Search for heavy resonances decaying into a vector boson and a Higgs boson in final states with charged leptons, neutrinos, and b quarks

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

heavy

resonances

decaying

into

a

vector

boson

and

a

Higgs

boson

in

final

states

with

charged

leptons,

neutrinos,

and

b

quarks

.

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:

Received25October2016

Receivedinrevisedform28December2016 Accepted15February2017

Availableonline22February2017 Editor:M.Doser

Keywords:

CMS Physics B2G Diboson VH Semileptonic

AsearchforheavyresonancesdecayingtoaHiggsbosonandavectorbosonispresented.Theanalysis isperformedusingdatasamplescollectedin2015bytheCMSexperimentattheLHCinproton–proton collisionsatacenter-of-massenergyof13 TeV,correspondingtointegratedluminositiesof2.2–2.5 fb−1_.

Thesearchisperformedinchannelsinwhichthevectorbosondecaysintoleptonicfinalstates(Z_→

νν

, W→

ν

,andZ→,with=e,

μ

),whiletheHiggsbosondecaystocollimatedbquarkpairsdetected asasinglemassivejet.Thediscriminatingpowerofajetmassrequirementandabjettaggingalgorithm are exploited to suppress the standard model backgrounds. The event yields observed in data are consistentwiththebackgroundexpectation.Inthecontextofatheoreticalmodel withaheavyvector triplet,aresonancewithmassless than2 TeVisexcludedat95%confidencelevel.Theresultsarealso interpreted in terms of limits on the parameters of the model, improving on the reach of previous searches.

©2017TheAuthor.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Thediscovery ofa HiggsbosonH attheCERN LHC[1–3] sug-geststhatthestandardmodel(SM)mechanismthatconnects elec-troweak (EW) symmetry breaking to the generation of particle massesislargelycorrect.However,therelativelylightvalueofthe HiggsbosonmassmH

=

125

.

09

±

0

.

21(stat)

±

0

.

11(syst) GeV[4–7]

leaves the hierarchy problem unsolved [8], pointing to phenom-enabeyond theSM, which could be unveiled by searches atthe LHC. Manytheories that incorporatephenomena beyond the SM postulate the existence of new heavy resonances coupled to the SMbosons.Amongthem,weaklycoupledspin-1Z [9,10]andW models[11]orstronglycoupledCompositeHiggs[12–14],and Lit-tleHiggsmodels[15–17]havebeenwidelydiscussed.

A large number of models are generalized in the heavy vec-tor triplet (HVT) framework [18], which introduces one neutral (Z)andtwoelectricallycharged(W) heavyresonances.The HVT modelisparametrizedintermsofthreeparameters:thestrength

gVofanewinteraction;thecouplingcHbetweentheheavyvector

bosons, the Higgs boson, and longitudinally polarized SM vector bosons;andthecouplingcF betweentheHVTbosonsandtheSM

fermions.In the HVTscenario, model Bwith parameters gV

=

3,

cH

=

0

.

976,andcF

=

1

.

024 [18] is used asthe benchmark.With

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

these values, the couplings of the heavy resonances to fermions and to SM bosons are similar, yielding a sizable branching frac-tionfortheheavyresonancedecayintoaSMvectorbosonW orZ (genericallylabeledasV)andaHiggsboson[18].

Bounds fromprevious searches [19–22] requirethe massesof theseresonancestobeabove1 TeV intheHVTframework.Inthis mass region, the two bosons produced in the resonance decay would have large Lorentz boosts in the laboratory frame. When decaying, each boson would generatea pair of collimated parti-cles, a distinctive signature, which can be well identified in the CMS experiment. Because of the large predicted branching frac-tion,thedecayofhigh-momentumHiggsbosonstobb finalstates isconsidered.TheHiggsbosonisreconstructedasoneunresolved jet, taggedascontaining atleastone bottom quark. Backgrounds from single quark and gluon jets are reduced by a jet mass re-quirement.Inordertodiscriminateagainstthelargemultijet back-ground,thesearchisfocusedontheleptonicdecaysofthevector bosons(Z

→

νν

,W

→

ν

,andZ

→

,with

=

e

,

μ

).

The main SM backgroundprocess is the productionof vector bosons withadditional hadronic jets (V

+

jets). The estimation of this background is based on events in signal-depleted jet mass sidebands,withatransferfunction,derivedfromsimulation,from thesidebandstothesignal-enrichedregion.Topquark production alsoaccountsforasizablecontributiontothebackgroundin1

fi-nalstates,andisdetermined fromsimulationnormalizedtodata indedicatedcontrolregions.Dibosonproductionprocesses,

includ-http://dx.doi.org/10.1016/j.physletb.2017.02.040

ingpairsofvectorbosons(VV)andtheSMproductionofaHiggs bosonandvectorboson(VH),representminorcontributionstothe overall background and are estimated from simulation. A signal wouldproduce a localized excess above a smoothly falling back-groundin the distribution ofthe kinematic variablemVH, whose

definitionandrelationshipto theresonancemassmX dependson

thefinalstate.ResultsareinterpretedinthecontextofHVT mod-elsinthebenchmarkscenario B[18].

2. Dataandsimulatedsamples

Thedatasamplesanalyzedinthisstudywerecollectedwiththe CMSdetector inproton–protoncollisions at a center-of-mass en-ergyof13 TeVduring 2015.Thesamplescorrespondtointegrated luminosities of2.2–2.5 fb−1, depending on thefinal state consid-ered.

Simulatedsignaleventsaregeneratedatleadingorder(LO) ac-cordingtothe HVTmodel B [18] withtheMadGraph5_amc@nlo v5.2.2.2 matrix element generator [23]. The Higgs boson is re-quiredtodecayintoabb pair,andthevectorbosonintoleptons. Acontributionfromvectorbosondecaysinto

τ

leptonsisalso in-cludedthroughsubsequentdecaystoe or

μ

thatsatisfytheevent selection. DifferentmX hypotheses inthe range 800to 4000 GeV

areconsidered,assuming aresonancewidthnarrowenough (0.1% oftheresonancemass)tobenegligiblewithrespecttothe exper-imental resolution.Thisapproximation isvalidina large fraction oftheHVTparameterspace,andwillbediscussedinSection8.

The analysis utilizes a set of simulated samples to character-izethemainSM backgroundprocesses.SamplesofV

+

jets events are produced withMadGraph_{5_a}mc_@nlo _{andnormalized to the} next-to-next-to-leading-order(NNLO)crosssection, computed us-ing fewz v3.1 [24]. The V boson p_T spectra are corrected to ac-count fornext-to-leading-order (NLO) QCDandEW contributions [25].TopquarkpairproductionissimulatedwiththeNLOpowheg v2generator[26–28]andrescaledtothecrosssectionvalue com-puted with Top

++

_{v2.0 [29] at NNLO. Minor SM backgrounds,} such asVV and VH production, andsingle top quark (t

+

X) pro-ductionin s-channel,t-channel, andintW associatedproduction, aresimulatedatNLOwithMadGraph5_amc@nlo.Multijet produc-tionissimulatedatleadingorderwiththesamegenerator.

Partonshoweringandhadronizationprocessesaresimulatedby interfacing theeventgenerators to pythia8.205 [30,31]withthe CUETP8M1 [32,33] tune. The NNPDF 3.0 [34] partondistribution functions(PDFs)areusedtomodelthemomentumdistributionof thecollidingpartonsinsidetheprotons.Generatedevents, includ-ing additionalproton–proton interactions within the samebunch crossing (pileup) at the level observed during 2015 data taking, areprocessedthroughafulldetectorsimulationbasedonGeant4 [35]andreconstructedwiththesamealgorithmsusedfordata.

3. CMSdetector

The central feature ofthe CMS detector is a superconducting solenoidof6 minternaldiameter.Withinthesolenoidvolumeare a silicon pixel andstrip tracker, a lead tungstate crystal electro-magnetic calorimeter(ECAL), anda brass and scintillator hadron calorimeter (HCAL), each composed of a barrel and two endcap sections.Forwardcalorimetersextendthepseudorapidity[36] cov-erage provided by the barrel and endcap detectors. Muons are measured ingas-ionizationdetectors embeddedin thesteel flux-returnyokeoutsidethesolenoid.

Thesilicontrackermeasureschargedparticleswithinthe pseu-dorapidity range

|

η

|

<

2

.

5. It consists of 1440 silicon pixel and 15 148 silicon strip detector modules andis located in the 3.8 T

field ofthe solenoid. For nonisolatedparticles of transverse mo-mentum 1

<

pT

<

10GeV and

|

η

|

<

1

.

4,the trackresolutions are

typically1.5%inpTand25–90(45–150) μminthetransverse

(lon-gitudinal) impactparameter [37]. The ECALprovides coverage up to

|

η

|

<

3

.

0. The dielectron mass resolution for Z

→

ee decays when both electrons are in the ECAL barrelis 1.9%, and is 2.9% when both electrons are in the endcaps. The HCAL covers the range of

|

η

|

<

3

.

0, which is extended to

|

η

|

<

5

.

2 through for-wardcalorimetry.Muonsaremeasuredinthepseudorapidityrange

|

η

|

<

2

.

4, with detection planes made using three technologies: drift tubes, cathodestrip chambers, andresistive-platechambers. Combiningmuontrackswithmatchingtracksmeasuredinthe sil-icon trackerresults in a pT resolution of 2–10% for muonswith

0

.

1

<

pT

<

1TeV[38].

Thefirstlevel(L1)oftheCMStriggersystem,composedof cus-tom hardware processors,uses informationfromthecalorimeters andmuondetectorstoselectthemostinterestingeventsinafixed timeintervaloflessthan4 μs.Thehigh-leveltrigger(HLT) proces-sorfarmfurtherdecreases theeventratefromaround 100 kHzto about1 kHz,beforedatastorage.

AdetaileddescriptionoftheCMSdetector,togetherwitha def-inition of thecoordinatesystemused andtherelevant kinematic variables,canbefoundinRef.[36].

4. Eventreconstruction

In CMS, a global event reconstruction is performed using a particle-flow(PF)algorithm[39,40],whichusesanoptimized com-bination of information from the various elements of the CMS detectorto reconstructandidentify individual particles produced ineach collision.The algorithmidentifieseach reconstructed par-ticleeitherasanelectron,amuon,aphoton,achargedhadron,or aneutralhadron.

ThePFcandidatesareclusteredintojetsusingtheanti-kT

algo-rithm[41]withadistanceparameterR

=

0

.

4 (AK4jets)orR

=

0

.

8 (AK8 jets). In order to suppress the contamination from pileup, charged particles not originating from the primary vertex, taken to be the one with the highest sum of p2

T over its constituent

tracks,are discarded.The residualcontaminationremovedis pro-portional to theeventenergy densityandthe jet area estimated usingtheFastJetpackage[42,43].Jetenergycorrections,extracted fromsimulation anddata inmultijet,

γ

+

jets, andZ

+

jetsevents, are applied as functionsof the transversemomentum and pseu-dorapidity tocorrectthe jetresponse andtoaccount forresidual differences between data and simulation. The jet energy resolu-tion amounts typically to 5% at 1 TeV [44]. Jets are required to pass an identification criterion, based on the jet composition in termsofthedifferentclassesofPFcandidates,inordertoremove spurious jets arising from detector noise. The pruning algorithm [45],which is designedto remove contributions from soft radia-tionandadditionalinteractions,isappliedtoAK8jets.Thepruned jet mass mj isdefinedas theinvariant mass associatedwith the

four-momentumoftheprunedjet,aftertheapplicationofthejet energycorrections[44].TheAK8jetsaresplitintotwosubjets us-ingthesoftdropalgorithm[46,47].

The combinedsecondaryvertexalgorithm [48]is usedforthe identificationofjetsthatoriginatefrombquarks(btagging). The algorithm uses thetracks andsecondary vertices associatedwith AK4jetsorAK8subjetsasinputstoaneural networktoproduce a discriminator withvaluesbetween 0and1,with highervalues indicatingahigherbquarkjetprobability.Thelooseandthetight operatingpointsareabout85and50%efficient,respectively,forb jetswithpTofabout100 GeV,withafalse-positive ratefor

The missing transverse momentum vector p

miss_T is defined as the projection of the negative vectorial sum of the momenta of allPFcandidatesonto theplane perpendiculartothe beams,and itsmagnitudeis referredto as Emiss_T . Themissinghadronic activ-ityHmiss_T isdefinedasthemagnitudeofthenegativevectorialsum ofthe transversemomentaofallAK4jetswith pT

>

20GeV.

Cor-rectionsforthe Emiss

T detectorresponseandresolutionarederived

from

γ

+

jets andZ

+

jetsevents,andapplied to simulatedevents [49].

Electronsare reconstructed in thefiducial region

|

η

|

<

2

.

5 by matching the energy deposits in the ECAL with tracks recon-structedinthetracker[50].Theelectronidentificationisbasedon thedistributionofenergydepositedalong theelectrontrajectory, thedirectionandmomentumofthetrackintheinnertracker,and itscompatibilitywiththeprimary vertexoftheevent. Additional requirements are applied to remove electrons produced by pho-tonconversions.Electronsarefurtherrequiredtobeisolatedfrom other activityin thedetector. The electronisolation parameteris definedasthesumoftransversemomentaofallthePFcandidates (excludingtheelectronitself)within

R

=

(

η

)

2

₊

_(φ)

2

_<

₀

_.

₃

aroundtheelectron direction,after thecontributionsfrompileup andotherreconstructedelectronsareremoved.Photonsare recon-structedasenergyclustersintheECAL,andaredistinguishedfrom jetsandelectronsusinginformationthatincludesisolationandthe transverseshapeoftheECALenergydeposit.

Muons are reconstructed within the acceptance of the CMS muon systems,

|

η

|

<

2

.

4, using the information from both the muonspectrometerandthesilicontracker[38].Muon candidates are identified via selection criteriabased on the compatibilityof tracks reconstructed from silicon tracker information only with tracksreconstructedfromthecombinationofthehitsinboththe trackerandmuon detector.Additional requirementsare basedon the compatibility of the trajectory with the primary vertex, and onthenumberofhitsobservedinthetrackerandmuonsystems. Themuonisolationiscomputedfromreconstructed trackswithin acone

R

<

0

.

3 aroundthe muon direction, ignoring the muon itself.

Hadronically decaying

τ

leptons are reconstructed combining oneorthreehadronicchargedPFcandidateswithuptotwo neu-tralpions,the latteralsoreconstructed bythe PFalgorithmfrom thephotonsarisingfromthe

π

0

_→

_{γ γ}

_decay[51].

5. Eventselection

Theset ofcriteria usedto identifythe Higgs bosoncandidate is the same for each event category. The highest-pT AK8 jet in

the event is required to have pT

>

200GeV and

|

η

|

<

2

.

5. The

prunedjet massmj must satisfy 105

<

mj

<

135GeV.The region

65

<

mj

<

105GeV is not used, to avoid overlaps with searches

targetingresonantVV finalstates.Inordertodiscriminateagainst the copious vector boson production in association with light-flavoredjets,eventsareclassifiedaccordingtothenumberof sub-jets(1 or 2)passingtheloosebtaggingselection;thosefailingthis requirementarediscarded.

Events are divided into categories depending on the number (0,1,or 2)andflavor (e or

μ

) ofthe reconstructedcharged lep-tons, and the presence of either 1 or 2 b-tagged subjets in the AK8jet.The twocategories withno chargedleptons are referred tocollectivelyasthezero-lepton(0

)channel.Similarly,the single-lepton (1

) and double-lepton (2

) channels each comprise four categories.Intotal,10exclusivecategoriesaredefined.

Inthe0

channel,candidatesignaleventsareexpectedtohave a large Emiss_T due to the boosted Z boson decaying into a pair of neutrinos, which escape undetected. Data are collected using triggers that require Emiss

T or HmissT greater than 90 GeV, without

including muons in the Emiss_T or Hmiss_T computation. A stringent selection is appliedto the reconstructed Emiss

T , whichis required

to begreater than 200 GeV,to ensurethat the triggerisfully ef-ficient. The copious multijet production is greatly suppressed by imposing requirementsonthe minimumazimuthal angular sepa-rationsbetweenjetsandthemissingtransversemomentumvector,

φ (

jet

,

pmiss

T

)

. All the AK8 and AK4jets in the eventmust

sat-isfy

φ (

jet

,

pmiss

T

)

>

0

.

5.TheHiggsbosonjetcandidatemustfulfill

the tighter requirement

φ (

jet

,

pmiss

T

)

>

2 and additionalcriteria

designedtoremoveeventsarisingfromdetectornoise.Events con-tainingisolatedleptonswithpT

>

10GeV,hadronically-decaying

τ

leptons with pT

>

18GeV,andphotons with pT

>

15GeV are

re-movedinordertoreduce thecontributionofotherSM processes. The tt backgroundcontributionisreducedby removing eventsin which any AK4 jet, excluding the Higgs boson jet candidate, is b tagged using the looseoperating point. Because of the lack of visibledecayproductsfromtheZ boson,reconstructionofthe res-onance mass is not directly viable. Instead, the Higgs boson jet momentumandthep

miss_T areusedtocomputethetransversemass

mT_VH

=

2Emiss_T Ejet_T

[

1

−

cos

φ (

jet

,

pmiss_T

)

]

.Thisvariableisutilized asanestimatorofmXforthe0

channel.

Events in the 1

channel are collected requiring one lepton to be reconstructed online. The pT threshold at trigger level is

105 GeV for electrons and45 GeV for muons. Offline, events are accepted if there is exactly one reconstructed electron or muon with pT larger than 135 GeV or 55 GeV, respectively, passing

re-strictive selection criteria. Events with additional leptons pass-ing looserselections, orhadronically decaying

τ

leptons, are dis-carded. Inthe single-electronchannel, multijetbackground is re-ducedbyrequiring Emiss_T

>

80GeV.Azimuthalangularseparations

φ (,

p

miss_T

)

<

2 and

φ (

jet

,

p

miss_T

)

>

2 are required to select a back-to-back topology.As for the 0

selection, eventswith addi-tionalb-taggedAK4jetsarevetoed.Thefour-momentumoftheW bosoncandidateis quantifiedusinga kinematicreconstruction of theneutrinomomentum.Thecomponentsoftheneutrino momen-tuminthetransverseplane areassumedtobeequalto p

miss_T .By constrainingtheinvariantmassofthechargedleptonandneutrino tobeequaltotheW bosonmass,aquadraticequationisderived for the longitudinal component of the neutrino momentum, pν_z. The reconstructed pν_z is chosen to be the real solution with the lower magnitude or, where both the solutions are complex, the real partwiththe lowestvalue. If theW boson has a transverse momentumgreaterthan200 GeV,itisusedtoconstructthe reso-nancecandidatemassmVH,otherwisetheeventisdiscarded.

The2

channelacceptseventscollectedwiththesametriggers asinthe1

channel.Anadditionalisolatedelectronormuonwith

pT

>

20GeV,withthesameflavorastheleadingoneandopposite

charge, isrequiredtobe reconstructedandidentified.Inorder to increasethesignalefficiency,alooseridentificationrequirementis appliedtobothelectrons,andoneofthetwomuonsisallowedto be identifiedonlyinthetracker.Iftheisolation conesofthetwo muonsoverlap,thecontributionofoneissubtractedfromthe iso-lationcalculationoftheotherineachcase.TheZ bosoncandidates are retained only if the dilepton invariant mass lies between 70 and110 GeV.ThetransversemomentumoftheZ bosoncandidate isrequiredtobeatleast200 GeV,otherwisetheeventisremoved. Additionally,theseparationin

η

and

φ

betweentheZ boson candi-dateandtheHiggsbosonjetisrequiredtosatisfy

|

η

(

Z

,

jet

)

|

<

5 and

φ (

Z

,

jet

)

>

2

.

5.Sincethett contributionissmall,novetoon additional b-taggedAK4 jetsis applied. The resonance candidate massmVHisdefinedastheinvariantmassoftheZ bosonandthe

AK8jet.

cat-egoriesforaresonancemassmX

=

1TeV,decreasingtoabout10%

formX

=

4TeV. Thisreduction isdue tothe degradationof track

reconstructionandbtaggingperformancesatverylarge pT,andto

thesmalleranglebetweenthetwobquarks,whichtendtobe re-constructedinonesinglesubjet.Thelossofefficiencyisrecovered by the 1b-tagged subjetcategories, which providean additional 10%signalefficiencyatmX

=

1TeV,and20%atmX

=

4TeV.

6. Estimatedandobservedbackground

Themainsourceofbackgroundeventsoriginatesfromthe pro-duction of a vector boson in association with jets, and the sub-sequent decay of the vector boson into one of the considered leptonic final states.This backgroundisrelevant both when gen-uinebjetsareidentifiedandwhenajetoriginatingfromalighter quarkoragluonismisidentifiedasoriginatingfromabquark.In the1

and2

channels,themaincontributionsareduetoW

→

ν

andZ

→

processes,respectively.Inthe0

channelZ

→

νν

and W

→

ν

processesaccount forapproximately60% and40% ofthe V

+

jets background, respectively. In the lattercase, the lepton is either emitted outside the detector acceptance, or is not recon-structed and identified. A sizable background originates from b jetsandW bosonsfromdecaysofpair-producedtopquarks.Minor contributionscomefromt

+

X,VV,VH,andmultijetprocesses.

Thenormalizationofthetopquarkbackground(tt andt

+

X)is determinedintopquarkenrichedcontrolregionswherethe simu-latedmj andmVHdistributionsarealsocheckedagainstdata.Four

top quark control regions are defined, depending on the number ofreconstructedleptons(0or1)andthenumberofb-tagged sub-jets(1or2).Thetopquarkcontrolregionsaredefinedbyinverting thebtaggingvetoontheAK4jetsintheevent,andbyapplyinga tightbtaggingselectiontoobtaina tt samplewithhigherpurity. Data are found to be in agreement with the shape of the sim-ulated mj andmVH distributions. Multiplicative scale factors are

[image:4.612.303.553.118.173.2]

derived for each region fromthe difference in normalization be-tween data andsimulation, after subtracting the contribution of the other backgrounds fromthe data. These factors, reported in Table 1,areappliedtocorrectthenormalizationofthett andt

+

X background.Inthe dileptonchannel,dueto thesmallnumberof events,thett normalizationandshapearetakenfromsimulation.

The contribution of the dominant V

+

jets background is esti-matedthroughaprocedurebasedondata.Signal-depletedsamples aredefined,containingeventsthatpassallselectionsdescribedin Section5apartfromtherequirementontheprunedjetmass.Two

mj sidebands (SB) are considered, andused to predict the

back-groundcontributions inthesignal region(SR).Thelower and up-persidebandsaccepteventsfallingintheranges30

<

mj

<

65GeV

and mj

>

135GeV, respectively. Analytic functions are fitted to

thedistributionsofmj foundinsimulation,consideringseparately

V

+

jets, tt andt

+

X,andallSM dibosonproductionprocesses.The

mj spectrumin V

+

jets events consistsof a smoothly falling

dis-tribution,whiledibosonsamplespresentoneortwopeaks corre-spondingtotheW/Z andHiggsbosonmasses.Topquarksamples haveinsteadone peakinthemjspectrumforhadronically

decay-ing W bosons and one for the top quark itself, in eventswhere thehadronicW bosonortopquarkisreconstructedwithinthe se-lectedAK8jet.

The shape and normalization of the mj distribution for the

mainV

+

jets backgroundisextractedfromafit ofthesumofall contributingprocesses to the SBdata,after fixing the shape and normalizationofthesubdominantbackgrounds.Thefitstothemj

distributionsareshowninFig. 1.Thenormalizationofthediboson processesisderivedfromsimulation,whilethetopquark normal-izationistakenfromthecontrolregionswiththeexceptionofthe dileptonchannels.Theprocedureisrepeatedselectingan

alterna-Table 1

Scalefactorsderivedforthenormalizationoftheestimatedtt andt+X backgrounds fromsimulation,for differenteventcategories.Electronand muoncategoriesare merged.Uncertaintiesduetothelimitedsizeoftheeventsamples(stat)andthe uncertaintyinthebtaggingefficiency(syst)arereportedseparately.

Category Scale factor Stat Syst

1 b tag 1 0.82 ±0.03 ±0.04

0 0.85 ±0.06 ±0.04

2 b tag 1 0.83 ±0.07 ±0.04

0 0.54 ±0.13 ±0.02

tivefunctiontomodelthemjdistributionforthemainbackground.

Thedifferencebetweentheresultsobtainedwiththemainandthe alternativefunctionisconsidered asasystematicuncertainty.The number of expectedandobserved events in theSR are reported separately foreach category inTable 2. Adeficit of2

.

4 standard deviationsisobservedinthe1

μ

,2btagcategory.

The shape of the V

+

jets background distribution in the mVH

variableisobtainedviaatransferfunctiondeterminedfrom simu-lationas:

α

(

mVH

)

=

Nsim_SR ,V+jets

(

mVH

)

Nsim_SB ,V+jets

(

mVH

)

(1)

where Nsim_SR,V+jets

(

mVH

)

,NSBsim,V+jets

(

mVH

)

aretwo-parameter

prob-ability densityfunctionsdetermined fromthemVH spectrainthe

SRandtheSBofthesimulatedV

+

jets sample,respectively.The ra-tio

α

(

mVH

)

accountsforthe correlationsandthesmallkinematic

differencesinvolvedintheinterpolationfromthesidebandstothe SR, andislargelyindependentoftheshape uncertaintiesandthe assumptions onthe overall cross section. The shape of the main backgroundisextractedfromdatainthemj sidebands,after

mul-tiplying theobtaineddistributionbythe

α

(

mVH

)

ratio.Theoverall

predictedbackground distributioninthe SR, N_SRpred

(

mVH

)

,isgiven

bythefollowingrelation:

N_SRpred

(

mVH

)

=

N_SBobs,V+jets

(

mVH

)

α

(

mVH

)

+

Nsim,tt_SR

(

mVH

)

+

Nsim,VVSR

(

mVH

)

(2)

where Nobs,V_SB +jets

(

mVH

)

istheprobabilitydistributionfunction

ob-tained from a fit to datain the mj sidebands of the sumof the

background components, and Nsim,tt_SR

(

mVH

)

and NSRsim,VV

(

mVH

)

are

the tt and dibosoncomponents, respectively,fixed tothe shapes andnormalizationsderived fromthesimulatedsamplesand con-trol regions. The observed data inthe SR are inagreement with thepredictedbackground,asshowninFig. 2.

Thevalidityandrobustnessofthismethodistestedondataby splitting thelower mj sidebandin twoandpredicting shape and

normalization of the intermediate sideband from the lower and upper sidebands. The number of events and distributions found in dataare compatiblewiththeprediction within thesystematic uncertainties.

The shape ofthereconstructed signal massdistribution is ex-tracted from the simulated signal samples. The signal shape is parametrized separately for each channel with a Gaussian peak and a powerlaw to modelthe lower tails. The resolutionof the reconstructedmVH isgivenbythewidthoftheGaussian corefor

the1

and2

channelsandbytheRMSofthemT

VHdistributionin

the 0

channel,andisfound tobe 10–16%,8–5%, 5–3%ofmX in

[image:5.612.101.508.80.680.2]

Fig. 1.PrunedjetmassdistributionoftheleadingAK8jetinthe0(upper),1(middle),and2(lower)categories,andseparatelyforthe1(top)and2(bottom)b-tagged subjetselections.Theshadedbandrepresentstheuncertaintyfromthefittodataintheprunedjetmasssidebands.Theobserveddataareindicatedbyblackmarkers.The dashedverticallinesseparatethelower(LSB)andupper(HSB)sidebands,theW andZ bosonsmassregion(VR),andthesignalregion(SR).Thebottompanelsreportthe pullsineachbin,(Ndata_−Nbkg_{)/σ,whereσisthePoissonuncertaintyindata.TheerrorbarsrepresentthenormalizedPoissonerrorsonthedata.(Forinterpretationofthe}

[image:6.612.90.497.81.675.2]

Fig. 2.ResonancecandidatemassmVHdistributionsinthe0(upper),1(middle),and2(lower)categories,andseparatelyforthe1(top)and2(bottom)b-taggedsubjet

selections.Theexpectedbackgroundeventsareshownwiththefilledarea,andtheshadedbandrepresentsthetotalbackgrounduncertainty.Theobserveddataareindicated byblackmarkers,andthepotentialcontributionofaresonancewithmX=2000GeV producedinthecontextoftheHVTmodelBwithgV=3 isshownwithasolidred

line.Thebottompanelsreportthepullsineachbin,(Ndata_−Nbkg_{)/σ,whereσisthePoissonuncertaintyindata.TheerrorbarsrepresentthenormalizedPoissonerrors}

[image:7.612.118.487.117.236.2]

Table 2

Expectedandobservednumbersofeventsinthesignalregion,foralleventcategories.Threeseparatesourcesof uncer-taintyintheexpectednumbersarereported:statisticaluncertaintyfromthefitprocedure(fit),theshapeofthetopquark anddibosonbackgrounddistributions(tt,VV),andthedifferencebetweenthenominalandalternativefunctionchoicefor thefit(alt.function).

Category Events Uncertainties

Observed Expected Fit tt, VV Alt. function

1 b tag 0 47 49.5 ±8.5 ±0.4 ±6.9

1e 57 73 ±23 ±1 ±6

1μ 119 123 ±8 ±1 ±5

2e 7 4.8 ±1.1 ±0.1 ±1.0

2μ 19 13.2 ±1.8 ±0.1 ±0.8

2 b tag 0 6 8.0 ±1.3 ±0.2 ±1.2

1e 7 8.7 ±1.0 ±0.3 ±0.5

1μ 14 29.5 ±3.4 ±1.0 ±0.9

2e 2 1.1 ±0.5 ±0.1 ±0.1

2μ 1 1.9 ±0.7 <0.1 ±0.3

7.Systematicuncertainties

The sensitivity of this analysis is limited by statistical rather thansystematicuncertainties.

The systematicuncertainty in the V

+

jets background yield is dominatedbythestatisticaluncertaintyassociatedwiththe num-ber ofdata events inthe mj sideband.Minor contributions arise

fromthepropagationoftheuncertaintiesintheshapeofthe func-tionmodelingthemj distributionsofthe tt andVV backgrounds.

The tt and t

+

X normalization uncertainty,in the 0

and1

cat-egories, originatesfrom thelimited numberof eventsin the top quark controlregions. The dibosonnormalizationuncertainty de-pends on the propagation of the theoretical uncertainties in the relevantphasespace,andisestimatedtobe20%.Giventherather largescalefactorobservedinthe0

,2btagtt controlregion,the topquark normalizationuncertaintyinthe 2

category is conser-vativelytakentobe50%.

The uncertainties in the V

+

jets background shape are esti-mated fromthe covariancematrix of the fit to data of the mVH

distributioninthesidebandregionsandfromtheuncertaintiesin themodelingofthe

α

(

mVH

)

ratio,whichdependsonthenumber

ofdataandsimulationevents,respectively.

Othersourcesofuncertaintyaffectboththenormalizationand shapeofthe simulatedsignal andthesubdominant backgrounds. Theuncertaintiesinthetriggerefficiencyandtheelectron,muon, and

τ

leptonreconstruction,identification, andisolation are eval-uated through specific studies ofevents withdilepton massesin theregion of the Z peak, andamount to a 6–8% uncertaintyfor thecategorieswithchargedleptons, and3% inthe 0

categories. Inthe1

and2

categories,theleptonenergyscaleandresolution arepropagatedtothesignalshape,andtheresultinguncertainties inthemeanandthewidthofthesignalmodelareestimatedtobe aslargeas16%and10%,respectively,dependingonthelepton fla-vorandsignalmass.Thejetenergyscaleandresolution[44]affect both shape and selection efficiencies. The jet energy corrections, propagatedtothejetmass,arealsotakenintoaccount,andare re-sponsiblefora5%variation inthe background,andavariationof 1–3%,depending onthemasshypothesis,inthenumberofsignal events.Thejet energyresolutionaccountsforan additional2–3% uncertainty. The effects are propagated to the mVH distributions

andconsidered asuncertainties in thesubdominant backgrounds andsignalsamples.Asaresult,inthesignalsamplea0.3% uncer-taintyisassignedtothemeanofthesignalshape,and1.0%tothe width.

Theefficiency forsignal eventsto enter theSR jet mass win-dowisevaluated withherwig[52,53]asanalternativeshowering algorithm.The7% differenceobservedwithrespecttothe default pythiashoweringistakentobethesystematicuncertainty.

Uncertainties on the b tagging efficiency [48] represent the largest source of normalization uncertainty for samples that are not normalizedtodata.Forthesignal efficiency,these uncertain-tiesintheyieldofbetween4–15%and8–30%,dependingonmVH,

are estimated in the 1 and2 b-tagged subjet categories, respec-tively;forbackgroundevents,respectiveuncertaintiesof5and12% arefoundinthetwocases.Anadditional10%btagginguncertainty isassigned tothe tt background toaccount forthe extrapolation fromthetopquarkcontrolregiontotheSR.

The factorization and renormalization scale uncertainties as-sociated withthe event generators are estimated by varying the corresponding scales up anddown by a factor of 2, andare re-sponsiblefora5%normalizationvariationintheestimateddiboson background. The effectof thesescale uncertainties is propagated to the tt and VV backgrounddistributions, and thedifference in the mVH distribution parameters is takenas an additional shape

uncertainty.Theeffectonthesignalshape modelingisnegligible, and the resulting normalizationuncertainty is 4–12%, depending onmVH.

Additional systematicuncertaintiesaffecting thenormalization ofbackgroundsandsignalfrompileupcontributions(3and0.5%), integratedluminosity(2.7%)[54],Emiss_T scaleandresolution(1%in the 0

channel),andthe choice of PDFs[55] (3% foracceptance, and4–18%forsignalnormalization)arealsoincludedinthe anal-ysis.

8. Resultsandinterpretation

Results are obtainedfrom a combined signal and background fit to the unbinned mVH distribution, based on a profile

likeli-hood. Systematic uncertainties are treated as nuisance parame-tersand areprofiled inthe statisticalinterpretation [56–59].The background-onlyhypothesisistestedagainsttheX

→

VH signalin thetencategories.Theasymptoticmodified frequentistmethodis usedtodeterminelimitsat95%confidencelevel(CL)onthe contri-butionfromsignal.Limitsarederivedontheproductofthecross sectionforaheavyvectorbosonX andthebranchingfractionsfor thedecaysX

→

VH andH

→

bb,denoted

σ

(

X

)

B

(

X

→

VH

)

B

(

H

→

bb

)

.Nospecificassumptionismadeon

B

(

H

→

bb

)

,sincethis de-caychannelhasnotyetbeenmeasured.The0

and2

categories are combined to provide upper limitsfor the casewhere X is a heavyspin-1vectorsingletZ,inthenarrow-widthapproximation. Similarlythe1

categoriesare combinedtoprovidelimitsforthe casewhereX is a heavyW.Theexclusionlimitsare reportedin Fig. 3.These limitsareverified withthemodified frequentist CLs

[image:8.612.52.261.63.367.2]

Fig. 3.Observedandexpected95%CLupperlimitsonσ(Z)B(Z→ZH)B(H→bb)

(top)andσ(W)B(W→WH)B(H→bb)(bottom)asafunctionoftheresonance massforasinglenarrowspin-1resonance,includingallstatisticalandsystematic uncertainties.Theinner greenandouteryellowbandsrepresentthe±1 and±2 standard deviationuncertaintiesonthe expectedlimit.The redsolidcurve cor-respondstothe crosssectionspredictedbythe HVTmodel B with gV=3.(For

interpretationofthereferencestocolorinthisfigurelegend,thereaderisreferred tothewebversionofthisarticle.)

The result of this study is primarily interpreted in the con-text of a simplified model with a triplet of heavy vector bosons (V±,V0_{)[18].Thepredictions ofthebenchmark model Bare}

su-perimposedon the exclusion limitsin Fig. 3. All the 0

, 1

, and 2

channelsarecombinedtoputstringentexclusionlimitsonthe HVTmodel,scenario B, assuming theZ andW crosssectionsas predictedby themodel.Therearenormalizationincreasescaused by eventmigrationbetweenthe leptonic channels, whichare es-timated to be 5–10% in the 0

channel, due to mis-assignedW events,and lessthan 1% in the 1

channel, due to mis-assigned Zevents.Fig. 4presentstheexclusionlimitsasafunction ofthe heavy tripletmass.AresonancewithmX

2

.

0TeV isexcluded at

95%CLintheHVTmodel B.

TheexclusionlimitshowninFig. 4canbeinterpretedasalimit inthe

gVcH

,

g2cF

/

gV

planeoftheHVTparameters,whereg rep-resentstheelectroweakcouplingconstant.Theexcluded regionof the parameter space for narrow resonances relative to the com-bination of all the considered channels is shown in Fig. 5. The fraction of the parameter space where the natural width of the resonances is larger than the typical experimental resolution of 5%,andthusthenarrowwidthapproximation isnotvalid,isalso indicated in Fig. 5. The exclusion ofthe parameter space signifi-cantlyimprovesonthereachof

√

s

=

8TeV searchesinthe1

[22] andall-hadronicchannels[20].Thesensitivityisequivalentwithin the statistical and systematic uncertainties to the corresponding

√

s

=

13TeV searchfromATLAS[60].

Fig. 4.Observedandexpected95%CLupperlimitwiththe±1 and±2 standard deviationuncertaintybandsonσ(X)B(X→VH)B(H→bb)intheHVTmodel B benchmarkscenariowithgV=3 asafunctionoftheresonancemass,forthe

[image:8.612.323.528.66.219.2]

combi-nationofalltheconsideredchannels.(Forinterpretationofthecolorsinthisfigure, thereaderisreferredtothewebversionofthisarticle.)

Fig. 5.ObservedexclusionintheHVTparameterplanegVcH,g2cF/gVforthree

differentresonancemasses(1.5,2.0,and2.5 TeV).TheparametergVrepresentsthe

couplingstrengthofthenewinteraction,cHthecouplingbetweentheHVTbosons

and theHiggsboson andlongitudinally polarizedSMvector bosons,andcF the

couplingbetweentheheavyvectorbosonsandtheSMfermions.Thebenchmark scenario BwithgV=3 isrepresentedbytheredpoint.Thegrayshadedarea

cor-respondstotheregionwheretheresonancenaturalwidthispredictedtobelarger thanthetypicalexperimentalresolution(5%),andthusthenarrow-width approx-imationbreaksdown.(Forinterpretationofthereferencestocolorinthisfigure legend,thereaderisreferredtothewebversionofthisarticle.)

9. Summary

A search for a heavy resonance with mass between 800 and 4000 GeV, decaying into a vector boson and a Higgs boson, has been described.The datasampleswere collected by theCMS ex-periment at

√

s

=

13TeV during 2015, and correspond to inte-gratedluminositiesof2.2–2.5 fb−1,dependingonthechannel.The final statesexplored includetheleptonicdecaymodesofthe vec-torboson,eventswithzero(Z

→

νν

), exactlyone(W

→

ν

),and two (Z

→

) charged leptons, with

=

e

,

μ

. Higgs bosons are reconstructedfromtheirdecaystobb pairs.Dependingonthe res-onance mass,upperlimits inthe range10–200 fb areset on the productofthecrosssectionforanarrowspin-1resonanceandthe branchingfractionsforthedecayoftheresonanceintoaHiggsand avectorboson,andforthedecayoftheHiggsbosonintoapairof b quarks.Resonanceswithmasseslower than2 TeV areexcluded withintheheavyvectortripletmodelinthebenchmarkscenario B with gV

=

3.Theseresultsrepresentasignificantreductioninthe

[image:8.612.328.525.283.431.2]

Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrativestaffs atCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentersand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythecomputinginfrastructure essential toour analyses. Finally, we acknowledge the enduring support for the construc-tionandoperationofthe LHCandtheCMSdetectorprovided by thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIEN-CIAS(Colombia);MSESandCSF(Croatia);RPF(Cyprus);SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Fin-land,MEC,andHIP(Finland);CEAandCNRS/IN2P3(France);BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hun-gary);DAEandDST (India);IPM(Iran);SFI(Ireland);INFN (Italy); MSIPandNRF (RepublicofKorea);LAS(Lithuania);MOE andUM (Malaysia); BUAP,CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland);FCT (Portugal);JINR (Dubna); MON, RosAtom,RAS, and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA(Thailand); TUBITAK and TAEK(Turkey); NASU andSFFR(Ukraine);STFC(UnitedKingdom);DOEandNSF(USA).

Individuals have received support from the Marie-Curie pro-gram and the European Research Council and EPLANET (Euro-pean Union); the Leventis Foundation; the Alfred P. Sloan Foun-dation; 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’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technolo-gie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS)of the CzechRepublic; the Councilof Science and Indus-trial Research, India; the HOMING PLUS program of the Foun-dation for Polish Science, cofinanced from European Union, Re-gional Development Fund, the Mobility Plus program of the Ministry of Science and Higher Education, the National Sci-ence Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2013/11/B/ST2/04202, 2014/13/B/ST2/02543 and 2014/15/B/ST2/03998,Sonata-bis2012/07/E/ST2/01406; theThalis andAristeiaprograms cofinancedbyEU-ESFandtheGreekNSRF; the National Priorities Research Program by Qatar National Re-search Fund;the ProgramaClarín-COFUND del Principado de As-turias;theRachadapisekSompotFundforPostdoctoralFellowship, Chulalongkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); andthe WelchFoundation,contractC-1845.

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TheCMSCollaboration

V. Khachatryan,

A.M. Sirunyan,

A. Tumasyan

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam,

E. Asilar,

T. Bergauer,

J. Brandstetter,

E. Brondolin,

M. Dragicevic,

J. Erö,

M. Flechl,

M. Friedl,

R. Frühwirth

1

,

V.M. Ghete,

C. Hartl,

N. Hörmann,

J. Hrubec,

M. Jeitler

1

,

A. König,

I. Krätschmer,

D. Liko,

T. Matsushita,

I. Mikulec,

D. Rabady,

N. Rad,

B. Rahbaran,

H. Rohringer,

J. Schieck

1

,

J. Strauss,

W. Waltenberger,

C.-E. Wulz

1

InstitutfürHochenergiephysik,Wien,Austria

O. Dvornikov,

V. Makarenko,

V. Zykunov

InstituteforNuclearProblems,Minsk,Belarus

V. Mossolov,

N. Shumeiko,

J. Suarez Gonzalez

NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus

S. Alderweireldt,

E.A. De Wolf,

X. Janssen,

J. Lauwers,

M. Van De Klundert,

H. Van Haevermaet,

P. Van Mechelen,

N. Van Remortel,

A. Van Spilbeeck

S. Abu Zeid,

F. Blekman,

J. D’Hondt,

N. Daci,

I. De Bruyn,

K. Deroover,

N. Heracleous,

S. Lowette,

S. Moortgat,

L. Moreels,

A. Olbrechts,

Q. Python,

S. Tavernier,

W. Van Doninck,

P. Van Mulders,

I. Van Parijs

VrijeUniversiteitBrussel,Brussel,Belgium

H. Brun,

B. Clerbaux,

G. De Lentdecker,

H. Delannoy,

G. Fasanella,

L. Favart,

R. Goldouzian,

A. Grebenyuk,

G. Karapostoli,

T. Lenzi,

A. Léonard,

J. Luetic,

T. Maerschalk,

A. Marinov,

A. Randle-conde,

T. Seva,

C. Vander Velde,

P. Vanlaer,

R. Yonamine,

F. Zenoni,

F. Zhang

2

UniversitéLibredeBruxelles,Bruxelles,Belgium

A. Cimmino,

T. Cornelis,

D. Dobur,

A. Fagot,

G. Garcia,

M. Gul,

D. Poyraz,

S. Salva,

R. Schöfbeck,

A. Sharma,

M. Tytgat,

W. Van Driessche,

E. Yazgan,

N. Zaganidis

GhentUniversity,Ghent,Belgium

H. Bakhshiansohi,

C. Beluffi

3

,

O. Bondu,

S. Brochet,

G. Bruno,

A. Caudron,

S. De Visscher,

C. Delaere,

M. Delcourt,

B. Francois,

A. Giammanco,

A. Jafari,

P. Jez,

M. Komm,

V. Lemaitre,

A. Magitteri,

A. Mertens,

M. Musich,

C. Nuttens,

K. Piotrzkowski,

L. Quertenmont,

M. Selvaggi,

M. Vidal Marono,

S. Wertz

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

N. Beliy

UniversitédeMons,Mons,Belgium

W.L. Aldá Júnior,

F.L. Alves,

G.A. Alves,

L. Brito,

C. Hensel,

A. Moraes,

M.E. Pol,

P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas,

W. Carvalho,

J. Chinellato

4

,

A. Custódio,

E.M. Da Costa,

G.G. Da Silveira

5

,

D. De Jesus Damiao,

C. De Oliveira Martins,

S. Fonseca De Souza,

L.M. Huertas Guativa,

H. Malbouisson,

D. Matos Figueiredo,

C. Mora Herrera,

L. Mundim,

H. Nogima,

W.L. Prado Da Silva,

A. Santoro,

A. Sznajder,

E.J. Tonelli Manganote

4

,

A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahuja

a

,

C.A. Bernardes

b

,

S. Dogra

a

,

T.R. Fernandez Perez Tomei

a

,

E.M. Gregores

b

,

P.G. Mercadante

b

,

C.S. Moon

a

,

S.F. Novaes

a

,

Sandra S. Padula

a

,

D. Romero Abad

b

,

J.C. Ruiz Vargas

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

A. Aleksandrov,

R. Hadjiiska,

P. Iaydjiev,

M. Rodozov,

S. Stoykova,

G. Sultanov,

M. Vutova

InstituteforNuclearResearchandNuclearEnergy,Sofia,Bulgaria

A. Dimitrov,

I. Glushkov,

L. Litov,

B. Pavlov,

P. Petkov

UniversityofSofia,Sofia,Bulgaria

W. Fang

6

BeihangUniversity,Beijing,China

M. Ahmad,

J.G. Bian,

G.M. Chen,

H.S. Chen,

M. Chen,

Y. Chen

7

,

T. Cheng,

C.H. Jiang,

D. Leggat,

Z. Liu,

F. Romeo,

S.M. Shaheen,

A. Spiezia,

J. Tao,

C. Wang,

Z. Wang,

H. Zhang,

J. Zhao

InstituteofHighEnergyPhysics,Beijing,China

Y. Ban,

G. Chen,

Q. Li,

S. Liu,

Y. Mao,

S.J. Qian,

D. Wang,

Z. Xu

C. Avila,

A. Cabrera,

L.F. Chaparro Sierra,

C. Florez,

J.P. Gomez,

C.F. González Hernández,

J.D. Ruiz Alvarez,

J.C. Sanabria

UniversidaddeLosAndes,Bogota,Colombia

N. Godinovic,

D. Lelas,

I. Puljak,

P.M. Ribeiro Cipriano,

T. Sculac

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia

Z. Antunovic,

M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,

D. Ferencek,

K. Kadija,

S. Micanovic,

L. Sudic,

T. Susa

InstituteRudjerBoskovic,Zagreb,Croatia

A. Attikis,

G. Mavromanolakis,

J. Mousa,

C. Nicolaou,

F. Ptochos,

P.A. Razis,

H. Rykaczewski,

D. Tsiakkouri

UniversityofCyprus,Nicosia,Cyprus

M. Finger

8

,

M. Finger Jr.

8

CharlesUniversity,Prague,Czechia

E. Carrera Jarrin

UniversidadSanFranciscodeQuito,Quito,Ecuador

E. El-khateeb

9

,

S. Elgammal

10

,

A. Mohamed

11

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

B. Calpas,

M. Kadastik,

M. Murumaa,

L. Perrini,

M. Raidal,

A. Tiko,

C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,

J. Pekkanen,

M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Härkönen,

T. Järvinen,

V. Karimäki,

R. Kinnunen,

T. Lampén,

K. Lassila-Perini,

S. Lehti,

T. Lindén,

P. Luukka,

J. Tuominiemi,

E. Tuovinen,

L. Wendland

HelsinkiInstituteofPhysics,Helsinki,Finland

J. Talvitie,

T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon,

F. Couderc,

M. Dejardin,

D. Denegri,

B. Fabbro,

J.L. Faure,

C. Favaro,

F. Ferri,

S. Ganjour,

S. Ghosh,

A. Givernaud,

P. Gras,

G. Hamel de Monchenault,

P. Jarry,

I. Kucher,

E. Locci,

M. Machet,

J. Malcles,

J. Rander,

A. Rosowsky,

M. Titov,

A. Zghiche

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

A. Abdulsalam,

I. Antropov,

S. Baffioni,

F. Beaudette,

P. Busson,

L. Cadamuro,

E. Chapon,

C. Charlot,

O. Davignon,

R. Granier de Cassagnac,

M. Jo,

S. Lisniak,

P. Miné,

M. Nguyen,

C. Ochando,

G. Ortona,

P. Paganini,

P. Pigard,

S. Regnard,

R. Salerno,

Y. Sirois,

T. Strebler,

Y. Yilmaz,

A. Zabi

LaboratoireLeprince-Ringuet,EcolePolytechnique,IN2P3-CNRS,Palaiseau,France

J.-L. Agram

12

,

J. Andrea,

A. Aubin,

D. Bloch,

J.-M. Brom,

M. Buttignol,

E.C. Chabert,

N. Chanon,

C. Collard,

E. Conte

12

,

X. Coubez,

J.-C. Fontaine

12

,

D. Gelé,

U. Goerlach,

A.-C. Le Bihan,

K. Skovpen,

P. Van Hove

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,

C. Bernet,

G. Boudoul,

E. Bouvier,

C.A. Carrillo Montoya,

R. Chierici,

D. Contardo,

B. Courbon,

P. Depasse,

H. El Mamouni,

J. Fan,

J. Fay,

S. Gascon,

M. Gouzevitch,

G. Grenier,

B. Ille,

F. Lagarde,

I.B. Laktineh,

M. Lethuillier,

L. Mirabito,

A.L. Pequegnot,

S. Perries,

A. Popov

13

,

D. Sabes,

V. Sordini,

M. Vander Donckt,

P. Verdier,

S. Viret

UniversitédeLyon,UniversitéClaudeBernardLyon1,CNRS-IN2P3,InstitutdePhysiqueNucléairedeLyon,Villeurbanne,France

A. Khvedelidze

8

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze

8

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann,

S. Beranek,

L. Feld,

A. Heister,

M.K. Kiesel,

K. Klein,

M. Lipinski,

A. Ostapchuk,

M. Preuten,

F. Raupach,

S. Schael,

C. Schomakers,

J. Schulz,

T. Verlage,

H. Weber,

V. Zhukov

13

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

A. Albert,

M. Brodski,

E. Dietz-Laursonn,

D. Duchardt,

M. Endres,

M. Erdmann,

S. Erdweg,

T. Esch,

R. Fischer,

A. Güth,

M. Hamer,

T. Hebbeker,

C. Heidemann,

K. Hoepfner,

S. Knutzen,

M. Merschmeyer,

A. Meyer,

P. Millet,

S. Mukherjee,

M. Olschewski,

K. Padeken,

T. Pook,

M. Radziej,

H. Reithler,

M. Rieger,

F. Scheuch,

L. Sonnenschein,

D. Teyssier,

S. Thüer

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

V. Cherepanov,

G. Flügge,

F. Hoehle,

B. Kargoll,

T. Kress,

A. Künsken,

J. Lingemann,

T. Müller,

A. Nehrkorn,

A. Nowack,

I.M. Nugent,

C. Pistone,

O. Pooth,

A. Stahl

14

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,

T. Arndt,

C. Asawatangtrakuldee,

K. Beernaert,

O. Behnke,

U. Behrens,

A.A. Bin Anuar,

K. Borras

15

,

A. Campbell,

P. Connor,

C. Contreras-Campana,

F. Costanza,

C. Diez Pardos,

G. Dolinska,

G. Eckerlin,

D. Eckstein,

T. Eichhorn,

E. Eren,

E. Gallo

16

,

J. Garay Garcia,

A. Geiser,

A. Gizhko,

J.M. Grados Luyando,

P. Gunnellini,

A. Harb,

J. Hauk,

M. Hempel

17

,

H. Jung,

A. Kalogeropoulos,

O. Karacheban

17

,

M. Kasemann,

J. Keaveney,

C. Kleinwort,

I. Korol,

D. Krücker,

W. Lange,

A. Lelek,

J. Leonard,

K. Lipka,

A. Lobanov,

W. Lohmann

17

,

R. Mankel,

I.-A. Melzer-Pellmann,

A.B. Meyer,

G. Mittag,

J. Mnich,

A. Mussgiller,

E. Ntomari,

D. Pitzl,

R. Placakyte,

A. Raspereza,

B. Roland,

M.Ö. Sahin,

P. Saxena,

T. Schoerner-Sadenius,

C. Seitz,

S. Spannagel,

N. Stefaniuk,

G.P. Van Onsem,

R. Walsh,

C. Wissing

DeutschesElektronen-Synchrotron,Hamburg,Germany

V. Blobel,

M. Centis Vignali,

A.R. Draeger,

T. Dreyer,

E. Garutti,

D. Gonzalez,

J. Haller,

M. Hoffmann,

A. Junkes,

R. Klanner,

R. Kogler,

N. Kovalchuk,

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14

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H. Tholen,

D. Troendle,

E. Usai,

L. Vanelderen,

A. Vanhoefer,

B. Vormwald

UniversityofHamburg,Hamburg,Germany

M. Akbiyik,

C. Barth,

S. Baur,

C. Baus,

J. Berger,

E. Butz,

R. Caspart,

T. Chwalek,

F. Colombo,

W. De Boer,

A. Dierlamm,

S. Fink,

R. Friese,

M. Giffels,

A. Gilbert,

P. Goldenzweig,

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F. Hartmann

14

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