. Varga-Kofarago ,A. Vargas , M. Vasileiou , A. Vasiliev , O. Vázquez Doce , V. Vechernin , E. Vercellin , S. VergaraLimón , L. Vermunt , R. Vértesi , M. Verweij , L. Vickovic , Z. Vilakazi , O. Villalobos Baillie ,G. Vino , A. Vinogradov , T. Virgili , V. Vislavicius , A. Vodopyanov , B. Volkel , M.A. Völkl ,K. Voloshin , S.A. Voloshin , G. Volpe , B. von Haller , I. Vorobyev , D. Voscek , J. Vrláková ,B. Wagner , M. Weber , A. Wegrzynek , S.C. Wenzel , J.P. Wessels , J. Wiechula , J. Wikne ,G. Wilk , J. Wilkinson , G.A. Willems , E. Willsher , B. Windelband , M. Winn , W.E. Witt ,J.R. Wright , Y. Wu , R. Xu , S. Yalcin , Y. Yamaguchi , K. Yamakawa , S. Yang , S. Yano , ,Z. Yasin , Z. Yin , H. Yokoyama , I.-K. Yoo , J.H. Yoon , S. Yuan , A. Yuncu , V. Yurchenko ,V. Zaccolo , A. Zaman , C. Zampolli , H.J.C. Zanoli , N. Zardoshti , A. Zarochentsev , P. Závada ,N. Zaviyalov , H. Zbroszczyk , M. Zhalov , S. Zhang , X. Zhang , Y. Zhang , V. Zherebchevskii ,Y. Zhi , D. Zhou , Y. Zhou , J. Zhu , , Y. Zhu , A. Zichichi , G. Zinovjev , N. Zurlo Affiliation notes I Deceased II Also at: Italian National Agency for New Technologies, Energy and Sustainable Economic Development(ENEA), Bologna, Italy
III
Also at: Dipartimento DET del Politecnico di Torino, Turin, Italy IV Also at: M.V. Lomonosov Moscow State University, D.V. Skobeltsyn Institute of Nuclear, Physics, Moscow,Russia V Also at: Institute of Theoretical Physics, University of Wroclaw, Poland
Collaboration Institutes A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation, Yerevan, Armenia AGH University of Science and Technology, Cracow, Poland Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine Bose Institute, Department of Physics and Centre for Astroparticle Physics and Space Science (CAPSS),Kolkata, India Budker Institute for Nuclear Physics, Novosibirsk, Russia California Polytechnic State University, San Luis Obispo, California, United States Central China Normal University, Wuhan, China Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico Chicago State University, Chicago, Illinois, United States π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration China Institute of Atomic Energy, Beijing, China Chungbuk National University, Cheongju, Republic of Korea Comenius University Bratislava, Faculty of Mathematics, Physics and Informatics, Bratislava, Slovakia COMSATS University Islamabad, Islamabad, Pakistan Creighton University, Omaha, Nebraska, United States Department of Physics, Aligarh Muslim University, Aligarh, India Department of Physics, Pusan National University, Pusan, Republic of Korea Department of Physics, Sejong University, Seoul, Republic of Korea Department of Physics, University of California, Berkeley, California, United States Department of Physics, University of Oslo, Oslo, Norway Department of Physics and Technology, University of Bergen, Bergen, Norway Dipartimento di Fisica dell’Università ’La Sapienza’ and Sezione INFN, Rome, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Turin, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Bologna, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Padova, Italy Dipartimento di Fisica e Nucleare e Teorica, Università di Pavia and Sezione INFN, Pavia, Italy Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Gruppo Collegato INFN, Salerno, Italy Dipartimento DISAT del Politecnico and Sezione INFN, Turin, Italy Dipartimento di Scienze e Innovazione Tecnologica dell’Università del Piemonte Orientale and INFN Sezionedi Torino, Alessandria, Italy Dipartimento di Scienze MIFT, Università di Messina, Messina, Italy Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy European Organization for Nuclear Research (CERN), Geneva, Switzerland Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, Split,Croatia Faculty of Engineering and Science, Western Norway University of Applied Sciences, Bergen, Norway Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, CzechRepublic Faculty of Science, P.J. Šafárik University, Košice, Slovakia Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Fudan University, Shanghai, China Gangneung-Wonju National University, Gangneung, Republic of Korea Gauhati University, Department of Physics, Guwahati, India Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn,Germany Helsinki Institute of Physics (HIP), Helsinki, Finland High Energy Physics Group, Universidad Autónoma de Puebla, Puebla, Mexico Hiroshima University, Hiroshima, Japan Hochschule Worms, Zentrum für Technologietransfer und Telekommunikation (ZTT), Worms, Germany Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania Indian Institute of Technology Bombay (IIT), Mumbai, India Indian Institute of Technology Indore, Indore, India Indonesian Institute of Sciences, Jakarta, Indonesia INFN, Laboratori Nazionali di Frascati, Frascati, Italy INFN, Sezione di Bari, Bari, Italy INFN, Sezione di Bologna, Bologna, Italy INFN, Sezione di Cagliari, Cagliari, Italy INFN, Sezione di Catania, Catania, Italy INFN, Sezione di Padova, Padova, Italy INFN, Sezione di Roma, Rome, Italy INFN, Sezione di Torino, Turin, Italy INFN, Sezione di Trieste, Trieste, Italy Inha University, Incheon, Republic of Korea π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration Institute for Gravitational and Subatomic Physics (GRASP), Utrecht University/Nikhef, Utrecht, Netherlands Institute for Nuclear Research, Academy of Sciences, Moscow, Russia Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia Institute of Physics, Homi Bhabha National Institute, Bhubaneswar, India Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic Institute of Space Science (ISS), Bucharest, Romania Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico iThemba LABS, National Research Foundation, Somerset West, South Africa Jeonbuk National University, Jeonju, Republic of Korea Johann-Wolfgang-Goethe Universität Frankfurt Institut für Informatik, Fachbereich Informatik undMathematik, Frankfurt, Germany Joint Institute for Nuclear Research (JINR), Dubna, Russia Korea Institute of Science and Technology Information, Daejeon, Republic of Korea KTO Karatay University, Konya, Turkey Laboratoire de Physique des 2 Infinis, Irène Joliot-Curie, Orsay, France Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS-IN2P3, Grenoble,France Lawrence Berkeley National Laboratory, Berkeley, California, United States Lund University Department of Physics, Division of Particle Physics, Lund, Sweden Moscow Institute for Physics and Technology, Moscow, Russia Nagasaki Institute of Applied Science, Nagasaki, Japan Nara Women’s University (NWU), Nara, Japan National and Kapodistrian University of Athens, School of Science, Department of Physics , Athens, Greece National Centre for Nuclear Research, Warsaw, Poland National Institute of Science Education and Research, Homi Bhabha National Institute, Jatni, India National Nuclear Research Center, Baku, Azerbaijan National Research Centre Kurchatov Institute, Moscow, Russia Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark Nikhef, National institute for subatomic physics, Amsterdam, Netherlands NRC Kurchatov Institute IHEP, Protvino, Russia NRC «Kurchatov»Institute - ITEP, Moscow, Russia NRNU Moscow Engineering Physics Institute, Moscow, Russia Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, United Kingdom Nuclear Physics Institute of the Czech Academy of Sciences, ˇRež u Prahy, Czech Republic Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States Ohio State University, Columbus, Ohio, United States
Petersburg Nuclear Physics Institute, Gatchina, Russia
Physics department, Faculty of science, University of Zagreb, Zagreb, Croatia
Physics Department, Panjab University, Chandigarh, India
Physics Department, University of Jammu, Jammu, India
Physics Department, University of Rajasthan, Jaipur, India
Physikalisches Institut, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
Physik Department, Technische Universität München, Munich, Germany
PINSTECH, Islamabad, Pakistan
Politecnico di Bari and Sezione INFN, Bari, Italy
Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für SchwerionenforschungGmbH, Darmstadt, Germany
Rudjer Boškovi´c Institute, Zagreb, Croatia
Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom
Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru π ± , K ± , p, p and φ in Xe–Xe collisions at √ s NN = 5.44 TeV ALICE Collaboration St. Petersburg State University, St. Petersburg, Russia
Stefan Meyer Institut für Subatomare Physik (SMI), Vienna, Austria
SUBATECH, IMT Atlantique, Université de Nantes, CNRS-IN2P3, Nantes, France
Suranaree University of Technology, Nakhon Ratchasima, Thailand
Technical University of Košice, Košice, Slovakia
The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland
The University of Texas at Austin, Austin, Texas, United States
Universidad Autónoma de Sinaloa, Culiacán, Mexico
Universidade de São Paulo (USP), São Paulo, Brazil
Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
Universidade Federal do ABC, Santo Andre, Brazil
University of Cape Town, Cape Town, South Africa
University of Houston, Houston, Texas, United States
University of Jyväskylä, Jyväskylä, Finland
University of Liverpool, Liverpool, United Kingdom
University of Science and Technology of China, Hefei, China
University of South-Eastern Norway, Tonsberg, Norway
University of Tennessee, Knoxville, Tennessee, United States
University of the Witwatersrand, Johannesburg, South Africa
University of Tokyo, Tokyo, Japan
University of Tsukuba, Tsukuba, Japan
Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
Université de Lyon, CNRS/IN2P3, Institut de Physique des 2 Infinis de Lyon , Lyon, France
Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France, Strasbourg, France
Université Paris-Saclay Centre d’Etudes de Saclay (CEA), IRFU, Départment de Physique Nucléaire (DPhN),Saclay, France
Università degli Studi di Foggia, Foggia, Italy
Università di Brescia and Sezione INFN, Brescia, Italy
Variable Energy Cyclotron Centre, Homi Bhabha National Institute, Kolkata, India
Warsaw University of Technology, Warsaw, Poland
Wayne State University, Detroit, Michigan, United States
Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
Wigner Research Centre for Physics, Budapest, Hungary
Yale University, New Haven, Connecticut, United States