Study of J/ψ meson production inside jets in pp collisions at sqrt(s)=8TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Study

of

J

/

ψ

meson

production

inside

jets

in

pp

collisions

at

√

s

=

8 TeV

.

The

CMS

Collaboration



CERN,Switzerland

a

r

t

i

c

l

e

i

n

f

o

a

b

s

t

r

a

c

t

Articlehistory: Received3October2019

Receivedinrevisedform31March2020 Accepted1April2020

Availableonline7April2020 Editor: M.Doser

Keywords: CMS J/psiMesons Jets

A study of the production of prompt J/ψ mesons contained in jets in proton-proton collisions at

√

s=8 TeV ispresented. Theanalysis is basedondata corresponding to anintegrated luminosity of 19.1 fb−1 _{collectedwiththe CMSdetector attheLHC. Forevents withatleast oneobserved jet,the} angularseparationbetweentheJ/ψmesonandthejetisusedtotestwhethertheJ/ψmesonispart ofthejet.TheanalysisshowsthatmostpromptJ/ψmesonshavingenergyabove15 GeV andrapidity

|y|<1 arecontainedinjetswithpseudorapidity|

η

jet|<1.Thedifferentialdistributionsoftheprobability tohaveaJ/ψmesoncontainedinajetas afunctionofjetenergyforafixedJ/ψenergyfractionare comparedtoatheoreticalmodelusingthefragmentingjetfunctionapproach.Thedataagreebestwith fragmentingjet functioncalculationsthatuse along-distance matrix elementparameterset inwhich prompt J/ψ mesonsare predicted tobeunpolarized.Thistechnique demonstratesanewway totest predictionsforpromptJ/ψproductionusingnonrelativisticquantumchromodynamics.

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

1. Introduction

The mechanismfor producing J

/

ψ

mesons as bound statesof charmquarkpairs(cc)inhadroniccollisionshasbeenunder inten-sive experimental andtheoretical study since the1974 discovery oftheJ

/

ψ

mesoninproton-nucleoncollisions [1] andine+e− an-nihilations [2]. The early theoretical descriptions of the hadronic productionprocess consideringonlycolor-singletproduction [3,4] were at odds with the differential cross section measurements as a function of the J

/

ψ

transverse momentum pJ_T/ψ made by experimenters at the Fermilab Tevatron [5] for pJ_T/ψ

>

6 GeV. A newtheoretical approach,nonrelativisticquantum chromodynam-ics(NRQCD), wasusedto addresstheproblem [6–8].The NRQCD modelincludes both color-singlet andcolor-octet amplitudes for thecc systemthatultimatelyproducestheJ

/

ψ

meson.Itprovedto becapableofexplainingthecrosssectiondata,using phenomeno-logical parameters called long-distance matrix elements (LDMEs) that areadjusted to describe J

/

ψ

meson productiondata. Within the NRQCD factorization assumption, the LDME parameters are processindependent.However,eachdeterminationofanLDMEset canchooseaspecificcollectionofJ

/

ψ

mesonproductiondataand J

/

ψ

meson kinematic requirements. Furthermore, different LDME sets that describe the production data may have different pre-dictions for the J

/

ψ

meson polarization [9]. Experiments [10,11]

 _{E-mailaddress:cms -publication -committee -chair @cern .ch.}

haveshownthatthepromptJ

/

ψ

mesonpolarization atlarge pJ_T/ψ

(

>

12 GeV) is small. Recent NRQCD studies extend the range of experimental input to includelow-pT dataand attemptto make

globalfitstothefull setofcharmoniuminformation.Areview of thesestudiescanbefoundinRef. [12].

A remaining theoretical problem is to determine the mecha-nism by which a cc systemin an angularmomentum state and quark color configuration 2S+1Ln_J hadronizes into a J

/

ψ

meson. Here, S, L, and J arethespin, orbital,andtotalangular momen-tumquantumnumbersofthe cc system.Itscolorstate islabeled byn,withn

=

1 or8referringtoacolor-singletorcolor-octet con-figuration, respectively.The J

/

ψ

mesonhas J

=

S

=

1 and n

=

1. The analysis described in this Letter combines the experimental measurement of J

/

ψ

mesons contained in jetswitha theoretical approach basedonthe fragmentingjetfunction (FJF)model [13]. TheFJFmodelpostulates thatthecc pairisnotproduceddirectly inthehardscattering,butisafragmentationproductofahigh-pT

jet. The model uses the methodology ofNRQCD to compute the crosssectioncontributionsforallrelevant2S+1_Ln

J terms.Eachcross section term hasa characteristicrelation betweenthe jet energy

EjetanditsfractioncarriedbytheJ

/

ψ

meson:z

=

EJ/ψ

/

Ejet.

Astudy ofJ

/

ψ

mesonscontainedinjetsintherapidityregion

yJ/ψ

>

2,dominatedbycharmfragmentationforlargez,hasbeen

reportedbytheLHCbCollaboration [14].TheLHCbanalysis,which measured the z distribution integratedover jet energy, doesnot havethesensitivitytoLDMEparametersetsthatcharacterizesthis analysis.

https://doi.org/10.1016/j.physletb.2020.135409

ThedataforthisanalysiswerecollectedbytheCMSdetectorin proton-proton(pp) collisions from the CERN LHC, corresponding to an integratedluminosity of 19.1 fb−1 _at

√

_s

₌

_{8 TeV. It isthe}

first experimental study of prompt J

/

ψ

mesons containedin jets produced in the gluon-dominated central rapidity region, where theFJFtheoryforgluonicjetfragmentationapplies.

2. Theoreticalframework

The hadronization process isnonperturbative. It is handledin the FJF approach by an NRQCD expansion of the fragmentation function for a jet initially produced in a hard scattering at high energy. The observables are Ejet and z. Following Ref. [13], the

differential cross section for dijet production, with one jet frag-mentingtoaJ

/

ψ

meson,canbewrittensymbolicallyas

d2

_σ

₍

_E jet

;

z

)

dEjetdz

=



A,B,i,j fA/p fB/pd

σA Bi j

(

cc X

,

n

,

J

j

)

⊗ F

S

⊗ G

Ji/ψ

(

Ejet

,

z

|

R

,

μ

).

(1)

Inthis expression, A and B are thepartons inthe colliding pro-tonswithfractionalflavorcontent fA/p

,

fB/p,respectively,whilei and j aretheoutgoingpartons.Thesymbolichard-scatteringcross sectiondσA Bi j

(

cc X

,

n

,

J

j

)

produces thefragmentingjetfrom out-going partoni andthe recoiljet

J

j fromoutgoingparton j.The fragmenting jet produces a cc system characterized by S, L, J ,

andn quantumnumbers,plus an inclusivehadronicstate X that

representstheremainder ofthejet.The function

F

S controlsthe evolutionof thefragmentingsystemdown tothe energyscale

μ

equaltothe massofthe cc system,toallow thedevelopment of jetstructure fromsoftgluons. Thenonperturbative fragmentation ofthecc systemintotheobservedJ

/

ψ

mesonisdescribedbythe function

G

J_i/ψ

(

Ejet

,

z

|

R

, μ)

,where Ejet is determinedin acone of

angularradius R.

The type of parton i that produces the fragmenting jet, and ultimatelythe J

/

ψ

meson, depends onthe jet rapidity region.In the central rapidity region covered by this analysis, gluon frag-mentationdominates [15].TheFJFexpression for

G

J_i/ψ sumsover allcontributingpartons,butthelightflavorcontributionsare sup-pressedandcanbeneglected.InRef. [13],thesmallcentralcharm quarkfragmentationcontributionwas absorbedintothe 3S₁1 con-tributiontogluonfragmentation,so

G

J/ψ _{inthisLetterrepresents}

onlygluonfragmentation.

In Ref. [16], the authors updated the work of Ref. [13] to make an explicit computation of the perturbative dijet double-differentialcrosssection,followedby thefragmentationofoneof thejetstoa J

/

ψ

meson.Theyintegratedoverthe kinematic vari-ablesof thesecond jetto give anFJF expressionforthe absolute differentialcrosssectiontoproduceajetofenergy Ejet that

frag-ments intoa J

/

ψ

meson carryingenergyfraction z of theparent jetenergyalongwiththeremainingfragments.IntheNRQCD de-composition of

G

J/ψ _{forcentral J}

_/

_ψ

_{meson hadroproductionwith}

pT

>

10 GeV,fourFJFtermsarerelevant:3S11

,

1S80

,

3_S8

1

,

and3P8J. Onlythe 1_S8

0 termhasall angularmomenta equalto zerointhe

cc restframe.IfthisNRQCDtermweretodominatethejet frag-mentationprocess,thentheJ

/

ψ

mesonwouldbeproduced unpo-larized.

3. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ing solenoidof6 m internal diameter,providinga magneticfield of3.8 T.Withinthesolenoidvolumeare asiliconpixelandstrip tracker,aleadtungstatecrystalelectromagneticcalorimeter,anda

brassandscintillatorhadroncalorimeter,eachcomposedofa bar-rel and two endcap sections.When combininginformation from theentiredetector,thejetenergyresolutionamounts typicallyto 15% at 10 GeV and 8% at 100 GeV [17]. Muons are detected in gas-ionization chambers embedded in the steel flux-return yoke outsidethesolenoid, covering thepseudorapidityrange

|

η

|

<

2

.

4. The silicon tracker measures charged particles within the pseu-dorapidity range

|

η

|

<

2

.

5. It consists of 1440 silicon pixel and 15 148siliconstrip detectormodules. Fornonisolatedparticles of 1

<

pT

<

10 GeV and

|

η

|

<

1

.

4, thetrackresolutionsare typically

1.5% in pT and25–90 (45–150)

μm in

the transverse

(longitudi-nal) impactparameter [18]. Matchingmuons to tracksmeasured in the silicon trackerresults in a relative transverse momentum resolution,formuonswith20

<

pT

<

100 GeV,of1.3–2.0%inthe

barrel [19].Eventsofinterestareselectedusingatwo-tiered trig-ger system [20]. The first level, composed of custom hardware processors, usesinformationfromthe calorimetersandmuon de-tectorstoselecteventsatarateofaround100 kHz withinafixed time interval of lessthan 4

μs.

The second level,known as the high-level trigger(HLT), consistsof a farmof processors running a version ofthe full event reconstruction software optimizedfor fast processing. Thisreduces theevent rateto around1 kHz be-foredatastorage.AmoredetaileddescriptionoftheCMSdetector, together witha definitionofthecoordinate systemusedandthe relevantkinematicvariables,canbefoundinRef. [21].

4. Eventselectionandbackgroundsubtraction

The experimentalmethodsfollowthoseusedby previousCMS analysesofinclusiveJ

/

ψ

and

ϒ(

n S)productionat

√

s

=

7 TeV [22–

26]. The event selection is based on a dimuon trigger involving the silicon tracker and muon systems. The trigger requires two oppositely charged muons with rapidity of the dimuon system

|

y

|

<

1

.

25 anditsinvariantmassrange2

.

7

<

mμμ

<

3

.

5 GeV.The

three-dimensionalfittothedimuonvertexmusthavea

χ

2

prob-ability (the p-value of the

χ

2 _{returned by the fit)}

_>

₀

_.

_{5%. Only}

dimuon pairsinwhichthe muonsbendaway fromeachother in the magnetic field are used to allow aprecise dimuon efficiency determination. Thedimuon pT trigger thresholdvaried from5to

9 GeV during thedata-takingperiod.The primaryeventvertexis definedas theone withthe largestsummed pT ofits associated

tracks.

TheofflineselectionrequiresadimuonpairwithpT

>

10 GeV,

|

y

|

<

1,energy E

>

15 GeV,andvertexfit

χ

2 _probability

_>

_1%.In

order to guarantee agreement to within 3% between the single-muonefficienciesfromcontrolsamplesandfromsimulation,each muon musthave pμ_T

>

6 GeV and

|

η

μ

|

<

2

.

1,or pμT

>

5 GeV and

|

η

μ

|

<

0

.

8.ThemuoncandidatemustsatisfytheCMS“tight”muon

qualityrequirementsonthenumberoftrackerhits,themuontrack fitquality,andthedistancealongthebeamlinefromtheprimary eventvertex [19].Nomuonisolationrequirementsareapplied, be-causewelookforJ

/

ψ

+

jetassociations. TheJ

/

ψ

signal invariant massrangeis2

.

95

<

mμμ

<

3

.

20 GeV.Afterthedataselection,we

observeatmostoneJ

/

ψ

candidateperevent.

The trigger does not use any information about jets in the event. Jets are reconstructed from particle-flow objects [27], us-ing an anti-kT algorithm with a distance parameter of 0.5 [28],

asimplementedinthe FastJet package [29].The jetresponsehas beencorrected totheparticle level [17]. AlthoughtheJ

/

ψ

candi-date isnot a particle-flowobject,its decaymuonsare. Thisdoes not exclude jetsthatconsist only ofaJ

/

ψ

meson. However, such jets constitute less than 10−4 _{of this sample and do not affect}

the results presentedhere. The jet propertiesincludethe energy

Ejet,thetransversemomentummagnitudepjetT ,thenumberof

con-stituents,andthenumberofincludedmuons.Eachbunchcrossing in the data produces, on average, 14 reconstructed pp vertices,

correspondingto21interactionsperbunchcrossing.Theextra in-teractionsproduceso-calledpileupdistortions,whicharecorrected usingtheproceduredescribedinRef. [17].Forthisanalysis,thejet selectionrequirementsarepjet_T

>

25 GeV and

|

η

jet

|

<

1.

TheJ

/

ψ

eventcandidatesareclassifiedasprompt,nonprompt, orcombinatorial.NonprompteventsincludethoseJ

/

ψ

mesonsthat comefromdecaysofb hadrons.Combinatorialcandidatesare acci-dentalpairingsofanidentified

μ

+anda

μ

−suchthatthedimuon invariantmassfallswithinthesignalmassinterval.Thenonprompt backgroundisstronglyreducedbyapplyingaselectiononthe vari-able



TD,whichisthe sumofthesquaresofthe significance(in

unitsofstandarddeviations) ofthe transversedistanceofclosest approachofeach muontrackto theprimaryvertex.The



TD

dis-tribution has a sharp peak near zero fromprompt events and a longtailatlarger



TDfromnonpromptsources,whichwefitwith

an exponential function. From a prompt J

/

ψ

meson Monte Carlo (MC)sample,wefindthat

>

99% oftheeventshave



TD

<

10.The

simulated



T D shapeagrees withthat indataforthis region,so werequire



TD

<

10 to definethe promptdimuonevents.Inthe

J

/

ψ

data, the exponential function that describes the nonprompt backgroundis extrapolated intothe range



T D

<

10 to estimate thefractionofnonprompteventsinthepromptsignalmassrange. Thisis (5

.

7

±

0

.

1)%.The events inthe prompt signal massrange alsocontaincombinatorialbackground,whichisdeterminedby in-terpolatingthemμμlow(2.70–2.90 GeV)andhigh(3.25–3.50 GeV)

sidebandregions.Wefindthatthecombinatorialbackground frac-tioninthe prompt signalmass rangeis (1

.

4

±

0

.

2)%.The quoted uncertainties inthe backgrounds are statisticalonly. All distribu-tionsshowninthisLetter havethe nonpromptandcombinatorial backgrounds subtracted. After background subtraction, there are 1

.

63

×

106 _promptJ

_/

_ψ

_{mesoncandidates.}

5. AssociationofjetsandJ

/

ψ

mesons

The analysismakes no restriction on the numberof jets that passthejetselectionrequirements,whichwe term“observed jet-s”. For jet requirements pjet_T

>

25 GeV and

|

η

jet

|

<

1, the

frac-tions of J

/

ψ

meson events that have 0, 1, 2, or 3 observed jets are(55

.

12

±

0

.

06)%,(34

.

03

±

0

.

05)%,(9

.

58

±

0

.

02)%,and (1

.

27

±

0

.

08)%, respectively, where the uncertainties are statistical only. For events with at least one observed jet, the association of a J

/

ψ

mesonwithajetismadeusingtheangularseparation



R

=

√

(

η

jet

−

η

μμ

)

2

+ (φ

jet

− φ

μμ

)

2. Here,

η

jet

(

η

μμ

)

and

φ

jet

(φ

μμ

)

are the pseudorapidity andazimuthal angle (modulo

π

), respec-tively,of thejet (dimuon)direction. The



R distribution forthe best-matchedjetissharplypeakedatzero,asseenforeventswith one observed jet in Fig. 1 (upper). The J

/

ψ

meson and the jet aredefinedasassociatedif



R

<

0

.

5.Furthermore,ifbothdecay muonsfromthe J

/

ψ

mesonare amongtheobjects thatcomprise thejet,wesaythattheJ

/

ψ

mesonisaconstituentofthejet.

Whentherearetwoobservedjetsintheevent,furtherevidence thatJ

/

ψ

mesonproductioncomesprimarilyfromjetsisshownin Fig.1(lower).Thisplotshows



R fortheJ

/

ψ

mesonwithrespect toeachobservedjetintwo-jetevents.Thehigher-energy(leading) jethas



Rl,thelower-energy(subleading)one



Rsl.Notethatthe

energylabelshereplay norole intheanalysis;thejetsneedonly topassthejet pTand

|

η

jet

|

requirementsgivenabove.TheJ

/

ψ

me-sonisnotrequiredtocomefromeitherjet.Theclustersofevents inFig.1(lower),near(



Rl

,



Rsl

)

= (

0

, π

)

and(π,0),showthat (94

.

1

±

0

.

1)%of thetime, the J

/

ψ

meson isa constituentof one ofthetwojetsintheevent. IneventswithaJ

/

ψ

mesonandtwo jets,themeanandRMSdeviationofthedistributionofthe num-berofjetconstituents,chargedandneutral,forthefragmentingjet (25

±

8)andtherecoiljet(29

±

8)aresimilar.Theshapesofthejet energyspectraforthejetcontainingtheJ

/

ψ

mesonandtherecoil

Fig. 1. Thedistributionsof(upper)R (jet,J/ψ)forone-jeteventsand(lower)Rl

(leadingjet,J/ψ)vs.Rsl(subleadingjet,J/ψ)fortwo-jetevents.

jet areindistinguishable. Thedifference inthe probabilityfor the J

/

ψ

meson tobe a jet constituentinthe one- and two-jet cases, alongwithadiscussionofthesmallexcessfor2

.

4

<



R

<

3

.

5 in Fig.1(upper),willbeaddressedinSection12.

6. ExperimentalapplicationoftheFJFapproach

TheauthorsofRefs. [13,16] emphasizethatexperimental sensi-tivitytotheFJFtermsinjetfragmentationcomesfrommeasuring thejetenergydependenceofthefunction

G

inEq. (1) atfixed z.

Inthe FJFframework,the dependenceofthefragmentingjet dif-ferentialcrosssectionontheJ

/

ψ

propertiescomessolelythrough thez variable.IntegratingEq. (1) overz givesthesingle-jet differ-entialcrosssectionfortheproductionofJ

/

ψ

mesonscontainedin jets, asafunction ofEjet.Thisisused asanormalizationtermin

Ref. [16],wherethedifferentialcrosssectionforajettofragment to a J

/

ψ

mesonwith the energy fraction z is calculated for jets having pjet_T

>

25 GeV andpseudorapidity

|

η

jet

|

<

1

.

2.Theresulting

J

/

ψ

mesonisrequired tohaveenergyabove 15 GeV andrapidity

|

yJ/ψ

|

<

1.Thejetfragmentationcrosssectionisnormalizedby

in-tegrating over the z range 0.3–0.8. The authors showedthat the jet energydependence ofthenormalized FJFterms isinsensitive to theexact z range used.At afixed z value,calledz1,the ratio

ofthefragmentingjetdifferentialcrosssectionduetoasingle FJF termi tothesumofthe crosssection integralsfor0

.

3

<

z

<

0

.

8 forallFJFtermsistermed

(

d

σ

˜

i

/

dEjetdz

)

|

z1inRef. [16].Thesumof

thisratiooverallfourFJFtermsisdenotedas

(

d

σ

˜

/

dEjetdz

)

|

z1.For

agivenLDMEparameterset,eachofthefourFJFtermsisdifferent. Also,changingtheLDMEparametersetchangestheFJFpredictions forthefourterms.

The authors of Ref. [16] cite next-to-leading order (NLO) cal-culations [30–33] to argue that the pJ_T/ψ range for the three

NRQCD term cannot contribute to the sum. Therefore, in com-puting

(

d

σ

˜

/

dEjet dz

)

|

z1 to compareto thesedata, only thethree

color-octet terms are included. However, in the low-z region in-cludedinthenormalizingintegral,the3_S1

1 NRQCDtermcanplay

aroleandisincludedintheircalculationfor0

.

3

<

z

<

0

.

8. Theexperimentalproxyfor

(

d

σ

˜

/

dEjetdz

)

|

z1,evaluatedforajet

energybincenteredatEc,iscalled

(

Ec

;

z1

)

:

(

Ec

;

z1

)

≡

N

(

Ec

;

z1

)



0.8

0.3 N

(

Ec

;

z

)

dz

,

(2)

whereN

(

Ec

;

z1

)

isthenumberofeventshavingaJ

/

ψ

meson

con-tainedinajetfora z interval



z centeredon z1 inthat Ejet bin.

The number of events is weighted to correct for the J

/

ψ

meson efficiency and acceptance, as described in Section 7, as well as correctedforjetefficiencyandjet energyresolution,asdescribed inSection 8.We usea z interval



z

= ±

0

.

025 aroundz1, which

is small enough to be insensitive to z variations in



andlarge enoughtoprovideareasonablenumberofeventsineach Ejet bin.

7. EfficiencycorrectionsforJ

/

ψ

mesons

Measuringthepropertiesofeventswhena J

/

ψ

mesonisajet constituentrequires an event-by-event J

/

ψ

meson efficiency cor-rection.Eachentryinthesignalorbackgroundeventdistributions has an event weight, defined as 1/J/ψ. The dimuon acceptance

times efficiency



J/ψ is determined using a simulated sample of

unpolarizedJ

/

ψ

mesonevents,uniformlydistributedin1 GeV wide

pT bins anduniformlydistributedover

|

yJ/ψ

|

<

1

.

5.Onlythe J

/

ψ

meson is simulated; studies [25,26] show that using a complete pythia[34] eventsimulationdoesnotchangetheefficiencyresults. TheJ

/

ψ

→ μ

+

μ

− decayissimulatedusingevtgen [35];radiative effects are treatedby photos _{[36];and the detectorresponse to} the two muons is simulated using the Geant4-based [37] CMS simulationprogram.ThesimulatedJ

/

ψ

mesonmustpassthe qual-ityrequirementslistedinSection4.Thetotalefficiency



J/ψ varies

withtherapidityandtransversemomentumoftheJ

/

ψ

meson be-causethemuonreconstruction,dimuonvertexreconstruction,and dimuontriggerefficienciesdependonthesevariables.Thereisalso anHLTtriggerinefficiencyiftwomuonsintheeventhaveasmall angularseparation.Thisisalsotakenfromsimulationandchecked againstdatatakenusingasingle-muontrigger.

8. Jetenergycorrectionsandunfolding

Acrucialpartoftheanalysisismeasuringtheenergyofthejet that contains the J

/

ψ

meson. Totest whether theremight be an influenceonthejetenergydistributionduetothepresenceofthe J

/

ψ

meson, we study the two-jet eventsshowninFig. 1(lower). Theenergy distributionsofthe fragmentingjet andtherecoiljet are compared for 0

.

3

<

z

<

0

.

8 and for z ranges of 0.40–0.45, 0.50–0.55,and0.60–0.65.Theshapesofthemeasuredenergy dis-tributions ofthe recoil andfragmentingjets foreach sample are indistinguishable.ThereisnoevidencethathavingaJ

/

ψ

mesonas aconstituentaffectsthejetenergydistribution.

ThejetenergydistributionsarecomparedtotheFJFmodel pre-dictions inbins ofjet energy.Experimentally, the jet energy bin width



Ejetisconstrainedbythefinitejetenergyresolutionofthe

CMSapparatus, which mustbe unfolded. We use



Ejet

=

8 GeV.

TheD’Agostini unfoldingmethod [38] fromthe RooUnfold pack-age [39] isusedtoextracttheunsmeared



distribution.The pro-cedureusesaninputgenerator-leveljetenergydistribution(truth distribution) derivedfrom pythia light-quarkorgluon jets. Simu-lationshows that formeasured jet energy Ejet

>

44 GeV,the jet

reconstructionefficiencyexceeds98.5%andisconsistent with be-ing energy independent. Thus, 44 GeV is the lowest jet energy

considered in the unfolding procedure. The unfolding procedure uses theCMSjet energyresolutionandjetfinding efficiency [27] to determine the unfolded jet energy matrix and the MISS ma-trix. The latteris filled for eventsthat fail the jet efficiencytest or falloutside theunfolded jet energywindow 44–140 GeV. The methodwasvalidatedusingseveraldifferentsimulatedjetenergy input truth distributions, including a fit to the pythia shape us-ingthesumofexponentialsandtherawdataitselfinabootstrap approach.There wasnochangeinthe unfoldeddistributionsthat exceeded

σ

stat/4foranyjetenergybin.Basedonunfoldingstudies insimulationthatusedthreetosixiterations,we foundthatfour unfolding iterationsgavestablematches tothe simulationevents andshowednosensitivity todifferentchoicesfortheinput truth distribution.Based onthesimulationresults,theunfolded jet en-ergy rangeis 56

<

Ejet

<

120 GeV. This rangeisstablewhen the

inputdistributionischanged.Henceforth,Ejet willrefertothe

un-foldedquantity,unlessotherwisenoted.

The unfoldedjetenergydistributionsforthe

(

E

;

z

)

functions have bin-to-bin correlations that affect thestatistical uncertainty in



foreach jetenergybin.Thestatisticaluncertaintiesare eval-uatedbyrepeatingtheunfoldingprocedure250times,formingthe covariancematrix,anddeterminingtheuncertaintyforeachjet en-ergy bin.The statisticaluncertainties computedbythisprocedure are0.02to0.06%.Theunfoldinginz isdominatedbythe Ejet

res-olution. The changes in z from the unfolding procedure for the regionofinterest(0.40–0.65)arelessthan0.01inz.Therefore,the measured z valuesareusedinthe

(

Ejet

;

z

)

determinations. 9. Systematicuncertainties

The systematic uncertainties arise from the determination of the eventweight,based onthe J

/

ψ

meson andmuonproperties, and from a bias in the J

/

ψ

-jet association, discussed below. The systematicuncertaintyinthejetenergyscaleissmallcomparedto thejetenergyresolutionusedintheunfolding.Varyingthejet en-ergybythejetenergyscalesystematic(

<

2

.

2%)uncertaintybefore theunfoldingmadenochangeinthe



results.

The CMSstudies at

√

s

=

8 TeV usingatag-and-probe method [22,23] showthat,fortheofflinerequirementsusedinthis analy-sis,theratioofthesingle-muonefficiencyindataandMC simula-tionisconsistentwithunitywithin

<

3%,independentofpμ_T [40]. The trackingefficiencyindataandsimulationagreeto within1% per track. The dimuon vertex and trigger simulation also have 1% systematic uncertainties. The dimuon HLT trigger inefficiency varieswithpJ_T/ψ intherange4.5–7.5%.Forthefewdimuonswith

pT

>

60 GeV,it can go up to 15%. The difference between unity

(noloss)andthesimulatedHLTtriggerefficiencyisassignedasthe HLTsystematicuncertaintyforeachevent.Alloftheabove system-atic uncertainties are addedin quadratureto determinethe total systematic uncertaintyin the weight foreach event. Toestimate theimpactoftheweightsystematicuncertaintyonthe

(

Ejet

;

z1

)

function,twoadditional

(

Ejet

;

z1

)

functionsaremadeforeachz1.

Oneusesdistributionsinwhichtheweightforeacheventisraised by onestandard deviation;intheother,theeventweightis low-eredby onestandard deviation.The shifted

(

Ejet

,

z1

)

valuesare

compared tothe unshiftedvalue ineach energybin.The relative systematicuncertaintyintheeventweightrangesfrom0.2to0.9% ofthestandard-weight

(

Ejet

;

z1

)

values.

In addition,thereisa selection biasintheJ

/

ψ

mesonandjet association that disfavors the configuration when the difference

η

jet

−

η

J/ψ hasthe oppositesignto

η

jet.The biasoriginatesfrom

eventsthatarelostinthesectionon

|

η

jet

−

η

J/ψ

|

andisevaluated

fromdata.Thenumberofeventsper Ejet bininthebiasedregion

is rescaledto matchthe yieldintheunbiased region.Halfofthe differencebetweenthemeasuredandcorrectednumberofevents ineach Ejetbinisassignedasitsbiassystematicuncertainty.The

Fig. 2. Comparisonof(Ejet;z1)versusEjetfromdatawithFJFpredictionsofthetotaldifferentialcrosssection,eachnormalizedtounitarea,fortheBCKL(squares),BK

(invertedtriangles),andChao(diamonds)LDMEparametersets.Thethreez1rangesare(upperleft)z1=0.425;(upperright)z1 =0.525;(lower)z1 =0.625.Thecurves

showthedetailedenergydependenceofthepredictions.Theverticalbarsonthedatapointsarethequadraturesumofthestatisticalandsystematicuncertainties.

weightandbiassystematicuncertainties areaddedinquadrature to obtain the systematicuncertainty in

(

Ejet

;

z1

)

, which ranges

from0.3to1.0%.Theseuncertaintiesarethenaddedinquadrature withtheuncertaintyin theunfolding procedurediscussed inthe previoussection.

10. TheFJFpredictionsofthejetenergyspectrum

In this analysis, we use three z1 values: 0.425, 0.525, and

0.625. These are the centers of three nonoverlapping z

subre-gionswith



z

=

0

.

05 fromthemeasurementregion0

.

3

<

z

<

0

.

8. In these three z regions, the FJF terms have different jet en-ergydistributionsforagivenLDME parameterset.Theauthorsof Ref. [16] supplied tablesofthe normalizeddifferential cross sec-tion terms

(

d

σ

˜

i

/

dEjet dz

)

|

z1, computed for

√

s

=

8 TeV and jet radius R

=

0

.

5. The cone algorithm used for the theoretical cal-culationdoesnotintroduce asystematiceffectsince thereareno backgroundorpileup sources inthe theory.Asdescribed in Sec-tion 6, we compare the data to sum of the 1_S8

0, 3S 8

1, and 3P 8

J FJF functionsfor the LDME parameter sets from Bodwin, Chung, Kim,andLee(BCKL) [30], ButenschoenandKniehl(BK) [41], and Chao,etal.(Chao) [42].The LDMEparametersets forthesethree studies are derived from different selections of J/

ψ

meson pro-ductionmeasurements,e.g.,theBKsetincludeselectroproduction data and uses a lower J/

ψ

meson pT limit than is used in the hadroproduction-only selection of the BCKL and Chao sets. All groups report that their LDME sets yield J/

ψ

meson differential crosssectionsthat agreewiththeJ

/

ψ

mesonproductiondataon whichtheextractionswerebased.

11. ComparisonofdatawithFJFtotalcrosssectionpredictions

Inthissectionwecomparethedatawiththepredictionforthe FJF total differential cross section from each of the three LDME sets.Fig. 2showsthe normalizedjet energydistributions forthe dataandtheFJFtotalcrosssectionpredictionsforeach LDMEset

Table 1

Theχ2_{value andtheassociated p-value(inparentheses)for7}

degreesoffreedomfromthecomparisonofthedataandthe pre-dictionsforthetotalFJFcrosssectionshapeatz1=0.425,0.525,

and0.625,usingtheBCKL,theBK,andtheChaoLDMEparameter sets.

0.425 0.525 0.625

BCKL 22.2 (0.23%) 11.0 (14%) 10.7 (15%) BK 59.6 (<0.001%) 60.1 (<0.001%) 64.0 (<0.001%) Chao 267 (<0.001%) 96 (<0.001%) 164 (<0.001%)

ateachofthethreez1valuesusedintheanalysis.The

uncertain-tiesinthedataincludethe statisticalandsystematiccomponents addedinquadrature.Foreach z1,thebin-averagedFJFvaluesare

usedtocalculatethe

χ

2 _{forthecomparisonoftheFJFtotal}

differ-ential crosssectionpredictionto thedata.TheLDME calculations from Refs. [30,41,42] have normalizationuncertainties, as shown in Ref. [16]. The FJF calculations give the ratio of the cross sec-tion inasmall-z regionto thecross sectionintegral over awide

z range. The uncertainty in the predicted FJF values due to the theory normalization uncertaintyis almost completely correlated for the numerator and denominator of the ratio. The resulting theoretical uncertainty is negligible compared to the experimen-taluncertaintyinthe

(

Ejet

;

z1

)

values.We thereforeignoreitin

computingthe

χ

2 _{valuestomatchdataandtheory.The}

_χ

2 _value

andtheassociated p-valueforcomparisonofdata toeach LDME set are given in Table 1. An a priori decision was made that a model prediction is an acceptable matchto the data only ifthe

χ

2 _{p-value islargerthan0.1%forsevendegreesoffreedom.}

Oth-erwise, we say that the model doesnot matchthe data.For all threez1ranges,theFJFpredictionsusingtheBCKLLDME

parame-tersmatchdata.NeithertheBKnortheChaoLDMEparametersets describethesejet+constituentJ

/

ψ

dataforanyz1 value.

The observation that these new data on J

/

ψ

meson produc-tionasconstituentsofjetsmatchtheFJFpredictionsfortheBCKL LDME parameter set and reject two others validates the FJF

ap-proachtotreatingjetsasamajorsourceofJ

/

ψ

productioninthe gluon-richcentral region inpp interactions. It alsodemonstrates that the BCKL LDME parameter set can describe newfeatures of J

/

ψ

hadronic production at large p_TJ/ψ. The BCKL LDME param-eters were developed from a completely different data set than theseJ

/

ψ

+

jetdata,sothereisnoapriorireasontoexpectthem to havepredictedthesemeasurements. The BCKL parameters are known to predict smallJ

/

ψ

polarization [30], in agreement with experiment [10,11] for the range of pJ_T/ψ values selected in this analysis (10-40 GeV). Because this analysis studies only high-pT

J

/

ψ

mesonproductionandshowsthattheBCKLLDMEparameters describe the process andother sets do not, itsuggests a tension betweenhigh-pTJ

/

ψ

resultsandglobalcharmoniumstudies [12]. 12. TotalfractionofJ

/

ψ

mesonsfromjets

Inthissection,wedeterminewhetherjetsarethemajorsource ofpromptenergeticJ

/

ψ

mesons(EJ/ψ

>

15 GeV)inthecentral

re-gion(

|

η

jet

|

<

1).Here,Ejetreferstothemeasuredjetenergybefore

unfolding.AsshowninFig.1(upper),foreventswithaJ

/

ψ

meson andonlyoneobservedjet,(84

.

0

±

0

.

1)%oftheJ

/

ψ

candidatesare within



R

<

0

.

5 ofthat jet.Thisisconsistent withjetsbeingthe dominantsourceof J

/

ψ

productioninthiskinematicrangewhen there is at least one observed jet in the event. However, events withoneormoreobservedjetshaving pjet_T

>

25 GeV accountfor only(44

.

9

±

0

.

1)%ofthepromptJ

/

ψ

mesonsample.

To understand the source of J

/

ψ

meson events with no jets passingthepjet_T

>

25 GeV requirement,termedzero-jetevents,we note thata jetthat hasa constituentJ

/

ψ

mesoncan failthe pjet_T

threshold even though the J

/

ψ

meson is observed. For instance, whenthepjet_T thresholdisraisedfrom25to30 GeV,thefractionof zero-jeteventswithan identifiedJ

/

ψ

mesonincreasesfrom55to 65%.Forone-jeteventsindatawithpjet_T thresholdsof30,35,and 40 GeV,theobservedjetisfoundwithin



R

<

0

.

5 oftheJ

/

ψ

me-sonintheevent(84

.

0

±

0

.

2)%ofthetime,i.e.,theprobabilityofa jethavingaconstituentJ

/

ψ

mesonisindependentofpjet_T .Onlyjets withEjet

>

44 GeV passthe pjetT

>

25 GeV requirementwith100%

efficiencyover therange 0

<

|

η

jet

|

<

1. Jetshaving Ejet

<

44 GeV

cancontainobservedJ

/

ψ

mesonswithEJ/ψ

>

15 GeV,butsomeof

thesejetswillnotpassthepjet_T

>

25 GeV requirement.

In order to correct forthis effect, we fit the Ejet distribution

for jets containing a J

/

ψ

meson to the sum of two exponential functionsintherange44

<

Ejet

<

150 GeV.Weusethefit to

ex-trapolatethenumberofjetscontaininga J

/

ψ

mesontolower Ejet

values,inordertoestimatethenumberofjetswithaconstituent J

/

ψ

mesonthat would bepresent inthelower-energy region for full pTacceptance.Jetreconstructionefficiencycorrectionsarenot

applied at this stage. The FJF model is valid for z

<

0

.

8 [13]. In thedata,only(1

.

3

±

0

.

1)%ofjetshavingaconstituentJ

/

ψ

meson have z

>

0

.

8; we truncate the model at z

=

0

.

8, setting a limit of Ejet

>

19 GeV for the extrapolation. Some jets in the Ejet

=

25–44 GeV range havesufficiently large polar angles to passthe

pjet_T

>

25 GeV requirement.Thesearesubtractedfromthe extrapo-lationtoavoiddoublecounting.Thenumberofjetsfrom extrapo-lationineach 1 GeV widejetenergybini iscorrectedforthejet reconstructionefficiency



i topredict thetotalnumber Ni ofjets withenergyEi.

In order to contribute to the data sample, a jet with energy

Ei mustproduceaJ

/

ψ

mesonwithenergy Ej.Theprobability Pj fortheJ

/

ψ

mesontohaveenergy Ej istakenfromthe resultsof thisanalysis, normalizedto unity for55 bins covering therange 15

<

EJ/ψ

<

70 GeV. The totalnumber Ai ofjets withenergy Ei

that contain aJ

/

ψ

mesonwithenergyfractionzi j

=

Ej

/

Ei inthe range0.3–0.8is Ai

=

Ni 55



j=1 Pjw

(

zi j

).

(3)

The function w

(

zi j

)

istheprobability thata jetofenergy Ei will contain a J

/

ψ

meson having energy Ej. To proceed, we need a specificmodelforthejetandJ

/

ψ

kinematics.Weusethejet frag-mentation modelinRef. [13] for Ejet

=

50 GeV.Theprobability is

zeroforz

>

0

.

8.Themodelpredictsthat(43

±

3 (stat))%oftheJ

/

ψ

mesonsshouldbeaccompaniedbyzeroobservedjets,comparedto 55%foundinthedata.

There are systematic uncertainties in this result. In a private communication, theauthors ofRef. [13] alsoprovideda z

proba-bility calculation for Ejet

=

20 GeV. The modelprediction forthe

numberofzero-jeteventsusingthe20 GeV z probability calcula-tiondiffersby 3%fromthe50 GeV result.Thisdifferenceistaken as the systematicuncertainty in the z fragmentationprobability. The uncertaintyin the MC predictionof the low-energy jet effi-ciencyis13%.Wealsomadeaclosuretestbyusingthemodelto predict thenumberofobservedjetslostwhenthe jet pT

thresh-old was raised from 25to 40 GeV.The model prediction agrees withthe actual numberoflostjetsto within (3.5

±

0.1)%. How-ever, there is a jet energy dependence in the matchingbetween the data andthe prediction. Extrapolating the bin-by-binjet en-ergydependenceofthatdifferenceintothe19–44 GeV range,the closure study givesa 7% systematic uncertaintyin the predicted number of zero-jet events having jet energies less than 44 GeV. Adding the systematic uncertainties in quadrature, the predicted fractionofzero-jeteventswithaJ

/

ψ

mesonasaconstituentofa jetwithpjet_T

<

25 GeV is(43

±

3 (stat)

±

7 (syst))%.

Ifwe applythisreasoningto resultsfromSection 5,thesmall peak intherange2

.

5

<



R

<

3

.

4 inFig.1(upper)isactuallythe recoiljetinadijetpairforwhichtheparentjetoftheJ

/

ψ

meson was not observed. Thisincreasesthe fractionofJ

/

ψ

mesons that are constituentsofa jetintheone-jet samplefrom(84

.

0

±

0

.

1)% to(94

.

3

±

0

.

1)%.Withthisinterpretation,andtheresultsfrom Sec-tion5,wefindthattheone- andtwo-jetfractionsforajettohave aconstituentJ

/

ψ

mesonarebothessentially94%.Theoverall frac-tion of J

/

ψ

mesons that comefrom jetsis,then, 0.94

·

45% = 42% from events withone ormore observed jets, plus 43% from the zero-jet sample. While thezero-jet modelis simple,it passesan experimental closuretest.Also, itfollowsthetrendofthedataas thejet pTrequirementisraisedinstepsfrom25to40 GeV.Using

it,we concludethat(85

±

3 (stat)

±

7 (syst))% oftheJ

/

ψ

mesons withinourkinematicacceptance,EJ/ψ

>

15 GeV and

|

yJ/ψ

|

<

1,are

constituentsofjetswithEjet

>

19 GeV and

|

η

jet

|

<

1. 13. Summary

The first analysis has been presented comparing data for prompt J

/

ψ

mesons produced as constituents of central gluonic jetswithatheoreticalanalysisbasedonthefragmentingjet func-tion(FJF)approach.ThetermpromptmeansthattheJ

/

ψ

mesonis consistent with originating from the primary vertex. In the FJF model, the jet fragments into a cc system in an angular mo-mentum state and quark color configuration 2S+1Ln_J, plus other hadrons. Here, S, L, and J are the spin, orbital, and total angu-lar momentum quantum numbers of the cc system and n

indi-cates a color-singlet (n = 1) or color-octet (n = 8) configuration. TheFJFanalysisusesthenonrelativisticquantumchromodynamics (NRQCD)approachtocomputethecrosssectionfortheformation ofaJ

/

ψ

mesonfromthecc systemforfourspecificS, J ,L,andn

configurations:1_S8 0,3S 8 1,3S 1 1,and3P 8 J.

The data were collected by the CMS Collaboration in proton-proton collisions at

√

s

=

8 TeV, corresponding to an integrated luminosity of 19

.

1 fb−1. The kinematic selectionsfor the analy-sisare EJ/ψ

>

15 GeV,

|

yJ/ψ

|

<

1, pjetT

>

25 GeV,and

|

η

jet

|

<

1.Inz

ranges0.40–0.45,0.50–0.55,and0.60–0.65,wherez istheJ

/

ψ

me-sonfractionofthejetenergy,theshapeofthemasureddifferential crosssectionasafunctionofEjetforJ

/

ψ

mesonproductionasajet

constituentiscomparedtotheFJFpredictionforthisquantity, us-ingthreedifferentlong-distancematrixelement(LDME)parameter sets. The FJFpredictions using the Bodwin, Chung, Kim, andLee (BCKL) [30] LDMEparametersmatchthedataforallthreez ranges.

Incontrast,theFJFpredictions fortheLDME parametersetsfrom ButenschoenandKniehl(BK) [41] andChao,et al.,(Chao) [42] dis-agree with the data for all three z ranges. This establishes the abilityoftheFJFanalysisto describeJ

/

ψ

mesonproductionfrom central gluonicjetsandthe ability ofthis kindofexperiment to distinguishamongdifferentsetsofLDME parameters,allofwhich describeinclusive J

/

ψ

meson productionfortheir choice ofdata. TheBCKLLDME set,constructedusinginclusivehadronic produc-tiondatawithpJ_T/ψ

>

10 GeV,notonlydescribestheproductionof high-pT J

/

ψ

mesonsasconstituentsofjetsbutalsopredictssmall

J

/

ψ

mesonpolarization.

Whenajetisobservedinanevent,thefractionofJ

/

ψ

mesons thatare jet constituentsis(94

.

2

±

0

.

1)%,averagedover one- and two-jet events.Using a simple model to estimate the fractionof J

/

ψ

mesonsthatare constituentsofjetsthat failtheanalysis pjet_T

requirement, we find that jetsare the source of(85

±

3 (stat)

±

7 (syst))% of the J

/

ψ

mesons produced in the kinematic region probedinthisstudy.Interpretingtheresults intheframeworkof the FJF model, jet fragmentation accounts for almost all prompt J

/

ψ

mesonsproduced atlarge p_TJ/ψ.The dataare consistent with anNRQCDtreatmentoftheFJFprocess usingtheBCKLparameter set.

Declarationofcompetinginterest

Theauthorsdeclarethattheyhavenoknowncompeting finan-cialinterestsorpersonalrelationshipsthatcouldhaveappearedto influencetheworkreportedinthispaper.

Acknowledgements

WethankIraRothstein,MatthewBaumgart,andPrashant Shri-vastavafortheirhelpincreatingthetablesofthepredictionsfrom theirfragmentingjetfunctionmodeltocomparewithourdata.We thankNoraBrambillaforeditorialinputandtheoreticalguidance.

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: BMBWFandFWF(Austria);FNRS andFWO (Belgium); CNPq, CAPES, FAPERJ,FAPERGS, andFAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT(Ecuador);MoER,ERCIUT,andERDF(Estonia);Academy ofFinland,MEC,andHIP(Finland);CEAandCNRS/IN2P3(France); BMBF, DFG, and HGF (Germany); GSRT (Greece); NKFIA (Hun-gary);DAEandDST (India);IPM(Iran);SFI(Ireland);INFN (Italy); MSIPandNRF(Republic ofKorea);MES (Latvia);LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP,

andUASLP-FAI(Mexico);MOS(Montenegro);MBIE(NewZealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna);MON,ROSATOM,RAS,RFBR,andNRCKI(Russia);MESTD (Serbia);SEIDI,CPAN,PCTI,andFEDER(Spain);MoSTR (SriLanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU andSFFR (Ukraine); STFC(United Kingdom); DOEandNSF (USA).

Individuals have received support from the Marie-Curie pro-gramandtheEuropeanResearchCouncilandHorizon2020Grant, contract No. 675440 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’A-griculture (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-lence ProgramÚNKP, theNKFIA research grants 123842, 123959, 124845, 124850, and 125105 (Hungary); the Council of Science andIndustrialResearch,India; theHOMING PLUSprogram ofthe 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 EstataldeFomentodelaInvestigaciónCientíficayTécnicade Exce-lenciaMaríadeMaeztu,grantMDM-2015-0509andthePrograma Severo Ochoa del Principado de Asturias; the Thalisand Aristeia programscofinancedbyEU-ESFandtheGreekNSRF;the Rachada-pisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University and theChulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); The Welch Foundation, contractC-1845;andtheWestonHavensFoundation(USA).

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TheCMSCollaboration

A.M. Sirunyan

†

,

A. Tumasyan

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam,

F. Ambrogi,

T. Bergauer,

J. Brandstetter,

M. Dragicevic,

J. Erö,

A. Escalante Del Valle,

M. Flechl,

R. Frühwirth

1

,

M. Jeitler

1

,

N. Krammer,

I. Krätschmer,

D. Liko,

T. Madlener,

I. Mikulec,

N. Rad,

J. Schieck

1

,

R. Schöfbeck,

M. Spanring,

D. Spitzbart,

W. Waltenberger,

C.-E. Wulz

1

,

M. Zarucki

InstitutfürHochenergiephysik,Wien,Austria

V. Drugakov,

V. Mossolov,

J. Suarez Gonzalez

InstituteforNuclearProblems,Minsk,Belarus

M.R. Darwish,

E.A. De Wolf,

D. Di Croce,

X. Janssen,

A. Lelek,

M. Pieters,

H. Rejeb Sfar,

H. Van Haevermaet,

P. Van Mechelen,

S. Van Putte,

N. Van Remortel

UniversiteitAntwerpen,Antwerpen,Belgium

F. Blekman,

E.S. Bols,

S.S. Chhibra,

J. D’Hondt,

J. De Clercq,

D. Lontkovskyi,

S. Lowette,

I. Marchesini,

S. Moortgat,

Q. Python,

K. Skovpen,

S. Tavernier,

W. Van Doninck,

P. Van Mulders

D. Beghin,

B. Bilin,

H. Brun,

B. Clerbaux,

G. De Lentdecker,

H. Delannoy,

B. Dorney,

L. Favart,

A. Grebenyuk,

A.K. Kalsi,

A. Popov,

N. Postiau,

E. Starling,

L. Thomas,

C. Vander Velde,

P. Vanlaer,

D. Vannerom

UniversitéLibredeBruxelles,Bruxelles,Belgium

T. Cornelis,

D. Dobur,

I. Khvastunov

2

,

M. Niedziela,

C. Roskas,

D. Trocino,

M. Tytgat,

W. Verbeke,

B. Vermassen,

M. Vit,

N. Zaganidis

GhentUniversity,Ghent,Belgium

O. Bondu,

G. Bruno,

C. Caputo,

P. David,

C. Delaere,

M. Delcourt,

A. Giammanco,

V. Lemaitre,

A. Magitteri,

J. Prisciandaro,

A. Saggio,

M. Vidal Marono,

P. Vischia,

J. Zobec

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

F.L. Alves,

G.A. Alves,

G. Correia Silva,

C. Hensel,

A. Moraes,

P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas,

W. Carvalho,

J. Chinellato

3

,

E. Coelho,

E.M. Da Costa,

G.G. Da Silveira

4

,

D. De Jesus Damiao,

C. De Oliveira Martins,

S. Fonseca De Souza,

L.M. Huertas Guativa,

H. Malbouisson,

J. Martins

5

,

D. Matos Figueiredo,

M. Medina Jaime

6

,

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 Manganote

3

,

F. Torres Da Silva De Araujo,

A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

C.A. Bernardes

a

,

L. Calligaris

a

,

T.R. Fernandez Perez Tomei

a

,

E.M. Gregores

b

,

D.S. Lemos,

P.G. Mercadante

b

,

S.F. Novaes

a

,

Sandra

S. Padula

a

a_{UniversidadeEstadualPaulista,SãoPaulo,Brazil} b_{UniversidadeFederaldoABC,SãoPaulo,Brazil}

A. Aleksandrov,

G. Antchev,

R. Hadjiiska,

P. Iaydjiev,

M. Misheva,

M. Rodozov,

M. Shopova,

G. Sultanov

InstituteforNuclearResearchandNuclearEnergy,BulgarianAcademyofSciences,Sofia,Bulgaria

M. Bonchev,

A. Dimitrov,

T. Ivanov,

L. Litov,

B. Pavlov,

P. Petkov

UniversityofSofia,Sofia,Bulgaria

W. Fang

7

,

X. Gao

7

,

L. Yuan

BeihangUniversity,Beijing,China

Z. Hu,

Y. Wang

DepartmentofPhysics,TsinghuaUniversity,Beijing,China

M. Ahmad,

G.M. Chen,

H.S. Chen,

M. Chen,

C.H. Jiang,

D. Leggat,

H. Liao,

Z. Liu,

S.M. Shaheen

8

,

A. Spiezia,

J. Tao,

E. Yazgan,

H. Zhang,

S. Zhang

8

,

J. Zhao

InstituteofHighEnergyPhysics,Beijing,China

A. Agapitos,

Y. Ban,

G. Chen,

A. Levin,

J. Li,

L. Li,

Q. Li,

Y. Mao,

S.J. Qian,

D. Wang,

Q. Wang

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

M. Xiao

ZhejiangUniversity,Hangzhou,China

C. Avila,

A. Cabrera,

C. Florez,

C.F. González Hernández,

M.A. Segura Delgado

J. Mejia Guisao,

J.D. Ruiz Alvarez,

C.A. Salazar González,

N. Vanegas Arbelaez

UniversidaddeAntioquia,Medellin,Colombia

D. Giljanovi ´c,

N. Godinovic,

D. Lelas,

I. Puljak,

T. Sculac

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia

Z. Antunovic,

M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,

S. Ceci,

D. Ferencek,

K. Kadija,

B. Mesic,

M. Roguljic,

A. Starodumov

9

,

T. Susa

InstituteRudjerBoskovic,Zagreb,Croatia

M.W. Ather,

A. Attikis,

E. Erodotou,

A. Ioannou,

M. Kolosova,

S. Konstantinou,

G. Mavromanolakis,

J. Mousa,

C. Nicolaou,

F. Ptochos,

P.A. Razis,

H. Rykaczewski,

D. Tsiakkouri

UniversityofCyprus,Nicosia,Cyprus

M. Finger

10

,

M. Finger Jr.

10

,

A. Kveton,

J. Tomsa

CharlesUniversity,Prague,CzechRepublic

E. Ayala

EscuelaPolitecnicaNacional,Quito,Ecuador

E. Carrera Jarrin

UniversidadSanFranciscodeQuito,Quito,Ecuador

Y. Assran

11

,

12

,

S. Elgammal

12

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

S. Bhowmik,

A. Carvalho Antunes De Oliveira,

R.K. Dewanjee,

K. Ehataht,

M. Kadastik,

M. Raidal,

C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,

L. Forthomme,

H. Kirschenmann,

K. Osterberg,

M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

F. Garcia,

J. Havukainen,

J.K. Heikkilä,

T. Järvinen,

V. Karimäki,

M.S. Kim,

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,

B. Fabbro,

J.L. Faure,

F. Ferri,

S. Ganjour,

A. Givernaud,

P. Gras,

G. Hamel de Monchenault,

P. Jarry,

C. Leloup,

E. Locci,

J. Malcles,

J. Rander,

A. Rosowsky,

M.Ö. Sahin,

A. Savoy-Navarro

13

,

M. Titov

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

S. Ahuja,

C. Amendola,

F. Beaudette,

P. Busson,

C. Charlot,

B. Diab,

G. Falmagne,

R. Granier de Cassagnac,

I. Kucher,

A. Lobanov,

C. Martin Perez,

M. Nguyen,

C. Ochando,

P. Paganini,

J. Rembser,

R. Salerno,

J.B. Sauvan,

Y. Sirois,

A. Zabi,

A. Zghiche