Search for a W ' boson decaying to a tau lepton and a neutrino in proton-proton collisions at root s=13 TeV

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https://www.sciencedirect.com/science/article/pii/S0370269319301820

DOI: 10.1016/j.physletb.2019.01.069

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©2019

by Elsevier. All rights reserved.

DIRETORIA DE TRATAMENTO DA INFORMAÇÃO

Cidade Universitária Zeferino Vaz Barão Geraldo

CEP 13083-970 – Campinas SP

Fone: (19) 3521-6493

http://www.repositorio.unicamp.br

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

a

W



boson

decaying

to

a

τ

lepton

and

a

neutrino

in

proton-proton

collisions

at

√

s

=

13

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:

Received30July2018

Receivedinrevisedform30January2019 Accepted31January2019

Availableonline15March2019 Editor:M.Doser Keywords: CMS Physics Tau MET

A search for a new high-mass resonance decaying to a

τ

lepton and a neutrino is reported. The analysisusesproton-protoncollisiondata collectedbytheCMSexperimentattheLHCat√s=13TeV, corresponding to an integrated luminosity of 35.9 fb−1_{. The search utilizes hadronically decaying}

_τ

leptons. No excess in the event yield is observed at high transverse masses of the

τ

and missing transverse momentum.Aninterpretation ofresultswithinthe sequentialstandard modelexcludesW boson massesbelow 4.0 TeV at 95% confidencelevel. Existinglimits are also improvedonmodels in whichthe W bosondecays preferentiallytofermions ofthethird generation.HeavyW bosonswith masseslessthan1.7–3.9 TeV,dependingonthecouplinginthenon-universalG(221)model,areexcluded at95%confidencelevel.Thesearethemoststringentlimitsonthismodeltodate.

©2019TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense

(http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3.

1. Introduction

Newchargedheavy gauge bosons, generallyreferred to asW bosons,arepredictedbyvariousextensionsofthestandardmodel (SM). An example is the sequential standard model (SSM) [1], featuring an extended gauge sector, which is often used as a benchmarkmodel.LeptonuniversalityholdsintheSSM;however, there exist models without this assumption. Nonuniversal gauge interaction models (NUGIMs) [2–6] predict an enhanced W bo-son branching fraction to the third generation fermions. In this approach,thehightopquarkmassisassociatedwiththelarge vac-uumexpectationvalueofthecorrespondingHiggsfield.

The analysis presented in this Letter searches for W

→

τ ν

events,wherethe

τ

leptondecayshadronically.Theleadingorder FeynmandiagramisshowninFig.1.InthisLetter,thesymbol

τ

h

willbeusedtodenotethevisiblepartofthehadronicdecayofthe

τ

,whichisreconstructedasa

τ

jetinthedetector.The hadronic decaysofthe

τ

leptonareexperimentallydistinctivebecausethey result in low charged-hadron multiplicity, unlike jets originating fromthehadronizationofpartonsproducedinthehardscattering process,which havehigh charged-hadronmultiplicity.The signa-tureofaW bosoneventissimilartothatofa W bosoneventin whichtheW bosonisproduced“off-shell”withahighmass.

SearchesforaWbosondecayingtoa

τ

leptonandaneutrino havebeenperformedpreviouslybytheCMS [7] andATLAS [8]

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

Fig. 1. Leading order Feynman diagram of the expected signal process W→τ ν.

laborationsatthe CERNLHC.Searches fora W boson havebeen performedalsoine

+

pmiss_T ,

μ

+

pmiss_T [9,10],WZ [11,12],qq [13, 14] and tb [15,16] channels.The ATLAS experimenthasexcluded anSSMWformassesbelow3.7 TeV inthe

τ

h

+

pmissT channel.The

CMSexperimenthasexcludedanSSMWformassesbelow5.2 TeV inthecombinationofelectronandmuonchannels.ThisLetter de-scribes a search fora W boson inthe

τ

h

+

pmissT channel using

proton-proton (pp)collisionscollectedin2016atacenter-of-mass energyof13 TeV.Thedatasetcorrespondstoan integrated lumi-nosity of 35.9 fb−1.The results are interpreted in the context of twomodels,theSSMandtheNUGIM.

2. Physicsmodels

2.1. ThesequentialstandardmodelWboson

In theSSM, the W boson is a heavy analog ofthe W boson. Itisaresonancewithfermionicdecaymodesandbranching frac-https://doi.org/10.1016/j.physletb.2019.01.069

0370-2693/©2019TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

tions similar to those of the SM W boson, with the addition of thedecayW

→

tb,whichbecomesrelevantforW bosonmasses largerthan180 GeV.IftheWbosonisheavyenough todecayto topandbottom quarks,theSSMbranchingfractionforthe decay W

→

τ ν

is8.5% [1].Undertheseassumptions, therelativewidth

/

M ofthe W bosonis

∼

3.3%. Withincreasingmass,a growing fractionofeventsisproduced off-shell andshifted tolowermass values.Assumingeventswithinawindowof

±

10%aroundthe ac-tualmassto beon-shell,theoff-shellfractionsare approximately 9,22and66%forWmassesof1,3and5 TeV,respectively.Decays intoWZ depend onthe specificmodelassumptions andare usu-allyconsidered to be suppressed in theSSM, asassumedby the currentsearch.

Inaccordancewithpreviousanalyses, itisassumedthatthere isnointerferencebetweentheproductionofthenewparticleand theproductionoftheSMW boson.Suchanabsenceofinterference wouldoccur,forexample,iftheWinteractsviaV+Acoupling [17]. Signal events forthe SSM W boson are simulatedat leading order (LO) with pythia 8.212 [18], using the NNPDF 2.3 [19,20] parton distribution function (PDF) set and tune CUETP8M1 [21]. The W samples are normalized to next-to-next-to-leading-order (NNLO)crosssectionsfrom fewz [22,23].

2.2. Couplingstrength

The W bosoncouplingstrength, gW, isgivenintermsofthe

SM weak coupling strength gW

=

e

/

sin2

θ

W

≈

0.65. Here,

θ

W is

the weak mixing angle. If the W is a heavier copy of the SM W boson, their coupling ratio is gW

/

gW

=

1 and the SSM W

theoretical cross sections,signal shapes, andwidths apply. How-ever,different couplingsare possible. Becauseof the dependence ofthewidthofa particleonitscoupling,andtheconsequent ef-fectonthetransversemassdistribution,alimitcanalsobeseton the couplingstrength. For thisstudy, a reweighting procedure is used.SomeselectedsignalsamplesaresimulatedatLOwith Mad-Graph_{(version 1.5.11)[24],forarangeofcouplingratios gW}

/

gW

from0.01 to 3.These signals exhibit different widths aswell as different cross sections. The generated distributions of the SSM pythiasampleswith g_W

/

gW

=

1 arereweighted to takeinto

ac-countthedecaywidthdependence,thusprovidingtheappropriate reconstructed transverse mass distributions for gW

/

gW

=

1. For

gW

/

gW

=

1,thetheoreticalLOcrosssectionsapply andthis

cou-plingstrengthisusedtocomparethestandardSSMsampleswith thereweightedones,allowingthereweightingmethodtobe veri-fied.

2.3. Nonuniversalgaugeinteractionmodel

Models with nonuniversal couplings predict an enhanced branchingfractionforthethirdgenerationoffermionsandexplain thelarge massof thetop quark. The nonuniversalgauge interac-tionmodels(NUGIMs)exhibitaSU

(2)

l

×

SU

(2)

h

×

U

(1)

symmetry,

andthusareoftencalledG(221)models.Heretheindiceslandh refertolightandheavy,respectively.TheweakSM SU

(2)

W group

is a low-energy limit oftwo gauge groups, a light SU

(2)

l anda

heavy SU

(2)

h, which govern the couplings to the light fermions

ofthefirsttwogenerationsandtotheheavyfermionsofthethird generation,respectively.Thesetwogroupsmix,resultinginan SM-likeSU

(2)

Wandanextendedgroup SU

(2)

E.TheSU

(2)

Eextended

gauge group gives rise to additionalgauge bosons such asa W. The mixing of the two gauge groupsinvolves a mixing angle of theextendedgroup,

θ

E,whichmodifiesthecouplingstotheheavy

boson.Consequently,themixingmodifiestheproductioncross sec-tion and, as illustrated in Fig. 2, the branching fractions of the

Fig. 2. BranchingfractionsB(W)asafunctionofthemixinganglecotθE,forW

bosondecaysintheNUGIMG(221)framework,ascalculatedinRefs. [2,25,26].For cotθE=1 thevaluescorrespondtothoseintheSSM,rescaledtoaccommodatethe

WH decaychannel.

W. For cotθE



3 the W decayspredominantly to third

genera-tion fermions. The branching fraction to WH issmaller than the branchingfractiontothirdgenerationfermions,asshowninFig.2. ForcotθE

=

1 thebranchingfractionsarethesameasthoseofthe

SSM,andtheW bosoncouplesdemocraticallytoallfermions.For cot

θ

E

<

1 thedecaysintolightfermionsaredominant.

IntheNUGIMG(221),theratioofthecouplings gW

/

gW is

re-latedtotheparametercot

θ

Ebythefollowingequation [26]:



W

= 

SSMW

(

4

+

1₄

)

cot2

θ

E

+

8 tan2

θ

E 12

+

1₄

= 

SSM W



gW gW



2 (1) Becauseofthisfunctionalrelationship,areinterpretation oflimits oncouplingstrengthwillyieldlimitsonNUGIMG(221),andthus itwasnotnecessarytogenerateasignalsampleforthismodel.

3. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ing solenoid of6 m internal diameter, providing a magneticfield of 3.8 T. Withinthesolenoidvolume are a siliconpixeland strip tracker,aleadtungstatecrystalelectromagneticcalorimeter(ECAL), andabrassandscintillatorhadron calorimeter(HCAL),each com-posed ofa barrelandtwo endcapsections. Forwardcalorimeters extendthepseudorapidity(

η

)coverageprovidedbythebarreland endcapdetectors. Muonsaredetected ingas-ionization chambers embeddedinthesteelflux-returnyokeoutsidethesolenoid.

Thesilicontrackermeasureschargedparticleswithintherange

|

η

|

<

2.5.It consistsof1440siliconpixel and15 148silicon strip detector modules. For nonisolated particles with transverse mo-mentum 1

<

pT

<

10GeV and

|

η

|

<

1.4,the trackresolutions are

typically 1.5% in pT and 25–90 μm in the transverse impact

pa-rameterand45–150 μminthelongitudinalimpactparameter.The ECALconsistsof75 848leadtungstatecrystals,whichprovide cov-erage of

|

η

|

<

1.48 in a barrel region (EB) and 1.48

<

|

η

|

<

3.0 in two endcapregions (EE). The HCALis a samplingcalorimeter, whichutilizesalternating layersofbrassasan absorberand plas-ticscintillatorasactivematerial,coveringtherange

|

η

|

<

3.Inthe forward region, the calorimetric coverage is extended to

|

η

|

<

5 byasteelandquartzfiberCherenkovhadronforwardcalorimeter. Muonsaremeasuredintherange

|

η

|

<

2.4,withdetectionplanes madeusingthreetechnologies:drifttubes,cathodestripchambers,

andresistiveplatechambers. Eventsofinterestareselectedusing atwo-tieredtriggersystem [27].

AmoredetaileddescriptionoftheCMSdetector,togetherwith adefinitionofthecoordinatesystemusedandtherelevant kine-maticvariables,canbefoundinRef. [28].

4. Backgroundsimulation

ThedominantSMbackgroundistheproductionofW+jets.This background is generated at LO using MadGraph5_amc@nlo ver-sion2.2.2withtheMLM merging [24,29] andtheNNPDF 3.0 [19, 20,30] PDF set for on-shell W boson production and using pythia8.212withtheNNPDF 2.3 PDFsetforoff-shellproduction. The differential cross section is reweighted as a function of the invariantmass ofthe SM W bosondecay products,incorporating NNLOquantumchromodynamics(QCD)andnext-to-leading-order (NLO)electroweak(EW)corrections.Theeffectwithrespecttothe LOcalculationcorrespondstoacorrectionfactor(K factor)forthe W bosontransversemassspectrum.TocombinetheQCDandEW differentialcrosssections,two differentmathematicalapproaches could be taken [31]:an additive or a multiplicative combination. Their effects differ by around 5%. The K factor assumed in this analysisisobtainedbytakingtheadditive combinationas recom-mended by Ref. [32] and the difference from the multiplicative combinationistreatedasasystematicuncertainty.The K factoris 1.15ata W massof 0.3 TeV and dropsmonotonically forhigher massesdown to0.6foramassof6 TeV. Thecalculation usesthe generators fewz 3.1 and mcsanc 1.01 [33] for theQCD and elec-troweakcorrections.

Other background processes are: Z/

γ

∗

→

generated with MadGraph_{5_amc@nlo version 2.3.2.2 [24] with the NNPDF 3.0} PDFset,dibosonprocessesgeneratedwith pythia 8.212andwith theNNPDF 2.3 PDF set, andtop quark processes generated with powheg 2.0 [34–39] and the NNPDF 3.0 PDF set. Background from jets that are falsely identified as

τ

h candidates is

domi-nated by Z

→

νν

+

jets events,which are simulated with Mad-Graph5_amc@nlo version2.3.2.2andwiththeNNPDF 3.0PDFset. Parton fragmentation and hadronization are performed with pythia8.212 withtheunderlyingeventtune CUETP8M1.The de-tector response is simulated using a detailed description of the CMSdetectorimplementedwiththe Geant4package [40].All sim-ulatedeventsamplesare normalizedto theintegratedluminosity of the recorded data, using the theoretical cross section values. Additional pp collisions during thesame bunch crossing (pileup) istakeninto account by superimposingsimulated minimumbias interactions onto all simulated events. The simulated events are weightedsothatthepileupdistributionmatchesthatofthedata, withanaverageofabout27interactionsperbunchcrossing.

5. Reconstructionandidentificationofphysicsobjects

Aparticle-flow(PF)algorithm [41] isusedtocombine informa-tionfromallCMSsubdetectorsinordertoreconstructandidentify individual particles in the event:muons, electrons, photons, and chargedandneutralhadrons.Theresultingsetofparticlesisused to reconstruct the

τ

h candidates, missing transverse momentum

(pmiss_T ),andjets.Thevector p

_Tmissisdefinedasthenegativevector

pT sumofall PFcandidates reconstructedintheevent.The

mag-nitudeofthisvectorisreferredtoaspmiss

T .TherawpmissT valueis

modifiedto account forcorrectionstotheenergy scaleofall the reconstructed jetsin the event [42]. The jets are clusteredusing theanti-kT jetfindingalgorithm [43,44].The reconstructedvertex

withthelargestvalueofsummedphysics-objectp2_T istakenasthe primaryvertex.

Electrons [45,46] arereconstructedbymatchingenergydeposits intheECALwithtracksegmentsintheinnertracker.Muon recon-struction [47] is performed by matching a track segment recon-structed in the inner trackerwitha track segmentreconstructed inthemuondetectorandperformingaglobalfitofthecharge de-positsfromthetwotracksegments.

The

τ

hreconstructioninCMSstartsfromjetsclusteredfromPF

candidates,usingtheanti-kT algorithmwithadistanceparameter

of 0.4. The

τ

h candidates are reconstructed using the

hadrons-plus-strips algorithm [48,49], which is designed to optimize the performance of

τ

h reconstruction and identification by

consider-ingspecific

τ

leptondecaymodes.Individual

τ

hdecaymodesare

reconstructedseparately.Thesignaturesdistinguishedbythe algo-rithm are: a single chargedhadron, a charged hadron andup to twoneutralpions,andthreechargedhadrons.

Requiring

τ

hcandidatestopassisolationrequirementsreduces

the jet

→

τ

h misidentificationprobability.The multivariant-based

(MVA-based)

τ

h identificationdiscriminantcombineisolation and

other variables with sensitivity to the

τ

lifetime, to provide the bestpossiblediscriminationfor

τ

hdecaysagainstquarkandgluon

jets. Hadronicallydecaying

τ

leptons inthisanalysisare required to satisfy the very loose working point of the MVA-based isola-tion [50]. This workingpoint has an efficiency of about 70% for genuine

τ

h, withabout0.4% misidentificationrateforquark- and

gluon-initiatedjets,forapTrangetypicalof

τ

horiginatingfroma

Wbosonofmassof2 TeV.Isolatedelectronshaveahigh probabil-itytobemisidentifiedas

τ

hobjectsthatdecaytoasinglecharged

hadron(h±orh±

π

0_{).Electronscanemitenergeticbremsstrahlung}

photonsastheytraversethematerialofthesilicontracker.When thisoccurs, theelectronandaccompanying photonsmaybe mis-takenly reconstructed as a hadronically decaying

τ

. Muons can also be reconstructed as

τ

h objects in the h± decay mode. The

τ

hcandidatesinthisanalysisarerequiredtopasstheloose

work-ingpointoftheantielectrondiscriminator,whichhasanefficiency ofabout85%forgenuine

τ

hevents,andamisidentificationrateof

about1.5%forelectrons.The

τ

hcandidatesarefurtherrequiredto

passthelooseworkingpointoftheantimuondiscriminator,which hasanefficiencyof

>

99% forgenuine

τ

hevents,witha

misiden-tificationrateofabout0.3%formuons [50,51].

6. Analysisstrategy

The discriminating variable used in thisanalysis is the trans-versemass,definedasfollows:

mT

=



2pτ_Tpmiss

T

[

1

−

cos

φ (

p

Tτ

,

pTmiss

)

],

(2)

where pτ_T is the magnitude of the transverse momentum vector ofthe

τ

hcandidatepτ

T,and

φ

isthedifferenceintheazimuthal

anglebetweenpτ

_T and

p_Tmiss.

Thestrategyofthisanalysisistoselectaheavybosoncandidate decayingalmostatresttoahadronicjetconsistentwitha

τ

h

can-didate andneutrinos, the latter manifesting themselves as pmiss_T . Signaleventsareselectedonlinewitha

τ

h

+

pmissT triggerthat

re-quires the pT ofthe

τ

h candidate tobe greater than 50 GeV and

the value of pmiss_T to be greater than 90 GeV. To ensurethat the triggerismaximallyefficientforselectedevents,theoffline selec-tion requires one isolated

τ

h candidate to have pτT greater than

80 GeV andpmiss

T tobegreaterthan200 GeV.

Althoughthere are two neutrinosin thefinal state, pmiss_T and the isolated

τ

h candidate are largely produced inopposite

direc-tions, which helps to distinguish signal from background events especiallythosecomingfromQCDmultijetproduction.Two selec-tion criteria exploit this behavior to reduce the background: the ratioofthepτ_T topmiss

Fig. 3. (Left)ThemTdistributionafterthefinalselection.Theblacksymbolswitherrorbarsshowdata,whilethefilledhistogramsrepresenttheSMbackgrounds.Signal

examplesforSSMWbosonswithmassesof0.6,1.0,4.0,and5.0 TeV areshownwiththeopenhistograms.(Right)Theintegraltransversemassdistribution,wherethevalue ineachbinisequaltothenumberofeventswithtransversemassequaltoorgreaterthantheleftofthebin.Thelowerpanelsshowtheratioofdatatoprediction,andthe graybandrepresentsthesystematicuncertainties.

andthe angle

φ (

pτ_T

,

p_Tmiss

)

has to be greater than 2.4radians. Consequently, the lowest mT value is about 300 GeV. To avoid

an overlap with the W boson search in the electron channel, events are rejected if they contain a loosely identified electron withpT

>

20GeV and

|

η

|

<

2.5,wherethelooseworkingpointis

≈

90% efficientforreal electrons.For similarreasons,events con-tainingalooselyidentified muonwith pT

>

20GeV and

|

η

|

<

2.4

arenotconsideredinthisanalysis,wherethelooseworkingpoint

is

>99%

efficientforrealmuons.

Afterallselections, themT distributions fortheobserved data

and expected background events are presented in Fig. 3 (left). Fig.3 (right)showsthe integral distribution,which isformed by fillingeachbinofthehistogramwiththesumofthatbinandall followingbins.Thesystematicuncertainties,whicharedetailedin Section7,areillustratedasagray bandinthelowerpanelsofthe plots.TheproductofthesignalefficiencyandacceptanceforSSM W

→

τ ν

eventsdependson theW bosonmass.The totalsignal efficiencyforthestudiedrangeofmT

>

300GeV variesfrom14%to

about24%asMW increasesfrom1to3 TeV.ForhigherWboson

masses,eventsshifttolowermTbecauseoftheincreasingfraction

ofoff-shell production(as showninFig. 3for a fewsignal mass points).Forexample,foraW bosonwithamassof5 TeV,the to-talsignalefficiencyisaround17%.Thetriggerthresholdaffectsthe signalefficiencyinthelow-massrange.Theseefficiencyvaluesare obtained assuming the W

→

τ ν

branching fraction to be unity. Theefficiencyvaluesare estimatedusing simulatedeventswhere the

τ

leptondecayshadronically.

The dominantbackground is fromthe off-shelltail ofthe mT

distributionoftheSMW boson, andisobtainedfromsimulation. ThebackgroundcontributionsfromZ(

→

νν

)

+

jets andQCD mul-tijeteventsarealsoobtainedfromsimulation.Thesebackgrounds primarilyariseasaconsequenceofjetsmisidentifiedas

τ

h

candi-dates.ThecontributionofQCDmultijetbackgroundissmall com-paredtoZ(

→

νν

)

+

jets inthesignalregion.Followingthestrategy inRef. [52],toensurethatthemisidentified

τ

backgroundis sim-ulated properly, the agreement between data and simulation is checkedinacontrolregiondominatedbyZ(

→

μμ

)

+

jets events, whereajetismisidentifiedasa

τ

hcandidate.ThepmissT is

recalcu-latedexcludingthemuonsfromtheZdecayinordertoreproduce the pmiss_T distribution of Z

→

νν

events. Specifically, the control region is defined as follows. Events are selected online using a dimuon trigger with muon pT thresholds of 17 and 8 GeV.They

must contain two oppositely charged muons with pT

>

20GeV

and

|

η

|

<

2.4, both passing loose identificationand isolation re-quirements.The invariantmass ofthedimuonsystemisrequired to be between 81 and 101 GeV. In addition, the events are re-quired to contain exactly one

τ

h candidate passing the same

se-lectionrequirementsasinthesignalregion,withpτ_T

>

20GeV and

|

η

τ

|

<

2.1. To remove the overlap between muon and

τ

h

candi-dates, theseparation betweenthem mustfulfill



R

(

μ

,

τ

h

)

>

0.1,

where



R isdefinedas



R

=



(

η

)

2

_{+ (φ)}

2_.Dataand

simula-tion arecompared usingdistributions ofthedimuonmass, pmiss_T ,

pT/pmissT ,mT,

η

τ and pτT.Fig. 4showsthe pτT distributionin the

control region.Data andsimulation agree within 50% in all bins except inone bin inthe tailofthe pτ_T distribution, giving confi-dencethat themisidentified

τ

h backgroundsource—about22% of

thetotalbackground—iscorrectlymodeledinthesimulation.

7. Systematicuncertainties

The uncertaintyinthe modelingofthemT distributioncan be

split into threecategories: uncertainties affecting shapeand nor-malization, uncertainties affectingonly normalizationandan un-certaintyduetolimitednumbersofeventsinsimulatedsamples.

The dominantuncertaintyofthe firstcategory comesfrom

τ

h

reconstruction and identification, affecting background anda po-tential signal in the same way. The uncertainty associated with the

τ

h identification is 5% [48]. An additional systematic

uncer-tainty, which dominates for high-pT

τ

h candidates, is related to

thedegreeofconfidencethattheMCsimulationcorrectlymodels the identification efficiency. This additional uncertainty increases linearlywithpτ_T andamountsto

+

5%/

−

35% at pτ_T

=

1TeV.The un-certainty isasymmetric becausestudiesindicate that the

τ

iden-tification efficiencyissmaller indatathanin simulation,andthe difference increasesasthe pT ofthe

τ

increases.Theuncertainty

Fig. 4. DistributionofpτT inthecontrolregion.Theblacksymbolswitherrorbars

showthedata,whilethehistogramsrepresenttheSMbackgrounds.Thelowerpanel showstheratioofdatatoprediction.

pmiss_T uncertainty from jets are the jet energy scale and jet en-ergyresolution [53].Fortheenergymeasurementsofotherobjects thefollowinguncertainties areapplied:3% [48] for

τ

h,0.6%inEB

and1.5% in EE, respectively, for electrons andphotons [54]; and 0.2%formuons [47].The contributiontothe uncertaintyin pmiss_T

associated with unclustered energy is estimated by varying this energyby

±

10%.Forthe

τ

plus pmiss_T trigger,ascalefactorof0.9 isapplied.Thescale factorhasan uncertaintyof10%.The uncer-tainty associatedwiththe choice ofthe PDF inthesimulation is evaluatedaccordingtothePDF4LHCprescription [55–57].The val-uesincrease withmT,rangingfromanuncertaintyof1to10%at

mT

=

0.5 to4.0 TeV.Forthe K factoroftheW bosonbackground,

the difference between additive and multiplicative combination, which is around 5%, is taken to be the systematic uncertainty. Thesimulatedeventsareweighted sothatthepileupdistribution matches the measured one, using a value for the total inelastic crosssectionof69.2 mb,whichhasanuncertaintyof

±

4.6% [58].

Uncertainties of the second category influence only the nor-malizationof the mT distribution. Kinematic distributions in the

Z(

→

μμ

)

+

jets control region demonstratethat dataand simu-lationagreewithin 50%formisidentified

τ

h background,whichis

composedofZ(

→

νν

)

+

jets andQCDmultijetevents.Thisguides theassignmentofa50% systematicuncertaintyinthe normaliza-tionofthesebackgrounds.Theuncertaintyintheelectron identifi-cationefficiency(veto)is2%andtheuncertaintyintheintegrated luminositymeasurementis2.5% [59].

Uncertaintiesin the third category arise fromlimited sizes of eventsamplesinthesimulationofbackgroundprocesses.In con-trasttoallotheruncertainties,theyarenotcorrelatedbetweenthe binsoftheinvariantmassdistribution.

Inthehigh-massregion,whereboththeexpectedandthe ob-served numbers of events are consistent with zero,the effect of thesystematicuncertaintyontheexclusionlimitsisnegligible.

Therelevantsystematicuncertaintiestakenintoaccountinthe estimation of potential signals include those associated with

τ

h

identification and energyscale, pmiss

T , trigger, pile-up simulation,

andintegratedluminosity. Theuncertainty inthe signal K factor

arisesfromthechoicesofPDFand

α

S.Thecombineduncertainty

is evaluated using the PDF4LHC prescription,where in the com-putation of each PDF set, the strong couplingconstant isvaried. Uncertaintiesfromdifferent PDFsets and

α

S variation are added

inquadrature.

8. Results

Thetransversemassdistribution inFig. 3showsnosignificant deviationsfromtheexpectedSMbackground.Signaleventsare ex-pected to be particularlyprominent atthe upper end of themT

distribution, where the expected SM background is low. The ex-pected andmeasured yields are summarized inTable 1 together withthedetailedsystematicuncertaintiesdescribedinSection7.

8.1. Statisticalanalysis

Upperlimitsontheproductoftheproductioncrosssectionand branchingfraction,

σ

(pp

→

W

)

B(

W

→

τ ν

),

aredeterminedusing aBayesianmethod [60,61] withauniformpositiveprior probabil-ity densityfor the signal cross section (known to have excellent frequentistpropertieswhenusedasatechnicaldevicefor generat-ing frequentistupperlimits).Alllimitspresentedhereareat95% confidencelevel(CL).Thenuisanceparametersassociatedwiththe systematicuncertaintiesaremodeledthroughlog-normal distribu-tions foruncertainties in the normalization. Uncertainties in the shapeofthedistributionsaremodeledthrough“template morph-ing” techniques [62]. The limitsare obtained fromthe entiremT

spectrumformT

>

320GeV,asdisplayed inFig.3.Thisprocedure

is performedfordifferentvaluesof parameters ofeach signal, to obtainlimitsintermsontheseparameters,suchastheW boson mass.

Table 1

Expectedyieldsfor thesignalandbackgroundeventscomparedtothemeasured event yieldsindata,forthreeregionsofmT.Alsoshownarethetotalsystematicuncertaintiesin

theestimateoftheeventnumbers.

Range of mT mT<0.5 TeV 0.5<mT<1 TeV mT>1 TeV

W+jets 786 ± 110 355 ± 68 21.8 ± 6.2 Z→νν+jets 238 ± 120 68 ± 35 0.9 ± 0.5 Multijet 68 ± 35 18 ± 10 <0.1 tt 68 ± 15 14.5 ± 4.5 <0.1 Z→ +jets 35.8 ± 8.7 10.4 ± 5.1 <0.1 Diboson (WW, WZ, Z Z) 24.9 ± 6.4 9.6 ± 3.5 0.7 ± 0.1 Single top quark 21.5 ± 6.5 7.0 ± 2.9 <0.1 Total background 1243 ± 160 485 ± 77 23.4 ± 6.2 SSM WM=600 GeV 28229 ± 4388 14012 ± 2798 45.6 ± 7.7 SSM WM=1 TeV 3767 ± 590 10079 ± 1581 355 ± 98 SSM WM=4 TeV 0.7 ± 0.1 3.0 ± 1.8 11.4 ± 3.9

Fig. 5. Expected(blackdashedline)andobserved(blacksolidline)95%CL upper limitsonthecrosssectionfortheproductionofSSMWboson.Theshadedbands aroundtheexpectedlimitrepresenttheoneandtwostandarddeviation(s.d.) un-certaintyintervals.TheNNLOtheoreticalcrosssectionwiththecorrespondingPDF uncertaintybandisalsoshown.

To determine a model-independent upper limit on the prod-uct of the cross section and branching fraction, all events above a threshold mmin_T are summed. From the number of background events,signal events,andobserveddataevents,the crosssection limitcanbecalculated.Theresultinglimitcanbereinterpretedin the framework of other models witha

τ

h and pmissT in the final

state.

8.2. ThesequentialstandardmodelW

The parameter of interest is the product of the signal cross section and the branching fraction,

σ

B(

W

→

τ ν

).

The branch-ing fractionincludes all

τ

lepton decay modes, to allow adirect comparisonwiththeWsearchesintheelectronandmuon chan-nels [9].

The upper limit on

σ

B(

W

→

τ ν

)

as a function of the SSM W boson massis shown inFig. 5. The observed limit is consis-tent withthe expected limit. The SSM W boson isexcluded for masses 0.4

<

MW

<

4.0TeV at 95% CL where the lower limit is

mainlydeterminedbythetriggerthresholdandtheupperoneby theavailabledata.Thisresultinthe

τ

channelmaybecompared with the lower mass limit of 5.2 TeV for an SSM W boson, ob-tained from the combination of electron and muon channels [9, 10].

8.3. Limitsonthecouplingstrength

Theupperlimitson thecross sectiondepend not onlyonthe massofa potentialexcess,butalsoon thewidth. Becauseofthe relationbetweenthecoupling ofaparticle anditswidth, a limit canalsobesetonthecouplingstrength.Inordertocomputethe limitforcouplings gW

/

gW

=

1,reweightedsamplesareusedthat

takeintoaccounttheappropriatesignalwidthandthedifferences in reconstructed mT shapes. For gW

/

gW

=

1 the theoretical LO

cross sectionsapply. Fora givenmass, the crosssection limit as afunctionofthecouplingstrength gW

/

gW isdetermined.

ForeachsimulatedW bosonmass,theexcluded crosssection isdeterminedfromtheintersectionofthetheoreticalcrosssection curve withthe observed cross section limit. The resulting inter-section pointsprovide theinput forthe exclusionlimitin a two-dimensionalplanemadeofgW

/

gW andMW,asdepictedinFig.6.

Fig. 6. Expected(blackdashedline)andobserved(blacksolidline)95%CL upper limits on the ratioofcouplings as afunction ofthe W bosonmass. The val-uesabovetheobservedlimitcontourareexcluded.Theshadedbandsaroundthe expectedlimitrepresenttheoneandtwostandarddeviation(s.d.)uncertainty in-tervals.

Thephasespaceabovetheobservedlimitcontourisexcluded.For lowmasses, gW

/

gW valuesdownto7

×

10−2 areexcluded.

8.4. Thenonuniversalgaugeinteractionmodellimits

In the NUGIM G(221) framework, the ratio of the couplings

gW

/

gW is related to the parameter cot

θ

E through Eq. (1). Thus

cot

θ

EcanbeextractedforeachvalueofgW

/

gW.Basedonthe

lim-itsoncouplingstrengthspresentedinFig.6,thetwo-dimensional limitoncotθEisshownasafunctionoftheWbosonmass.Fig.7

(left) shows the width of the W boson as a function of cotθE

and MW. For cotθE

>

6.5, the width becomes so large that the

modelisnolongervalid.Thelimit,showninFig.7(right),focuses on theparameter spacecot

θ

E

≥

1 where the

τ

hchannel sets the

moststringentbounds, asillustratedinFig.2.Forlowervaluesof cot

θ

E,other channelsare moresensitive.Dependingonthevalue

ofcot

θ

E,themassoftheW bosoncanbeexcludedat95%CL up

to3.9 TeV intheNUGIMG(221)framework.

8.5. Themodel-independentcrosssectionlimit

TheshapeanalysisassumesacertainsignalshapeinmT.

How-ever, alternative new physics processes yielding a

τ

h

+

pmissT

fi-nal state could cause an excess of a different shape. A model-independent cross section limit isdetermined usinga single bin rangingfromalowerthresholdonmT toinfinity.Noassumptions

ontheshapeofthesignalmT distributionhavetobe madeother

than that of a flatproduct of acceptancetimes efficiency, A



,as a functionofW mass.Inordertodeterminethelimit fora spe-cific model from the model-independent limit shown here, only the model-dependent part of the efficiency needs to be applied. The experimentalefficienciesforthesignalare alreadytakeninto account, includingthe effectof thekinematic selection ofevents containing

τ

h and pmissT (the selectionson pT

/

pmissT and

φ

),the

geometrical acceptance (selection on

η

), and the trigger thresh-old.

A factor fmT that reflects the effectof the thresholdm

min T on

the signal is determinedby counting theevents withmT

>

mminT

anddividingtheresultbythenumberofgeneratedevents.The re-constructionefficiencyisnearlyconstantovertheentire mTrange

Fig. 7. Left:ThewidthoftheWbosonasafunctionofMWandmixinganglecotθE intheNUGIMG(221)framework.Right:Expected(blackdashedline)andobserved

(blacksolidline)95%CL upperlimitsonthemixinganglecotθEasafunctionoftheWbosonmass.Theregionleftofthesolidlineisexcluded.Theshadedbandsrepresent

theoneandtwostandarddeviation(s.d.)uncertaintybands.

Fig. 8. Expected(blackdashedline)andobserved(blacksolidline)95%CL model-independentupperlimitsontheproductofcrosssection,branchingfraction,and acceptanceforaresonancedecayingintotheτ νchannel.Theshadedbands repre-senttheoneandtwostandarddeviation(s.d.)uncertaintybands.

probed here, therefore fmT can be evaluated at generator level.

A limitontheproductofthecrosssectionandbranchingfraction

(

σ

B

A



)

excl canbeobtainedbydividingtheexcludedcrosssection

ofthe model-independentlimit

(

σ

B

A



)

MI given inFig. 8by the

calculatedfraction fmT

(

m min T

):

(

σ

B

A



)

excl

=

(

σ

B

A



)

MI

(

mminT

)

fmT

(

m min T

)

(3) Here,

B

isthe branchingfractionofthenewparticle decayingto

τ

+

ν

.Modelswithatheoreticalcrosssection

(

σ

B)

theo largerthan

(

σ

B)

excl can be excluded. The procedure described here can be

appliedto all models involvingthe two-bodydecayofa massive state,whichexhibit back-to-backkinematics similartothose ofa generic W.If the kinematicpropertiesare different, thefraction ofevents fmT

(

m

min

T

)

mustbedeterminedfortheparticularmodel

considered.

Theresultingcrosssectionlimitasafunctionofmmin

T isshown

inFig.8.ThehighestmT eventindatawas foundat1.65 TeV,

af-terwhichthe limit becomes flat.The results dependstrongly on thethreshold mmin_T . Values of theproduct

σ

B

A



between 50fb (mmin_T

>

400GeV) and 0.4fb (mmin_T

>

2TeV) are excluded forthe

mmin

T thresholdsgiveninbrackets.

9. Summary

Asearchfornewphysicsinfinalstateswithahadronically de-caying

τ

leptonandmissingtransversemomentumhasbeen per-formedbytheCMSexperiment,usingproton-protoncollisiondata atthecenter-of-massenergy

√

s

=

13TeV withanintegrated lumi-nosityof35.9 fb−1.Nosignificantexcesscomparedtothestandard model expectation is observed in the transverse mass of the

τ

andmissing transverse momentum.A sequential standard model W boson is excluded in the mass range 0.4

<

MW

<

4.0TeV at

95% confidencelevel.Couplingsthatare weakerthan assumedin thesequentialstandardmodelcanbe excludeddowntovaluesof 7

×

10−2 _{for M}

W

=

1TeV. Within the nonuniversal gauge

inter-action SU

(2)

×

SU

(2)

×

U

(1)

model, the lower limit on the W bosonmassdependsonthecouplingconstantandvariesfrom1.7 to3.9 TeV at95%confidencelevel.Forcot

θ

E

>

1,theseresults

ob-tainedinthe

τ

channelprovidethemoststringentconstraintson thismodeltodate.Inaddition,amodel-independentlimitis pro-videdallowingtheresultstobeinterpretedinothermodelsgiving thesamefinalstatewithsimilarkinematicdistributions.

Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrative staffsatCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentersand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythe computinginfrastructureessential to ouranalyses. Finally, we acknowledge the enduring support for the construc-tionandoperation oftheLHC andtheCMSdetectorprovidedby thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO(Belgium); CNPq,CAPES, FAPERJ, FAPERGS, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIENCIAS (Colombia); MSES andCSF (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 (RepublicofKorea); 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); TÜBITAK and TAEK (Turkey); NASU andSFFR(Ukraine); STFC (United Kingdom);DOE andNSF (USA).

Individuals have received support from the Marie-Curie pro-gramme and the European Research Council and Horizon 2020 Grant,contract No. 675440 (EuropeanUnion);theLeventis Foun-dation;the Alfred P. Sloan Foundation; the Alexander von Hum-boldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie etdans l’Agriculture (FRIA-Belgium); the Agentschapvoor Innovatie door Wetenschap en Technologie (IWT-Belgium); the F.R.S.-FNRS and FWO (Belgium) under the “Excellence of Science - EOS” - be.h projectn.30820817; theMinistryofEducation,Youth andSports (MEYS) of the Czech Republic; the Lendület (“Momentum”) Pro-gramme and the János Bolyai Research Scholarship of the Hun-garian Academy of Sciences, the New National Excellence Pro-gram ÚNKP, the NKFIA research grants 123842, 123959, 124845, 124850 and 125105 (Hungary); the Council of Science and In-dustrial Research, India; the HOMING PLUS programme of the Foundation for Polish Science, cofinanced from European Union, Regional DevelopmentFund, theMobility Plusprogrammeofthe Ministry of Science and Higher Education, the National Science Centre (Poland), contractsHarmonia 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 EstataldeFomento delaInvestigación CientíficayTécnica de Ex-celencia María de Maeztu, grant MDM-2015-0509 and the Pro-grama Severo Ochoa del Principado de Asturias; the Thalis and Aristeia programmes cofinanced by EU-ESF andthe Greek NSRF; theRachadapisekSompotFundforPostdoctoralFellowship, Chula-longkornUniversityandtheChulalongkornAcademicintoIts 2nd CenturyProjectAdvancement Project(Thailand);theWelch Foun-dation,contractC-1845;andtheWestonHavensFoundation(USA).

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TheCMSCollaboration

A.M. Sirunyan,

A. Tumasyan

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam,

F. Ambrogi,

E. Asilar,

T. Bergauer,

J. Brandstetter,

M. Dragicevic,

J. Erö,

A. Escalante Del Valle,

M. Flechl,

R. Frühwirth

1

,

V.M. Ghete,

J. Hrubec,

M. Jeitler

1

,

N. Krammer,

I. Krätschmer,

D. Liko,

T. Madlener,

I. Mikulec,

N. Rad,

H. Rohringer,

J. Schieck

1

,

R. Schöfbeck,

M. Spanring,

D. Spitzbart,

A. Taurok,

W. Waltenberger,

J. Wittmann,

C.-E. Wulz

1

,

M. Zarucki

InstitutfürHochenergiephysik,Wien,Austria

V. Chekhovsky,

V. Mossolov,

J. Suarez Gonzalez

InstituteforNuclearProblems,Minsk,Belarus

E.A. De Wolf,

D. Di Croce,

X. Janssen,

J. Lauwers,

M. Pieters,

H. Van Haevermaet,

P. Van Mechelen,

N. Van Remortel

UniversiteitAntwerpen,Antwerpen,Belgium

S. Abu Zeid,

F. Blekman,

J. D’Hondt,

I. De Bruyn,

J. De Clercq,

K. Deroover,

G. Flouris,

D. Lontkovskyi,

S. Lowette,

I. Marchesini,

S. Moortgat,

L. Moreels,

Q. Python,

K. Skovpen,

S. Tavernier,

W. Van Doninck,

P. Van Mulders,

I. Van Parijs

D. Beghin,

B. Bilin,

H. Brun,

B. Clerbaux,

G. De Lentdecker,

H. Delannoy,

B. Dorney,

G. Fasanella,

L. Favart,

R. Goldouzian,

A. Grebenyuk,

A.K. Kalsi,

T. Lenzi,

J. Luetic,

N. Postiau,

E. Starling,

L. Thomas,

C. Vander Velde,

P. Vanlaer,

D. Vannerom,

Q. Wang

UniversitéLibredeBruxelles,Bruxelles,Belgium

T. Cornelis,

D. Dobur,

A. Fagot,

M. Gul,

I. Khvastunov

2

,

D. Poyraz,

C. Roskas,

D. Trocino,

M. Tytgat,

W. Verbeke,

B. Vermassen,

M. Vit,

N. Zaganidis

GhentUniversity,Ghent,Belgium

H. Bakhshiansohi,

O. Bondu,

S. Brochet,

G. Bruno,

C. Caputo,

P. David,

C. Delaere,

M. Delcourt,

B. Francois,

A. Giammanco,

G. Krintiras,

V. Lemaitre,

A. Magitteri,

A. Mertens,

M. Musich,

K. Piotrzkowski,

A. Saggio,

M. Vidal Marono,

S. Wertz,

J. Zobec

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

F.L. Alves,

G.A. Alves,

M. Correa Martins Junior,

G. Correia Silva,

C. Hensel,

A. Moraes,

M.E. Pol,

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,

H. Malbouisson,

D. Matos Figueiredo,

M. Melo De Almeida,

C. Mora Herrera,

L. Mundim,

H. Nogima,

W.L. Prado Da Silva,

L.J. Sanchez Rosas,

A. Santoro,

A. Sznajder,

M. Thiel,

E.J. Tonelli Manganote

3

,

F. Torres Da Silva De Araujo,

A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahuja

a

,

C.A. Bernardes

a

,

L. Calligaris

a

,

T.R. Fernandez Perez Tomei

a

,

E.M. Gregores

b

,

P.G. Mercadante

b

,

S.F. Novaes

a

,

S.S. Padula

a

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

A. Aleksandrov,

R. Hadjiiska,

P. Iaydjiev,

A. Marinov,

M. Misheva,

M. Rodozov,

M. Shopova,

G. Sultanov

InstituteforNuclearResearchandNuclearEnergy,BulgarianAcademyofSciences,Sofia,Bulgaria

A. Dimitrov,

L. Litov,

B. Pavlov,

P. Petkov

UniversityofSofia,Sofia,Bulgaria

W. Fang

5

,

X. Gao

5

,

L. Yuan

BeihangUniversity,Beijing,China

M. Ahmad,

J.G. Bian,

G.M. Chen,

H.S. Chen,

M. Chen,

Y. Chen,

C.H. Jiang,

D. Leggat,

H. Liao,

Z. Liu,

F. Romeo,

S.M. Shaheen

6

,

A. Spiezia,

J. Tao,

C. Wang,

Z. Wang,

E. Yazgan,

H. Zhang,

S. Zhang,

J. Zhao

InstituteofHighEnergyPhysics,Beijing,China

Y. Ban,

G. Chen,

A. Levin,

J. Li,

L. Li,

Q. Li,

Y. Mao,

S.J. Qian,

D. Wang,

Z. Xu

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

Y. Wang

TsinghuaUniversity,Beijing,China

C. Avila,

A. Cabrera,

C.A. Carrillo Montoya,

L.F. Chaparro Sierra,

C. Florez,

C.F. González Hernández,

M.A. Segura Delgado

B. Courbon,

N. Godinovic,

D. Lelas,

I. Puljak,

T. Sculac

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia

Z. Antunovic,

M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,

D. Ferencek,

K. Kadija,

B. Mesic,

A. Starodumov

7

,

T. Susa

InstituteRudjerBoskovic,Zagreb,Croatia

M.W. Ather,

A. Attikis,

M. Kolosova,

G. Mavromanolakis,

J. Mousa,

C. Nicolaou,

F. Ptochos,

P.A. Razis,

H. Rykaczewski

UniversityofCyprus,Nicosia,Cyprus

M. Finger

8

,

M. Finger Jr.

8

CharlesUniversity,Prague,CzechRepublic

E. Ayala

EscuelaPolitecnicaNacional,Quito,Ecuador

E. Carrera Jarrin

UniversidadSanFranciscodeQuito,Quito,Ecuador

Y. Assran

9

,

10

,

S. Elgammal

10

,

S. Khalil

11

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,

H. Kirschenmann,

J. Pekkanen,

M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Havukainen,

J.K. Heikkilä,

T. Järvinen,

V. Karimäki,

R. Kinnunen,

T. Lampén,

K. Lassila-Perini,

S. Laurila,

S. Lehti,

T. Lindén,

P. Luukka,

T. Mäenpää,

H. Siikonen,

E. Tuominen,

J. Tuominiemi

HelsinkiInstituteofPhysics,Helsinki,Finland

T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon,

F. Couderc,

M. Dejardin,

D. Denegri,

J.L. Faure,

F. Ferri,

S. Ganjour,

A. Givernaud,

P. Gras,

G. Hamel de Monchenault,

P. Jarry,

C. Leloup,

E. Locci,

J. Malcles,

G. Negro,

J. Rander,

A. Rosowsky,

M.Ö. Sahin,

M. Titov

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

A. Abdulsalam

12

,

C. Amendola,

I. Antropov,

F. Beaudette,

P. Busson,

C. Charlot,

R. Granier de Cassagnac,

I. Kucher,

A. Lobanov,

J. Martin Blanco,

M. Nguyen,

C. Ochando,

G. Ortona,

P. Paganini,

P. Pigard,

R. Salerno,

J.B. Sauvan,

Y. Sirois,

A.G. Stahl Leiton,

A. Zabi,

A. Zghiche

LaboratoireLeprince-Ringuet,Ecolepolytechnique,CNRS/IN2P3,UniversitéParis-Saclay,Palaiseau,France

J.-L. Agram

13

,

J. Andrea,

D. Bloch,

J.-M. Brom,

E.C. Chabert,

V. Cherepanov,

C. Collard,

E. Conte

13

,

UniversitédeStrasbourg,CNRS,IPHCUMR7178,Strasbourg,France

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,

C. Bernet,

G. Boudoul,

N. Chanon,

R. Chierici,

D. Contardo,

P. Depasse,

H. El Mamouni,

J. Fay,

L. Finco,

S. Gascon,

M. Gouzevitch,

G. Grenier,

B. Ille,

F. Lagarde,

I.B. Laktineh,

H. Lattaud,

M. Lethuillier,

L. Mirabito,

A.L. Pequegnot,

S. Perries,

A. Popov

14

,

V. Sordini,

G. Touquet,

M. Vander Donckt,

S. Viret

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

A. Khvedelidze

8

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze

8

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann,

L. Feld,

M.K. Kiesel,

K. Klein,

M. Lipinski,

M. Preuten,

M.P. Rauch,

C. Schomakers,

J. Schulz,

M. Teroerde,

B. Wittmer,

V. Zhukov

14

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

A. Albert,

D. Duchardt,

M. Endres,

M. Erdmann,

S. Ghosh,

A. Güth,

T. Hebbeker,

C. Heidemann,

K. Hoepfner,

H. Keller,

L. Mastrolorenzo,

M. Materok,

M. Merschmeyer,

A. Meyer,

P. Millet,

S. Mukherjee,

T. Pook,

M. Radziej,

H. Reithler,

M. Rieger,

A. Schmidt,

D. Teyssier,

S. Wiedenbeck

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

G. Flügge,

O. Hlushchenko,

T. Kress,

A. Künsken,

T. Müller,

A. Nehrkorn,

A. Nowack,

C. Pistone,

O. Pooth,

D. Roy,

H. Sert,

A. Stahl

15

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,

T. Arndt,

C. Asawatangtrakuldee,

I. Babounikau,

K. Beernaert,

O. Behnke,

U. Behrens,

A. Bermúdez Martínez,

D. Bertsche,

A.A. Bin Anuar,

K. Borras

16

,

V. Botta,

A. Campbell,

P. Connor,

C. Contreras-Campana,

F. Costanza,

V. Danilov,

A. De Wit,

M.M. Defranchis,

C. Diez Pardos,

D. Domínguez Damiani,

G. Eckerlin,

T. Eichhorn,

A. Elwood,

E. Eren,

E. Gallo

17

,

A. Geiser,

J.M. Grados Luyando,

A. Grohsjean,

P. Gunnellini,

M. Guthoff,

M. Haranko,

A. Harb,

J. Hauk,

H. Jung,

M. Kasemann,

J. Keaveney,

C. Kleinwort,

J. Knolle,

D. Krücker,

W. Lange,

A. Lelek,

T. Lenz,

K. Lipka,

W. Lohmann

18

,

R. Mankel,

I.-A. Melzer-Pellmann,

A.B. Meyer,

M. Meyer,

M. Missiroli,

G. Mittag,

J. Mnich,

V. Myronenko,

S.K. Pflitsch,

D. Pitzl,

A. Raspereza,

M. Savitskyi,

P. Saxena,

P. Schütze,

C. Schwanenberger,

R. Shevchenko,

A. Singh,

H. Tholen,

O. Turkot,

A. Vagnerini,

G.P. Van Onsem,

R. Walsh,

Y. Wen,

K. Wichmann,

C. Wissing,

O. Zenaiev

DeutschesElektronen-Synchrotron,Hamburg,Germany

R. Aggleton,

S. Bein,

L. Benato,

A. Benecke,

V. Blobel,

M. Centis Vignali,

T. Dreyer,

E. Garutti,

D. Gonzalez,

J. Haller,

A. Hinzmann,

A. Karavdina,

G. Kasieczka,

R. Klanner,

R. Kogler,

N. Kovalchuk,

S. Kurz,

V. Kutzner,

J. Lange,

D. Marconi,

J. Multhaup,

M. Niedziela,

D. Nowatschin,

A. Perieanu,

A. Reimers,

O. Rieger,

C. Scharf,

P. Schleper,

S. Schumann,

J. Schwandt,

J. Sonneveld,

H. Stadie,

G. Steinbrück,

F.M. Stober,

M. Stöver,

A. Vanhoefer,

B. Vormwald,

I. Zoi

UniversityofHamburg,Hamburg,Germany

M. Akbiyik,

C. Barth,

M. Baselga,

S. Baur,

E. Butz,

R. Caspart,

T. Chwalek,

F. Colombo,

W. De Boer,

A. Dierlamm,

K. El Morabit,

N. Faltermann,

B. Freund,

M. Giffels,

M.A. Harrendorf,

F. Hartmann

15

,