Measurement of prompt ψ(2S) production cross sections in proton–lead and proton–proton collisions at √sNN =5.02TeV

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Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Measurement

of

prompt

ψ (2S)

production

cross

sections

in

proton–lead

and

proton–proton

collisions

at

√

s

_NN

=

5.02 TeV

.The CMS Collaboration CERN,Switzerland

a r t i c l e i n f o a b s t ra c t

Articlehistory:

Received6May2018

Receivedinrevisedform2January2019 Accepted29January2019

Availableonline1February2019 Editor: M.Doser

Keywords:

CMS pPb

ψ(2S)

Measurementsofpromptψ(2S)mesonproductioncrosssectionsinproton–lead(pPb)andproton–proton (pp)collisionsatanucleon–nucleoncenter-of-massenergyof√sNN=5.02TeV arereported.Theresults arebasedonpPb andpp datacollectedbytheCMSexperimentattheLHC,correspondingtointegrated luminositiesof34.6 nb−1 _and_{28.0 pb}−1_,_{respectively.} _The_nuclear_{modiﬁcation}_factor_R

pPb ismeasured forpromptψ(2S)inthetransversemomentumrange4<pT<30GeV/c andthecenter-of-massrapidity range−2.4<yCM<1.93.The resultsonψ(2S) RpPb are comparedtothecorresponding modiﬁcation factorforpromptJ/ψ mesons.Theresultspointtodifferentnucleareffectsatplayintheproductionof theexcitedcharmoniumstatecomparedtothegroundstate,intheregionofbackwardrapidityandfor pT<10GeV/c.

1. Introduction

The studyof quarkonium productionin nuclear collisions has a long and rich history, dating back to the original proposal by MatsuiandSatzpredictingJ/ψsuppressioninheavyioncollisions duetoDebyescreeninginthequark–gluonplasma(QGP) [1].After thisproposal, the ﬁrstJ/ψ measurements inheavy ion collisions were performedin ﬁxed target experiments atthe CERN SPS, at anucleon–nucleoncenter-of-massenergyof√sNN≈20GeV [2,3].

A similarlevelofsuppressionwaslaterobservedingold–gold col-lisions at the BNL RHIC, at √sNN=200GeV [4,5]. At the CERN

LHC, the production of charmonium (J/ψ, ψ(2S)) and bottomo-nium(ϒ(1S), ϒ(2S),ϒ(3S)) stateshasbeen studiedin lead–lead (PbPb)collisionsat√sNN=2.76 and5.02 TeV [6–12],bringingnew

elementsfortheunderstanding ofthemedium producedin high-energyheavyioncollisions.

Thequarkoniumyieldscanbemodiﬁed inheavyioncollisions becauseof severaleffects [13], including suppression [1] and re-combinationofcharmquarkpairs [14] insidethehotmatter(QGP), and cold nuclear matter effects. An unambiguous interpretation ofthenucleus–nucleusLHC resultsrequiresaquantitative under-standingofcoldnuclear mattereffects.Thenuclearparton distri-butionfunctions(nPDFs)areknowntobedifferentfromthoseina

_E-mail_address:_cms_-publication_-committee_-chair_@cern_.ch_.

freeproton [15,16].Inaddition,gluonradiationinduced by multi-plepartonscatteringinthenucleusleadstotransversemomentum (pT)broadeningandcoherentenergyloss,resultinginasigniﬁcant

quarkoniumsuppressioninnuclearcollisionsatallavailable ener-gies [17,18].Thesephenomena arebeststudiedinproton-nucleus collisions, inwhichhotmedium effects,suchasthoseduetothe QGP,arelikelytobelimited.

Many charmonium production measurements have been per-formed inproton-inducedcollisions, onseveralnuclei, attheSPS [19–22], HERA [23], and Tevatron [24]. A global analysis of the ﬁxed-target measurements can be found in Ref. [25]. At RHIC, J/ψ and ψ(2S) data in deuteron-gold collisions have been re-ported by the PHENIX [26] and STAR [27] Collaborations. At the LHC, the cross section of J/ψ in proton–lead (pPb) collisions at √

sNN=5.02TeV hasbeenmeasured bythe ALICE [28,29],ATLAS

[30],CMS [31],andLHCb [32] Collaborations.Asigniﬁcant suppres-sionoftheprompt J/ψ yield inpPb collisionshasbeenobserved atforwardrapidity( y)andlowpT,whilenostrongnucleareffects

are reportedat backward rapidity, where forward andbackward indicate, respectively,the directionsof theproton andPbbeams. Measurementsofthe ϒ(1S) in pPb collisionsat√sNN=5.02TeV

have also been performed by the ALICE [33], ATLAS [34], and LHCb [35] experiments,indicatingthattheϒ(1S)stateisless sup-pressedthantheJ/ψ.

Additionalinformationcanbeobtainedbystudyingthe behav-ioroftheexcitedstates,whicharelesstightlyboundcomparedto

https://doi.org/10.1016/j.physletb.2019.01.058

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thegroundstatesandmightsufferstronger suppressioninheavy ioncollisions.AttheLHC,theALICE [36] andCMS [11] Collabora-tionshavereportedastrongersuppressionoftheψ(2S)state com-paredtothe J/ψ inPbPb collisions. InpPb collisions,ALICE [37], ATLAS [34],andLHCb [38] datashowthatψ(2S)suppression, inte-gratedovertransversemomentum,ismorepronounced thanthat oftheJ/ψ.Thisobservationsuggestsﬁnal-stateeffectsforthe ex-citedstates,possiblyduetoinelasticinteractionswiththemedium produced in pPb collisions [39]. In the bottomonium sector, the doubleyield ratios ϒ(3S)/ϒ(1S)and ϒ(2S)/ϒ(1S) in pPb relative topp collisionshavebeenmeasuredbyCMS [40] andfoundtobe lessthanunity, againindicatingstronger ﬁnal-stateeffectsinthe productionofexcitedquarkoniumstates.

This Letter reports measurements of the cross sections for prompt ψ(2S) production in pp and pPb collisions at √sNN=

5.02TeV, with the ψ(2S) decaying to μ+μ−, over the pT range

4–30 GeV/c and center-of-massrapidityrange−2.4<yCM<1.93.

The data were collected with the CMS detector at the LHC, in 2013for the pPb sample andin 2015for the pp sample, corre-sponding to integrated luminosities of 34.6±1.2nb−1 [41] and 28.0±0.6pb−1 [42],respectively.Inaddition,themodification of quarkonium productioninpPb collisions isquantified bythe nu-clearmodificationfactor, RpPb,whichisdefinedastheratioofthe

cross sections in pPb and pp collisions divided by the Pb mass number, A=208.The ψ(2S) RpPb isdetermined asafunction of

yCMandpT,andiscomparedtothatoftheJ/ψ mesonsmeasured

atthesamecenter-of-massenergy [31].Thisistheﬁrst measure-mentofψ(2S) RpPb at√sNN=5.02TeV in differentialbinsof pT

and yCM that uses the pp data measured atthe same

center-of-massenergy. 2. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ing solenoidof6 m internaldiameter, providinga magneticfield of3.8 T.Withinthesolenoidvolume thereareasiliconpixeland strip tracker,a leadtungstatecrystalelectromagnetic calorimeter, andabrass andscintillatorhadron calorimeter,eachcomposedof abarrelandtwoendcapsections.Forwardcalorimetersextendthe pseudorapidity (η) coverage provided by the barrel and endcap detectors.The forwardhadron (HF) calorimeteruses steel as ab-sorberandquartzfibers asthesensitive material.Thetwohalves of the HF are located at ±11.2 m from the nominal interaction point.Togethertheyprovidecoverageintherange3.0<|η|<5.2 andalsoserveasluminositymonitors.Muonsaredetectedin gas-ionization chambersembedded inthe steelflux-returnyoke out-side the solenoid, in the range |η|<2.4, with detection planes madeusingthreetechnologies:drifttubes,cathodestripchambers, andresistive-platechambers.Matchingmuonstotracksmeasured inthesilicontrackerresultsinarelative pT resolutionfortypical

muonsinthisanalysisof1.3–2.0%inthebarrelandbetterthan6% intheendcaps [43].AmoredetaileddescriptionoftheCMS detec-tor,together witha deﬁnitionofthecoordinatesystemused and therelevantkinematicvariables,canbefoundinRef. [44]. 3. Eventselection

The pPb collisions at √sNN=5.02TeV correspond to a

pro-ton beam energy of 4 TeV and a lead beam energy of 1.58 TeV per nucleon. The proton beam traveled in the −η direction (in the detectorcoordinate system) in theﬁrst part of the run, cor-responding to an integrated luminosity Lint=20.7 nb−1, and in

theoppositedirectioninthesecondpartoftherun,corresponding toLint=13.9 nb−1.Particlesemittedat|ηCM|=0 inthenucleon–

nucleoncenter-of-massframearedetectedinthelaboratoryframe

at ηlab= ±0.465 depending ontheprotonbeamdirection.Inthis

paper,dataforhalfoftherunwerereﬂectedsothatpositive η al-wayscorrespondstothedirectionoftheprotonbeam.Thepp data set,collectedatthesamecollisionenergyasthepPb sample, cor-respondstoLint=28.0pb−1.Inthepp sample,thedimuonsfrom

ψ(2S)decaysarereconstructedwithin|yCM|<2.4 andinthesame

pT rangeasthepPb data,4<pT<30GeV/c.

Inelastic hadronic collisions are selected by requiring at least oneHFtowerwithmorethan3 GeV oftotalenergyineachofthe two HF calorimeters. Thisis not required inpp collisions, which sufferlessfromphoton-inducedinteractionscomparedtopPb col-lisions.Thepp andpPb eventsarefurtherselectedtohaveatleast one reconstructed primary vertex composed of two ormore as-sociated tracks,excludingthetwomuons, within25 cmfromthe nominal interaction point along the beamaxis and within 2 cm inthetransverseplane.Torejectthebeam-gasbackgroundevents, thefractionofgood-qualitytracksassociatedwiththeprimary ver-texisrequiredtobelargerthan25%whentherearemorethan10 tracksperevent.

The dimuoneventsare selectedby thelevel-1trigger,a hard-ware-based triggersystem requiringtwo muon candidatesin the muon detectorswith no explicitlimitations on their pT or η. In

theoﬄineanalysis,muonsarerequiredtobewithinthefollowing kinematic regions, which ensure single-muonreconstruction eﬃ-cienciesabove10%:

pμ_T >3.3 GeV/c for|η_labμ| <1.2,

pμ_T > (4− [1.1|ημ_lab|])GeV/c for 1.2<|ημ_lab| <2.1,

pμ_T >1.3 GeV/c for 2.1<|ημ_lab| <2.4.

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The oppositely chargedmuon pairs are further selected to origi-natefromacommonvertexwitha χ2_probability_greater_than_1%,

andtosurvivestandardidentiﬁcationcriteria [43].Inorderto re-movecosmic-raymuons,thetransverseandlongitudinaldistances of closest approach betweenthe muon trajectory andthe recon-structed primary vertexare required to be lessthan 0.3 cm and 20 cm, respectively. All of these selections are common to both thepp andthepPb datasets.

4. Yieldextraction

Thepromptψ(2S)signalextractionprocedureissimilartothat in previous CMSanalyses [8,11], andisthe samefor thepp and pPb data sets. Thedimuon massdistribution isfittedwithsignal (including both the J/ψ and ψ(2S) resonances) and background contributions using an extended unbinned maximum likelihood procedure [45].WhilethescopeofthepresentLetteristhe mea-surementofthepromptψ(2S)production,theJ/ψresonancewas includedintheψ(2S)fittoincreasethepeakfittingstability.Ithas beencheckedthatthepromptJ/ψresultsobtainedinthisanalysis agreewiththeonesinRef. [31],whichusedadifferentmethodfor separating prompt from nonprompt charmonia. The prompt J/ψ

resultsofRef. [31] aretheonesusedinthisLetterforcomparison withthenewanalysisofψ(2S)production.Bothresonanceshapes are modeledby theweighted sumofaCrystalBall(CB) [46] and a Gaussian function. The CB function, gCB(m), combines a

Gaus-sian core anda power law tail withexponent n, accountingfor energy lossdueto ﬁnal-statephoton radiation,witha parameter

α deﬁningthetransitionbetweentheGaussianandthepowerlaw functions:

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gCB(m)= ⎧ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎩ N √ 2π σCB exp −(m−m0)2 2σ2 CB , form−m0 σCB >−α; N √ 2π σCB n |α| n exp −|α|2 2 × n |α|− |α|− m−m0 σCB −n , form−m0 σCB <−α. (2)

The CB and Gaussian functions have independent widths, σCB

and σG, to accommodate the dependence of the dimuon

invari-antmass resolution on the dimuonrapidity and pT, butshare a

commonmeanm0 representingtheJ/ψ mass. Thesignal models

used for the ψ(2S) and J/ψ share the same α and n param-eters. The mean and the width of the Gaussian model for the

ψ(2S) are obtainedfrom those of the J/ψ, scaled by their mass ratio (mψ (2S)/mJ/ψ=1.1903 [47]). The following parameters are leftfree inthe ﬁt:m0, σCB, σG, NJ/ψ (theJ/ψ yield), Nψ (2S) (the ψ(2S) yield), f (the relativecontributionof theGaussian andCB functions),and α. Based on simulation studies, the value of the parametern is ﬁxed to 2.1. The parameter α is left free, cover-ing thevariation of signal shapesineach of the pT andrapidity

bins.Thesamevalue for f is usedinthedeﬁnitionofthe ψ(2S)

andJ/ψsignalshapes.Theunderlyingbackgroundisdescribedby a Chebyshev polynomial ofdegree N (1≤N≤3).The degree of theChebyshevpolynomialisobtainedineach(pT,yCM)binofthe

analysisusingalog-likelihoodratiotest.Severalalternativeﬁtting procedureshavebeentested,andtheyieldvariationswithrespect tothenominalresultare includedasa systematicuncertainty, as explained inSection 6. The two pPb data sets, corresponding to each proton beam direction, are merged and analyzed together afterhaving veriﬁed that theindependent results are compatible witheachother.

TheJ/ψ andψ(2S)comingfromb hadron decays(nonprompt charmonia) are evaluated using the displacement of the μ+μ−

vertex from the primary collision vertex. This secondary μ+μ−

vertexischaracterizedbythepseudo-properdecaylength,

J/ψ=Lxy

mJ/ψ

pT

, (3)

where Lxy is the transverse distance between the primary and dimuonvertices,mJ/ψ isthemassoftheJ/ψ [47] (assumedforall muonpairs), andpT isthetransversemomentumofthedimuon.

Prompt charmonia are selected by requiring J/ψ to be smaller thana threshold value l0, whichis tuned usingsimulation

sepa-ratelyforthepp andpPb collisionssystems,inordertokeep90% ofthetotalpromptcharmonia [11].Sincethe J/ψ resolution im-proveswithincreasingdimuonpT,thel0valuesalsodependonpT.

Thel0 valuesusedremovebetween70%and90%(80%and90%)of

thenonpromptψ(2S)inpPb (pp)collisions,fromlow- tohigh-pT.

Theyields soobtainedhaveasmallnonpromptcontamination, whichiscorrectedusingthe numberofsimulatedeventspassing andfailingthe J/ψ thresholdcriteria [11]. The full value ofthis correctionisalsopropagatedasasourceofsystematicuncertainty. Fig.1showsthedimuoninvariant massdistributionswiththe J/ψ andψ(2S)peaksinpPb andpp data,foroneofthebinswith thesmallestsignal-to-backgroundratio(lowestpTandmost

back-wardy),afterapplyingtheJ/ψ selection,togetherwiththecurves resultingfrom theﬁts. The rawprompt ψ(2S) yield extractedin these bins is ∼300 for the pPb, and twice as much for the pp samples.

Fig. 1. Dimuoninvariantmassdistributionshowingthe J/ψ and ψ(2S)peaksin pPb (toppanel)andpp (bottompanel)data,afterapplyingtheJ/ψ selection,for

−2.4<yCM<−1.93 and4<pT<6.5GeV/c.Theﬁtstothedistributionsarealso

shown.

5. Acceptanceandeﬃciencycorrections

Simulated events are used to obtain the acceptance and eﬃ-ciencycorrectionfactorsforthemeasuredψ(2S)yields.Theevents aregeneratedusing pythia 6.424 [48] forpPb collisionsand pythia 8.209 [49] for pp collisions. The generated particles in the pPb Monte Carlo (MC) are boosted by the β of the center-of-mass system in the laboratory frame, resulting in y= ±0.465. The promptJ/ψandψ(2S)areassumedtobeproducedunpolarizedin both pp andpPb collisions, whichissupported bymeasurements inpp collisionsat√s=7TeV [50,51].Theﬁnal-stateQEDradiation ofthedecaymuonsissimulatedusing photos 215.5 [52].Finally, theCMSdetectorresponseissimulatedusing Geant4 [53].

Theacceptanceinagiven(pT,yCM)binisdeﬁnedasthe

frac-tion of generated ψ(2S) mesons resulting in a detectable muon pair, i.e., passing the single muon selection criteria defined in Eq. (1).Theefficiencyisgivenbythefractionofgeneratedand de-tectablemuonpairsthatresultinareconstructedmuonpair,also passingthetriggerandofflineselections.Thecombinedψ(2S) ac-ceptance andefficiencyfor pPb(pp) resultsranges between13% (14%)inthelowestpTregion(4.0<pT<6.5GeV/c)and66%(67%)

inthehighestpT region(10.0<pT<30.0GeV/c). Itismaximum

in the overlap region between barrel and endcap detectors, and decreasestominimumvaluesfor|yCM|>2.

Theindividualcomponentsofthesimulation-baseddimuon ef-ﬁciency (track reconstruction, muon identiﬁcation and selection, andtriggering)areprobedusingsinglemuonsfromJ/ψmeson de-cays inboth simulatedandcollision data,withthetag-and-probe

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(T&P)method [31,54].Thedata-to-simulationratiosofsinglemuon eﬃcienciesobtainedfromT&P,calculatedasafunctionofmuon η

andpT,areusedasweights(scalefactors)tocorrectevent-by-event

thedimuoneﬃciency.Theeffectofthiscorrectiononthedimuon eﬃciencyissimilarforpp andpPb eventsandrangesfrom0.99to 1.33, withlargercorrectionsatlower pT andmore

forward/back-wardrapidities.

6. Systematicuncertainties

The following sources of point-to-point systematic uncertain-tiesareconsidered forbothpp andpPb data:theyieldextraction method,giventhechoiceofsignalandbackgroundmodels; accep-tance and eﬃciency corrections, including T&P scale factors and thepossible differencein thedimuon pT spectrum betweendata

andsimulation;andthenonpromptcharmoniacontamination.The evaluationofthesesystematicuncertaintiesisdescribedbelow.

• Signalshapevariation. Thissystematicuncertaintyisobtained by changing the fitting constraints on the CB shape param-eters. In the nominal fits, the CB parameter n isfixed from simulation,n=2.1,andtheparameter α isleftfree.Inafirst variation,theparameter α isfixed totheMC-basedvalue1.7, andn isleftfree.Asecondvariationconsistsinfixingboth pa-rameterstothevaluesextractedfromMC,n=2.1 and α=1.7. The maximum difference, in each analysis bin, between the yieldsextractedwiththenominalfitandeitherofthese vari-ations,istakenasasystematicuncertainty.

• Backgroundshapevariation. Thedegree N of theChebyshev polynomialischangedtoN+1 ifN<3,andtoN−1 ifN=3. Thesystematicuncertaintyisestimatedastheabsolute differ-enceintheyieldswithrespecttothenominalcase.

• SimulateddimuonpTspectrum. Theacceptanceandeﬃciency

correctionfactorsdependontheshapeofthesimulatedψ(2S)

pTdistribution;thedifferencebetweendataandsimulationis

asource ofsystematicuncertainty.The ratioofthecorrected yields in data and simulation is evaluated as a function of pT,foreachrapiditybin.Continuousweightingfactorsare

ob-tainedby ﬁttingthesedata-to-simulationratioswitha linear functioninpT.Theacceptanceandeﬃciencyvaluesare

evalu-atedagainafterweightingthepTdistributionofthegenerated

ψ(2S)mesonsinthesimulationbythefunctionobtained.The differencebetweenthereweighedsimulationandthenominal yieldsistakenasasystematicuncertainty.

• T&Pscalefactors. ThestatisticaluncertaintyontheT&Pscale factors,aswellassystematicuncertaintiesintheirderivation, areaccountedforasasystematicuncertainty.These uncertain-tiesarefurtherdescribedinRef. [31].

• Nonprompt contamination. The difference between the promptmesonyields withandwithoutthecorrectionforthe residualnonpromptcontamination ispropagatedasa system-aticuncertainty.

Thesystematicuncertaintyinthe yieldextraction,determined by summing the uncertainties from the signal and background shape variations in quadrature, is in the range 1.0–22% and 0.4–6.5%forthepPb andpp results,respectively. Thislarge range is mostly driven by the variation of the signal over background ratio across the analysis bins. The dominant part in this uncer-tainty isfrombackgroundmodeling,withanaverage overallthe pTandyCM binsof3.9(2.4)%andamaximumof22(4.9)%forthe

pPb(pp)results.The averagesignal modelingcontributionis1.9% and1.4%,forthepPb andpp results,respectively.

Thesystematicuncertaintyintheacceptanceandeﬃciency cor-rection factors, combining the dimuon pT spectrum reweighting

Fig. 2. Differentialcrosssection(multipliedbythedimuonbranchingfraction)of promptψ(2S)productioninpPb collisionsat√sNN=5.02TeV,asafunctionofpT,

inseveralrapiditybinsandseparatelyforbackward(toppanel)andforward (bot-tompanel)rapidityregions.Statisticalandsystematicuncertaintiesarerepresented witherrorbarsandboxes,respectively.Thefullycorrelatedluminosityuncertainty of3.5%isnotincludedinthepoint-by-pointuncertainties.

and T&P uncertainties, lies within 2.0–7.4% and 1.9–8.1% for the pPb and pp results, respectively. The prompt selection method induces an uncertainty of 4.5–15% (0.2–8.0%) for the pPb (pp)

results,withthemaximumvalueinthelowestpT bininthe

back-ward y region.The totalsystematicuncertainty,calculatedasthe suminquadrature oftheindividual uncertainties,is intherange 5–26% (4–11%) for the pPb (pp) cross section measurements. In general, the uncertainty is minimum in the highest pT bins in

the central y region,and increaseswhen going to lower pT and

forward/backward y regions. For the RpPb measurement, the pp

and pPb uncertainties are considered independent and added in quadraturepoint-by-point.Thetotalsystematicuncertaintyinthis caseisintherange5.0–22.6%.

The global(common to all points) systematicuncertaintydue totheuncertaintyintheintegratedluminosity ofthepPbandpp data sets is 3.5% [41] and 2.3% [42], respectively. For the cross section results, this uncertainty is not included to the point-to-point uncertainties, while for the RpPb results the two numbers

are addedinquadratureanddisplayed asaboxaround RpPb=1.

The dominantsourceofuncertaintyforthe RpPb measurementis

thestatisticaluncertaintyinthepPb data. 7. Results

The promptψ(2S)productioncrosssection (multipliedby the

ψ(2S) branching fraction to μ+μ−, B(ψ(2S)→μ+μ−)) in the dimuondecaychannelisdeterminedas

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Fig. 3. Differentialcrosssection(multipliedbythedimuonbranchingfraction)of promptψ(2S)productioninpp collisionsat√s=5.02TeV asafunctionofpT,in

four yCM bins.Statisticalandsystematicuncertaintiesarerepresentedwitherror

barsandboxes,respectively.Thefullycorrelatedluminosityuncertaintyof2.3%is notincludedinthepoint-by-pointuncertainties.

B(ψ (2S)→μ+μ−) d 2_σ dpTd yCM= Nψ (_ﬁt2S)/(accε) LintpTyCM , (4)

whereN_ﬁtψ (2S) istheextractedrawyieldofpromptψ(2S)mesons ina given(pT,yCM) bin,(accε)istheproductofthedimuon

ac-ceptanceandeﬃciencydescribedinSection5,andpTandyCM

arethewidthsofthekinematicbinconsidered.

Figs. 2 and 3 show the production cross sections of prompt

ψ(2S) mesons in pPb and pp collisions at √sNN=5.02TeV,

re-spectively. The results are givenas a function of pT and in four

rapidity bins, separately forforward (the directionof the proton beam) andbackward (the directionofthePb beam)rapidities in thecaseofthepPb measurements.

The second observable considered is the nuclear modiﬁcation factor,deﬁnedas RpPb(pT,yCM)≡ (d2σ/dpTd yCM)pPb A(d2_σ_/_dp Td yCM)pp . (5)

In the absence ofany nuclear effects the measured yield in pPb collisions wouldbe justa superpositionof A=208 (the number ofnucleons inthe Pbnucleus)pp collisions, andthe RpPb would

beone.

Fig.4showstherapiditydependenceofthepromptψ(2S)RpPb

inthree pT ranges:4–6.5, 6.5–10, and10–30 GeV/c.In the

back-wardrapidityregion,thepromptψ(2S)mesonsaresuppressedin theintermediate pTregion,andcompatiblewithunityintherest.

Intheforwardrapidityregion,theRpPbisconsistentwithunityfor

all pT bins (althoughsystematicallysmaller). Forcomparison,the

promptJ/ψnuclearmodiﬁcationfactor [31] isalsoshowninFig.4. The measuredvalue of RpPb forprompt ψ(2S)mesons,when

in-tegratedover pT andrapidity (6.5<pT<30GeV/c, |y|<1.6), is

0.852±0.037stat±0.062syst. Theprompt J/ψ RpPb inthe same

kinematic range is 1.108±0.021stat±0.055syst. The RpPb for

prompt J/ψ mesons lies systematically above that of the ψ(2S)

state. The difference between the two sets of results was

quan-Fig. 4. Rapiditydependenceofthepromptψ(2S)RpPbinthreepTranges.Forcomparison,thepromptJ/ψ nuclearmodiﬁcationfactor [31] isalsoshown.Statisticaland

systematicuncertaintiesarerepresentedwitherrorbarsandboxes,respectively.Thefullycorrelatedglobaluncertaintyof4.2%(thataffectsbothcharmonia)isdisplayedas aboxaroundRpPb=1.

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Fig. 5. Transversemomentumdependenceofthepromptψ(2S)RpPbinfourrapidityranges.Statisticalandsystematicuncertaintiesarerepresentedwitherrorbarsand

boxes,respectively.Thefullycorrelatedglobaluncertaintyof4.2%isdisplayedasaboxaroundRpPb=1.

tiﬁed,separately forthe backward andforward regions, by com-paringthe two distributions witha χ2_-test, _removing _the

corre-lated uncertainties from the integrated luminosity. The p-values are<0.05 forthelowesttwo pT rangesinthebackwardrapidity

region,and>0.37 inall theotherrapidity and pT intervals. This

showsthat,witha p-valuecutoffof 0.05,the twosets ofresults areincompatible witheach otherinthebackward rapidityregion for pT<10GeV/c, but are compatiblein the rest. This suggests

thepresenceofdifferentnucleareffectsatplay intheproduction oftheexcitedcharmoniumstatecomparedtothegroundstate,in theregionofbackwardrapidityandforpT<10GeV/c.

Fig.5showsthe pT dependenceofthe promptψ(2S) RpPb in

sevenrapiditybins,fromthemostbackward−2.4<yCM<−1.93

to themostforward 1.5<yCM<1.93 accessible regions.Also in

thiscase, a χ2_-test _was _used _to _quantify _the _{signiﬁcance}_of _the

difference oftheresultsfromunity, inwhich thefullycorrelated globaluncertainty, displayed as a box around RpPb=1, was not

included.The p-valuesarebelow0.05 onlyinthemostbackward region.Thispoints tothepresenceofnucleareffectsaffectingthe

ψ(2S) production in the most backward region that persists at largetransversemomentum.

The suppression of prompt ψ(2S) mesons as compared to prompt J/ψ mesons,seenin Fig.4,iscompatiblewithwhat was measured by the ALICE [37], ATLAS [34], and LHCb [38] Collab-orations for pT integrated charmonium production in pPb

colli-sionsatthesamecollisionenergy.WhilenPDFs [15,16] and coher-ent energyloss [17,18] are themost discussedeffects to explain prompt J/ψ meson suppression, these two phenomena are ex-pected to affect the RpPb of prompt J/ψ and ψ(2S) mesons by

asimilaramount.Onthecontrary,theﬁnal-stateinteractionwith

hadronsmovingalongwiththeproducedcharmoniummightlead to a stronger suppression of the ψ(2S) meson, due to its larger size [39,55]. Thepresentmeasurements,coveringwide transverse momentum(4<pT<30GeV/c)andrapidity(−2.4<yCM<1.93)

ranges, willhelp understand theoriginof thesuppression of ex-citedquarkoniumstatesinpPb collisionsattheLHC.

8. Summary

Thedatacollectedby CMSinpp andpPb collisionsat√sNN=

5.02TeV areusedto investigateprompt ψ(2S) mesonproduction. Theresultsarebasedondatasamplescorrespondingtointegrated luminosities of28.0 pb−1 forpp collisions and34.6 nb−1 forpPb collisions.Thenuclearmodiﬁcationfactor(RpPb)ofpromptψ(2S),

inthekinematicrange4<pT<30GeV/c and−2.4<yCM<1.93,

is determined andcompared to that of prompt J/ψ mesons, re-portedinRef. [31].Thepromptψ(2S)productionissuppressedin the intermediate 6.5–10 GeV/c pT interval inthe region of

back-ward rapidity.The RpPb is consistent withunity everywhereelse

(althoughsystematically smaller). The RpPb values ofpromptJ/ψ

when compared to those of prompt ψ(2S) mesons,point to dif-ferent nuclear effects at play in the production of the excited charmonium state compared to the ground state, in the region of backward rapidity and for pT<10GeV/c. The effects of

nu-clearpartondistributionfunctionsorcoherentenergylossare ex-pected to affectthe RpPb ofprompt J/ψ andψ(2S) by a similar

amount, thus the resultshint the presence ofﬁnal-state interac-tions with the medium (partonic or hadronic) produced in pPb collisions.

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Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrativestaffs atCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentersand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythecomputinginfrastructure essential toour analyses. Finally, we acknowledge the enduring support for the construc-tionandoperationofthe LHCandtheCMSdetectorprovided by thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIEN-CIAS(Colombia);MSESandCSF(Croatia);RPF(Cyprus);SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Fin-land,MEC,andHIP(Finland);CEAandCNRS/IN2P3(France);BMBF, DFG,and HGF (Germany); GSRT (Greece);NKFIA (Hungary);DAE and Department of Science and Technology (India); IPM (Iran); SFI(Ireland);INFN(Italy);MSIPandNRF(RepublicofKorea);LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONA-CYT,LNS,SEP,andUASLP-FAI(Mexico);MBIE(NewZealand);PAEC (Pakistan);MSHEandNSC(Poland);FCT(Portugal);JINR(Dubna); MON, ROSATOM, RAS and RFBR (Russia); MESTD (Serbia); SEIDI, CPAN,PCTI andFEDER(Spain); SwissFundingAgencies (Switzer-land); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thai-land);TUBITAKandTAEK(Turkey);NASUandSFFR(Ukraine);STFC (UnitedKingdom);DOEandNationalScienceFoundation(USA).

Individuals have received support from the Marie-Curie pro-gramandtheEuropeanResearchCouncilandHorizon2020Grant, contract No. 675440 (European Union); the Leventis Founda-tion; the Alfred P. Sloan Foundation; the Alexander von Hum-boldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dansl’Industrie et dans l’Agriculture (FRIA-Belgium);the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the F.R.S. - FNRS and FWO (Belgium) under the “Excellence of Science – EOS” – be.h project n. 30820817; the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Lendület (“Mo-mentum”) Program and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences, the New National Excel-lenceProgram ÚNKP,the NKFIA research grants 123842, 123959, 124845, 124850 and 125105 (Hungary); the Council of Science andIndustrial Research,India;the HOMING PLUSprogramofthe Foundation for Polish Science, cofinanced from European Union, Regional Development Fund, the Mobility Plus program of the Ministry of Science and Higher Education, the National Science Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/ 02861,Sonata-bis2012/07/E/ST2/01406;theNationalPriorities Re-search Program by Qatar National Research Fund; the Programa Estatal de Fomento de la Investigación Científica y Técnica de ExcelenciaMaríade Maeztu,grantMDM-2015-0509 andthe Pro-grama Severo Ochoa del Principado de Asturias; the Thalis and Aristeiaprograms cofinancedbyEU-ESF andtheGreek NSRF;the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chula-longkornUniversity andthe ChulalongkornAcademicintoIts 2nd CenturyProjectAdvancementProject (Thailand);theWelch Foun-dation,contractC-1845;andtheWestonHavensFoundation(USA). References

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TheCMSCollaboration

A.M. Sirunyan,A. Tumasyan YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, F. Ambrogi, E. Asilar,T. Bergauer, J. Brandstetter, E. Brondolin,M. Dragicevic, J. Erö,

A. Escalante Del Valle,M. Flechl, M. Friedl,V.M. Ghete, J. Hrubec, M. Jeitler1, N. Krammer,I. Krätschmer, D. Liko,T. Madlener, I. Mikulec,N. Rad, H. Rohringer, J. Schieck1, R. Schöfbeck, M. Spanring,D. Spitzbart, A. Taurok,W. Waltenberger, J. Wittmann, C.-E. Wulz1, M. Zarucki

InstitutfürHochenergiephysik,Wien,Austria

V. Chekhovsky, V. Mossolov,J. Suarez Gonzalez InstituteforNuclearProblems,Minsk,Belarus

E.A. De Wolf,D. Di Croce, X. Janssen, J. Lauwers,M. Pieters,M. Van De Klundert, H. Van Haevermaet, P. Van Mechelen, N. Van Remortel

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S. Abu Zeid,F. Blekman, J. D’Hondt, I. De Bruyn, J. De Clercq, K. Deroover, G. Flouris, D. Lontkovskyi, S. Lowette,I. Marchesini, S. Moortgat, L. Moreels,Q. Python, K. Skovpen, S. Tavernier,W. Van Doninck, P. Van Mulders,I. Van Parijs

VrijeUniversiteitBrussel,Brussel,Belgium

D. Beghin,B. Bilin, H. Brun, B. Clerbaux, G. De Lentdecker,H. Delannoy, B. Dorney, G. Fasanella,L. Favart, R. Goldouzian, A. Grebenyuk,A.K. Kalsi,T. Lenzi, J. Luetic, E. Starling,C. Vander Velde, P. Vanlaer,

D. Vannerom

UniversitéLibredeBruxelles,Bruxelles,Belgium

T. Cornelis,D. Dobur, A. Fagot,M. Gul, I. Khvastunov2,D. Poyraz, C. Roskas, D. Trocino, M. Tytgat, W. Verbeke,B. Vermassen, M. Vit, N. Zaganidis

GhentUniversity,Ghent,Belgium

H. Bakhshiansohi,O. Bondu, S. Brochet,G. Bruno, C. Caputo, P. David,C. Delaere, M. Delcourt, B. Francois,A. Giammanco, G. Krintiras,V. Lemaitre, A. Magitteri, A. Mertens, M. Musich, K. Piotrzkowski,A. Saggio, M. Vidal Marono, S. Wertz, J. Zobec

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

F.L. Alves,G.A. Alves,L. Brito, G. Correia Silva,C. Hensel, A. Moraes,M.E. Pol, P. Rebello Teles CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato3, E. Coelho, E.M. Da Costa, G.G. Da Silveira4, D. De Jesus Damiao,C. De Oliveira Martins, S. Fonseca De Souza, H. Malbouisson, D. Matos Figueiredo, M. Melo De Almeida,C. Mora Herrera,L. Mundim, H. Nogima,W.L. Prado Da Silva, L.J. Sanchez Rosas, A. Santoro,A. Sznajder, M. Thiel, E.J. Tonelli Manganote3,F. Torres Da Silva De Araujo, A. Vilela Pereira UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahujaa,C.A. Bernardesa, L. Calligarisa,T.R. Fernandez Perez Tomeia,E.M. Gregoresb, P.G. Mercadanteb,S.F. Novaesa,Sandra S. Padulaa, D. Romero Abadb,

a_Universidade_Estadual_Paulista,_São_Paulo,_Brazil b_Universidade_Federal_do_ABC,_São_Paulo,_Brazil

A. Aleksandrov, R. Hadjiiska,P. Iaydjiev, A. Marinov, M. Misheva, M. Rodozov,M. Shopova, G. Sultanov InstituteforNuclearResearchandNuclearEnergy,BulgarianAcademyofSciences,Soﬁa,Bulgaria

A. Dimitrov,L. Litov, B. Pavlov,P. Petkov UniversityofSoﬁa,Soﬁa,Bulgaria

W. Fang5, X. Gao5,L. Yuan BeihangUniversity,Beijing,China

M. Ahmad, J.G. Bian, G.M. Chen,H.S. Chen, M. Chen, Y. Chen, C.H. Jiang, D. Leggat,H. Liao, Z. Liu, F. Romeo,S.M. Shaheen, A. Spiezia,J. Tao, C. Wang, Z. Wang, E. Yazgan, H. Zhang,J. Zhao

InstituteofHighEnergyPhysics,Beijing,China

Y. Ban, G. Chen, J. Li,Q. Li, S. Liu, Y. Mao,S.J. Qian, D. Wang,Z. Xu StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

Y. Wang

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C. Avila,A. Cabrera, C.A. Carrillo Montoya, L.F. Chaparro Sierra, C. Florez, C.F. González Hernández, M.A. Segura Delgado

UniversidaddeLosAndes,Bogota,Colombia

B. Courbon, N. Godinovic, D. Lelas,I. Puljak, T. Sculac

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia Z. Antunovic, M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,D. Ferencek, K. Kadija,B. Mesic, A. Starodumov6, T. Susa InstituteRudjerBoskovic,Zagreb,Croatia

M.W. Ather,A. Attikis, G. Mavromanolakis, J. Mousa,C. Nicolaou, F. Ptochos, P.A. Razis, H. Rykaczewski UniversityofCyprus,Nicosia,Cyprus

M. Finger7, M. Finger Jr.7 CharlesUniversity,Prague,CzechRepublic E. Ayala

EscuelaPolitecnicaNacional,Quito,Ecuador E. Carrera Jarrin

UniversidadSanFranciscodeQuito,Quito,Ecuador

Y. Assran8,9,M.A. Mahmoud10,9, Y. Mohammed10

AcademyofScientiﬁcResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

S. Bhowmik, A. Carvalho Antunes De Oliveira,R.K. Dewanjee, K. Ehataht, M. Kadastik, L. Perrini, M. Raidal, C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola, H. Kirschenmann,J. Pekkanen,M. Voutilainen DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Havukainen, J.K. Heikkilä, T. Järvinen,V. Karimäki, R. Kinnunen, T. Lampén, K. Lassila-Perini,S. Laurila, S. Lehti, T. Lindén,P. Luukka, T. Mäenpää, H. Siikonen,E. Tuominen, J. Tuominiemi

HelsinkiInstituteofPhysics,Helsinki,Finland T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon, F. Couderc,M. Dejardin, D. Denegri, J.L. Faure, F. Ferri, S. Ganjour, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry,C. Leloup,E. Locci, M. Machet, J. Malcles,G. Negro, J. Rander, A. Rosowsky, M.Ö. Sahin,M. Titov

IRFU,CEA,UniversitéParis-Saclay,Gif-sur-Yvette,France

A. Abdulsalam11,C. Amendola, I. Antropov, F. Beaudette, P. Busson, L. Cadamuro, C. Charlot,

R. Granier de Cassagnac, I. Kucher, S. Lisniak,A. Lobanov, J. Martin Blanco, M. Nguyen, C. Ochando, G. Ortona,P. Pigard, R. Salerno,J.B. Sauvan, Y. Sirois, A.G. Stahl Leiton, Y. Yilmaz, A. Zabi,A. Zghiche LaboratoireLeprince-Ringuet,Ecolepolytechnique,CNRS/IN2P3,UniversitéParis-Saclay,Palaiseau,France

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J.-L. Agram12,J. Andrea, D. Bloch,J.-M. Brom, E.C. Chabert,V. Cherepanov, C. Collard, E. Conte12, F. Drouhin12,J.-C. Fontaine12, D. Gelé, U. Goerlach,M. Jansová, P. Juillot, A.-C. Le Bihan, N. Tonon, P. Van Hove

UniversitédeStrasbourg,CNRS,IPHCUMR7178,F-67000Strasbourg,France S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,C. Bernet, G. Boudoul,N. Chanon, R. Chierici,D. Contardo, P. Depasse, H. El Mamouni, L. Finco,S. Gascon, M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde, I.B. Laktineh,H. Lattaud, M. Lethuillier, L. Mirabito,A.L. Pequegnot, S. Perries, A. Popov13, V. Sordini,M. Vander Donckt, S. Viret, S. Zhang UniversitédeLyon,UniversitéClaudeBernardLyon1,CNRS-IN2P3,InstitutdePhysiqueNucléairedeLyon,Villeurbanne,France

T. Toriashvili14

GeorgianTechnicalUniversity,Tbilisi,Georgia Z. Tsamalaidze7

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann,L. Feld, M.K. Kiesel, K. Klein, M. Lipinski,M. Preuten, M.P. Rauch,C. Schomakers, J. Schulz, M. Teroerde,B. Wittmer, V. Zhukov13

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

A. Albert, D. Duchardt, M. Endres,M. Erdmann, S. Erdweg, T. Esch,R. Fischer, S. Ghosh, A. Güth, T. Hebbeker,C. Heidemann, K. Hoepfner, S. Knutzen,L. Mastrolorenzo, M. Merschmeyer,A. Meyer, P. Millet,S. Mukherjee,T. Pook, M. Radziej, H. Reithler,M. Rieger, F. Scheuch, A. Schmidt, D. Teyssier, S. Thüer

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

G. Flügge,O. Hlushchenko, B. Kargoll, T. Kress, A. Künsken, T. Müller,A. Nehrkorn, A. Nowack, C. Pistone, O. Pooth,H. Sert, A. Stahl15

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,T. Arndt, C. Asawatangtrakuldee, I. Babounikau, K. Beernaert,O. Behnke, U. Behrens, A. Bermúdez Martínez, D. Bertsche, A.A. Bin Anuar, K. Borras16,V. Botta, A. Campbell,P. Connor, C. Contreras-Campana, F. Costanza, V. Danilov,A. De Wit, M.M. Defranchis, C. Diez Pardos, D. Domínguez Damiani,G. Eckerlin, T. Eichhorn, A. Elwood, E. Eren, E. Gallo17,A. Geiser,

J.M. Grados Luyando, A. Grohsjean, P. Gunnellini, M. Guthoff,A. Harb, J. Hauk, H. Jung,M. Kasemann, J. Keaveney, C. Kleinwort,J. Knolle,D. Krücker, W. Lange, A. Lelek, T. Lenz,K. Lipka, W. Lohmann18, R. Mankel, I.-A. Melzer-Pellmann,A.B. Meyer, M. Meyer, M. Missiroli, G. Mittag, J. Mnich, S.K. Pﬂitsch, D. Pitzl,A. Raspereza, M. Savitskyi,P. Saxena,P. Schütze, C. Schwanenberger, R. Shevchenko, A. Singh, N. Stefaniuk,H. Tholen, A. Vagnerini, G.P. Van Onsem,R. Walsh, Y. Wen,K. Wichmann, C. Wissing, O. Zenaiev

DeutschesElektronen-Synchrotron,Hamburg,Germany

R. Aggleton,S. Bein, A. Benecke, V. Blobel, M. Centis Vignali, T. Dreyer,E. Garutti, D. Gonzalez, J. Haller, A. Hinzmann, M. Hoffmann,A. Karavdina, R. Klanner, R. Kogler,N. Kovalchuk, S. Kurz, V. Kutzner, J. Lange,D. Marconi,J. Multhaup, M. Niedziela, D. Nowatschin, A. Perieanu, A. Reimers, O. Rieger, C. Scharf,P. Schleper, S. Schumann, J. Schwandt,J. Sonneveld, H. Stadie, G. Steinbrück, F.M. Stober, M. Stöver,D. Troendle, E. Usai, A. Vanhoefer, B. Vormwald

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M. Akbiyik, C. Barth,M. Baselga, S. Baur, E. Butz,R. Caspart, T. Chwalek, F. Colombo, W. De Boer, A. Dierlamm, N. Faltermann,B. Freund, M. Giffels,M.A. Harrendorf,F. Hartmann15,S.M. Heindl, U. Husemann,F. Kassel15, I. Katkov13,S. Kudella, H. Mildner, M.U. Mozer, Th. Müller, M. Plagge, G. Quast, K. Rabbertz,M. Schröder, I. Shvetsov, G. Sieber,H.J. Simonis, R. Ulrich, S. Wayand, M. Weber, T. Weiler, S. Williamson,C. Wöhrmann, R. Wolf

InstitutfürExperimentelleTeilchenphysik,Karlsruhe,Germany

G. Anagnostou, G. Daskalakis,T. Geralis,A. Kyriakis, D. Loukas, G. Paspalaki,I. Topsis-Giotis InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

G. Karathanasis,S. Kesisoglou, A. Panagiotou, N. Saoulidou, E. Tziaferi, K. Vellidis NationalandKapodistrianUniversityofAthens,Athens,Greece

K. Kousouris,I. Papakrivopoulos, Y. Tsipolitis NationalTechnicalUniversityofAthens,Athens,Greece

I. Evangelou, C. Foudas,P. Gianneios, P. Katsoulis, P. Kokkas, S. Mallios,N. Manthos, I. Papadopoulos, E. Paradas, J. Strologas,F.A. Triantis, D. Tsitsonis

UniversityofIoánnina,Ioánnina,Greece

M. Csanad, N. Filipovic,G. Pasztor, O. Surányi,G.I. Veres MTA-ELTELendületCMSParticleandNuclearPhysicsGroup,EötvösLorándUniversity,Budapest,Hungary

G. Bencze,C. Hajdu, D. Horvath19,Á. Hunyadi, F. Sikler,T.Á. Vámi, V. Veszpremi, G. Vesztergombi† WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni, S. Czellar, J. Karancsi21,A. Makovec, J. Molnar,Z. Szillasi InstituteofNuclearResearchATOMKI,Debrecen,Hungary

M. Bartók20,P. Raics, Z.L. Trocsanyi, B. Ujvari InstituteofPhysics,UniversityofDebrecen,Debrecen,Hungary

S. Choudhury, J.R. Komaragiri IndianInstituteofScience(IISc),Bangalore,India

S. Bahinipati22, P. Mal, K. Mandal, A. Nayak23, D.K. Sahoo22, S.K. Swain NationalInstituteofScienceEducationandResearch,HBNI,Bhubaneswar,India

S. Bansal, S.B. Beri,V. Bhatnagar, S. Chauhan,R. Chawla, N. Dhingra, R. Gupta, A. Kaur, A. Kaur, M. Kaur, S. Kaur,R. Kumar, P. Kumari, M. Lohan, A. Mehta,S. Sharma, J.B. Singh, G. Walia

PanjabUniversity,Chandigarh,India

A. Bhardwaj,B.C. Choudhary, R.B. Garg, M. Gola,S. Keshri, Ashok Kumar, S. Malhotra,M. Naimuddin, P. Priyanka, K. Ranjan,Aashaq Shah, R. Sharma

UniversityofDelhi,Delhi,India

R. Bhardwaj24,M. Bharti,R. Bhattacharya, S. Bhattacharya, U. Bhawandeep24,D. Bhowmik, S. Dey, S. Dutt24,S. Dutta, S. Ghosh,K. Mondal, S. Nandan, A. Purohit, P.K. Rout, A. Roy,S. Roy Chowdhury, S. Sarkar,M. Sharan, B. Singh, S. Thakur24

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P.K. Behera

IndianInstituteofTechnologyMadras,Madras,India

R. Chudasama, D. Dutta, V. Jha, V. Kumar, P.K. Netrakanti, L.M. Pant, P. Shukla BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz,M.A. Bhat, S. Dugad, B. Mahakud, S. Mitra, G.B. Mohanty, R. Ravindra Kumar Verma,N. Sur, B. Sutar

TataInstituteofFundamentalResearch-A,Mumbai,India

S. Banerjee, S. Bhattacharya, S. Chatterjee,P. Das, M. Guchait,Sa. Jain, S. Kumar, M. Maity25, G. Majumder,K. Mazumdar, N. Sahoo, T. Sarkar25

TataInstituteofFundamentalResearch-B,Mumbai,India

S. Chauhan,S. Dube, V. Hegde, A. Kapoor, K. Kothekar, S. Pandey, A. Rane, S. Sharma IndianInstituteofScienceEducationandResearch(IISER),Pune,India

S. Chenarani26, E. Eskandari Tadavani,S.M. Etesami26, M. Khakzad, M. Mohammadi Najafabadi, M. Naseri, F. Rezaei Hosseinabadi, B. Safarzadeh27, M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b, C. Calabriaa,b, A. Colaleoa, D. Creanzaa,c,L. Cristellaa,b, N. De Filippisa,c,

M. De Palmaa,b, A. Di Florioa,b, F. Erricoa,b,L. Fiorea,A. Gelmia,b, G. Iasellia,c, S. Lezkia,b,G. Maggia,c, M. Maggia,G. Minielloa,b,S. Mya,b,S. Nuzzoa,b, A. Pompilia,b, G. Pugliesea,c,R. Radognaa, A. Ranieria, G. Selvaggia,b, A. Sharmaa, L. Silvestrisa,15,R. Vendittia,P. Verwilligena, G. Zitoa

a_INFN_Sezione_di_Bari,_Bari,_Italy b_Università_di_Bari,_Bari,_Italy c_Politecnico_di_Bari,_Bari,_Italy

G. Abbiendia,C. Battilanaa,b,D. Bonacorsia,b, L. Borgonovia,b,S. Braibant-Giacomellia,b, R. Campaninia,b,A. Castroa,b,F.R. Cavalloa, S.S. Chhibraa,b, G. Codispotia,b, M. Cuﬃania,b,

G.M. Dallavallea,F. Fabbria,A. Fanfania,b,P. Giacomellia, L. Guiduccia,b,S. Marcellinia,G. Masettia, F.L. Navarriaa,b,A. Perrottaa,A.M. Rossia,b,T. Rovellia,b, G.P. Sirolia,b, N. Tosia

a_INFN_Sezione_di_Bologna,_Bologna,_Italy b_Università_di_Bologna,_Bologna,_Italy

S. Albergoa,b, A. Di Mattiaa,R. Potenzaa,b,A. Tricomia,b,C. Tuvea,b

a_INFN_Sezione_di_Catania,_Catania,_Italy b_Università_di_Catania,_Catania,_Italy

G. Barbaglia,K. Chatterjeea,b,V. Ciullia,b,C. Civininia,R. D’Alessandroa,b, E. Focardia,b, G. Latino, P. Lenzia,b, M. Meschinia, S. Paolettia,L. Russoa,28, G. Sguazzonia,D. Stroma, L. Viliania

a_INFN_Sezione_di_Firenze,_Firenze,_Italy b_Università_di_Firenze,_Firenze,_Italy

L. Benussi,S. Bianco, F. Fabbri, D. Piccolo,F. Primavera15 INFNLaboratoriNazionalidiFrascati,Frascati,Italy

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F. Ferroa, F. Raveraa,b,E. Robuttia, S. Tosia,b

a_INFN_Sezione_di_Genova,_Genova,_Italy b_Università_di_Genova,_Genova,_Italy

A. Benagliaa, A. Beschib, L. Brianzaa,b, F. Brivioa,b, V. Cirioloa,b,15,M.E. Dinardoa,b,S. Fiorendia,b, S. Gennaia, A. Ghezzia,b_,_{P. Govoni}a,b_, _{M. Malberti}a,b_,_{S. Malvezzi}a_,_{R.A. Manzoni}a,b_, _{D. Menasce}a_,

L. Moronia,M. Paganonia,b, D. Pedrinia,S. Pigazzinia,b,29,S. Ragazzia,b,T. Tabarelli de Fatisa,b

a_INFN_Sezione_di_{Milano-Bicocca,}_Milano,_Italy b_Università_di_{Milano-Bicocca,}_Milano,_Italy

S. Buontempoa, N. Cavalloa,c, A. Di Crescenzoa,b,S. Di Guidaa,d,15,F. Fabozzia,c, F. Fiengaa,b, G. Galatia,b,A.O.M. Iorioa,b, W.A. Khana, L. Listaa, S. Meolaa,d,15,P. Paoluccia,15, C. Sciaccaa,b, E. Voevodinaa,b

a_INFN_Sezione_di_Napoli,_Napoli,_Italy b_Università_di_Napoli_‘Federico_II’,_Napoli,_Italy c_Università_della_Basilicata,_Potenza,_Italy d_Università_G._Marconi,_Roma,_Italy

P. Azzia,N. Bacchettaa,L. Benatoa,b, D. Biselloa,b, A. Bolettia,b, A. Bragagnolo,R. Carlina,b,P. Checchiaa, M. Dall’Ossoa,b,P. De Castro Manzanoa, T. Dorigoa,U. Dossellia,F. Gasparinia,b,U. Gasparinia,b,

A. Gozzelinoa, S. Lacapraraa,P. Lujan, M. Margonia,b, A.T. Meneguzzoa,b,P. Ronchesea,b,R. Rossina,b, F. Simonettoa,b,A. Tiko, E. Torassaa, M. Zanettia,b,P. Zottoa,b,G. Zumerlea,b

a_INFN_Sezione_di_Padova,_Padova,_Italy b_Università_di_Padova,_Padova,_Italy c_Università_di_Trento,_Trento,_Italy

A. Braghieria,A. Magnania,P. Montagnaa,b, S.P. Rattia,b,V. Rea, M. Ressegottia,b, C. Riccardia,b, P. Salvinia, I. Vaia,b, P. Vituloa,b

a_INFN_Sezione_di_Pavia,_Pavia,_Italy b_Università_di_Pavia,_Pavia,_Italy

L. Alunni Solestizia,b,M. Biasinia,b, G.M. Bileia,C. Cecchia,b, D. Ciangottinia,b,L. Fanòa,b, P. Laricciaa,b, E. Manonia, G. Mantovania,b, V. Mariania,b,M. Menichellia,A. Rossia,b,A. Santocchiaa,b, D. Spigaa

a_INFN_Sezione_di_Perugia,_Perugia,_Italy b_Università_di_Perugia,_Perugia,_Italy

K. Androsova,P. Azzurria,G. Bagliesia,L. Bianchinia,T. Boccalia,L. Borrello, R. Castaldia, M.A. Cioccia,b, R. Dell’Orsoa,G. Fedia, L. Gianninia,c,A. Giassia, M.T. Grippoa,F. Ligabuea,c, T. Lomtadzea, E. Mancaa,c, G. Mandorlia,c, A. Messineoa,b, F. Pallaa,A. Rizzia,b, P. Spagnoloa, R. Tenchinia,G. Tonellia,b,

A. Venturia, P.G. Verdinia

a_INFN_Sezione_di_Pisa,_Pisa,_Italy b_Università_di_Pisa,_Pisa,_Italy

c_Scuola_Normale_Superiore_di_Pisa,_Pisa,_Italy

L. Baronea,b,F. Cavallaria, M. Cipriania,b,N. Dacia, D. Del Rea,b,E. Di Marcoa,b,M. Diemoza, S. Gellia,b, E. Longoa,b, B. Marzocchia,b,P. Meridiania, G. Organtinia,b,F. Pandolﬁa, R. Paramattia,b, F. Preiatoa,b, S. Rahatloua,b,C. Rovellia,F. Santanastasioa,b

a_INFN_Sezione_di_Roma,_Rome,_Italy b_Sapienza_Università_di_Roma,_Rome,_Italy

N. Amapanea,b, R. Arcidiaconoa,c,S. Argiroa,b,M. Arneodoa,c,N. Bartosika,R. Bellana,b, C. Biinoa, N. Cartigliaa, F. Cennaa,b,M. Costaa,b, R. Covarellia,b,A. Deganoa,b,N. Demariaa, B. Kiania,b,

C. Mariottia, S. Masellia, E. Migliorea,b,V. Monacoa,b,E. Monteila,b,M. Montenoa, M.M. Obertinoa,b, L. Pachera,b, N. Pastronea,M. Pelliccionia,G.L. Pinna Angionia,b, A. Romeroa,b,M. Ruspaa,c, R. Sacchia,b, K. Shchelinaa,b, V. Solaa, A. Solanoa,b,A. Staianoa

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a_INFN_Sezione_di_Torino,_Torino,_Italy b_Università_di_Torino,_Torino,_Italy

c_Università_del_Piemonte_Orientale,_Novara,_Italy

S. Belfortea,V. Candelisea,b, M. Casarsaa,F. Cossuttia,G. Della Riccaa,b,F. Vazzolera,b, A. Zanettia

a_INFN_Sezione_di_Trieste,_Trieste,_Italy b_Università_di_Trieste,_Trieste,_Italy

D.H. Kim,G.N. Kim, M.S. Kim, J. Lee,S. Lee, S.W. Lee, C.S. Moon, Y.D. Oh, S. Sekmen,Y.C. Yang KyungpookNationalUniversity,RepublicofKorea

H. Kim,D.H. Moon,G. Oh

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea J. Goh,T.J. Kim

HanyangUniversity,Seoul,RepublicofKorea

S. Cho,S. Choi, Y. Go, D. Gyun,S. Ha,B. Hong, Y. Jo,K. Lee, K.S. Lee, S. Lee, J. Lim, S.K. Park,Y. Roh KoreaUniversity,Seoul,RepublicofKorea

H. Kim

SejongUniversity,Seoul,RepublicofKorea

J. Almond,J. Kim, J.S. Kim, H. Lee,K. Lee, K. Nam,S.B. Oh, B.C. Radburn-Smith, S.h. Seo, U.K. Yang, H.D. Yoo,G.B. Yu

SeoulNationalUniversity,Seoul,RepublicofKorea

H. Kim,J.H. Kim, J.S.H. Lee, I.C. Park UniversityofSeoul,Seoul,RepublicofKorea

Y. Choi,C. Hwang, J. Lee,I. Yu SungkyunkwanUniversity,Suwon,RepublicofKorea

V. Dudenas, A. Juodagalvis,J. Vaitkus VilniusUniversity,Vilnius,Lithuania

I. Ahmed,Z.A. Ibrahim, M.A.B. Md Ali30,F. Mohamad Idris31,W.A.T. Wan Abdullah, M.N. Yusli, Z. Zolkapli

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

M.C. Duran-Osuna, H. Castilla-Valdez,E. De La Cruz-Burelo, G. Ramirez-Sanchez, I. Heredia-De La Cruz32, R.I. Rabadan-Trejo,R. Lopez-Fernandez, J. Mejia Guisao, R. Reyes-Almanza,A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

S. Carrillo Moreno, C. Oropeza Barrera, F. Vazquez Valencia UniversidadIberoamericana,MexicoCity,Mexico

J. Eysermans,I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada BenemeritaUniversidadAutonomadePuebla,Puebla,Mexico

A. Morelos Pineda

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D. Krofcheck

UniversityofAuckland,Auckland,NewZealand S. Bheesette,P.H. Butler UniversityofCanterbury,Christchurch,NewZealand

A. Ahmad, M. Ahmad, M.I. Asghar,Q. Hassan, H.R. Hoorani, A. Saddique,M.A. Shah, M. Shoaib,M. Waqas NationalCentreforPhysics,Quaid-I-AzamUniversity,Islamabad,Pakistan

H. Bialkowska, M. Bluj,B. Boimska, T. Frueboes,M. Górski, M. Kazana, K. Nawrocki, M. Szleper, P. Traczyk,P. Zalewski

NationalCentreforNuclearResearch,Swierk,Poland

K. Bunkowski,A. Byszuk33, K. Doroba,A. Kalinowski, M. Konecki,J. Krolikowski, M. Misiura, M. Olszewski, A. Pyskir,M. Walczak

InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland

P. Bargassa,C. Beirão Da Cruz E Silva, A. Di Francesco, P. Faccioli, B. Galinhas, M. Gallinaro,J. Hollar, N. Leonardo,L. Lloret Iglesias,M.V. Nemallapudi, J. Seixas,G. Strong, O. Toldaiev, D. Vadruccio,J. Varela LaboratóriodeInstrumentaçãoeFísicaExperimentaldePartículas,Lisboa,Portugal

A. Baginyan, P. Bunin,I. Golutvin, V. Karjavin, V. Korenkov, G. Kozlov, A. Lanev,A. Malakhov,

V. Matveev34,35, V.V. Mitsyn,P. Moisenz, V. Palichik,V. Perelygin, S. Shmatov, V. Smirnov,V. Troﬁmov, B.S. Yuldashev36, A. Zarubin,V. Zhiltsov

JointInstituteforNuclearResearch,Dubna,Russia

V. Golovtsov, Y. Ivanov, V. Kim37,E. Kuznetsova38, P. Levchenko,V. Murzin, V. Oreshkin,I. Smirnov, D. Sosnov,V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev

PetersburgNuclearPhysicsInstitute,Gatchina(St.Petersburg),Russia

Yu. Andreev,A. Dermenev, S. Gninenko, N. Golubev, A. Karneyeu,M. Kirsanov, N. Krasnikov, A. Pashenkov,D. Tlisov, A. Toropin

InstituteforNuclearResearch,Moscow,Russia

V. Epshteyn, V. Gavrilov, N. Lychkovskaya,V. Popov, I. Pozdnyakov, G. Safronov, A. Spiridonov, A. Stepennov, V. Stolin, M. Toms,E. Vlasov, A. Zhokin

InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia T. Aushev, A. Bylinkin35

MoscowInstituteofPhysicsandTechnology,Moscow,Russia

R. Chistov39,M. Danilov39,P. Parygin, D. Philippov,S. Polikarpov, E. Tarkovskii NationalResearchNuclearUniversity‘MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

V. Andreev,M. Azarkin35, I. Dremin35,M. Kirakosyan35, S.V. Rusakov,A. Terkulov P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Baskakov,A. Belyaev, E. Boos,A. Demiyanov, A. Ershov, A. Gribushin,O. Kodolova, V. Korotkikh, I. Lokhtin,I. Miagkov, S. Obraztsov, S. Petrushanko,V. Savrin, A. Snigirev, I. Vardanyan