ϒ suppression at forward rapidity in Pb–Pb collisions at sNN=5.02TeV

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Articlehistory:

Received23May2018

Receivedinrevisedform28October2018 Accepted12November2018

Availableonline29December2018 Editor: M.Doser

Inclusive ϒ(1S) and ϒ(2S) production have been measuredin Pb–Pbcollisions at the centre-of-mass energypernucleon–nucleon pair√sNN=5.02 TeV,usingthe ALICEdetector atthe CERNLHC.The ϒ mesons are reconstructed in the centre-of-mass rapidity interval 2.5<y<4 and in the transverse-momentum range pT<15 GeV/c,via their decays to muon pairs. In thisLetter, we present results onthe inclusiveϒ(1S) nuclearmodificationfactor RAA as afunctionofcollisioncentrality, transverse momentumandrapidity.Theϒ(1S) andϒ(2S) RAA,integratedoverthecentralityrange0–90%,are0.37± 0.02(stat)±0.03(syst)and0.10±0.04(stat)±0.02(syst),respectively,leadingtoaratioRϒ(_AA2S)/Rϒ(_AA1S)of 0.28±0.12(stat)±0.06(syst).Theobservedϒ(1S) suppressionincreaseswiththecentralityofthecollision andnosignificantvariationisobservedasafunctionoftransversemomentumandrapidity.

©2018PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Adetailedstudyofthepropertiesof theQuark–Gluon Plasma (QGP) [1] is the main goal of heavy-ion experiments at ultra-relativisticenergies [2–6].Quarkonia,i.e. boundstatesofcharmor bottomquark–antiquarkpairs,aresensitiveprobesofcolor decon-finement,duetotheQuantum-ChromoDynamicsDebyescreening mechanism [7–9] leading to quarkonium suppression. Moreover, thevariousquarkoniumstateshavedifferentbindingenergiesand thereforedifferentdissociationtemperatures ina QGP, leading to sequentialsuppression[7,10]. Theoryestimates[11] indicate that bottomoniumformationmayoccurbeforeQGPthermalization[12] becauseofthelargebottomquark mass.Inthissituation,a quan-titativedescriptionofthe influenceofthemedium on thebound states becomes challenging. While the dissociation temperatures varysignificantly between differentmodels [8,9], it is commonly acceptedthatthewidthsofthespectralfunctionsofthe bottomo-nium statesincrease compared to the widthsin vacuum, dueto the high temperature of the surrounding medium [13]. Finally, taking into account that feed-down processes from higher-mass resonances(around40%forthe

ϒ

(1S) and30% forthe

ϒ

(2S) [9]) arenot negligible,the evaluationof themedium temperaturevia bottomoniummeasurementsremainsacomplexendeavour.

Thefirst studies ofquarkonium productionin heavy-ion colli-sions were devoted to charmonium states, anda suppression of theiryieldswas observedattheSPS [14–16],atRHIC [17,18] and

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

attheLHC [19–22]. TheweakerJ/

ψ

suppression observedatLHC energies, where the centre-of-mass energy per nucleon–nucleon pair (

√

sNN) is one order of magnitude larger than at RHIC, can

be explained by means of a competitive (re)generation mecha-nism, which occurs during the deconfined phase and/or at the hadronization stage [23–26]. Thisproduction mechanismstrongly dependson the(re)combination probability of deconfinedquarks presentinthemediumandthusontheinitialnumberofproduced cc pairs. Theeffect hasbeenfound tobe more importantatlow

pT andinthemostcentralcollisions[22,20,27].

The high-energy collisions delivered by the LHC allow for a detailed studyof bottomonium states. For bottomonium produc-tion, perturbative calculations of production rates in elementary nucleon–nucleoncollisionsaremorereliablethanforcharmonium yieldsduetothehighermassofthebottomquarkwithrespectto charm.Sincethe numberofproducedbb pairsincentralheavy-ion collisions amountto afewpairsper eventattheLHC,the proba-bilityfor(re)generationofbottomoniathrough(re)combination is muchsmallerthaninthecaseofcharmonia.

The

ϒ

(1S) nuclearmodificationfactor RAA isquantified asthe

ratioof the

ϒ

(1S) yieldinnucleus–nucleus collisions tothe pro-ductioncrosssection measuredinpp collisionsscaled bythe nu-clearoverlapfunction



TAA



.ThelatterisobtainedviatheGlauber

model [28,29]. Astrong suppression ofthe

ϒ

(1S) state inPb–Pb collisions has been observed at

√

sNN

=

2

.

76 TeV by ALICE [30]

andCMS[31,32] intherapidity ranges2

.

5

<

y

<

4 and

|

y

|

<

2

.

4, respectively. The suppression increaseswith the centralityof the collision, reaching about60% and 80% forthe mostcentral colli-sionsatmid [32] andforwardrapidity [30],respectively.Moreover,

https://doi.org/10.1016/j.physletb.2018.11.067

the

ϒ

(2S) suppressionreachesabout 90%and for

ϒ

(3S) dataare compatiblewithacompletesuppression[32].Asafunctionof pT

the

ϒ

(1S) RAA,measured forpT

<

20 GeV/c byCMS [32],is

com-patiblewithaconstantvalue.Whenconsideringthe y-dependence

resultingfromthecomparisonofALICEandCMSresults,thereis an indication for a stronger suppression at forward y. Transport models [26,33] aswell asan anisotropic hydro-dynamical model [34] fairlyreproducetheexperimental observationsofCMS,while theytendtooverestimatetheRAAvaluesmeasuredbyALICE.

The bottomoniumsuppression due tothe QGPshould be dis-entangledfromthesuppressionduetoColdNuclearMatter(CNM) effects, such as the nuclear modification of the parton distribu-tionfunctionsduetoshadowing[35,36],aswellaspartonenergy loss[37].Theseeffectsonthebottomoniumproductionwere stud-iedinp–PbcollisionsbyALICE[38] andLHCb[39],who reported for the

ϒ

(1S) a nuclear modification factor slightly lower than unityatforward rapidityandcompatiblewithunity atbackward rapidity, although with significant uncertainties. Recently, ATLAS resultsindicateasignificantsuppressionofthe

ϒ

(1S) for pT

<

40

GeV/c aroundmid-rapidity [40]. Additional measurements at for-ward/backwardrapiditywithhigherstatistics,areneededtofully constrain the models and perform a meaningful extrapolation of CNMeffectstoPb–Pbcollisions.

In this Letter we present the first results on the

ϒ

(1S) and

ϒ

(2S) RAA measured by the ALICE Collaboration in Pb–Pb

colli-sions at

√

sNN

=

5

.

02 TeV. The pp reference cross sections used

inthe RAA calculationshavebeendetermined byaninterpolation

procedurebasedonvariousALICE[41,42] andLHCb[43,44] results atdifferentenergies.Thenuclearmodificationfactorforthe

ϒ

(1S) ispresentedasafunctionofthecentralityofthecollisionandalso differentially in pT andrapidity. Forthe

ϒ

(2S), an RAA value

in-tegratedover thecentralityofthe collisionisquoted. Finally,the resultsarecomparedtotheoreticalcalculations.

2. Experimentalapparatusanddatasample

An extensivedescriptionof theALICEapparatus canbe found in[45,46].TheanalysispresentedinthisLetterisbasedonmuons detected atforwardrapidity (2

.

5

<

y

<

4)1 withthemuon spec-trometer [47].Thedetectorsrelevantfor

ϒ

measurementsinPb–Pb collisionsaredescribedbelow.

TheSiliconPixelDetector,correspondingtothetwo innermost layers ofthe Inner TrackingSystem [48], is usedforthe primary vertexdetermination.Theinnerandouterlayercoverthe pseudo-rapidityranges

|

η

|

<

2 and

|

η

|

<

1

.

4,respectively.

TheV0scintillatorhodoscopes [49] providethecentrality esti-mate.They are made oftwo arraysof scintillatorsplaced in the pseudo-rapidity ranges 2

.

8

<

η

<

5

.

1 and

−

3

.

7

<

η

<

−

1

.

7. The logical AND of the signals from the two hodoscopes constitutes theMinimumBias(MB)trigger.TheMBtriggerisfullyefficientfor thestudied0–90%mostcentralcollisions.

TheZeroDegreeCalorimeters (ZDC)areinstalled at

±

112

.

5 m fromthe nominalinteraction point along the beam line. Eachof thetwoZDCsiscomposedoftwosamplingcalorimetersdesigned for detecting spectator protons, neutrons andnuclear fragments. Theevaluationofthesignalamplitude oftheZDCsallows forthe rejectionofeventscorrespondingtoanelectromagneticinteraction ofthecollidingPbnuclei[50].

Themuonspectrometercovers thepseudorapidityrange

−

4

<

η

<

−

2

.

5.Itiscomposedofafrontabsorber, whichfiltersmuons

1 _{IntheALICEreferenceframe,themuonspectrometercoversanegativeηrange}

andconsequentlyanegativey range.Wehavechosentopresentourresultswitha positivey notation.

upstream ofthemuon tracker,consistingoffivetracking stations with two planes of cathode-pad chambers each, andof a dipole magnetprovidinga 3 T

·

mintegratedmagneticfield.Downstream of the tracking system, a 1.2 m thick iron wall stops efficiently the punch-through hadrons. The muon trigger systemis located downstream of the iron wall and consists of two stations, each one equippedwithtwoplanesofResistive PlateChambers (RPC), withanefficiencyhigherthan 95% [51].Themuon-triggersystem isabletodeliversingleanddimuontriggersselectingmuonswith

pT largerthana programmablethreshold,viaan algorithmbased

ontheRPCspatialinformation [52].Throughoutitsentirelength,a conicalabsorbershieldsthemuonspectrometeragainstsecondary particles produced by the interaction of primary particles in the beampipe.

The trigger condition used for data taking is a dimuon-MinimumBias(

μμ

-MB)triggerformedby thelogicalANDofthe MBtriggerandanunlike-signdimuontriggerwitha pT threshold

of1 GeV/c foreachofthetwomuons.

ThecentralityestimationisperformedusingaGlauberfittothe sumofthesignalamplitudesoftheV0scintillators [53–55]. Cen-tralityrangesaregivenaspercentagesofthetotalhadronicPb–Pb cross section.In additionto thecentrality,the Glauber model al-lows an estimate of the average number of participantnucleons



Npart



,of the averagenumber ofbinary collisions



Ncoll



andof

thenuclearoverlapfunction



TAA



,foreachcentralityinterval[56].

In the present analysis, the data sample corresponds to an inte-gratedluminosity Lint

≈

225 μb−1 inthecentralityinterval0–90%

that hasbeendividedintofourcentralityclasses:0–10%,10–30%, 30–50%and50–90%.

3. Dataanalysis

The evaluationof RAA is performedthroughthe following

ex-pression: RAA

=

Nϒ BRϒ→μ+μ−· (A×

ε

)ϒ→μ+μ−·Nμμ-MB·Fnorm·

σ

ppϒ· TAA , (1)

where Nϒ _{is the numberof detected resonance decays to muon}

pairs, while BRϒ→μ+_μ−

= (

2

.

48

±

0

.

05

)

% and

(

1

.

93

±

0

.

17

)

% are the branching ratios for the dimuon decay of

ϒ

(1S) and

ϒ

(2S), respectively [57].The

(

A

×

ε

)

ϒ→μ+μ− factoristheproductof

ac-ceptanceanddetectionefficiencyforthe

ϒ

stateunderstudy.The normalization factor Nμμ-MB

·

Fnorm is the product of the

num-ber of analyzed

μμ

-MB events and the inverse of the proba-bility to obtain an unlike-sign dimuon trigger in a MB-triggered event [22].Adatasetof1

.

5

·

109 minimumbiasequivalentevents,

Nμμ-MB

·

Fnorm,hasbeenusedforbottomoniummeasurements.

Fi-nally,

σ

ϒ

pp is the referencepp cross section and



TAA



represents

thenuclearoverlapfunction [55].

Thesignalyieldsareevaluatedbyperformingfitstothe

μ

+

μ

−

invariant massdistributions.Inordertoimprovethepurityofthe dimuonsampleasetofselectioncriteria [30] hasbeenappliedon the muon tracks, includingthe requestof the matchingbetween the tracks reconstructed in the trigger and tracking detectors of themuonspectrometerandacutonthetracktransverse momen-tum(pT

>

2 GeV/c).Thelattercuthasasmalleffect(

∼

2%)onthe

number of detected resonances. The raw

ϒ

yields are extracted using thesumof threeextended Crystal Ball(CB)functions [58], one foreach of

ϒ

(1S),

ϒ

(2S) and

ϒ

(3S). The extended CB func-tion consistsof a Gaussian corewith non-Gaussian tails onboth sidestotakeintoaccounttheradiativecontributionsofthe

ϒ

pro-duction andtheabsorber effects ofmuon energylossin thelow masstail,whereas thehighmasstailisattributedtothemultiple

Fig. 1. Redandmagentasolidlinescorrespondtoϒ(1S) andϒ(2S) signalfunctions,respectively.Thecontributionfromϒ(3S) yieldiscompatiblewithzero.Dottedbluelines representthebackground(left)andresidualbackground(right),respectively.Thesumofthevariousfunctionsisalsoshownasasolidblueline.

Coulombscatteringinthefrontabsorberandthemomentum reso-lutionofthetrackingchambers.Thebackgroundisfittedwiththe sumoftwo exponentialfunctions(see left panel ofFig.1). Since the signal-to-background (S/B)ratio is low in the tail regions of theextendedCBfunctions, thetailparameters arefixedtovalues obtainedfrom the Monte Carlo(MC) simulation. The mass posi-tionand thewidth parameters of the

ϒ

(1S) are left free forthe integratedspectrum(i.e. centralityclass0–90%,pT

<

15 GeV/c and

2

.

5

<

y

<

4). Whereas for the signal extraction asa function of centrality,themasspositionandwidth(160

±

15 MeV/c2)ofthe

ϒ

(1S) arefixedto thevaluesobtainedinthefittothe centrality-integrated(0–90%)massspectrum.Finally,forstudiesasafunction of pT and y, the mass position and the width obtained for the

centrality-integratedmass spectrum are scaled accordingto their evolution observedin the MC. Due to the poorS/B ratio forthe highermassstates,thevaluesofthemassofthe

ϒ

(2S) and

ϒ

(3S) arefixed to thePDG massdifferenceswithrespect tothe

ϒ

(1S), and the ratio of

ϒ

(2S) (

ϒ

(3S)) to

ϒ

(1S) widths is fixed to val-ues fromthe MC simulation, i.e. 1.03 (1.06). In the fit shownin Fig.1onlysignalscorresponding tothe

ϒ

(1S) and

ϒ

(2S) are vis-ible,sincethe

ϒ

(3S) contribution iscompatiblewithzero events. Alternatively, the combinatorial background is modeled with the event-mixingmethod.Inthisapproach,aninvariant massdimuon spectrum is constructed by pairing muonsfrom different events with similar multiplicities as described in [22]. The combinato-rialbackgroundisthensubtractedfromtherawdimuonspectrum (rightpanel ofFig. 1)andtheresultingdistributionisfittedwith thesumofthreeextended CBandanexponential functionto ac-countfortheresidualbackground.Finally,thenumberofdetected

ϒ

resonances, Nϒ_{,is obtained as the average [58] of the fitting}

methodsdescribedabove(andalsobelowinthediscussionon sig-nalsystematics),leadingtoNϒ(1S)

₌

₁₁₂₆

_±

_53(stat)

_±

_{47(syst) and}

Nϒ(2S)

₌

₇₇

_±

_33(stat)

_±

_17(syst).

Themeasured

ϒ

yields, Nϒ_{,arecorrected forthe detector}

ac-ceptanceandefficiencyusingMCsimulations.Sincetheoccupancy ofthedetectorvarieswiththecentralityofthecollisions,the gen-erated

ϒ

decaysareembeddedintorealMBeventstosimulatethe variousparticlemultiplicityscenariosasindata.The pTandy

dis-tributionsofthegenerated

ϒ

areobtainedfromexistingpp mea-surements [59–61] using the interpolation procedure described in [62]. The EKS98 nuclear shadowing parameterization [35] is used to includean estimate of CNM effects. Since available data favora small ornull polarization for

ϒ

(1S) [63–66], an unpolar-izedproductionisassumed. Thevariations oftheperformance of

thetrackingandtriggeringsystemsthroughoutthedata-taking pe-riodaswellastheresidualmisalignmentofthetrackingchambers aretakenintoaccountinthesimulation.The A

×

ε

values,forthe range pT

<

15 GeV/c, 2

.

5

<

y

<

4 and the0–90% centralityclass

are0

.

263 and0

.

264 forthe

ϒ

(1S) and

ϒ

(2S),respectively,witha negligible statisticaluncertainty. A decrease of 2% is observed in

A

×

ε

forthe0–10%centralcollisionswithrespecttothe50–90% sample dueto the higher occupancy in the most central events. The A

×

ε

ishigherby20%in3

<

y

<

3

.

5 comparedtothevalues at2

.

5

<

y

<

3 and3

.

5

<

y

<

4 mainlyduetothegeometric accep-tanceofthedetector,whereasithasnovariationasafunctionof

pT.ThesystematicuncertaintyonA

×

ε

isdiscussedbelow.

The systematic uncertainty on the signal extraction is evalu-atedusingvarious functionsformodellingthebackgroundshape, as well as adopting two fitting ranges, i.e. (7–14) GeV/c2 and (7.5–14.5)GeV/c2_{.Thetailparametersofthesignalfunctionshave}

been varied using estimates provided by two MC particle trans-port models:GEANT4 [67] andGEANT3 [68].Inthecentrality, pT

or y differential studies, the mass position and width are also varied by amounts,whichcorrespond totheuncertainties on the masspositionandthewidthreturnedbythefittothe centrality-integratedinvariantmassspectrum. Theratioof

ϒ

(2S) (

ϒ

(3S))to

ϒ

(1S) widthsisvariedfrom1(1)to1.06(1.12).ThevaluesofNϒ

andtheirstatisticaluncertaintiesareobtainedbytakingthe aver-ageof Nϒ _{andofthecorresponding statisticaluncertainties from}

the variousfits. Thisprocedure isapplied to bothfits ofthe raw and combinatorial-background subtracted spectra. The systematic uncertainties areestimatedastherootmeansquare ofthe distri-bution of Nϒ _{obtained from the various fits. The effect induced}

by the pT

>

2 GeV/c cutonsingle muonsonthe A

×

ε

-corrected

ϒ

yields was estimatedby varyingthatcut by

±

0.2GeV/c inthe MC.A

±

2%maximumvariationon Nϒ

_/(

_A

_×

_ε

₎

_{wasobservedand}

includedinthesystematicuncertainties.

Various sources contribute to the systematic uncertainties of

A

×

ε

,suchasthe pT and y shapesoftheinput distributionsfor

theMCsimulations,thetriggerefficiency,thetrackreconstruction efficiencyandfinallythematchingefficiencybetweentracksinthe muon tracking and triggering chambers. Various sets of simula-tions areproducedwithdifferent

ϒ

input pT and y distributions,

obtainedfromempiricalparameterizationsand/orextrapolationsof availabledatasetsatdifferentenergies.Themaximumrelative dif-ferenceof A

×

ε

forthevariousshapesistakenasthesystematic uncertaintyduetotheinputMC.Inordertocalculatethe system-aticuncertaintyontriggerefficiency,thetriggerresponsefunction

Table 1

SummaryofthesystematicuncertaintiesfortheRAAcalculation.TypeI(II)referstocorrelated(uncorrelated)systematicuncertainties.

Sources ϒ(1S) ϒ(2S)

Centrality y pT Integrated Integrated

Signal extraction 4.3–6.1%(II) 4.2–6.8%(II) 5.2–8.7%(II) 4.1% 21.7%

Muon pTcut 0.3–2.4%(II) 0.1–1.2%(II) 0.1–2.4%(II) 0.7% 0.7%

Input MC 0.9%(I) 0.6–2.6%(II) 1–1.4%(II) 0.9% 0.9%

Tracker efficiency 3%(I) and 0–1%(II) 1%(I) and 3%(II) 1%(I) and 3%(II) 3% 3%

Trigger efficiency 3%(I) 1.4–3.7%(II) 0.4–2.6%(II) 3% 3%

Matching efficiency 1%(I) 1%(II) 1%(II) 1% 1%

Centrality 0.2–2.4%(II) – – – –

Fnorm 0.5%(I) 0.5%(I) 0.5%(I) 0.5% 0.5%

TAA 3.1–5.3%(II) 3.2%(I) 3.2%(I) 3.2% 3.2%

BRϒ→μ+μ−·σϒpp 6.3%(I) 6.6–11.3%(II) 5.5–11.5%(II) 6.3% 7.5%

for single muons is evaluated using eitherMC or data. The two response functions are then separately applied to simulations of an

ϒ

sample and the difference obtained for the

ϒ

reconstruc-tion efficiencyis taken assystematic uncertainty. The systematic uncertainty on the tracking efficiency is obtained starting from an evaluation of the single muon tracking efficiency in MC and data.Thisevaluationisperformedviaaprocedure,detailedin[22], basedontheredundancyofthetrackingchamberinformation.The dimuontrackingefficiencyisthenobtainedbycombiningthe sin-gle muon efficiencies and the systematicuncertainty is taken as thedifferenceofthevaluesobtainedwiththeprocedurebasedon MCanddata.Themuon tracksfordataanalysisarechosenbased on a selection on the

χ

2 _{ofthe matching betweena track}

seg-mentinthetriggersystemwithatrackinthetrackingchambers. The matching systematics are obtainedby varying the

χ

2

selec-tioncut indata andMC andcomparingtheeffects onthe muon reconstructionefficiency [22].

The systematic uncertainty on the centrality measurement is evaluated by varying the V0 signal amplitude by

±

0

.

5% corre-spondingto90%ofthehadroniccrosssectioninPb–Pbcollisions, usedasanchorpointtodefine thecentralityclasses.The system-atic uncertainty on the evaluationof

σ

ϒ

pp is detailedin the next

section.Finally,thesystematicuncertaintyevaluationofFnormand



TAA



are described in [22] and [53], respectively. The different

systematicuncertaintysourcesonthe RAAcalculationare

summa-rizedinTable1.Iftheabovementionedsystematicuncertaintyis correlatedasa functionofcentrality, pT or y,itisquotedas

cor-related(type I) systematic uncertainty, otherwise it istreated as uncorrelated(typeII).

4. Proton–protonreferencecrosssections

Theppreferencecrosssectionfor

ϒ

(1S) and

ϒ

(2S) production arecomputedbymeansofaninterpolationprocedureasdescribed for

ϒ

(1S) in [69].Theenergyinterpolationforthe

ϒ

crosssection, asa function of rapidity andfor the pT and y integrated result,

usesthemeasurements of

ϒ

productioncrosssectionsinpp col-lisionsat

√

s

=

7 and8TeV byALICE[41,42] andat

√

s

=

2

.

76

,

7 and8TeVby LHCb[43,44].Theinterpolationisperformedby us-ing variousempiricalfunctionsand, inaddition,the shapeofthe energydependenceof thebottomonium crosssectionscalculated usingtwo theoreticalmodels,i.e.theLeadingOrderColour Evap-orationModel(LO-CEM)[70] andtheFixedOrderNext-to-Leading Logs(FONLL)model [71].The lattergivescross sectionsforopen beauty,whichishereusedasaproxytostudytheevolutionofthe bottomoniumcross section [69]. Theenergy interpolationfor the

ϒ

(1S) crosssectionasafunctionof pTisbasedonLHCb

measure-ments only, since the pT coverage of the results of this analysis

(pT

<

15 GeV/c) is more extended than that of the

correspond-ing ALICEpp data (pT

<

12 GeV/c). The result of the

interpola-tion procedure gives BR_ϒ(1S)→μ+_μ−

·

σ

ppϒ(1S)

=

1221

±

77(syst) pb

Table 2

Theinterpolatedbranchingratiotimescrosssectionofϒ(1S) forthepTandy bins

understudy.Thequoteduncertaintiesaresystematic.

pT(GeV/c) y BRϒ(1S)→μ+μ−·σppϒ(1S)(pb) [0–2] [2.5–4] 226±26 [2–4] 361±20 [4–6] 288±24 [6–15] 311±23 [0–15] [2.5–3] 506±57 [3–3.5] 415±28 [3.5–4] 288±24

andBRϒ(2S)→μ+μ−

·

σ

ppϒ(2S)

=

302

±

23(syst) pb assuming

unpolar-ized quarkonia and integrating over the ranges 2

.

5

<

y

<

4 and

pT

<

15 GeV/c.Theuncertaintiescorrespondtothequadraticsum

of two terms. The first term dominates the total uncertainty on the interpolated value andreflects the statistical and systematic uncertainties on the data points used in the interpolation pro-cedure. The second term is relatedto the spreadamong the in-terpolated cross sections obtained by using either the empirical functionsorthe energydependenceestimatedfromthe theoreti-cal modelsmentionedabove.Thenumericalvaluesobtainedfrom theinterpolationprocedurearesummarizedinTable2forthe var-iouskinematicrangesusedintheanalysis.

5. Results

The nuclearmodificationfactorsforinclusive

ϒ

(1S) and

ϒ

(2S) productioninPb–Pb collisionsat

√

sNN

=

5

.

02 TeV fortheranges pT

<

15 GeV/c, 2

.

5

<

y

<

4 and the 0–90% centrality class

are Rϒ(_AA1S)

=

0

.

37

±

0

.

02(stat)

±

0

.

03(syst) and Rϒ(_AA2S)

=

0

.

10

±

0

.

04(stat)

±

0

.

02(syst), respectively. The ratio R_AAϒ(2S)

/

Rϒ(_AA1S) is 0

.

28

±

0

.

12(stat)

±

0

.

06(syst). Since the decay kinematics of the two

ϒ

states is very similar, mostof the systematic uncertainty sources entering the ratiocancel out except those on the signal extraction and on the pp crosssection, which are the dominant contributions to the total systematic uncertainty. The measure-ments show a strong suppression for both bottomonium states with themore weakly bound state being significantly more sup-pressed. The ratio between the

ϒ

(1S) RAA at

√

sNN

=

5

.

02 TeV

and2.76TeV [30] is 1

.

23

±

0

.

21(stat)

±

0

.

19(syst).The sourcesof systematic uncertainties entering the calculation of the ratio are considered uncorrelated, except forthe



TAA



component, whose

uncertaintycancelsout.Theratioiscompatiblewithunitywithin uncertainties.

Thecentrality, pT andy dependencesofthe

ϒ

(1S) RAA at

for-wardrapidityat

√

sNN

=

5

.

02 TeVareshowninFig.2.Adecrease

of RAA with increasing centrality is observed down to Rϒ(_AA1S)

=

0

.

34

±

0

.

03(stat)

±

0

.

02(syst) forthe0–10%mostcentralcollisions. No significant pT-dependence is observed up to pT

=

15 GeV/c

Fig. 2. Inclusiveϒ(1S) RAAasafunctionofcentrality(top),pT(left)andy (right)atforwardrapidityat√sNN=5.02 TeV.ALICEresultsat√sNN=2.76 TeVasafunction

ofcentralityand y areshownforcomparison [30].Theverticalerrorbarsandtheboxesrepresentthestatisticalanduncorrelatedsystematicuncertainties,respectively. Therelativecorrelateduncertaintyisshownasboxesatunity.ALICEϒ(1S) RAAmeasurementsat√sNN=5.02 TeVarecomparedtopredictionsfromtwotransportmodels

[33,72] andonehydro-dynamicalmodel[34] asafunctionofcentrality(top),pT(left)andy (right).Seetextfordetailsonthemodels.

withinuncertainties.Thenuclearmodificationfactorshowsno sig-nificantdependence on rapidity.The

ϒ

(1S) RAA asa function of

centralityandrapiditymeasuredbyALICEat

√

sNN

=

2

.

76 TeV [30]

are alsoshownin Fig. 2.Similar trends can be observedat both collisionenergies.

Theinclusive

ϒ

(1S) RAA measurementsarecompared inFig.2

to several calculations: two transport models (TM) [33,72] and onehydro-dynamicalmodel[34].Todescribethequarkonium mo-tioninthemedium,bothtransportcodes usearate-equation ap-proach which accounts for both suppression and (re)generation mechanisms in the QGP. In the TM1 model [33] the evolution ofthe thermal medium is based ona thermal-fireball expansion while the TM2 model [72] uses a 2+1 dimensional version of the idealhydrodynamic equations.The two models usedifferent rateequationsandbothmodels includeafeed-downcontribution fromhigher-mass bottomonia to the

ϒ

(1S). In TM2,two sets of feed-down fractions are assumed. Finally, the

ϒ

(1S) production cross section in pp collisions at

√

s

=

5

.

02 TeV in the rapidity range2

.

5

<

y

<

4 istaken asd

σ

ppϒ(1S)

/

d y

=

28

.

8 nb inTM1 and

d

σ

ppϒ(1S)

/

d y

=

30 nb in TM2. Those values deviate by about 2

σ

(TM1)and1

.

4

σ

(TM2)fromtheresultobtainedusingthepp inter-polationmethodreportedintheprevioussection.TM1predictions areshownasbandsaccountingforshadowingeffectsascalculated in [36]. The upper limit shownin Fig. 2 corresponds to the ex-treme case of the absence of shadowing while the lower limit

reflects a reduction of 30% due to shadowing. The TM1 model implements the feed-down fractions reported in[9]. In the TM2 model, the shadowing parameterization is based on EKS98 [35] andthebandedgescorrespondtotwodifferentsetsoffeed-down fractions (27%from

χ

b; 11% from

ϒ(

2S

+

3S

)

and37% from

χ

b;

12%from

ϒ(

2S

+

3S

)

)adoptedbytheauthors.Inthethirdmodel [34], a thermal suppression of the bottomonium states is calcu-latedusinga complex-valued heavy-quarkpotential parametrized bymeansoflatticeQCDandembeddedinamediumevolving ac-cording to 3+1d anisotropic hydrodynamics.In this recent study, the RAA shows no sensitivity to the plasma shear

viscosity-to-entropy density ratio (4

π η

/

s) parameter of the hydro evolution, whichisthereforesetto4

π η

/

s

=

2 consistentwithparticle spec-trafits.Thebandofthemodelquantifiestheheavy-quarkpotential uncertainty,which hasbeenestimatedbyincludinga

±

15% vari-ation of theDebye mass ofthe QCD medium that is tuned by a fit to the real-part of the lattice in-medium heavy-quark poten-tial.Furthermore,thepredictionsshownarereferringtotheinitial momentum-spaceanisotropyparameter

ξ

0

=

0,whichcorresponds

to a perfectly isotropic QGP at the starting point of the hydro-dynamicalevolutionat

τ

0

=

0

.

3 fm/c.Finally,thismodelaccounts

forfeed-down contributions butit includes neither a (re)genera-tionmechanismnorCNMeffects.Thecentralitydependenceofthe

ϒ

(1S) RAAisfairlyreproducedbythemodelcalculationsinthetop

panelofFig.2.ThedataarebestdescribedbyTM1when (re)gen-eration isincludedandby TM2when (re)generationisnot taken

into account. The hydro-dynamical model describesthe trend of thedata, thefact that thedatalie on theupper edgeofthe un-certaintybandforNpart

>

70 couldindicateasmallerDebyemass

andthus astrongerheavy-quarkpotential.Thedataasafunction of pT (bottomleftpanel ofFig.2)canbedescribed withor

with-out the(re)generation scenarioofthe TM1modelwhile showing agreementwiththehydro-dynamicalmodelfortheupperedgeof theuncertaintyband.Finally,the y-dependenceofthe

ϒ

(1S) RAA

isdescribed, within uncertainties, by the hydro-dynamicalmodel inthe bottom rightpanel ofFig. 2despite the possibly different trendbetweendataandcalculations.

Thelow

ϒ

(1S) RAA reportedinthisLetterraisestheimportant

question whetherdirect

ϒ

(1S) aresuppressed atLHCenergies or only the feed-down contribution from higher mass states. How-ever,thelargeuncertaintiesofthecurrentmeasurements ofCNM effects[38–40] preventafirmconclusion.

6. Summary

The nuclearmodification factors ofinclusive

ϒ

(1S) and

ϒ

(2S) productionatforwardrapidity(2

.

5

<

y

<

4)andforpT

<

15 GeV/c

inPb–Pbcollisionsat

√

sNN

=

5

.

02 TeVhavebeenmeasuredusing

theALICEdetector.Theobserved

ϒ

(1S) suppressionincreaseswith the centrality of the collision andno significant variation is ob-servedasafunctionoftransversemomentumorrapidity.Alarger suppression of the

ϒ

(2S) bound state compared to the ground stateisalsoreported.Transportanddynamicalmodelcalculations reproducequalitativelythecentralityandkinematicdependenceof the

ϒ

(1S) nuclearmodificationfactor.

Acknowledgements

The ALICE Collaboration would like to thank all its engineers andtechnicians fortheir invaluablecontributionstothe construc-tionoftheexperimentandtheCERNacceleratorteamsforthe out-standingperformanceoftheLHCcomplex.TheALICECollaboration gratefully acknowledges the resources and support provided by all Gridcentres andtheWorldwide LHCComputing Grid(WLCG) collaboration. The ALICE Collaboration acknowledges the follow-ing funding agencies for their support in building and running the ALICE detector: A. I.Alikhanyan National Science Laboratory (YerevanPhysicsInstitute)Foundation(ANSL),StateCommittee of Science andWorld Federationof Scientists (WFS), Armenia; Aus-trian Academy of Sciences and Österreichische Nationalstiftung für Forschung, Technologie undEntwicklung, Austria; Ministry of CommunicationsandHighTechnologies,NationalNuclearResearch Center,Azerbaijan;Conselho NacionaldeDesenvolvimento Cientí-ficoeTecnológico(CNPq), UniversidadeFederaldo RioGrande do Sul(UFRGS), Financiadorade Estudose Projetos(Finep)and Fun-dação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Brazil; Ministry of Science & Technology of China (MSTC), Na-tionalNaturalScienceFoundationofChina(NSFC)andMinistryof EducationofChina(MOEC),China;MinistryofScienceand Educa-tion,Croatia;MinistryofEducation,YouthandSportsoftheCzech Republic,CzechRepublic;TheDanishCouncilforIndependent Re-search — Natural Sciences, the Carlsberg Foundation and Danish NationalResearchFoundation(DNRF), Denmark;HelsinkiInstitute ofPhysics(HIP),Finland;Commissariatàl’EnergieAtomique(CEA) andInstitutNationaldePhysiqueNucléaireetdePhysiquedes Par-ticules (IN2P3) andCentre National de la Recherche Scientifique (CNRS), France; Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF) and GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany; General Secretariat forResearchandTechnology,MinistryofEducation,Researchand

Religions, Greece; National Research Development and Innova-tion Office, Hungary; Department ofAtomic Energy, Government of India (DAE), Department of Science and Technology, Govern-ment of India (DST), University Grants Commission, Government of India (UGC) and Council of Scientific and Industrial Research (CSIR), India; Indonesian Institute of Sciences, Indonesia; Centro Fermi - MuseoStorico della Fisica e Centro Studi e Ricerche En-rico Fermi andIstituto Nazionale diFisica Nucleare (INFN), Italy; Institute forInnovativeScienceandTechnology,NagasakiInstitute of AppliedScience (IIST), Japan Societyforthe Promotion of Sci-ence(JSPS)KAKENHIandJapaneseMinistryofEducation,Culture, Sports, Science and Technology (MEXT), Japan; Consejo Nacional deCiencia(CONACYT)yTecnología,throughFondodeCooperación Internacional en Ciencia y Tecnología (FONCICYT) and Dirección General de Asuntos del Personal Academico (DGAPA), Mexico; NederlandseOrganisatievoorWetenschappelijkOnderzoek(NWO), Netherlands; The Research Council of Norway, Norway; Commis-sion on Science and Technology for Sustainable Development in theSouth(COMSATS),Pakistan;PontificiaUniversidadCatólicadel Perú,Peru;MinistryofScienceandHigherEducationandNational Science Centre, Poland; Korea Institute of Science and Technol-ogyInformationandNationalResearchFoundationofKorea(NRF), Republic of Korea;Ministry of Educationand Scientific Research, Institute of Atomic Physics and Romanian National Agency for Science, Technology and Innovation, Romania; Joint Institute for Nuclear Research(JINR), MinistryofEducationandScienceofthe Russian FederationandNationalResearch CentreKurchatov Insti-tute, Russia; Ministry of Education, Science, Research and Sport of the Slovak Republic, Slovakia; National Research Foundation of South Africa, South Africa; Centro de Aplicaciones Tecnológi-cas yDesarrolloNuclear(CEADEN),Cubaenergía,Cuba andCentro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT),Spain;SwedishResearchCouncil(VR) andKnut&Alice WallenbergFoundation(KAW),Sweden;EuropeanOrganizationfor Nuclear Research, Switzerland; National Science and Technology Development Agency (NSDTA), Suranaree University of Technol-ogy (SUT) andOffice of theHigher EducationCommission under NRU projectofThailand,Thailand;TurkishAtomicEnergy Agency (TAEK),Turkey;NationalAcademyofSciencesofUkraine,Ukraine; ScienceandTechnologyFacilitiesCouncil(STFC),UnitedKingdom; NationalScienceFoundationoftheUnitedStatesofAmerica(NSF) andUnitedStatesDepartmentofEnergy,OfficeofNuclear Physics (DOENP),UnitedStatesofAmerica.

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ALICECollaboration

S. Acharya

139

,

F.T. Acosta

20

,

D. Adamová

93

,

J. Adolfsson

80

,

M.M. Aggarwal

98

,

G. Aglieri Rinella

34

,

M. Agnello

31

,

N. Agrawal

48

,

Z. Ahammed

139

,

S.U. Ahn

76

,

S. Aiola

144

,

A. Akindinov

64

,

M. Al-Turany

104

,

S.N. Alam

139

,

D.S.D. Albuquerque

121

,

D. Aleksandrov

87

,

B. Alessandro

58

,

R. Alfaro Molina

72

,

Y. Ali

15

,

A. Alici

10

,

53

,

27

,

A. Alkin

2

,

J. Alme

22

,

T. Alt

69

,

L. Altenkamper

22

,

I. Altsybeev

111

,

M.N. Anaam

6

,

C. Andrei

47

,

D. Andreou

34

,

H.A. Andrews

108

,

A. Andronic

142

,

104

,

M. Angeletti

34

,

V. Anguelov

102

,

C. Anson

16

,

T. Antiˇci ´c

105

,

F. Antinori

56

,

P. Antonioli

53

,

R. Anwar

125

,

N. Apadula

79

,

L. Aphecetche

113

,

H. Appelshäuser

69

,

S. Arcelli

27

,

R. Arnaldi

58

,

O.W. Arnold

103

,

116

,

I.C. Arsene

21

,

M. Arslandok

102

,

B. Audurier

113

,

A. Augustinus

34

,

R. Averbeck

104

,

M.D. Azmi

17

,

A. Badalà

55

,

Y.W. Baek

60

,

40

,

S. Bagnasco

58

,

R. Bailhache

69

,

R. Bala

99

,

A. Baldisseri

135

,

M. Ball

42

,

R.C. Baral

85

,

A.M. Barbano

26

,

R. Barbera

28

,

F. Barile

52

,

L. Barioglio

26

,

G.G. Barnaföldi

143

,

L.S. Barnby

92

,

V. Barret

132

,

P. Bartalini

6

,

K. Barth

34

,

E. Bartsch

69

,

N. Bastid

132

,

S. Basu

141

,

G. Batigne

113

,

B. Batyunya

75

,

P.C. Batzing

21

,

J.L. Bazo Alba

109

,

I.G. Bearden

88

,

H. Beck

102

,

C. Bedda

63

,

N.K. Behera

60

,

I. Belikov

134

,

F. Bellini

34

,

H. Bello Martinez

44

,

R. Bellwied

125

,

L.G.E. Beltran

119

,

V. Belyaev

91

,

G. Bencedi

143

,

S. Beole

26

,

A. Bercuci

47

,

Y. Berdnikov

96

,

D. Berenyi

143

,

R.A. Bertens

128

,

D. Berzano

34

,

58

,

L. Betev

34

,

P.P. Bhaduri

139

,

A. Bhasin

99

,

I.R. Bhat

99

,

H. Bhatt

48

,

B. Bhattacharjee

41

,

J. Bhom

117

,

A. Bianchi

26

,

L. Bianchi

125

,

N. Bianchi

51

,

J. Bielˇcík

37

,

J. Bielˇcíková

93

,

A. Bilandzic

116

,

103

,

G. Biro

143

,

R. Biswas

3

,

S. Biswas

3

,

J.T. Blair

118

,

D. Blau

87

,

C. Blume

69

,

G. Boca

137

,

F. Bock

34

,

A. Bogdanov

91

,

L. Boldizsár

143

,

M. Bombara

38

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G. Bonomi

138

,

M. Bonora

34

,

H. Borel

135

,

A. Borissov

18

,

142

,

M. Borri

127

,

E. Botta

26

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C. Bourjau

88

,

L. Bratrud

69

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P. Braun-Munzinger

104

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M. Bregant

120

,

T.A. Broker

69

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M. Broz

37

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E.J. Brucken

43

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E. Bruna

58

,

G.E. Bruno

34

,

33

,

D. Budnikov

106

,

H. Buesching

69

,

S. Bufalino

31

,

P. Buhler

112

,

P. Buncic

34

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O. Busch

131

,

i

,

Z. Buthelezi

73

,

J.B. Butt

15

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J.T. Buxton

95

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J. Cabala

115

,

D. Caffarri

89

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H. Caines

144

,

A. Caliva

104

,

E. Calvo Villar

109

,

R.S. Camacho

44

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P. Camerini

25

,

A.A. Capon

112

,

F. Carena

34

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W. Carena

34

,

F. Carnesecchi

27

,

10

,

J. Castillo Castellanos

135

,

A.J. Castro

128

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E.A.R. Casula

54

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C. Ceballos Sanchez

8

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S. Chandra

139

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B. Chang

126

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W. Chang

6

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S. Chapeland

34

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M. Chartier

127

,

S. Chattopadhyay

139

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S. Chattopadhyay

107

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A. Chauvin

103

,

116

,

C. Cheshkov

133

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B. Cheynis

133

,

V. Chibante Barroso

34

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D.D. Chinellato

121

,

S. Cho

60

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P. Chochula

34

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T. Chowdhury

132

,

P. Christakoglou

89

,

C.H. Christensen

88

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P. Christiansen

80

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T. Chujo

131

,

S.U. Chung

18

,

C. Cicalo

54

,

L. Cifarelli

10

,

27

,

F. Cindolo

53

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J. Cleymans

124

,

F. Colamaria

52

,

D. Colella

65

,

34

,

52

,

A. Collu

79

,

M. Colocci

27

,

M. Concas

58

,

ii

,

G. Conesa Balbastre

78

,

Z. Conesa del Valle

61

,

J.G. Contreras

37

,

T.M. Cormier

94

,

Y. Corrales Morales

58

,

P. Cortese

32

,

M.R. Cosentino

122

,

F. Costa

34

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S. Costanza

137

,

J. Crkovská

61

,

P. Crochet

132

,

E. Cuautle

70

,

L. Cunqueiro

142

,

94

,

T. Dahms

103

,

116

,

A. Dainese

56

,

S. Dani

66

,

M.C. Danisch

102

,

A. Danu

68

,

D. Das

107

,

I. Das

107

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S. Das

3

,

A. Dash

85

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S. Dash

48

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S. De

49

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A. De Caro

30

,

G. de Cataldo

52

,

C. de Conti

120

,

J. de Cuveland

39

,

A. De Falco

24

,

D. De Gruttola

10

,

30

,

N. De Marco

58

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S. De Pasquale

30

,

R.D. De Souza

121

,

H.F. Degenhardt

120

,

A. Deisting

104

,

102

,

A. Deloff

84

,

S. Delsanto

26

,

C. Deplano

89

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P. Dhankher

48

,

D. Di Bari

33

,

A. Di Mauro

34

,

B. Di Ruzza

56

,

R.A. Diaz

8

,

T. Dietel

124

,

P. Dillenseger

69

,

Y. Ding

6

,

R. Divià

34

,

Ø. Djuvsland

22

,

A. Dobrin

34

,

D. Domenicis Gimenez

120

,

B. Dönigus

69

,

O. Dordic

21

,

L.V.R. Doremalen

63

,

A.K. Dubey

139

,

A. Dubla

104

,

L. Ducroux

133

,

S. Dudi

98

,

A.K. Duggal

98

,

M. Dukhishyam

85

,

P. Dupieux

132

,

R.J. Ehlers

144

,

D. Elia

52

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E. Endress

109

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H. Engel

74

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E. Epple

144

,

B. Erazmus

113

,

F. Erhardt

97

,

M.R. Ersdal

22

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B. Espagnon

61

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G. Eulisse

34

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J. Eum

18

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D. Evans

108

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S. Evdokimov

90

,

L. Fabbietti

103

,

116

,

M. Faggin

29

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J. Faivre

78

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A. Fantoni

51

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M. Fasel

94

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L. Feldkamp

142

,

A. Feliciello

58

,

G. Feofilov

111

,

A. Fernández Téllez

44

,

A. Ferretti

26

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A. Festanti

29

,

34

,

V.J.G. Feuillard

102

,

J. Figiel

117

,

M.A.S. Figueredo

120

,

S. Filchagin

106

,

D. Finogeev

62

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F.M. Fionda

22

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G. Fiorenza

52

,

F. Flor

125

,

M. Floris

34

,

S. Foertsch

73

,

P. Foka

104

,

S. Fokin

87

,

E. Fragiacomo

59

,

A. Francescon

34

,

A. Francisco

113

,

U. Frankenfeld

104

,

G.G. Fronze

26

,

U. Fuchs

34

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C. Furget

78

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A. Furs

62

,

M. Fusco Girard

30

,

J.J. Gaardhøje

88

,

D.S. Hwang

19

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J.P. Iddon

127

,

S.A. Iga Buitron

70

,

R. Ilkaev

106

,

M. Inaba

131

,

M. Ippolitov

87

,

M.S. Islam

107

,

M. Ivanov

104

,

V. Ivanov

96

,

V. Izucheev

90

,

B. Jacak

79

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N. Jacazio

27

,

P.M. Jacobs

79

,

M.B. Jadhav

48

,

S. Jadlovska

115

,

J. Jadlovsky

115

,

S. Jaelani

63

,

C. Jahnke

120

,

116

,

M.J. Jakubowska

140

,

M.A. Janik

140

,

C. Jena

85

,

M. Jercic

97

,

O. Jevons

108

,

R.T. Jimenez Bustamante

104

,

M. Jin

125

,

P.G. Jones

108

,

A. Jusko

108

,

P. Kalinak

65

,

A. Kalweit

34

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J.H. Kang

145

,

V. Kaplin

91

,

S. Kar

6

,

A. Karasu Uysal

77

,

O. Karavichev

62

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T. Karavicheva

62

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P. Karczmarczyk

34

,

E. Karpechev

62

,

U. Kebschull

74

,

R. Keidel

46

,

D.L.D. Keijdener

63

,

M. Keil

34

,

B. Ketzer

42

,

Z. Khabanova

89

,

A.M. Khan

6

,

S. Khan

17

,

S.A. Khan

139

,

A. Khanzadeev

96

,

Y. Kharlov

90

,

A. Khatun

17

,

A. Khuntia

49

,

M.M. Kielbowicz

117

,

B. Kileng

36

,

B. Kim

131

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D. Kim

145

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D.J. Kim

126

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E.J. Kim

13

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H. Kim

145

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J.S. Kim

40

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J. Kim

102

,

M. Kim

102

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60

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S. Kim

19

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T. Kim

145

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T. Kim

145

,

S. Kirsch

39

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I. Kisel

39

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S. Kiselev

64

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A. Kisiel

140

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J.L. Klay

5

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C. Klein

69

,

J. Klein

34

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58

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C. Klein-Bösing

142

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S. Klewin

102

,

A. Kluge

34

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M.L. Knichel

34

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A.G. Knospe

125

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C. Kobdaj

114

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M. Kofarago

143

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M.K. Köhler

102

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T. Kollegger

104

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N. Kondratyeva

91

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E. Kondratyuk

90

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A. Konevskikh

62

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M. Konyushikhin

141

,

O. Kovalenko

84

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V. Kovalenko

111

,

M. Kowalski

117

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I. Králik

65

,

A. Kravˇcáková

38

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L. Kreis

104

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M. Krivda

65

,

108

,

F. Krizek

93

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M. Krüger

69

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E. Kryshen

96

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M. Krzewicki

39

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A.M. Kubera

95

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V. Kuˇcera

60

,

93

,

C. Kuhn

134

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P.G. Kuijer

89

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J. Kumar

48

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L. Kumar

98

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S. Kumar

48

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S. Kundu

85

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P. Kurashvili

84

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A. Kurepin

62

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A.B. Kurepin

62

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A. Kuryakin

106

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S. Kushpil

93

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J. Kvapil

108

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M.J. Kweon

60

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Y. Kwon

145

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S.L. La Pointe

39

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P. La Rocca

28

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Y.S. Lai

79

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I. Lakomov

34

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R. Langoy

123

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K. Lapidus

144

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A. Lardeux

21

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P. Larionov

51

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E. Laudi

34

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R. Lavicka

37

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R. Lea

25

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L. Leardini

102

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S. Lee

145

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F. Lehas

89

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S. Lehner

112

,

J. Lehrbach

39

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R.C. Lemmon

92

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I. León Monzón

119

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P. Lévai

143

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X. Li

12

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X.L. Li

6

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J. Lien

123

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R. Lietava

108

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B. Lim

18

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S. Lindal

21

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V. Lindenstruth

39

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S.W. Lindsay

127

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C. Lippmann

104

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M.A. Lisa

95

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V. Litichevskyi

43

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A. Liu

79

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H.M. Ljunggren

80

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W.J. Llope

141

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D.F. Lodato

63

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V. Loginov

91

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C. Loizides

94

,

79

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P. Loncar

35

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X. Lopez

132

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E. López Torres

8

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A. Lowe

143

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P. Luettig

69

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J.R. Luhder

142

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M. Lunardon

29

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G. Luparello

59

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M. Lupi

34

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A. Maevskaya

62

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M. Mager

34

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S.M. Mahmood

21

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A. Maire

134

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R.D. Majka

144

,

M. Malaev

96

,

Q.W. Malik

21

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L. Malinina

75

,

iii

,

D. Mal’Kevich

64

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P. Malzacher

104

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A. Mamonov

106

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V. Manko

87

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F. Manso

132

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V. Manzari

52

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Y. Mao

6

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M. Marchisone

129

,

73

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133

,

J. Mareš

67

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G.V. Margagliotti

25

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A. Margotti

53

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J. Margutti

63

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A. Marín

104

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C. Markert

118

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M. Marquard

69

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N.A. Martin

104

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P. Martinengo

34

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J.L. Martinez

125

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M.I. Martínez

44

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G. Martínez García

113

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M. Martinez Pedreira

34

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S. Masciocchi

104

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M. Masera

26

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A. Masoni

54

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L. Massacrier

61

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E. Masson

113

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A. Mastroserio

52

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136

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A.M. Mathis

116

,

103

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P.F.T. Matuoka

120

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A. Matyja

117

,

128

,

C. Mayer

117

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M. Mazzilli

33

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M.A. Mazzoni

57

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F. Meddi

23

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Y. Melikyan

91

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A. Menchaca-Rocha

72

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E. Meninno

30

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J. Mercado Pérez

102

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M. Meres

14

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C.S. Meza

109

,

S. Mhlanga

124

,

Y. Miake

131

,

L. Micheletti

26

,

M.M. Mieskolainen

43

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D.L. Mihaylov

103

,

K. Mikhaylov

64

,

75

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A. Mischke

63

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A.N. Mishra

70

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D. Mi´skowiec

104

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J. Mitra

139

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C.M. Mitu

68

,

N. Mohammadi

34

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A.P. Mohanty

63

,

B. Mohanty

85

,

M. Mohisin Khan

17

,

iv

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D.A. Moreira De Godoy

142

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L.A.P. Moreno

44

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S. Moretto

29

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A. Morreale

113

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A. Morsch

34

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V. Muccifora

51

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E. Mudnic

35

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D. Mühlheim

142

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S. Muhuri

139

,

M. Mukherjee

3

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J.D. Mulligan

144

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M.G. Munhoz

120

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K. Münning

42

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M.I.A. Munoz

79

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R.H. Munzer

69

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H. Murakami

130

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S. Murray

73

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L. Musa

34

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J. Musinsky

65

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C.J. Myers

125

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J.W. Myrcha

140

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B. Naik

48

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R. Nair

84

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B.K. Nandi

48

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R. Nania

53

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10

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E. Nappi

52

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A. Narayan

48

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M.U. Naru

15

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A.F. Nassirpour

80

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H. Natal da Luz

120

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C. Nattrass

128

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S.R. Navarro

44

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K. Nayak

85

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R. Nayak

48

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T.K. Nayak

139

,