Evidence of rescattering effect in Pb–Pb collisions at the LHC through production of K(892)0⁎ and ϕ(1020) mesons

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Evidence

of

rescattering

effect

in

Pb–Pb

collisions

at

the

LHC

through

production

of

K

∗

(

892

)

0

and

φ (

1020

)

mesons

.

ALICE

Collaboration



a

r

t

i

c

l

e

i

n

f

o

a

b

s

t

r

a

c

t

Articlehistory:

Received21November2019

Receivedinrevisedform10January2020 Accepted13January2020

Availableonline16January2020 Editor:L.Rolandi

MeasurementsofK∗(892)0_{andφ(1020)resonanceproductioninPb–Pbandppcollisionsat}√_s NN=5.02

TeV withthe ALICEdetector attheLargeHadronColliderare reported. The resonancesare measured at midrapidity (|y| < 0.5) via their hadronic decay channels and the transverse momentum (pT)

distributionsareobtainedforvariouscollisioncentralityclassesupto

p

T=20 GeV/c. The

p

T-integrated

yield ratio K∗(892)0/K in Pb–Pb collisions shows significant suppression relative to pp collisions and decreases towards more central collisions. In contrast, the φ(1020)/K ratio does not show any suppression. Furthermore, the measured K∗(892)0_{/K ratio in central Pb–Pb collisions is significantly}

suppressedwithrespecttotheexpectationsbasedonathermalmodelcalculation,whiletheφ(1020)/K ratio agrees with the model prediction. These measurements are an experimental demonstration of rescatteringofK∗(892)0 _{decayproductsinthe hadronicphaseofthecollisions.The K}∗₍₈₉₂₎0_/Kyield

ratios in Pb–Pb and pp collisions are used to estimate the time duration between chemical and kinetic freeze-out,which is found to be ∼ 4–7fm/c for central collisions. The pT-differential ratios

of K∗(892)0_{/K, φ(1020)/K, K}∗₍₈₉₂₎0_/

_π

_{, φ(1020)/}

_π

_{, p/K}∗₍₈₉₂₎0 _{and p/φ (1020) are also presented}

for Pb–Pb and pp collisions at √sNN = 5.02 TeV. These ratios show that the rescattering effect is

predominantlyalow-pTphenomenon.

©2020TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Several measurements in high-energy heavy-ion collisions at theLarge HadronCollider (LHC) [1–3] andthe Relativistic Heavy Ion Collider (RHIC) [4–9] have shown that a strongly-coupled Quark-GluonPlasma(QGP)isformedthatsubsequentlyhadronizes. Resonances,shortlivedhadronsthatdecayviastronginteractions, playanimportantroleincharacterizingthepropertiesofhadronic matterformedinheavy-ioncollisions [10–16].Severalresonances havebeenobservedinppandnuclearcollisions [10–19]: f2

(

1270

)

,

ρ

(

770

)

0,

(

1232

)

++, f0

(

980

)

,K∗

(

892

)

0,±,

(

1385

)

,

(

1520

)

and

φ (

1020

)

with lifetimes of the order of 1.1 fm

/

c, 1.3 fm

/

c, 1.6 fm

/

c,2.6fm

/

c,4.16fm

/

c,5.5fm

/

c,12.6fm

/

c and 46.3fm

/

c, re-spectively [20]. The wide range oftheir lifetimes allows them to be good probes of the dynamics of the system formed in ultra-relativisticheavy-ioncollisions [21–27].

In the hadronicphase of the evolution of the system formed inheavy-ioncollisions,therearetwoimportanttemperaturesand corresponding timescales: the chemical freeze-out, when the in-elastic collisions among the constituents are expected to cease, and the later kinetic freeze-out, when all (elastic) interactions

 _{E-mailaddress:alice-publications@cern.ch.}

stop [28–30]. If resonances decay before kinetic freeze-out,then theirdecayproductsaresubjecttohadronicrescatteringthatalters their momentum distributions. This leads to inability to recon-struct the parent resonance using the invariant mass technique, resulting ina decreasein themeasured yield relative to the pri-mordialresonanceyield, i.e.the yieldatchemicalfreeze-out.The fraction of resonances that cannot be recovered dependson the lifetimeofthehadronicphase(definedasthetimebetween chem-icalandkinetic freeze-out),thehadronicinteractioncrosssection of resonancedecayproducts, the particle densityinthe medium andtheresonancephase spacedistributions.Forexample,a pion fromaK∗

(

892

)

0 mesondecaycould scatter withanother pionin the medium as

π

−

π

+

→

ρ

0

_→

_π

−

_π

+_{. At the same time, after}

thechemical freeze-out,pseudoelastic interactionscould regener-ateresonancesinthemedium,leadingtoanenhancementoftheir yields. Forexample, interactions like

π

K

→

K∗

(

892

)

0

→

π

K and K−K+

→ φ(

1020

)

→

K−K+couldhappenuntilkineticfreeze-out. Hence,resonancesareprobesoftherescatteringandregeneration processesduringtheevolutionofthefireballfromchemicalto ki-neticfreeze-out.Indeed,transport-basedmodelcalculationsshow that both rescattering andregeneration processes affectthe final resonance yields [31,32]. Thermal statistical models, which have successfullyexplaineda hostofparticleyields inheavy-ion colli-sions acrossawide rangeofcenter-of-massenergies [33–36],are

https://doi.org/10.1016/j.physletb.2020.135225

0370-2693/©2020TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

abletoexplainthemeasuredresonanceyieldsonlyafterincluding rescatteringeffects [37,38].

Inthispaper,the measurementofthe productionofK∗

(

892

)

0

and

φ (

1020

)

vector mesons atmidrapidity inPb–Pb and pp col-lisions at

√

sNN

=

5.02 TeV is presented. Although both vector

mesons have similar masses, their lifetimediffers by a factorof largerthan10.Thisaspectisexploitedtoestablishthedominance of rescattering in central Pb–Pb collisions at the LHC. The kaon andpion daughters of the short-lived K∗

(

892

)

0

→

K

π

rescatter withotherhadronsinthemedium.Themagnitudeoftheeffectis mainlydeterminedbythepion-pioninteractioncrosssection [39], whichismeasuredtobesignificantlylarger(factor 5)thanthe to-talkaon-pioninteractioncrosssection [40].Thelatterdetermines themagnitudeoftheregenerationeffect [41].Thuswith rescatter-ing dominatingoverregeneration, theobservable K∗

(

892

)

0 yields should decrease compared to the primordial yields, and there-fore, a suppression of the K∗

(

892

)

0

/

K yield ratio is expected in heavy-ioncollisionsrelativeto ppcollisions.Furthermore,this ra-tioisexpectedtodecreasewithincreaseinsystemsize,which is determinedbythecollisioncentrality(maximumforcentral colli-sions).Incontrast,becauseofalargerlifetimecomparedtothatof the hadronic phase, the

φ (

1020

)

meson yields are not expected to be affected by rescattering [14,32]. The

φ (

1020

)

mesons are also expectednot to be affectedby the regeneration dueto sig-nificantlylower KK crosssection compared to K

π

and

π π

cross sections [39,40].Hence theindependenceofthe

φ (

1020

)/

Kyield ratio ofthe systemsize will act as a baseline for corresponding K∗

(

892

)

0

/

Kmeasurements,therebysupportingthepresenceofthe rescattering effect in heavy-ion collisions. The lower K∗

(

892

)

0

/

K yieldratioinPb–Pb collisions comparedtopp atthesame

√

sNN

can then be used to estimate the time span between chemical andkineticfreeze-outinheavy-ioncollisions.Furthermore,dueto thescatteringofthedecayproducts,thelow-pT K∗

(

892

)

0 areless

likelyto escapethe hadronicmedium beforedecaying,compared tohigh-pT K∗

(

892

)

0 [32].ThiscouldaltertheK∗

(

892

)

0 pT spectra

in Pb–Pb collisions compared to pp, while no such effect is ex-pectedfor

φ

mesons.Therefore, studying pT-differential ratios of

K∗

(

892

)

0 and

φ (

1020

)

mesons withrespectto other non-strange (

π

) and strange (K) mesons, and baryons (p) in Pb–Pb and pp collisions will help to establish the pT dependence of

rescatter-ingeffectsanddisentanglethemfromotherphysicsprocesseslike radialflowthatmodifiestheshapesofthe pT distributionsatlow

andintermediate transverse momenta. Inaddition, the measure-ments at

√

sNN

=

5.02 TeV are compared to results fromPb–Pb

collisions at

√

sNN

=

2.76TeV [14,42]. Since productionof

parti-clesandantiparticlesisequalatmidrapidityatLHCenergies,the averageoftheyieldsofK∗

(

892

)

0andK∗

(

892

)

0ispresentedinthis paper andis denoted by the symbol K∗0 unless specified other-wise.The

φ (

1020

)

isdenotedbythesymbol

φ

.

The paperis organized asfollows: In section 2, the detectors usedintheanalysisarebrieflydescribed.Insection3,thedataset, theanalysistechniques,theprocedureforextractionoftheyields ofK∗0 _and

_φ

_{mesons andthe studyofthesystematic}

uncertain-ties are presented.In section 4, the yields obtained by invariant massreconstruction ofK∗0 _and

_φ

_{mesonsasa functionof}

trans-versemomentuminPb–Pb andppcollisions at

√

sNN

=

5.02TeV,

the pT-integrated ratios of K∗0 and

φ

relative to chargedkaons,

andpT-differentialratiosrelativetocharged

π

,Kandprotonsare

reported.Finally,insection5thefindingsaresummarized.

2. Experimentalapparatus

Themeasurements of K∗0 and

φ

meson productioninpp and Pb–Pbcollisions havebeenperformedusingthedatacollected by theALICEdetectorintheyear2015. Thedetails oftheALICE

de-tector can be found in Refs. [43–45]. So we briefly focus on the following main detectors used for this analysis. The forward V0 detector,a scintillatordetectorwitha timing resolutionlessthan 1ns,isusedforcentralityselection,triggering andbeam-induced background rejection. The V0 consists oftwo sub-detectors, V0A andV0C,placedatasymmetricpositions,oneoneach sideofthe interaction point with full azimuthal acceptance and cover the pseudorapidity ranges 2.8

<

η

<

5.1 and -3.7

<

η

<

-1.7, re-spectively.ThecentralityclassesinPb–Pbcollisionsaredetermined fromthesumofthemeasuredsignalamplitudesinV0AandV0C, asdiscussedinRefs. [46,47].Thecollisiontimeinformationis pro-vided by T0 which consist of two arrays of Cherenkov counters T0AandT0C,positionedonbothsidesoftheinteractionpoint [48]. TheZeroDegreeCalorimeter(ZDC)consistsoftwotungsten-quartz neutron andtwo brass-quartzprotoncalorimeterplacedata dis-tanceof113monbothsidesof theinteractionpoint.Itisusedto rejectthebackgroundeventsandtomeasurethespectator nucle-ons.

In the central barrel, the Inner Tracking System(ITS) andthe TimeProjectionChamber(TPC)areusedforcharged-particle track-ingandprimarycollisionvertexreconstruction.TheITSconsistsof three sub-detectors of two layers each, covering a central pseu-dorapidity range

|

η

| <

0.9: Silicon Pixel Detector (SPD), Silicon Drift Detector (SDD) andSilicon Strip Detector (SSD).The TPC is themainchargedparticletrackingdetector,andhasfullazimuthal coverage inthe pseudorapidity range

|

η

| <

0.9. Alongwithtrack reconstruction,it alsoprovides ameasurementofthemomentum and excellent particle identification (PID). The TPC provides the measuredspecificenergyloss(dE

/

dx)toidentifytheparticles, es-pecially inlowmomentumrange(p

<

1GeV/c)wherethedE

/

dx ofparticlesarewellseparated.Toextendtheparticleidentification tohigher pT,theTimeofFlight(TOF)detectorisusedinaddition

totheTPCinformation.TheTOFisbasedontheMultigapResistive PlateChamber(MRPC) technologyandmeasures thearrivaltimes of particles with a resolution of the order of 80 ps. It covers a pseudorapidityrange

|

η

| <

0.9andprovidesexcellentPID capabil-ities intheintermediate pT rangeby exploitingthetime-of-flight

information.

3. Datasampleandanalysisdetails

Theppdatawerecollectedusingaminimumbias(MB)trigger. The logic for MB trigger requiresat leastone hit in V0Aor V0C andonehitinthecentralbarreldetectorSPDincoincidencewith theLHCbunch crossing[49,50].Inppcollisions,a criterionbased on the offline reconstruction of multiple primary vertices in the SPD [45] isappliedtoreduce thepileup,whichiscausedby mul-tiple interactionsinthesamebunch crossing.Therejectedpileup events arelessthan 1% ofthetotal events.ThePb–Pb datawere also collectedusing aMB trigger withalogic thatrequires a co-incidenceofsignalsinV0AandV0C.TheMB-triggeredeventsare analyzed ifthey havea reconstructed collision vertexwhose po-sition alongthe beamaxis(Vz, z is thelongitudinal direction)is within 10cmfromthe nominalinteractionpoint inboth ppand Pb–Pb collisions.Backgroundeventsare rejectedusingthetiming informationfromtheZeroDegreeCalorimeters(ZDCs)andV0 de-tectors.

ThePb–Pb analysisisperformedin8centralityclassesdefined in Ref. [46]: 0–10%, 10–20%, 20–30%, 30–40%, 40–50%, 50–60%, 60–70% and 70–80%. The 0–10% class corresponds to the most central Pb–Pb collisions, with smallimpact parameter, while the 70–80%classcorrespondstoperipheralPb–Pbcollisions,withlarge impact parameter. The total number of events that are analyzed after passingthe eventselectioncriteriaare

∼

110million forpp and

∼

30millionforPb–Pb collisions.Charged tracksare selected

foranalysisbasedontrackselectioncriteriathatensuregoodtrack quality,asdoneinpreviouswork [42].Inparticular,atrackinthe TPCisrequestedtohaveaminimumof70crossedrows (horizon-tal segments along the transverse readout plane of the TPC) out of a maximum possible 159 [51]. A pT-dependent selection

cri-terionon the distanceof closest approachto the collisionvertex inthetransverse(xy)plane(DCAxy)andalongthelongitudinal di-rection(DCAz)isusedtoreducethecontaminationfromsecondary chargedparticlescomingfromweakly decayinghadrons. In addi-tionto these selection criteria, tracks are requiredto have pT

>

0.15GeV

/

c inbothppandPb–Pbcollisions.Charged particlesare acceptedinthe pseudorapidity range

|

η

| <

0.8, which ensures a uniformacceptance.

The particle identificationexploits both the TPCand the TOF. ForK∗0 _and

_φ

_{reconstruction in Pb–Pb collisions, charged}

parti-clesareidentifiedaspionorkaonifthemeanspecificenergyloss (



dE

/

dx



) measured by the TPC fallswithin two standard devia-tions(2

σ

TPC)fromtheexpecteddE

/

dx valuesfor

π

orKoverthe

entire momentum range. If the TOF information is available for thetrack, inaddition to the TPC, a TOF-based selection criterion 3

σ

TOF isappliedoverthemeasuredmomentumrange,where

σ

TOF

is the standard deviation from the expected time-of-flight for a givenspecies.Theserequirementshelpinreducingthebackground underthe signalpeakover alargemomentum rangeandprovide a better separation between signal and backgroundwith respect toTPCPID only.ForK∗0 _{reconstructioninpp collisions,thesame}

PID selection criteriaare applied to identify pion andkaon can-didatesas are usedin Pb–Pb collisions. Forthe

φ

reconstruction inppcollisions, thekaoncandidatesare identifiedusinga 6

σ

TPC,

4

σ

TPCand2

σ

TPC selectiononthemeasureddE

/

dx distributionsin

themomentumrangesp

<

0.3GeV

/

c,0.3

<

p

<

0.4GeV

/

c andp

>

0.4GeV

/

c,respectively. Ontop ofthis, theTOF-basedselection criterionof3

σ

TOF isappliedovertheentiremeasuredmomentum

rangeinppcollisionsiftheTOFinformationisavailable.

3.1.Yieldextraction,correctionsandnormalization

TheK∗0 and

φ

resonancesarereconstructedbycalculatingthe invariantmassoftheirdecayproductsthroughthehadronicdecay channelsK∗0

₍

_K∗0

₎

_→

_K+

_π

−

₍

_K−

_π

+

₎

_{(BranchingRatio,BR=66.666}

±

0.006% [20])and

φ

→

K+K− (BR =49.2

±

0.5% [20]), respec-tively.OppositelychargedKand

π

(orK)fromthesameeventare paired to reconstruct the invariant mass distributions of K∗0(

φ

). TheK

π

andKK pairsareselectedintherapidity range

|

y

| <

0.5 inboth pp and Pb–Pb collisions. The invariant mass distribution exhibits a signal peak and a large combinatorial background re-sulting from the uncorrelated K

π

(KK) pairs. The combinatorial background is estimated using a mixed-event technique in both collision systems.The mixed-event background is constructed by combiningkaonsfromoneeventwiththeoppositelycharged

π

(K) fromdifferenteventsforK∗0

_(φ)

_{.The eventswhicharemixedare}

requiredto havesimilar characteristics.In Pb–Pb, twoevents are mixedifthey belong to the same centralityclass andthe differ-encebetween the collision vertex position is

|

Vz

| <

1 cm. In ppcollisions, two eventsare mixedwitha condition of

|

Vz

| <

1cm and a difference in charged-particle densityat midrapidity (

|

y

|

<

0

.

5) of less than 5. To minimize the statistical fluctua-tionsinthebackgrounddistribution,eacheventismixedwithfive otherones. Theinvariant massdistributionfromthemixed-event isnormalizedtothesame-eventoppositely-chargedpair distribu-tion in the mass region 1.1–1.3 (resp. 1.04–1.06) GeV

/

c2 for K∗0 (resp.

φ

), whichisaway fromthemasspeak (6



forK∗0 _and7



for

φ

,



is the width ofthe resonance). Afterthe combinatorial background subtraction, the signal peak is observed on top of a residualbackground.ThelatterisduetothecorrelatedK

π

orKK

pairsthatoriginatefromjetsandfromthemisidentificationof par-ticles.It isshowninRef. [42] that theresidualbackgroundhasa smooth dependenceonmassandthe shapeofthebackground is well described by a second order polynomial [14,42]. The invari-ant mass distributions after mixed-event background subtraction arefittedwithaBreit-Wigner(resp.Voigtian)functionforthe sig-nal peakof K∗0 _(resp.

_φ

_{) plus asecond order polynomial forthe}

residual background [42]. The Voigtian function is a convolution of a Breit-Wigner distribution and a Gaussian, where the width

σ

of theGaussian accountsforthe massresolution. Thelatter is

pT-dependentandvariesbetween1and2MeV

/

c2.Therawyields

are measured as a functionof pT for K∗0 and

φ

in pp collisions

andinvariouscentralityclassesinPb–Pbcollisions.Adetailed de-scriptionoftheyieldextractionprocedureisgiveninRef. [42].

The measured yields are affected by the detector acceptance andreconstructionefficiency( A

×

ε

rec).Thisisestimatedbymeans

ofdedicatedMonteCarlosimulationsusingthePYTHIA(PYTHIA6 Perugia 2011tune andPYTHIA8Monash2013tune) [52,53] and HIJING [54] eventgenerators forpp andPb–Pbcollisions, respec-tively. The generated particles are then propagated through the detectormaterialusingGEANT3 [55].The A

×

ε

rec iscalculatedas

a function of pT andis definedasthe ratioof thereconstructed

K∗0₍

_φ

_{) to the generated K}∗0₍

_φ

_{), both within}

_|

_y

_|

_<

_{0.5. For the}

reconstructionofresonances,thesametrackandPIDselection cri-teriaare appliedtothesimulationsasusedintheanalysisofthe measured data. The A

×

ε

rec is calculated for K∗0(

φ

) that decay

throughthehadronicchannelK±

π

∓(K+K−),henceitdoesnot in-cludethecorrectionforBR.InPb–Pbcollisions,the A

×

ε

rechasa

weakcentralitydependenceandtherawyieldsarecorrectedusing the A

×

ε

recoftherespectivecentralityclass.

Theproceduretocorrecttherawyieldsisgivenby

1 Nevent d2_N d ydpT

=

1 Nacc_event d2_Nraw d ydpT

ε

trig

.

ε

vert

.

ε

sig

(

A

×

ε

rec

) .

BR

.

(1)

The rawyields are normalizedto thenumberof acceptedevents (N_eventacc ) andcorrectedfor A

×

ε

rec,triggerefficiency(

ε

trig),vertex

reconstructionefficiency(

ε

vert),signalloss(

ε

sig)andtheBRofthe

decaychannel.The yieldsinpp arenormalizedto thenumberof inelasticcollisionswithatriggerefficiencycorrection,

ε

trig=0.757

±

0.019 [56]. Thevertexreconstructionefficiencyinppcollisions isfound to be

ε

vert = 0.958.The signal losscorrection factor

ε

sig

is determined based on MC simulations as a function of pT and

accountsfortheresonancesignallostduetotriggerinefficiencies. The

ε

sig(pT) correctionisonlysignificantfor pT

<

2.5GeV

/

c and

has a value of lessthan 5% both forK∗0 _and

_φ

_{in pp collisions.}

In Pb–Pb collisions, theyields of K∗0 and

φ

in a givencentrality class are normalized by the number of events in the respective V0M(sum ofV0AandV0Camplitude)eventcentralityclass.The correctionfactors

ε

trig,

ε

vertand

ε

sig(pT)arecompatiblewithunity

inthereportedcentralityclassesinPb–Pbcollisionsandhenceare notused.

3.2. Systematicuncertainties

The systematic uncertainties in the measurement of K∗0 and

φ

yields in pp and Pb–Pb collisions are summarized in Table 1. Thesourcesofsystematicuncertaintiesarerelatedtotheyield ex-traction method, PID and track selection criteria, global tracking efficiency,theknowledgeoftheALICEmaterialbudgetandofthe interaction crosssection of hadronsinthe detectormaterial.The uncertaintiesare reportedforthreetransversemomentumvalues, low,midandhighpT.ForPb–Pbcollisions allthesystematic

un-certaintiesexcepttheonerelatedtotheyieldextractionare com-mon inthevarious centralityclassesandthe valuesgiveninthe

Table 1

SystematicuncertaintiesinthemeasurementofK∗0_and

_φ

_{yieldsinppandPb–Pbcollisionsat}√_s

NN=5.02TeV.These

un-certaintiesareshownfor threetransversemomentumvalues,low,midandhighpT.ForPb–Pbcollisionsallthesystematic

uncertaintiesexceptyieldextractionarecommoninvariouscentralityclassesandthevaluesgiveninthetableareaveraged overallcentralityclasses.

Systematicvariation Pb–Pb pp

K∗0 _{φ K}∗0 _φ

pT(GeV/c) pT(GeV/c) pT(GeV/c) pT(GeV/c)

0.6 4.5 18 0.5 4.25 18 0.1 4.25 18 0.5 4.25 18 Yield extraction (%) 7.3 7.5 10.1 4.4 1.9 4.9 11.8 7.9 8.2 2.4 3.5 3.5 Track selection (%) 2.7 1.4 3.0 3.0 1.3 1.0 1.4 1.0 1.9 4.0 2.0 5.5 Particle identification (%) 5.4 3.0 5.0 1.0 1.5 2.4 2.1 3.2 6.9 0.3 1.7 6.5 Global tracking efficiency (%) 4.7 7.4 4.0 4.7 8.2 3.1 2.0 3.1 3.4 2.0 3.2 2.4

Material budget (%) 1.4 0 0 5.7 0 0 3.4 0 0 5.7 0 0

Hadronic Interaction (%) 2.4 0 0 1.3 0 0 2.8 0 0 1.3 0 0

Total (%) 10.9 11.0 12.3 9.2 8.6 6.4 13.0 9.1 11.4 7.7 5.4 9.5

Fig. 1. ThepTdistributionsof(a)K∗0and(b)

φ

mesonsinppcollisionsandvariouscentralityclassesinPb–Pbcollisionsat√sNN=5.02TeV.Thevaluesareplottedatthe

centerofeachbin.Thestatisticalandsystematicuncertaintiesareshownasbarsandboxes,respectively.

tableareaveragedoverallcentralities.Theyieldextractionmethod includes the uncertainties due to variations of the fitting range, thechoiceofcombinatorialbackgroundestimationtechnique, nor-malization range and residual background shape. The uncertain-tiesduetoyield extractionareestimatedto be7.9–11.8% forK∗0

(resp.2.4–3.5% forthe

φ

)in ppand7.3–10.1% (resp. 1.9–4.9%) in Pb–Pbcollisions. The PIDsystematicuncertainties variesbetween 2.1–6.9% (0.3–6.5%) for K∗0 (

φ

) in pp and Pb–Pb collisions. The contributiontotheuncertaintyfromtheglobaltrackingefficiency iscalculatedfromthecorrespondingvaluesforsinglecharged par-ticles [51] andresultsina2.0–8.2%uncertaintybycombiningthe two charged tracks used in the invariant mass reconstruction of K∗0 _and

_φ

_{. The contribution from variation of the track}

selec-tion criteria is 1.0–5.5%. The systematic uncertainties due to the hadronic interaction cross section are estimated to be less than 2.8%andcontributeonlyatlow pT (

<

2GeV

/

c).Theuncertainties

in the description of the material budget of ALICEdetector sub-systems inGEANT3 (see Ref. [57] fordetails)give a contribution lowerthan5.7% ontheyields ofK∗0 _and

_φ

_{inpp andPb–Pb}

col-lisions. The material budget uncertainty is significant only at pT

<

2 GeV

/

c and negligible at higher pT. The total pT-dependent

systematicuncertainties ontheK∗0(

φ

)yields are estimatedtobe 9.1–13.0% (5.4–9.5%) in pp collisions and 10.9–12.3% (6.4–9.2%) inPb–Pb collisions.Thecommonsystematicuncertainties for dif-ferent particles (global tracking efficiency, material budget and

hadronicinteraction)are canceled outincalculatingparticleyield ratioslikeK∗0

_/

_Kand

_φ/

_K.

4. Resultsanddiscussion

4.1. TransversemomentumspectrainppandPb–Pbcollisions

The pT distributions of the K∗0 and

φ

mesons for

|

y

|

<

0

.

5,

normalized to thenumber ofevents andcorrected forefficiency, acceptanceandbranchingratioofthedecaychannel,areshownin Fig.1.TheresultsforPb–Pb collisionsarepresentedforeight dif-ferentcentralityclasses(0–10%upto70–80%in10%wide central-ityintervals)togetherwiththeresultsfrominelasticppcollisions atthesameenergy.

The pT-integratedparticleyieldshavebeenextractedusingthe

proceduredescribedinRefs. [14,42].ThepTdistributionsarefitted

witha Lévy-Tsallisfunction [58,59] inpp anda Boltzmann-Gibbs blast-wavefunction[60] inPb–Pbcollisions.Theyieldshavebeen extracted from the data in the measured pT region and the fit

functionshavebeenusedtoextrapolateintotheunmeasured(low and high pT) region. The low-pT extrapolation covers pT

<

0.4

GeV

/

c forK∗0₍

_φ

_{)andaccountsfor8.6% (7.2%)and12.5%(12.7%)of}

thetotalyieldinthe0–10%and70–80%centralityclassesinPb–Pb collisions,respectively.Inppcollisions,theK∗0ismeasuredinthe range 0

<

pT

<

20GeV

/

c.Forthe

φ

meson, thelow-pT

Fig. 2. pT-integrated particle yield ratios K∗0/K− and φ/K− as a function of

dNch/dη1/3 measuredatmidrapidityinpp,p–PbandPb–Pbcollisionsat √sNN

=5.02TeV.ForPb–Pbcollisionsat√sNN=2.76TeV,the

φ/

K− valuesaretaken

fromRef. [14] andtheK∗0

/K−valuesaretakenfromRef. [42].Theratiosforp– Pbcollisionsare taken fromRef. [17].Statisticaluncertainties (bars)areshown togetherwith total(hollowboxes) andcharged-particle multiplicity-uncorrelated (shadedboxes) systematicuncertainties.Thermalmodelcalculationswith chemi-calfreeze-outtemperatureTch=156MeVforthemostcentralPb–Pbcollisions

[34,64] arealsoshown.EPOS3modelpredictions [32] ofK∗0_{/K and}

_φ/

_{K ratiosin}

Pb–Pbcollisionsarealsoshownasvioletlines.

yield.Theextrapolatedfractionoftheyieldisnegligiblefor pT

>

20GeV

/

c. 4.2.Particleratios

Fig. 2 shows the K∗0

_/

_{K and}

_φ/

_{K ratios as a function of}



dNch

/

d

η



1/3 [46,47,51] forPb–Pb collisions at

√

sNN

=

2.76[14, 42] and5.02TeV,p–Pb collisionsat

√

sNN

=

5.02TeV [17] andpp

collisions at

√

s

=

5.02 TeV. The kaon yields in Pb–Pb at

√

sNN

=

5.02 TeV are from Ref. [51]. The



dNch

/

d

η



1/3 measured at

midrapidity, is used here asa proxy for the systemsize. This is supported by the observation of the linear increase in the HBT radiiwith



dNch

/

d

η



1/3 [61,62].TheK∗0

/

K ratiodecreasesfor

ris-ing



dNch

/

d

η



1/3 while the

φ/

K ratio is almost independent of



dNch

/

d

η



1/3.Theratiosexhibit asmooth trendacrossthe

differ-entcollisionsystemsandcollisionenergiesstudied.TheK∗0

_/

_{K and}

φ/

K ratiosinPb–Pb collisionsat

√

sNN

=

2.76and5.02TeVarein

agreementwithinuncertainties.

Theresonanceyieldsaremodifiedduringthehadronicphaseby rescattering(whichwouldreducethemeasuredyields)and regen-eration(whichwouldincreasethemeasuredyields).Theobserved dependenceoftheK∗0

_/

_{K ratioonthecharged-particlemultiplicity}

isconsistentwiththebehaviorthatwouldbeexpectedif rescatter-ingisthecauseofthesuppression.Thefactthatthe

φ/

K ratiodoes notexhibitsuppressionwithcharged-particlemultiplicitysuggests that the

φ

, which has a lifetime an order of magnitude larger than that ofthe K∗0_{, decays predominantlyoutside thehadronic}

medium. Theoretical estimates suggest that about 55% of the of K∗0 _{mesonswith momentum p}

₌

_{1 GeV}

_/

_{c, decaywithin 5 fm}

_/

_c

ofproduction (a typical estimate for the time between chemical and kinetic freeze-out in heavy-ion collisions [22,32,63]), while only7% of

φ

mesons with p

=

1 GeV

/

c decaywithin that time. This supports the hypothesis that the experimentally observed decrease of the K∗0

_/

_{K ratio with charged-particle multiplicity is}

caused by rescattering. A similar suppression has also been ob-served for

ρ

0

_/

_π

_{[15] and}

_

∗

_/

_{[13] in central Pb–Pb collisions}

relativetoperipheralPb–Pbandppcollisionsat

√

sNN

=

2.76TeV.

Inaddition,theK∗0

/

K ratiofromthermalmodelcalculations with-outrescatteringeffectsandwithchemicalfreeze-outtemperature

Fig. 3. Lowerlimitonthehadronicphaselifetimebetweenchemical andkinetic freeze-outasafunctionofdNch/dη1/3inp–Pb [17] andPb–Pbcollisionsat√sNN

=5.02TeV.Thebarsandbandsrepresentthestatisticalandsystematic uncertain-ties,respectively,propagatedtothelifetimefromtheuncertaintiesassociatedwith themeasuredK∗0_{/KratiosinPb–Pb (p–Pb)andppcollisionsat}√_s

NN=5.02TeV. Tch

=

156 MeV for the most central Pb–Pb collisions [34,64] is

found to be higher than thecorresponding measurements, while the measured

φ/

K ratio agrees with the thermal model predic-tions.The K∗0

/

K and

φ/

K ratiosinPb–Pbcollisionsarealso com-pared to EPOS3 model calculationswithand without a hadronic cascadephasemodeled byUrQMD [32].TheEPOS3model predic-tionsshowninthefigureareforPb–Pbcollisions at

√

sNN

=

2.76

TeVbutnosignificantqualitativedifferencesareexpectedbetween the two energies. The EPOS3 generator withUrQMD reproduces theobservedtrendoftheK∗0

_/

_{K and}

_φ/

_{K ratioswhichfurther}

sup-portstheexperimentaldata.

The fact that K∗0

/

K− decreases with increasing



dNch

/

d

η



1/3

implies that rescattering of the decay products of K∗0 in the hadronic phase is dominantover K∗0 regeneration. This suggests that K∗0

_↔

_K

_π

_{is not in balance. Hence in Pb–Pb the K}∗0

_/

_K−

ratiocan be used toget an estimate ofthetime between chem-icalandkineticfreeze-out,

τ

,as,

[

K∗0

/

K−

]

kinetic

= [

K∗0

/

K−

]

chemical

×

e−τ/τK∗0_{, where}

τ

_{K∗0 is the K}∗0 _{lifetime. Here,}

τ

_{K∗0 is taken}

as 4.16 fm

/

c ignoring any medium modification of the width of the invariant mass distribution of K∗0_{. Furthermore, it is}

as-sumed that

[

K∗0

/

K−

]

chemical is given by the values measured in ppcollisionsandthePb–Pb collisiondataprovidesanestimatefor

[

K∗0

_/

_K−

_]

kinetic. This is equivalent to assuming that all K∗0’s that decaybeforekineticfreeze-outarelostduetorescatteringeffects and there is no regeneration effect between kinetic and chemi-cal freeze-out which issupported by AMPT simulations [31]. All theassumptions listedabove leadto anestimate of

τ

asalower limitforthetime spanbetweenchemical andkinetic freeze-outs. AdecreaseintheK∗0

/

Kratiowithincreasingmultiplicityhas pre-viously alsobeenobserved in p–Pbcollisionsat

√

sNN =5.02TeV

[17].Thismightindicatethepresenceofrescatteringeffectinhigh multiplicity p–Pb collisions and is suggestive of a finite lifetime ofthehadronicphase.Forcomparisonwehavealsoestimatedthe hadronicphaselifetimeinp–Pbdata.Fig.3showstheresultsfor

τ

boostedbyaLorentzfactor(

∼

1.65forp–Pb collisionsand1.75for Pb–Pb collision) asa function of



dNch

/

d

η



1/3.Neglecting higher

order terms, theLorentz factor isestimated as



1

+ (

pT/mc

)

2_.

Here m is the rest mass of the resonance and



pT is used as anapproximation forp forthemeasurementsatmidrapidity.The time interval between chemical and kinetic freeze-out increases withthe systemsize asexpected. Forcentral Pb–Pb collisionsat

√

Fig. 4. Particleyieldratios(K∗0_+K∗0_)/(K+_+K−_{)inpanel(a)and(2φ)/(K}+_+K−_{)inpanel(b),bothasafunctionofpTforcentralityclasses0–10%and70–80%inPb–Pb} collisionsat√sNN=5.02TeV.Forcomparison,thecorrespondingratiosarealsoshownforinelasticppcollisionsat√s=5.02TeV.Thestatisticaluncertaintiesareshown

asbarsandsystematicuncertaintiesareshownasboxes.Inthetext(K∗0_+K∗0_),(K+_+K−_{)aredenotedbyK}∗0_{andK,respectively.}

Fig. 5. Particleyieldratios(K∗0_+K∗0_)/(π+_+π−_{)inpanel(a)and(2φ)/(π}+_+π−_{)inpanel(b),bothasafunctionofpTforcentralityclasses0–10%and70–80%inPb–Pb} collisionsat√sNN=5.02TeV.Forcomparison,thecorrespondingratiosarealsoshownforinelasticppcollisionsat√s=5.02TeV.Thestatisticaluncertaintiesareshown

asbarsandsystematicuncertaintiesareshownasboxes.Inthetext(K∗0_+K∗0_),(π+_+π−_{)aredenotedbyK}∗0_{andπ,respectively.}

kinetic freeze-out is about 4–7 fm

/

c. This is of the same order of magnitude asthe K∗0 lifetime, but aboutan order of magni-tude shorter than the

φ

lifetime. A smooth increase of

τ

with systemsizefromp–Pb toPb–Pb collisionsisobserved.TheEPOS3 generatorwithUrQMDreproduces theincreasingtrendof

τ

with multiplicity qualitatively [32]. If a constant chemical freeze-out temperatureisassumed, then the increase of

τ

withmultiplicity inPb–Pb collisionscorrespondstoadecreaseofthekinetic freeze-outtemperature.Thisisinqualitativeagreementwithresultsfrom blast-wave fits to identified particle pT distributions [51], which

are interpreted asdecrease inthe kinetic freeze-out temperature fromperipheraltocentralcollisions.

Further,to quantify the pT-dependenceofthe rescattering

ef-fect observed in Pb–Pb collisions, a set of pT-differential yield

ratios was studied: K∗0

_/

_K,

_φ/

_K,K∗0

_/

_π

_,

_φ/

_π

_{, p}

_/

_K∗0 _{and p}

_/φ

_as

showninFigs.4,5and6.Thechoiceoftheratiosismotivatedby thefollowingreasons:(a)theratioofresonanceyieldsrelativeto theonesofkaonsandpionscanshedlightontheshapesofthepT

distributionsofmesonswithdifferentmassandquarkcontent,and (b)theratiosoftheprotonyieldwithrespecttotheyields ofthe

resonancesallowcomparisonsamonghadronsofsimilarmass,but differentbaryon numberandquark contentto bemade. Forcase (a), ratiosin0–10%, 70–80%Pb–Pb collisions andpp collisions at

√

sNN

=

5.02TeVarecompared.Forcase(b),ratiosin0–10%Pb–

Pbcollisions andpp collisions at

√

sNN

=

5.02TeVare compared

with0–5%inPb–Pb collisionsat

√

sNN

=

2.76TeV.Theratiosfor

70–80%inPb–Pbcollisionsareclosertothecorrespondingresults inpp collisions.Noticeably,therearedistinct differencesbetween centralandperipheral(pp)collisionsintheratiosforpT below

∼

2 GeV

/

c and intermediate pT (between 2 and 6 GeV

/

c) but the

ratiosareconsistentathigher pT[42].

Atlow pT,theK∗0

/

KandK∗0/

π

forcentralcollisionsarelower

than in peripheral (pp) collisions, while the corresponding yield ratios for

φ

meson arecomparable within theuncertainties. This observation is consistent with the suppression of K∗0 _{yields due}

torescatteringinthehadronicphase.Itdemonstratesthat rescat-tering affects low momentum particles. At intermediate pT, both

ratios show an enhancement forcentral Pb–Pb collisions relative toperipheralandppcollisions,whichismoreprominentfor

φ/

K,

Fig. 6. Particleyieldratios(p+p)/(K∗0_+K∗0

)inpanel(a)and(p+ ¯p)/(2φ)inpanel(b),bothasafunctionofpT for0–10%centralPb–Pb collisionsandinelasticpp

collisionsat√sNN=5.02 TeV.Forcomparison,similarratiosarealsoshownfor0–5%centralPb–Pb collisionsat√sNN=2.76 TeV [42].Thestatisticaluncertaintiesare

shownasbarsandsystematicuncertaintiesareshownasboxes.Inthetext(K∗0_+K∗0

)and(p+p)aredenotedbyK∗0_{andp,respectively.}

radialflowincentralcollisions relativetoperipheralandpp colli-sions [51].GiventhatthemassesofK∗0 _and

_φ

_{mesonsarelarger}

thanthose ofthe chargedkaonandpion,the resonances experi-encea largerradialfloweffect.IncentralPb–Pb collisions,for pT

below5 GeV

/

c, the p

/φ

ratiois observed to be independent of

pTandthe p

/

K∗0 ratioexhibitsaweak pT-dependencewithinthe

uncertainties, in contrast to the decrease of both ratios with pT

observedinppcollisions. Inturn,thissuggeststhattheshapesof the pT distributionsaresimilarforK∗0,

φ

and p inthis pT range.

Although the quark contents are different, the masses of these hadrons are similar, indicating that this is the relevant quantity indeterminingspectrashapes.Thisisconsistentwithexpectations fromhydrodynamic-based models [65,66]. Within the uncertain-ties,the p

/

K∗0 andp

/φ

ratiosforcentralPb–Pb collisionsat

√

sNN

=5.02TeVand2.76TeV [42] areconstantatintermediate pT.This

isconsistent with theobservation ofsimilar order radial flow at bothenergies, obtained fromthe analysisof pT spectra ofpions,

kaonsandprotons [51].ForpT

>

6GeV

/

c,theK∗0

/

K,

φ/

K,K∗0

/

π

,

φ/

π

,p

/

K∗0 andp

/φ

yieldratiosincentralcollisionsaresimilarto peripheral andpp collisions, indicating that fragmentationis the dominanthadronproductionmechanisminthis pT region.Thisis

consistentwithpreviousmeasurementsat

√

sNN =2.76TeV [42]. 5. Summary

Thetransverse momentum distributionsof K∗0 and

φ

mesons havebeenmeasuredatmidrapidity(

|

y

|

<

0

.

5)forvariouscollision centralities in Pb–Pb and inelastic pp collisions at

√

sNN

=

5.02

TeV using the ALICE detector. The K∗0 _{yields relative to charged}

kaonsin Pb–Pb collisionsshow a suppression withrespectto pp collisions, which increases with the system size, quantified us-ing



dNch

/

d

η



1/3 measured at midrapidity. In contrast, no such

suppression is observed for the

φ

mesons. The lack of suppres-sionfor the

φ

meson can be attributed to the fact that mostof themdecayoutsidethefireballbecauseofitslongerlifetime(

τ

φ = 46.3

±

0.4 fm

/

c). Because of a shorter lifetime (

τ

K∗0 = 4.16

±

0.05 fm

/

c), a significant number of produced K∗0 _{decays in the}

hadronicmedium.Thedecayproduct(s)undergointeractionswith otherhadrons inthemedium resultingin asignificant changein their momentum, and no longer contributing to the K∗0 signal reconstructed in the experiment. Althoughboth rescatteringand regenerationarepossible,theresultspresentedhererepresentan

experimental demonstration of the predominance of rescattering effects in the hadronic phase of the system produced in heavy-ioncollisions.Theeffectofrescatteringincreaseswiththesystem size.Furthermore,theK∗0

/

K yieldratiosincentralPb–Pb collisions aresignificantlylowercomparedtothevaluesfromthermalmodel calculationswithoutrescatteringeffects,whilethemeasured

φ/

K yieldratioagreeswiththemodelcalculation.Thisfurther corrob-orates the hypothesis that rescatteringaffects the measured K∗0

yields in Pb–Pb collisions. A lower limit for the lifetime of the hadronicphaseisdetermined byusingtheK∗0

/

KratiosinPb–Pb andpp collisions at

√

sNN

=

5.02 TeV.The lifetime, asexpected,

increaseswithsystemsize.ForcentralPb–Pb collisions,itisabout 4–7fm

/

c.

The pT-differentialyieldratiosofK∗0

/

π

andK∗0

/

Karestudied

incentralPb–Pb,peripheralPb–Pb andppcollisionstounderstand the pT-dependence of the rescattering effect. It is observed that

rescatteringdominantly affectsthe hadronsat pT

<

2 GeV

/

c. At

intermediate pT (2–6 GeV

/

c), the

φ/

K,

φ/

π

, K∗0

/

π

, p

/

K∗0 and p

/φ

yieldratiosareenhancedincentralPb–Pb collisionsrelativeto peripheralPb–Pb andppcollisions.Inaddition,thespectralshapes ofK∗0_,

_φ

_{andp,whichhavecomparablemasses,aresimilarwithin}

theuncertaintiesfor pT below5GeV

/

c inPb–Pb collisions. These

measurementsdemonstratetheeffectofhigherradialflowin cen-tralPb–Pb collisionsrelativetoperipheralPb–Pb andppcollisions. Acomparisonofthe p

/

K∗0 _andp

_/φ

_{ratiosforcentralPb–Pb}

col-lisions at

√

sNN

=

5.02and2.76TeV showstheconstancyof the

ratios with pT.Thisis consistentwiththeobservation of

compa-rable radial flow at

√

sNN

=

5.02 TeV and2.76 TeV. For higher pT, above 6 GeV

/

c, all the ratios agree within the uncertainties

forcentralandperipheralPb–Pb,andppcollisions,indicatingthat particleproductionviafragmentationathightransversemomenta isnotsignificantlymodifiedinthepresenceofamedium.

Acknowledgements

The ALICE Collaboration would like to thank all its engineers andtechniciansfortheir invaluablecontributions tothe construc-tion of the experiment and the CERN accelerator teams for the outstanding performance ofthe LHC complex.The ALICE Collab-oration gratefully acknowledges the resources and support pro-videdbyallGridcenters andtheWorldwideLHCComputingGrid (WLCG) collaboration. The ALICE Collaboration acknowledges the

followingfundingagencies fortheirsupport inbuildingand run-ningtheALICEdetector:A.I.AlikhanyanNationalScience Labora-tory(YerevanPhysicsInstitute)Foundation(ANSL),State Commit-teeofScienceandWorldFederationofScientists(WFS),Armenia; Austrian Academy of Sciences, Austrian Science Fund (FWF): [M 2467-N36] and Nationalstiftung für Forschung, Technologie und Entwicklung,Austria; MinistryofCommunicationsandHigh Tech-nologies, National Nuclear Research Center, Azerbaijan; Conselho Nacionalde DesenvolvimentoCientífico e Tecnológico (CNPq), Fi-nanciadorade Estudose Projetos(Finep), Fundação de Amparoà Pesquisa doEstado de São Paulo (FAPESP)andUniversidade Fed-eraldoRioGrandedoSul(UFRGS),Brazil;MinistryofEducationof China (MOEC), MinistryofScience& Technology ofChina(MSTC) andNational NaturalScience Foundation ofChina (NSFC), China; Ministry of Science and Education andCroatian Science Founda-tion,Croatia;CentrodeAplicacionesTecnológicasyDesarrollo Nu-clear(CEADEN), Cubaenergía, Cuba; Ministry ofEducation, Youth and Sports of the Czech Republic, Czech Republic; The Danish Council for Independent Research | Natural Sciences, the Villum Fonden and Danish National Research Foundation (DNRF), Den-mark;Helsinki Instituteof Physics(HIP),Finland; Commissariatà l’ÉnergieAtomique (CEA), Institut Nationalde Physique Nucléaire et de Physique des Particules (IN2P3) and Centre National de la Recherche Scientifique (CNRS) and Région des Pays de la Loire, France; Bundesministerium für Bildung und Forschung (BMBF) andGSIHelmholtzzentrumfürSchwerionenforschungGmbH, Ger-many;GeneralSecretariatforResearchandTechnology,Ministryof Education,Research andReligions,Greece; NationalResearch De-velopmentandInnovationOffice,Hungary; DepartmentofAtomic Energy, Government of India (DAE), Department of Science and Technology, Government of India (DST), University Grants Com-mission,GovernmentofIndia(UGC)andCouncilofScientific and Industrial Research (CSIR), India; Indonesian Institute of Science, Indonesia;CentroFermi- MuseoStoricodellaFisicaeCentroStudi e Ricerche Enrico Fermi and Istituto Nazionale di Fisica Nucle-are (INFN), Italy; Institute forInnovativeScience and Technology, Nagasaki Institute of Applied Science (IIST), Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) and JapanSocietyforthePromotionofScience(JSPS)KAKENHI,Japan; Consejo Nacional de Ciencia (CONACYT) y Tecnología, through FondodeCooperaciónInternacionalenCienciayTecnología (FON-CICYT)andDirección GeneraldeAsuntos delPersonalAcademico (DGAPA), Mexico;Nederlandse Organisatievoor Wetenschappelijk Onderzoek(NWO), Netherlands;The ResearchCouncil ofNorway, Norway; Commission on Science andTechnology for Sustainable Development in the South (COMSATS), Pakistan; Pontificia Uni-versidad Católica del Perú, Peru; Ministry of Science and Higher EducationandNationalScience Centre, Poland;Korea Institute of Science andTechnology InformationandNationalResearch Foun-dation of Korea (NRF), Republic of Korea; Ministry of Education andScientificResearch,InstituteofAtomicPhysicsandMinistryof ResearchandInnovationandInstituteofAtomicPhysics,Romania; Joint Institute for Nuclear Research (JINR), Ministry of Education and Science of the Russian Federation, National Research Centre KurchatovInstitute,RussianScienceFoundationandRussian Foun-dation for Basic Research,Russia; Ministry of Education,Science, ResearchandSportofthe SlovakRepublic, Slovakia; National Re-searchFoundationofSouthAfrica,SouthAfrica;SwedishResearch Council (VR) and Knut & Alice Wallenberg Foundation (KAW), Sweden;EuropeanOrganizationforNuclearResearch,Switzerland; Suranaree University of Technology (SUT), National Science and TechnologyDevelopmentAgency(NSDTA)andOfficeoftheHigher Education Commission under NRU project of Thailand, Thailand; Turkish AtomicEnergy Agency (TAEK), Turkey;NationalAcademy ofSciences ofUkraine,Ukraine; Science andTechnologyFacilities

Council (STFC), United Kingdom; National Science Foundation of theUnitedStatesofAmerica(NSF)and(DOENP),UnitedStatesof America.

References

[1]ALICECollaboration,K.Aamodt,etal.,EllipticflowofchargedparticlesinPb– Pbcollisionsat2.76TeV,Phys.Rev.Lett.105(2010)252302,arXiv:1011.3914 [nucl-ex].

[2]ALICECollaboration,K.Aamodt,etal.,Suppressionofchargedparticle produc-tionatlargetransversemomentumincentralPb–Pbcollisionsat√sN N=2.76 TeV,Phys.Lett.B696(2011)30–39,arXiv:1012.1004 [nucl-ex].

[3]ALICECollaboration,K.Aamodt,etal.,Higherharmonicanisotropicflow mea-surementsofchargedparticlesinPb–Pbcollisionsat √sN N=2.76TeV,Phys. Rev.Lett.107(2011)032301,arXiv:1105.3865 [nucl-ex].

[4]STARCollaboration,J.Adams,etal.,Experimentalandtheoreticalchallengesin thesearchforthequarkgluonplasma:theSTARCollaboration’scritical assess-mentoftheevidencefromRHICcollisions,Nucl.Phys.A757(2005)102–183, arXiv:nucl-ex/0501009 [nucl-ex].

[5]PHENIXCollaboration, K. Adcox,et al., Formation ofdensepartonicmatter inrelativisticnucleus-nucleuscollisionsat RHIC:experimentalevaluationby thePHENIXcollaboration,Nucl. Phys.A757(2005)184–283,arXiv:nucl-ex/ 0410003 [nucl-ex].

[6]BRAHMSCollaboration, I.Arsene,etal.,Quarkgluonplasmaandcolorglass condensateatRHIC?ThePerspectivefromtheBRAHMSexperiment,Nucl.Phys. A757(2005)1–27,arXiv:nucl-ex/0410020 [nucl-ex].

[7]PHOBOSCollaboration,B.B.Back,etal.,ThePHOBOSperspectiveondiscoveries atRHIC,Nucl.Phys.A757(2005)28–101,arXiv:nucl-ex/0410022 [nucl-ex]. [8]M.Gyulassy,L.McLerran,NewformsofQCDmatterdiscoveredatRHIC,Nucl.

Phys.A750(2005)30–63,arXiv:nucl-th/0405013 [nucl-th].

[9]E.Shuryak,Physicsofstronglycoupledquark-gluonplasma,Prog.Part.Nucl. Phys.62(2009)48–101,arXiv:0807.3033 [hep-ph].

[10]STARCollaboration,M.M.Aggarwal,etal.,K∗0_{productioninCu+CuandAu+Au}

collisionsat√sN N =62.4GeVand200GeV,Phys.Rev.C84(2011)034909, arXiv:1006.1961 [nucl-ex].

[11]STARCollaboration,J.Adams,etal.,K∗(892)0_{resonanceproductioninAu+Au}

andp+pcollisionsat√sNN=200GeVatSTAR,Phys.Rev.C71(2005)064902,

arXiv:nucl-ex/0412019 [nucl-ex].

[12]STAR_√ Collaboration,B.I.Abelev,etal.,Strangebaryonresonanceproductionin

sN N =200-GeVp+pandAu+Aucollisions,Phys.Rev.Lett.97(2006)132301, arXiv:nucl-ex/0604019 [nucl-ex].

[13]ALICECollaboration,S.Acharya,etal.,Suppressionof(1520)resonance pro-ductionincentralPb–Pbcollisionsat√sNN=2.76TeV,Phys.Rev.C99(2019)

024905,arXiv:1805.04361 [nucl-ex].

[14]ALICECollaboration, B.Abelev,et al., K∗(892)0 and φ(1020)production in Pb–Pbcollisionsat√sNN =2.76TeV,Phys.Rev.C91(2015)024609,arXiv:

1404.0495 [nucl-ex].

[15]ALICECollaboration,S.Acharya,etal.,Productionoftheρ(770)0_mesoninpp

andPb–Pbcollisionsat√sNN=2.76TeV,Phys.Rev.C99 (6)(2019)064901,

arXiv:1805.04365 [nucl-ex].

[16]STARCollaboration,B.I.Abelev,etal.,Energyandsystemsizedependenceof

φmesonproductioninCu+CuandAu+Aucollisions,Phys.Lett.B673(2009) 183–191,arXiv:0810.4979 [nucl-ex].

[17]ALICECollaboration,J.Adam,etal.,ProductionofK∗(892)0_{andφ(1020)in}

p–Pbcollisionsat√sNN=5.02TeV,Eur.Phys.J.C76 (5)(2016)245,arXiv:

1601.07868 [nucl-ex].

[18]ALICECollaboration,B.Abelev,etal.,ProductionofK∗(892)0_{andφ(1020)in}

pp collisionsat√s=7 TeV,Eur.Phys.J.C72(2012)2183,arXiv:1208.5717 [hep-ex].

[19]STARCollaboration,B.I.Abelev,etal.,Hadronicresonanceproductionind+Au collisionsat√sN N =200-GeVatRHIC,Phys.Rev.C78(2008)044906,arXiv: 0801.0450 [nucl-ex].

[20]Particle Data Group Collaboration, M. Tanabashi, et al., Review of particle physics,Phys.Rev.D98 (3)(2018)030001.

[21]G.E.Brown,M.Rho, ScalingeffectiveLagrangiansinadensemedium, Phys. Rev.Lett.66(1991)2720–2723.

[22]M.Bleicher,J.Aichelin,Strangeresonanceproduction:probingchemical and thermalfreezeoutinrelativisticheavyioncollisions,Phys.Lett.B530(2002) 81–87,arXiv:hep-ph/0201123 [hep-ph].

[23]G.Torrieri,J.Rafelski,Strangehadronresonancesasasignatureoffreezeout dynamics,Phys.Lett.B509(2001)239–245,arXiv:hep-ph/0103149 [hep-ph]. [24]S.C.Johnson,B.V.Jacak,A.Drees,Rescatteringofvectormesondaughtersin

high-energyheavyioncollisions,Eur.Phys.J.C18(2001)645–649,arXiv:nucl -th/9909075 [nucl-th].

[25]C.Markert,R.Bellwied,I.Vitev,Formationanddecayofhadronicresonances intheQGP,Phys.Lett.B669(2008)92–97,arXiv:0807.1509 [nucl-th]. [26]A.Ilner,J.Blair,D.Cabrera,C.Markert,E.Bratkovskaya,Probingthehotand

densenuclearmatterwith K∗,K¯∗vectormesons,Phys.Rev.C99 (2)(2019) 024914,arXiv:1707.00060 [hep-ph].

[27]V.M.Shapoval,P.Braun-Munzinger,Yu.M.Sinyukov,K∗(892)andφ(1020) pro-ductionandtheirdecayintothehadronicmediumattheLargeHadron Col-lider,Nucl.Phys.A968(2017)391–402,arXiv:1707.06753 [hep-ph]. [28]R.Rapp,E.V.Shuryak,Resolvingtheanti-baryonproductionpuzzlein

high-energyheavyioncollisions,Phys.Rev.Lett.86(2001)2980–2983,arXiv:hep -ph/0008326 [hep-ph].

[29]C.Song,V.Koch,Chemicalrelaxationtime ofpionsinhothadronicmatter, Phys.Rev.C55(1997)3026–3037,arXiv:nucl-th/9611034 [nucl-th]. [30]J. Rafelski,J.Letessier, G.Torrieri, Strangehadronsand their resonances:a

diagnostictool ofQGPfreezeout dynamics,Phys. Rev.C64(2001) 054907, arXiv:nucl-th/0104042 [nucl-th];

J.Rafelski,J.Letessier,G.Torrieri,Phys.Rev.C65(2002)069902(Erratum). [31]S. Singha,B. Mohanty, Z.-W.Lin,Studying re-scatteringeffectin heavy-ion

collisionthroughK*production,Int.J.Mod.Phys.E24 (05)(2015)1550041, arXiv:1505.02342 [nucl-ex].

[32]A.G.Knospe,C.Markert,K.Werner,J.Steinheimer,M.Bleicher,Hadronic reso-nanceproductionandinteractioninpartonicandhadronicmatterintheEPOS3 modelwithandwithoutthehadronicafterburnerUrQMD,Phys.Rev.C93 (1) (2016)014911,arXiv:1509.07895 [nucl-th].

[33]A.Andronic,P.Braun-Munzinger,J.Stachel,Thermalhadronproductionin rel-ativisticnuclearcollisions:theHadronmassspectrum,thehorn,andtheQCD phasetransition,Phys.Lett.B673(2009)142–145,arXiv:0812.1186 [nucl-th]; A.Andronic,P.Braun-Munzinger,J.Stachel,Phys.Lett.B678(2009)516 (Erra-tum).

[34]A.Andronic, P.Braun-Munzinger, K.Redlich, J.Stachel,Decoding the phase structureofQCDviaparticle productionat highenergy,Nature561 (7723) (2018)321–330,arXiv:1710.09425 [nucl-th].

[35]J. Cleymans, K. Redlich, Chemical and thermal freezeout parameters from 1 AGeVto200 AGeV,Phys.Rev.C60(1999)054908,arXiv:nucl-th/9903063 [nucl-th].

[36]S.Chatterjee,S.Das,L.Kumar,D.Mishra,B.Mohanty,R.Sahoo,N. Sharma, Freeze-outparametersinheavy-ioncollisionsatAGS,SPS,RHIC,andLHC ener-gies,Adv.HighEnergyPhys.2015(2015)349013.

[37]W.Broniowski,W.Florkowski,B.Hiller,Thermalanalysisofproductionof res-onancesinrelativistic heavyion collisions,Phys. Rev.C 68(2003) 034911, arXiv:nucl-th/0306034 [nucl-th].

[38]R.Rapp,π+-π−emissioninhigh-energynuclearcollisions,Nucl.Phys.A725 (2003)254–268,arXiv:hep-ph/0305011 [hep-ph].

[39]S.D. Protopopescu, M. Alston-Garnjost, A. Barbaro-Galtieri, S.M. Flatte, J.H. Friedman,T.A.Lasinski,G.R.Lynch,M.S.Rabin,F.T.Solmitz,π π partialwave analysisfromreactionsπ+p →π+ π−++andπ+p→K+ K− ++ at 7.1-GeV/c,Phys.Rev.D7(1973)1279.

[40]M.J.Matison,A.Barbaro-Galtieri,M.Alston-Garnjost,S.M.Flatte,J.H.Friedman, G.R.Lynch,M.S.Rabin,F.Solmitz,StudyofK+ π−scatteringinthereaction

K+p→K+π−++at12-GeV/c,Phys.Rev.D9(1974)1872.

[41]M.Bleicher,etal.,Relativistichadronhadroncollisionsintheultrarelativistic quantummoleculardynamicsmodel,J.Phys.G25(1999)1859–1896,arXiv: hep-ph/9909407 [hep-ph].

[42]ALICECollaboration,J.Adam,etal.,K∗(892)0andφ(1020)mesonproduction athightransversemomentuminppandPb–Pbcollisionsat√sNN=2.76TeV,

Phys.Rev.C95 (6)(2017)064606,arXiv:1702.00555 [nucl-ex].

[43]ALICECollaboration,P.Cortese,etal.,ALICE:physicsperformancereport,vol. II,J.Phys.G32(2006)1295–2040.

[44]ALICECollaboration,K.Aamodt,etal.,TheALICEexperimentattheCERNLHC, J.Instrum.3(2008)S08002.

[45]ALICECollaboration,B.Abelev,etal.,PerformanceoftheALICEexperimentat theCERNLHC,Int.J.Mod.Phys.A29(2014)1430044,arXiv:1402.4476 [nucl -ex].

[46]ALICE Collaboration, J.Adam, et al., Centrality dependenceof the charged-particlemultiplicitydensityatmidrapidityinPb–Pbcollisionsat√sNN=5.02

TeV,Phys.Rev.Lett.116 (22)(2016)222302,arXiv:1512.06104 [nucl-ex].

[47]ALICECollaboration,K.Aamodt,etal.,Centralitydependenceofthe charged-particlemultiplicitydensityatmid-rapidityinPb–Pbcollisionsat√sN N=2.76 TeV,Phys.Rev.Lett.106(2011)032301,arXiv:1012.1657 [nucl-ex].

[48]ALICECollaboration,J.Adam,etal.,Determinationoftheeventcollisiontime withtheALICEdetectorattheLHC,Eur.Phys.J.Plus132 (2)(2017)99,arXiv: 1610.03055 [physics.ins-det].

[49]ALICECollaboration,P.Cortese,etal.,ALICEtechnicaldesignreportonforward detectors:FMD,T0andV0,CERN-LHCC-2004-025,2004.

[50]ALICECollaboration,E.Abbas,etal.,PerformanceoftheALICEVZEROsystem, J.Instrum.8(2013)P10016,arXiv:1306.3130 [nucl-ex].

[51]ALICECollaboration,S.Acharya,etal.,Productionofchargedpions,kaonsand (anti-)protonsinPb-Pbandinelasticppcollisionsat√sNN=5.02TeV,arXiv:

1910.07678 [nucl-ex].

[52]P.Z.Skands,TuningMonteCarlogenerators:thePerugiatunes,Phys.Rev.D82 (2010)074018,arXiv:1005.3457 [hep-ph].

[53]P.Skands,S.Carrazza,J.Rojo,TuningPYTHIA8.1:theMonash2013tune,Eur. Phys.J.C74 (8)(2014)3024,arXiv:1404.5630 [hep-ph].

[54]X.-N.Wang,M.Gyulassy,HIJING:aMonteCarlomodelformultiplejet produc-tioninpp,pAandAAcollisions,Phys.Rev.D44(1991)3501–3516. [55] R.Brun,F.Bruyant,F.Carminati,S.Giani,M.Maire,A.McPherson,G.Patrick,

L.Urban,GEANT:DetectorDescriptionandSimulationTool,CERNProgram Li-brary.LongWriteupW5013,1993,http://cds.cern.ch/record/1082634. [56]C.Loizides,J.Kamin,D.d’Enterria,ImprovedMonteCarloGlauberpredictions

at present andfuture nuclearcolliders,Phys. Rev.C97 (5)(2018)054910, arXiv:1710.07098;

C.Loizides,J.Kamin,D.d’Enterria,Phys.Rev.C99 (1)(2019)019901(Erratum). [57]ALICECollaboration,B.Abelev,etal.,Productionofchargedpions,kaonsand protonsatlargetransversemomentainppandPb–Pbcollisionsat√sNN=2.76

TeV,Phys.Lett.B736(2014)196–207,arXiv:1401.1250 [nucl-ex].

[58]C.Tsallis,PossiblegeneralizationofBoltzmann-Gibbsstatistics,J.Stat.Phys.52 (1988)479–487.

[59]STARCollaboration,B.I.Abelev,etal.,Strangeparticleproductioninp+p col-lisions at √sNN = 200GeV, Phys. Rev.C75 (2007)064901, arXiv:nucl-ex/

0607033 [nucl-ex].

[60]E.Schnedermann,J.Sollfrank,U.W.Heinz,Thermalphenomenologyofhadrons from200AGeVS+Scollisions,Phys.Rev.C48(1993)2462–2475,arXiv:nucl -th/9307020 [nucl-th].

[61]ALICECollaboration,K.Aamodt,etal.,Two-pionBose-Einsteincorrelationsin centralPb–Pbcollisionsat√sN N=2.76TeV,Phys.Lett.B696(2011)328–337, arXiv:1012.4035 [nucl-ex].

[62]M.A.Lisa,S.Pratt,R.Soltz,U.Wiedemann,Femtoscopyinrelativisticheavyion collisions,Annu.Rev.Nucl.Part.Sci.55(2005)357–402,arXiv:nucl-ex/0505014 [nucl-ex].

[63]S.A. Bass, A. Dumitru,M. Bleicher, L. Bravina, E.Zabrodin,H. Stoecker, W. Greiner,Hadronicfreezeout followingafirstorderhadronizationphase tran-sitioninultrarelativisticheavyioncollisions,Phys.Rev.C60(1999)021902, arXiv:nucl-th/9902062 [nucl-th].

[64]J.Stachel,A.Andronic,P.Braun-Munzinger,K.Redlich,ConfrontingLHCdata withthestatisticalhadronizationmodel,J.Phys.Conf.Ser.509(2014)012019, arXiv:1311.4662 [nucl-th].

[65]C.Shen,U.Heinz,P.Huovinen,H.Song,RadialandellipticflowinPb+Pb col-lisionsattheLargeHadronColliderfromviscoushydrodynamics,Phys.Rev.C 84(2011)044903,arXiv:1105.3226 [nucl-th].

[66]V.Minissale,F.Scardina,V.Greco,Hadronsfrom coalescenceplus fragmen-tationinAAcollisionsatenergiesavailableattheBNLRelativisticHeavyIon CollidertotheCERNLargeHadronCollider,Phys.Rev.C92 (5)(2015)054904, arXiv:1502.06213 [nucl-th].

ALICECollaboration

S. Acharya

141

,

D. Adamová

94

,

A. Adler

74

, J. Adolfsson

80

,

M.M. Aggarwal

99

,

G. Aglieri Rinella

33

,

M. Agnello

30

, N. Agrawal

10

,

53

,

Z. Ahammed

141

,

S. Ahmad

16

, S.U. Ahn

76

, A. Akindinov

91

,

M. Al-Turany

106

,

S.N. Alam

141

,

D.S.D. Albuquerque

122

,

D. Aleksandrov

87

, B. Alessandro

58

,

H.M. Alfanda

6

, R. Alfaro Molina

71

,

B. Ali

16

, Y. Ali

14

, A. Alici

10

,

26

,

53

,

A. Alkin

2

,

J. Alme

21

,

T. Alt

68

,

L. Altenkamper

21

,

I. Altsybeev

112

, M.N. Anaam

6

, C. Andrei

47

, D. Andreou

33

,

H.A. Andrews

110

,

A. Andronic

144

,

M. Angeletti

33

,

V. Anguelov

103

,

C. Anson

15

,

T. Antiˇci ´c

107

,

F. Antinori

56

,

P. Antonioli

53

,

R. Anwar

125

, N. Apadula

79

, L. Aphecetche

114

,

H. Appelshäuser

68

,

S. Arcelli

26

,

R. Arnaldi

58

,

M. Arratia

79

,

I.C. Arsene

20

,

M. Arslandok

103

,

A. Augustinus

33

, R. Averbeck

106

,

S. Aziz

61

, M.D. Azmi

16

,

A. Badalà

55

,