Search for WZ resonances in the fully leptonic channel using pp collisions at root s=8 TeV with the ATLAS detector

(1)

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

WZ resonances

in

the

fully

leptonic

channel

using

pp collisions

at

√

s

=

8 TeV with

the

ATLAS

detector

.ATLASCollaboration

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

Articlehistory:

Received17June2014

Receivedinrevisedform30July2014 Accepted15August2014

Availableonline20August2014 Editor:W.-D.Schlatter

AsearchforresonantWZ productionintheν (,=e,μ)decaychannelusing20.3 fb−1_of√_s₌

8 TeV pp collisiondatacollectedbytheATLASexperimentatLHCispresented.Nosigniﬁcantdeviation fromtheStandardModelpredictionisobservedandupperlimitsontheproductioncrosssectionsofWZ

resonancesfromanextendedgaugemodelWandfromasimpliﬁedmodelofheavyvectortripletsare derived.Acorrespondingobserved(expected)lowermasslimitof1.52(1.49) TeVisderivedfortheW

atthe95%conﬁdencelevel.

1. Introduction

Thesearch fordibosonresonancesisan essentialcomplement totheinvestigationofthesourceofelectroweaksymmetry break-ing.Despitethecompatibilitybetweenthepropertiesofthenewly discoveredparticle atthe LHC [1–4] withthose expectedforthe StandardModel(SM) Higgsboson,the naturalnessproblem asso-ciated witha light Higgsboson suggeststhat the SM islikely to beaneffectivetheoryvalidonlyatlowenergies.Extensionsofthe SM, such as GrandUniﬁed Theories [5], Little Higgs models [6], Technicolor[7–10],moregeneric CompositeHiggsmodels[11,12], ormodelsofextradimensions[13–15],predictdibosonresonances athighmasses.

This Letter presents a search for resonant WZ production in the fully leptonic decay channels WZ→ ν (,=e, μ) us-ing20.3 fb−1 ofpp collisiondatacollectedbytheATLASdetector ata centre-of-massenergy of√s=8 TeV.Fourpossible leptonic decaychannels(eνee,eνμμ, μνee and μνμμ)areconsidered.To interpretthe results,the extendedgauge model (EGM)[16] with a spin-1 W boson is used asa benchmark signal hypothesis. In thismodel,the couplingsoftheEGM W boson totheSM parti-clesareidenticaltothoseofthe W boson,exceptforitscoupling to WZ, which is suppressed with respect to the SM WWZ triple

gaugecouplingby afactorof(mW/mW)2 andentailsalinear re-lationshipbetweentheresonancewidthandmass.The branching ratio BR(W→WZ) varies between 1% and 2% for a W mass range200–2000 GeV. Inother scenarios, such asfor leptophobic

W bosons [17–19], the decayto a pairof gauge bosons can be a dominantchannel. A narrow W resonanceis predictedin the EGM,withanintrinsicdecaywidththatisnegligiblewithrespect

_E-mail_address:_{atlas.publications@cern.ch}_.

totheexperimentalresolutionsonthereconstructedWZ invariant

mass. Possible interferences betweensignal andSM backgrounds are assumedto besmallandareneglected. Underthese assump-tions,theﬁnalresultspresentedherecanbereinterpretedinterms of anynarrow spin-1 resonancefor a givensignal eﬃciencyand acceptance.

AphenomenologicalLagrangianforheavy vectortriplets(HVT) [20]hasrecentlybeenintroduced,wherethecouplingsofthenew fields to fermions andgauge bosons are defined in termsof pa-rameters.ByscanningtheseparametersthegenericLagrangian de-scribesalargeclassofmodels.Thetripletfield,whichmixeswith theSMgaugebosons,couplestothefermioniccurrentthroughthe combinationofparameters g2cF/gV andto theHiggsandvector bosons through gVcH,where g is theSU(2)L gauge coupling,the parameter gV represents the couplingstrength to vector bosons, and cF and cH allow to modify the couplings andare expected tobeclosetounityinmostspecificmodels.Twobenchmark mod-els,providedinRef.[20],areusedhereaswell.InModelA,weakly coupledvectorresonancesarisefromanextensionoftheSMgauge group [21]. In Model B, the heavy vector triplet is produced in a strongly coupled scenario, for example in a Composite Higgs model [22]. InModel A, the branching fractionsto fermions and gaugebosonsarecomparable,whereasforModelB,fermionic cou-plingsaresuppressed.

Direct searchesforWZ resonanceshavebeenreportedby sev-eralexperiments.TheATLASCollaboration reportedonsearchesfor a Wresonanceusingapproximately1 fb−1_of_data_for_the_ν channel and 4.7 fb−1 ofdata forthe νj j channel, where j isa hadronic jet,both at√s=7 TeV, andexcluded an EGM W bo-sonwithmassbelow0.76 TeV[23]and0.95 TeV[24]respectively. TheCMSCollaboration searchedfortheproductionofgenericWZ

resonancesinthesemileptonicﬁnalstate,andobtainedupper lim-its on the production cross section asa function of signal mass

http://dx.doi.org/10.1016/j.physletb.2014.08.039

(2)

andwidth[25].Theyalsoanalyzed dijetsignaturescontainingjets taggedasW and Z bosondecays,andexcluded EGM W bosons withmassesbelow1.7 TeV[26].Theadvantageofthethree-lepton

WZ finalstateoveritspartialorfullyhadronicfinalstate counter-parts isits better sensitivity atthe lower end ofthe mass spec-trumduetoitssignificantlysmallerSMbackgroundsandsuperior mass resolution. The CMS Collaboration analyzed 5 fb−1 of data at √s=7 TeV in the ν channel, and EGM W bosons with massesbelow1.143 TeV[27]wereexcluded.

2. TheATLASdetector

The ATLAS detector [28] consists of an inner tracking detec-tor (ID), electromagnetic (EM) and hadronic calorimeters, and a muon spectrometer. The ID is immersedin a 2 Taxial magnetic ﬁeld, generated by a superconducting solenoid, andconsists ofa silicon pixel detector, a silicon microstrip detector, anda transi-tion radiationtracker. The ID provides a pseudorapidity coverage of|η|<2.5.1

The EM calorimeters are composed of interspersed lead and liquid argon, acting as absorber and active material respectively, withhighgranularityinboththebarrel(|η|<1.475)andend-cap up to the endof the trackeracceptance (1.375<|η|<2.5), and somewhat coarsergranularityfrom|η|=2.5 to 3.2.The hadronic calorimeter uses steel and scintillator tiles in the barrel region, whiletheendcapsuseliquidargonastheactivematerialand cop-perasanabsorber.Themuonspectrometer(MS)isbasedonthree largesuperconductingair-coretoroidsarrangedwithaneight-fold azimuthal coilsymmetry aroundthe calorimeters.Three layers of precision tracking chambers, consisting of drift tubes and cath-ode strip chambers, enable precise muon trackmeasurements in thepseudorapidityrangeof|η|<2.7,andresistive-plateand thin-gapchambersprovide muon triggering capabilityin therange of |η|<2.4.

3. DataandMonteCarlo modelling

The data analyzed herewere collected by the ATLAS detector attheLHC in pp collisions at√s=8 TeV duringthe2012 data-takingrun. Events are selected usinga combination(logical OR) of isolated andnon-isolated single-lepton (e or μ) triggers. The

pT thresholds are 24 GeV for isolated single-lepton triggers and 60 (36) GeVfornon-isolatedsingle-e (μ)triggers.Therequirement thatthreehigh-pTleptons areintheﬁnalstate givesatrigger ef-ﬁciencyabove 99.5%.Afterdata-qualityrequirements areapplied, the total integrated luminosity is 20.3 fb−1 with an uncertainty of 2.8%[29].

ThebaselineEGMWsignalsaregeneratedwithPYTHIA8.162 [30]andtheMSTW2008LO[31]partondistributionfunction(PDF) set. The production cross section times branching fraction (with

W →eν, μν, τ ν, where all τ decays are considered, and Z → ee, μμ) arescaledtotheir theoreticalpredictionsat next-to-next-to-leading order (NNLO) using ZWPROD [32], which are 1.43 pb for mW =200 GeV, 4.12 fb for mW =1 TeV, and 0.08 fb for

mW=2 TeV.IntheW→τ ν component,onlytheleptonic τ de-cays enter the signal acceptance, albeitslightly andonly at high signal mass, whereas the Z →τ τ component is totally negligi-ble.TheintrinsicdecaywidthsoftheEGM Wscalelinearlywith

1 _ATLAS_uses_a_right-handed_coordinate_system_with_its_origin_at_the_nominal in-teractionpoint(IP)inthecentreofthedetectorandthez-axisalongthebeampipe. Thex-axispointsfromtheIPtothecentreoftheLHCring,andthey-axispoints upward.Cylindricalcoordinates(r,φ)areusedinthetransverseplane,φbeingthe azimuthalanglearoundthebeampipe.Thepseudorapidityisdefinedintermsof thepolarangleθasη= −ln tan(θ/2).Theseparationbetweenfinal-stateparticles isdefinedas R=( η)2_{+ ( φ)}2_._The_transverse_momentum_is_denoted_by_p_T.

Table 1

OverviewoftheprimaryMCsamples.Thebackgroundsfrommisidentiﬁedjetsare estimatedfromthedata.

Process Generator Parton Shower PDF

W PYTHIA PYTHIA MSTW2008LO

WZ POWHEG-BOX PYTHIA

Z Z POWHEG-BOX PYTHIA CT10

Zγ SHERPA SHERPA

t¯t+W/Z MadGraph PYTHIA CTEQ6L1

mW athigh massand are 5.5 GeV formW=200 GeV, 36 GeV formW=1 TeV,and72 GeV formW=2 TeV. Theseare signiﬁ-cantlylessthantheexperimentalresolutions,whichhaveGaussian widths of theorder of 25 GeV formW =200 GeV, 100 GeV for

mW =1 TeV, and 180 GeV for mW=2 TeV. MC samples were produced for the EGM W signal from 200 GeV to 400 GeV at intervals of 50 GeV and from 400 GeV to 2 TeV at intervals of 200 GeV.Aninterpolationprocedureisadoptedtoobtainthe dis-tributions for mass points between 200 GeV and 400 GeV with 25 GeV stepsize andfrom400 GeV to2 TeV with 50 GeV step size.

The dominant SM WZ background is modelled by POWHEG-BOX[33–36],a next-to-leading-order(NLO) eventgenerator com-bined with the NLO CT10 PDF set [37]. Background events

aris-ing from Z Z aremodelledwithPOWHEG-BOX,while thosefrom

t¯t+W/Z processes are generated with MadGraph 5.1.4.8 [38] togetherwiththeCTEQ6L1[39]PDFset.Alltheseeventsare inter-facedwithPYTHIA,usingtheAU2tune[40]forpartonshowering. Asecondcategoryofbackgroundarisesfromphotons misiden-tified aselectrons, mainly from Zγ production.A photon can be misreconstructedasanelectronifitliesclosetoachargedparticle trackorifthephoton convertstoe+e− afterinteractingwiththe materialinfrontofthecalorimeter.Thiscontributionisestimated usingsimulatedZγ MCeventsgeneratedwithSHERPA1.4.0[41]. Finally, a third category of background includes all other sources where one or more jets are misidentified as an isolated lepton. The contributions from these fake backgrounds are esti-mated usingadata-drivenmethodasdescribed inSection 6.The contributionfromeventswithonlyonejetmisidentifiedasan iso-latedleptonisfoundtobedominantwhilethosewithmorethan onearefoundtobenegligible.Thus,inthisanalysisthefake

back-groundsaredenotedby+jets.

An overview of the major MC samples used is presented in Table 1.

MonteCarlo(MC) eventsare processedthroughthefull detec-tor simulation [42] using geant4 [43], and their reconstruction is performed with the same software used to reconstruct data events.Correctionfactorsforleptonreconstruction and identiﬁca-tioneﬃcienciesareappliedtothesimulationtoaccountfor differ-ences with respect to data. The simulated lepton four-momenta are tuned, via calorimeter energy scaling and momentum reso-lution smearing, to reproduce the distributions observed in data fromleptonicW ,Z and J/ψdecaysaftercalibration.Furthermore, additionalinelastic pp collisioneventsare overlaid withthe hard scattering process in the MC simulation and then reweighted to reproducetheobservedaveragenumberofinteractionsper bunch-crossingindata.

4. Objectreconstruction

Electroncandidates are reconstructedin theregion ofthe EM calorimeter with|η|<2.47 bymatching the calorimeterclusters to the tracks inthe ID. The transitionregion betweenthe barrel and endcap calorimeters (1.37<|η|<1.52) is excluded. Candi-date electrons must satisfy the medium quality deﬁnition [44]

(3)

re-optimizedfor2012data-takingconditions,whichisbasedona setofrequirementsonthecalorimetershowershape,trackquality, andtrackmatching withthecalorimetercluster. Thelongitudinal impact parameter z0 of the associated track with respect to the primaryvertex(PV),whichisdeﬁnedasthevertexwiththelargest sumofsquaredtransversemomentaofassociatedtracks,must sat-isfy|z0sinθ|<0.5 mm.Thetransverseimpactparameterd0ofthe associatedtrackmustsatisfy|d0/σd0|<6,where σd0 isthe uncer-tainty onthe measurement ofd0.To reduce thebackgrounddue tojetsmisidentiﬁedaselectrons,electroncandidatesarerequired to be isolated in both the calorimeter and the ID. The isolation requirements are Riso

Cal<0.16 and RisoID <0.16, where RisoCal is the totaltransverseenergyrecordedinthecalorimeterswithinacone ofsize R=0.3 around the lepton direction, excluding the en-ergyofthelepton itself,divided bythelepton ET,and RisoID isthe sumofthepTofthetracksinaconeofsize R=0.3 aroundthe leptondirection,excluding thetrackofthelepton, dividedbythe lepton pT.

Muoncandidates are reconstructedwithin the range|η|<2.5 by combining tracks in the ID and the MS. Robust reconstruc-tion isensured by requiringa minimumnumber of hitsin each ofthesub-detectorsofIDtobeassociatedwiththereconstructed IDtracks.Moreover,themuonreconstructedtrackmustsatisfythe requirements|z0sinθ|<0.5 mm and|d0/σd0|<3.5.Themeasured momentaintheIDandtheMS arerequiredtobeconsistentwith each other bysatisfying |(q/p)ID− (q/p)MS|<5σ, where(q/p)ID and(q/p)MS are the charge q over momentum p in the ID and theMS respectively, and σ is thetotal uncertaintyonthe differ-encebetweenq/p measurementsintheIDandtheMS.Themuon isolationrequirementsare Riso

Cal<0.2 andRisoID <0.15.

When the Z boson has high momentum (600 GeV), its

collimated lepton decay products can be within a cone of size R=0.3.Tomaintaina highefficiencyforhigh-masssignalsthe isolationrequirementsimposedontheleptonsaremodifiedtonot includeinthecalculationofRiso_CalandRiso_ID theenergyandmomenta ofanyclose-bysame-flavourleptons.Foran mW=1.4 TeV signal, the relative efficiency gain, with respect to the selection with-out modifying the isolation requirements,is ofthe order of 60%. Finally,to reduce photon conversionbackgrounds frommuon ra-diation, if a muon and an electron are separated by less than R=0.1 fromeachother,theelectroncandidateisdiscarded.

The missing transverse momentum, with magnitude Emiss

T , is

themomentumimbalanceinthetransverseplane.TheEmiss

T is

cal-culatedfromthe negative vectorsumofthe transversemomenta of all reconstructed objects, including muons, electrons, photons andjets,aswellasclustersofcalorimetercellsnotassociatedwith theseobjects[45].

Attributingthe E_Tmiss tothe transversecomponentofthe neu-trino momentum, its longitudinal component (pν_z) is derived by requiringthattheneutrinoandtheleptonattributedtotheW

bo-son decayhave an invariant mass equal tothe pole mass ofthe

W boson:80.385 GeV [46].This constraintresultsin aquadratic equationwithtwosolutionsforpν_z.Ifthesolutionsarerealtheone withthe smallerabsolutevalue iskept.Ifthesolutions are com-plexonlytherealpartiskept.Ingeneral,about30%oftheevents arefoundtohavecomplexsolutions,mainlyduetothe Emiss_T reso-lutionatthereconstructionlevel.TheinvariantmassoftheWZ→ ν systemisreconstructed fromthefour-vectorsofthe

candi-date W and Z bosonsandisused asthediscriminating variable

forthesignal.

5. Eventselection

The PV of the event must have at least three associated trackswith pT>0.4 GeV.CandidateWZ→ νeventsarethen

required to haveexactlythreechargedleptons with pT>25 GeV andE_Tmiss>25 GeV.Eventsarerejectedifafourthleptonisfound with pT>20 GeV. At least one of the three leptons is required to be geometrically matched to an object that ﬁred the trigger. Two opposite-sign same-ﬂavour leptons are required to have an invariant mass (m) within 20 GeV of the Z boson pole mass:

91.1875 GeV[47].Iftwo possibilities exist, thepair that hasm

closest to the Z boson pole mass is chosen to form the Z

can-didate. To suppress the Z +jets background where one jet is reconstructed as an isolated electron, the electrons used in the reconstruction of the W bosons are required to satisfy tighter identiﬁcationcriteria(tight)thanthoserequiredfortheleptons used in the reconstruction of Z boson decays (medium). These strictercriteriaaredescribedinRef.[44].

To improvethe sensitivityto resonant signals, eventsare fur-ther required to have y(W,Z)<1.5, where y(W,Z) is the rapidity2 _difference_between_the _{W and} _{Z bosons.} _This_selection

has an eﬃciency exceeding 82% forall W masses andreaching 94%formW=200 GeV.

Finally,two signal regions are deﬁned, one more sensitive for high-massWsignals(mW250 GeV)andtheotheronefor low-mass W signals (mW 250 GeV). The high-mass signal region (SRHM) is deﬁned by the additional requirement φ (,EmissT )< 1.5,where φ (,Emiss_T )istheazimuthalanglebetweenthelepton attributed to the W candidate decayand the missing transverse momentum vector.Conversely, thelow-mass signalregion (SRLM) isrequiredtohave φ (,Emiss_T )>1.5,whichhashighacceptance forlow-masssignals.

6. Backgroundestimations

The major backgrounds come fromthe SM WZ, Z Z and t¯t+

W/Z processes with at least three prompt leptons in the ﬁnal

state. A control region dominated by SM WZ events (CRSMWZ) is deﬁned to check the modelling of the MC predictions for these backgrounds. The selection criteriaused forthisregion are simi-lartothoseforthesignalregions exceptthat therequirementon y(W,Z)isreversed andtherequirementon φ (,Emiss

T )is

re-moved. The reversalof the y(W,Z) selection reduces possible signalcontaminationtonegligiblelevels,assumingprevious exclu-sionresults[23,27].Intotal,323eventsareobservedindataforall fourchannelscombinedandthe SMbackgroundsare expectedto be298±4(stat.)±26(syst.)events,wherethecomputationofthe systematicuncertainties isdetailedinSection 7.Good agreement isalsofound betweendataandthe SMpredictions intheshapes of various kinematical distributions. The mWZ distribution in the SMWZ controlregionisshowninFig. 1.

Contributions from the +jets background, where at least one lepton originates from hadronic jets, are estimated using a data-driven method. A lepton-like jet is defined as a jet that is reconstructedasaleptonandsatisfiesalllepton selectioncriteria but,inthemuoncase,failseitherthecalorimeterortrackisolation requirement,or,intheelectroncase,failstheisolationormedium quality requirementbutpassesalooserset ofelectron identifica-tion qualityrequirements.A “fakefactor”,definedasthe number ofeventsinwhichajetsatisfiesthenominalleptonselection cri-teriadivided bythenumberofeventsinwhichajetsatisfiesthe lepton-like jet criteria, is computed. It can be interpreted as the probabilitythatalepton-likejetisinsteadreconstructedasa nom-inallepton.Thefakebackgroundisdominatedbyeventswithone jet misidentified as an isolated lepton, while contributions from other processes with two or three jets misidentified as isolated

2 _Rapidity_is_deﬁned_as_y_{= (}₁

(4)

Fig. 1. Distribution of WZ invariant mass (mWZ)in the SM WZ control region

(CRSMWZ)forthefourν channelscombined.Theuncertaintybandsuponthe expectedbackgroundincludeboththestatisticalandsystematicuncertaintiesinthe MCsimulationandthefake-backgroundestimationaddedinquadrature. leptons are found to be negligible. The fake background is thus estimatedby applying the fakefactor to a data sample (denoted as“tight+loose sample”)selectedusingallsignalselection crite-ria exceptfor a requirement that one of the three leptons must bea lepton-likejet.Sincetheelectronidentiﬁcationandisolation requirementsaredifferentforthosecomingfroma Z oraW

can-didatedecay, the electron fake factor iscalculated separately for thesetwocases.

Thelepton fakefactoris measured intwodifferent data sam-ples: dijet and Z+jets events. In both cases the tag-and-probe method[48,49]isused,butthetagobjectsaredifferent.Thelarger numberofeventswithinthedijetsample permitsameasurement ofthedependenceoftheleptonfakefactoronthelepton pTor η. Usingthe Z+jets sample,ontheother hand,leadstoa measure-mentwherethekinematicdistributions andﬂavourcompositions are closer to that of the signal region, albeit with signiﬁcantly fewer events allowing only a measurement of the fake factor as asinglenumber.

Inthe tight+loosesample andthe two samplesusedforthe fake-factormeasurement,thebackgroundscontainingprompt lep-tonsare estimatedusingMC simulation andsubtracted fromthe datasamples.Theseincludethe productionof Z+jets simulated withALPGEN2.14[50],t¯t withMC@NLO4.03[51], W+jets and

Wγ withALPGEN,aswell asthepreviouslymentioned WZ, Z Z , Zγ, and tt¯+W/Z MC samples. The parton showering is mod-elled by HERWIG/JIMMY [52,53] for Z+jets, t¯t, W +jets, and

Wγ events. The eventsremaining aftersubtraction are thus the expectedleptonyieldsduetomisidentiﬁedjets.

The dijet sample is selected with one tag jet and one probe jet that arealmost back-to-back,with φ >2.5. Thetag jetsare normalhadronic jetsandthe probe jet is requiredto satisfy the selectioncriteriaforalepton-likejet oranominallepton.Thetag jets are reconstructed up to |η|=4.5 from calorimeter clusters withtheanti-kt algorithm [54] usingadistanceparameter of0.4 andarecalibratedtothehadronicenergyscale.Theyarerequired tohavepT>25 GeV.ForjetswithpT<50 GeV and|η|<2.4,the scalar pT sumofthe tracks that are associated withthe PV and that fall into the jet area must be at least 50% of the scalar pT sumof all tracks falling into the samejet area. The dijet events

are selected by single-muon and single-photon triggers, with pT and ET thresholds of 24 and 20 GeV in the muon and electron cases respectively.The muon/electronrequirementsatthe trigger level arelooserthanthe lepton-likejet selectioncriteriainorder to allow for an unbiased measurement of the lepton fake factor. Tobettermimicthekinematicpropertiesofthesignalregion,the

Emiss

T isrequiredtobehigherthan25 GeV,whichalsohelpsreject the Z+jets background.Theprobejetandthemissingtransverse momentum are requiredto have a transverse mass smaller than 40 GeVtosuppresstheW+jets background.Theprobejetisthen examinedtodeterminewhetheritsatisﬁesthenominallepton se-lectioncriteriaorthoseofthelepton-likejet.

The Z +jets sample is defined as having one same-flavour opposite-chargeleptonpairconsistent withthe Z bosondecayas thetaggedobject,andaprobejetthatsatisfiestheselection crite-riaforalepton-like jetoranominallepton.Theyareselected by a setofsingle-leptonanddileptontriggerstoimprovethetrigger efficiency.Tosuppressthecontributionfrompromptleptonsfrom

WZ production, events are required tohave Emiss_T <25 GeV. The probejetisusedformeasuringthefakefactor.

In boththe dijetand Z+jets samples,severalsources of sys-tematic uncertainty for the measurement of the fake factors are considered,stemmingfromthetriggerbias,kinematicandflavour differences withrespect tothe signal region, the Emiss_T threshold requirement, andprompt-lepton subtraction. In the dijetsample, possible biasesrelatedtothe tag-jet pT threshold,the transverse mass requirement on the probe jet and Emiss_T system, and the azimuthal angle between the tag jet and the probe jet are also considered. Likewise, additional biases associated with the mea-surement in the Z +jets sample, such as potential systematic kinematicdifferencesbetweenthelow- andhigh-Emiss_T regions,are also considered. The total uncertainties on the fakefactors mea-sured using the dijet sample ranges from 8% to 33% for muons with pT<50 GeV and electrons with pT<70 GeV. Beyond the above pTrangesthefakefactorsareassigneda100%systematic uncertaintyduetothesubtractionofpromptbackgrounds.The to-tal uncertainties on thefake factors measuredusing the Z+jets sample range from 27% to 36% for different lepton flavours and definitions.Theuncertaintiesonthefakefactorsareappliedtothe fake-backgroundestimateasnormalizationuncertainties.

The fakefactors,whichare oftheorderof0.1forboth lepton ﬂavours,aremeasuredinbothsamples.The pT-binnedcentral val-uesfromthedijetsample measurementaretheonesusedinthis analysis. The differences between the fake factors from the two samples canbe up to ∼60% and are the dominantcontributions tothefake-factoruncertainty.

The observedandpredictedbackgroundeventyields are com-pared in an +jets-enriched control region (CR+jets) where eventsarerequiredtohavethesameleptonselectionandZ mass

requirementasinthenominalsignalselectionbutwithEmiss_T less than 25 GeV and the transverse mass of the W candidate less than 25 GeV. In this region, a total of 204 events are observed indatawithanSMexpectationof195±4(stat.)±38(syst.)events. Good agreement is found between observed data and estimated background for various kinematic distributions. The Z candidate

invariantmassdistributionisshowninFig. 2.

7. Systematicuncertainties

Relative uncertainties on theexpected yields ofthe dominant

WZ background and the EGM W signal with mW=1 TeV in

SRHM areshowninTable 2.Theseuncertaintiesarerepresentative ofthosefoundforother signalmassesandbackgroundtypes.The lepton-related onesinclude uncertainties fromthe lepton trigger, identiﬁcation,energyscale,energyresolution,isolation,andimpact

(5)

Table 2

RelativeuncertaintiesintheexpectedyieldsfortheSMWZ backgroundandtheEGMWsignalwithmW=1 TeV inthehigh-masssignalregion(SRHM).Therenormalization

andfactorizationscales,togetherwiththePDFuncertaintiesontheﬁducialcrosssectionareincludedundertheoreticaluncertaintyforSMWZ background.ForEGMW

signal,thetheoreticaluncertaintystandsfortheeffectsofthe scaleandPDFuncertainties,addedinquadrature,onitsacceptance.Shape-relateduncertaintiesarenot includedhere.Similarresultsarefoundinthelow-masssignalregion(SRLM).

Uncertainty sources SM WZ EGM W(mW=1 TeV) eνee μνee eνμμ μνμμ eνee μνee eνμμ μνμμ MC statistics 2.7% 2.0% 2.0% 2.2% 2.5% 2.5% 2.5% 2.5% Lepton-related 3.1% 2.1% 1.8% 1.9% 3.7% 2.6% 2.1% 2.4% Emiss T -related 2.8% 1.9% 2.6% 1.7% 1.1% 0.4% 0.4% 0.4% Luminosity 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% 2.8% Theory 9.5% 9.5% 9.5% 9.5% 0.6% 0.5% 0.2% 0.2%

Fig. 2. Z candidateinvariantmassdistributioninthe+jets backgroundcontrol region(CR+jets).Theuncertaintybandsuponthe expectedbackgroundinclude boththestatisticalandsystematicuncertaintiesintheMCsimulationandthe fake-backgroundestimationaddedinquadrature.

parameters. The uncertainties on the lepton momentum and jet energyscales andresolutionsarepropagated totheEmiss

T calcula-tion.OtherEmiss

T -relateduncertaintiesincludethoseonsoftenergy depositsdueto additional pp collisions, andenergydeposits not associatedwith anyreconstructed object.Both thenormalization and shape uncertainties are taken into account from the above sources.

Cross-sectionuncertainties for the dominant SM physics pro-cesses are computed via MCFM [55], which provides NLO QCD calculationsfordibosonproductioncrosssections.Therelative un-certaintyduetohigher-ordercorrectionstotheWZ crosssections is5% [56].Therenormalizationandfactorizationscalesare varied by afactor oftwo relative to their nominalvalues.The resulting sumin quadratureof the uncertainties in SRHM on the WZ, Z Z , andZγ crosssectionsarefoundtobe6.9%,4.3%,and5.0% respec-tively.PDF uncertainties are derived by comparing the predicted crosssectionsusingtheNLO CT10andMSTWPDFaswellasthe CT10eigenvectorerrorPDFsets(90%conﬁdencelevel).The result-inguncertaintiesare4.1%,4.7%and3.2%forthesethreeprocesses respectively.

Given that the SM background modelling suffers from low MC event counts in the tail of the mWZ distribution, an extrap-olation method is devised to smooth the predicted yields. The method consistsin performing two independent χ2 _ﬁts, _one _on theWZ backgroundintheregionwithmWZ>500 GeV,anda sec-ond on the sum of all non-WZ backgrounds in the region with

mWZ>300 GeV, each withthe power-law function N(x)=c0xc1, where x is mWZ. The overall normalizationof the fittedfunction issettotheexpectednumberofeventsforeachofthetwotypes ofbackground.Thenon-WZ backgroundsarefittedjointlytogain from their combined size, thus reducing the total uncertainty in the fit, which is computed via the minimization function’s Hes-sianerrormatrix.Otherfittingfunctionssuchasanexponentialor moreelaboratepower-lawfunctionswere tested,buttheirshapes werefoundtobewithintheuncertaintiesfromthesimple power-lawfunction givenabove. Hence,only theuncertainties fromthe simplepower-lawfunctionareconsidered,andthesedominateall otheruncertaintiesintherangemWZ>800 GeV (e.g.thefit uncer-taintyreaches50%ofthetotalexpectedyieldsatmWZ=800 GeV, and400%atmWZ=1.6 TeV).

Additionally, the shapes of the mWZ distribution for the SM

WZ process predictedby POWHEG-BOXand themulti-leg

gener-atorsSHERPAandMadGraph,aswell asNLO generatorssuchas MC@NLOarecompared.Thelargestdeviationsfromthe POWHEG-BOXdistributionare usedassystematicuncertainties onthe pre-dictedmWZ shape.

Aprocedurewas developedtoobtainthemWZ distributionfor any given mW mass point using a functional interpolation be-tween theavailablemWZ signaltemplates. Thesedistributionsare individuallyﬁttedwithacrystalballfunctionusingRooFit[57]. The4crystalballparametersarethen eachﬁttedasafunctionof the Wmassto buildthemWZ templateforanyintermediate W mass point. All systematic uncertainties are individually interpo-lated.

TheoreticaluncertaintiesontheEGMWsignalyieldsprimarily comefromuncertainties on thereconstructed signal’sacceptance timeseﬃciencyduetothePDF setused.Theuncertainties inthe signal acceptance due to the PDF are derived from the MSTW eigenvectorerrorsets,andthedifferencebetweenthepredictions oftheCT10andMSTWPDFsets,combinedinquadrature.

8. Results

ThemWZ spectruminthetwo signal regionsisscrutinized for excesses of data over the predicted SM backgrounds. A total of

449 WZ candidate events in SRHM are observed in the data

af-terapplyingall eventselection criteria, tobe compared withthe SM prediction of 421±5(stat.)₋+56₃₉(syst.) events. The correspond-ing numbers in SRLM are 617 events selected in the data and 563±5(stat.)₋+₄₃55(syst.) events expected from SM processes. The observed mWZ distribution in SRHM is compared to the expected SMbackgrounddistributioninFig. 3,whichcombinesallfour lep-ton decaychannels. Thecontributions fromhypotheticalEGM W

bosons withmassesof600, 1000,and1400 GeVare alsoshown. Abreakdownofthesignal,backgrounds,andobserveddatayields inSRHM isshowninTable 3foreachindividual channelandalso for all four channels combined.The mWZ distribution in SRLM is showninFig. 4.

(6)

Table 3

Theestimatedbackgroundyields,theobservednumberofdataevents,andthepredictedsignalyieldforasetofWresonancemassesinthehigh-masssignalregion(SRHM).

eνee μνee eνμμ μνμμ Combined Backgrounds: WZ 56.5±1.5±6.1 68.6±1.4±7.0 70.1±1.4±7.2 89.8±2.0±9.1 285±3±29 Z Z 8.7±0.1±0.9 8.7±0.2±0.8 11.7±0.2±1.3 11.6±0.2±1.1 40.7±0.4±3.9 Zγ 6.4±0.8±1.5 <0.05 8.1±0.9±1.2 <0.05 14.5±1.2±2.2 t¯t+W/Z 2.5±0.1±0.8 3.2±0.1±1.0 2.6±0.1±0.8 3.3±0.1±1.0 11.6±0.2±3.5 +jets 12.7±1.0+8.9 −5.6 19±2+ 11 −4 14±1+ 13 −7 23±2+ 15 −7 69±3+ 47 −24 Sum of backgrounds 87±2+₋119 100±2+ 13 −8 107±2+ 15 −11 128±3+ 18 −12 421±5+ 56 −39 Data 99 90 136 124 449 Signals: W→WZ (M(W)=600 GeV) 54.2±1.6±2.7 62.2±1.7±3.1 59.9±1.7±3.0 68.2±1.8±3.4 244±3±12 W→WZ (M(W)=1000 GeV) 7.1±0.2±0.4 7.4±0.2±0.4 7.1±0.2±0.4 7.1±0.2±0.4 28.6±0.4±1.3 W→WZ (M(W)=1400 GeV) 1.3±0.1±0.1 1.3±0.1±0.1 1.3±0.1±0.1 1.2±0.1±0.1 5.1±0.1±0.2

Fig. 3. ObservedandpredictedWZ invariantmass(mWZ)distributionforeventsin

thehigh-masssignalregion(SRHM).Anextrapolationofthebackgroundstothe very-high-massregionwas performedusingapower-lawfunctionto ﬁtfor the SM WZ andthesumofallotherbackgroundsseparately.PredictionsfromW sam-pleswithmassesof600 GeV,1000 GeVand1400 GeVarealsoshown,stacked on topofthe expectedbackgrounds.The uncertaintybands uponthe expected backgroundincludeboththestatisticalandsystematicuncertaintiesintheMC sim-ulationandthefake-backgroundestimationaddedinquadrature.

The mWZ distribution isused to build a binned log-likelihood ratio(LLR)teststatistic[58].Thesystematicuncertaintiesare rep-resented by nuisance parameters for both the backgrounds and signals. Conﬁdence levels (CL)for thesignal-plus-background hy-pothesis (CLs+b) and background-only hypothesis (CLb) are com-putedbyintegratingtheLLRdistributionsobtainedfromsimulated pseudo-experimentsusingPoissonstatistics.

To check the consistency between the observed data and ex-pected SM backgrounds, the p-value, defined as 1−CLb, for a backgroundfluctuation to give rise to an excess atleast aslarge asthat observed indata iscomputed. The obtained p-valuesare reportedinTable 4forthesignalhypothesisofaWparticlewith massfrom 200 GeVto 2 TeV.The lowest local p-value probabil-ityisfoundtobe 8%forthe375 GeV resonancemasshypothesis, equivalent to a 1.75σ local excess, indicating that no significant excessisobserved.

Inthemodiﬁedfrequentistapproach[59],the95%CLexcluded crosssection iscomputedasthecrosssection forwhich CLs, de-ﬁnedastheratioCLs+b/CLb,isequalto0.05. Forthemasspoints above 400 GeV, only the high-mass signal region is used in the

Fig. 4. ObservedandpredictedWZ invariantmass(mWZ)distributionforeventsin

the low-masssignalregion(SRLM).Predictions fromaW samplewith massof 200 GeVarealsoshown.TheW curveisscaledby1/10 forbetterdisplay.The uncertaintybandsupontheexpectedbackgroundincludeboththestatisticaland systematicuncertaintiesintheMCsimulationandthefake-backgroundestimation addedinquadrature.

calculationbystatisticallycombiningallleptondecaychannels.For themasspointsbeloworequalto400 GeV,thetwosignalregions arefurthercombinedtomaximizethesensitivityofthesearch.

Fig. 5presentsthe95%CLupperlimitson σ(pp→X)×B(X→ WZ) asafunction ofthe signal resonancemass,where X stands

for the signal resonance,together withthe theoretical cross sec-tionsoftheEGMWandHVTbenchmarkmodels.Thelattercross sections are calculated via the web interface [60] provided by the authorsofRef. [20].The exclusionregionin parameterspace {(g2/gV)cF,gVcH}isshowninFig. 6.ThefermioncouplingcF was setto thesamevalueforquarksandleptons.The couplingscVVV,

cVVHH andcVVW,whichinvolveverticeswithmorethanoneheavy vectorbosonandwhichhavenegligibleeffectonthecrosssection, weresettozero.Table 4presentstheexpectedandobservedlimits foraselectedsetofsignalmasspointsaswellastheEGMW sig-nalacceptance A andcorrectionfactorC .Theacceptance A is de-finedasthenumberofgeneratedeventsfoundwithinthefiducial region atparticle leveldivided by the totalnumber ofgenerated events,while C isdefinedasthenumberofreconstructedevents passingthenominalselectionrequirementsdividedbythenumber ofgeneratedeventswithinthefiducialregionatparticlelevel.The fiducialregionselectioncriteriaconsistofthesamekinematic

(7)

se-Table 4

Theexpectedandobserved95%CLupperlimitsontheproductioncrosssectionofnarrowresonancesdecayingtoWZ asafunctionoftheirmass.Thehigh-masssignal region(SRHM)andlow-masssignalregion(SRLM)ﬁducialacceptancesatparticlelevel( A)andcorrectionfactors(C )foran EGMWasimplementedinPYTHIAarealso given.SRLM wasnotusedinsettingthelimitsforthemasspointsbeyond400 GeVduetotheirverylowacceptances.Errorsshownarestatistical.Thep-value,deﬁnedas 1−CLb,isalsoshownforeachmasspointinthelastcolumn.

mW [GeV] Excludedσ×B [fb] SRHM A/C SRLM A/C p-value Expected Observed 200 2613 3182 0.025±0.001/0.75±0.05 0.135±0.003/0.57±0.02 0.36 250 1902 1853 0.111±0.002/0.55±0.02 0.070±0.002/0.80±0.03 0.48 300 751 1195 0.202±0.003/0.57±0.01 0.024±0.001/1.42±0.07 0.22 350 427 894 0.269±0.004/0.61±0.01 0.0093±0.0006/2.5±0.2 0.094 375 330 670 0.29±0.01/0.62±0.02 0.007±0.001/2.9±0.6 0.080 400 281 526 0.311±0.005/0.63±0.01 0.0048±0.0005/3.3±0.4 0.094 600 90 115 0.426±0.006/0.68±0.01 not used 0.29 800 52 40 0.475±0.006/0.68±0.01 0.71 1000 38 33 0.505±0.007/0.68±0.01 0.59 1200 31 24 0.526±0.007/0.66±0.01 0.71 1400 25 21 0.530±0.007/0.66±0.01 0.81 1600 23 21 0.533±0.007/0.63±0.01 0.83 1800 23 21 0.544±0.007/0.60±0.01 0.82 2000 24 22 0.535±0.007/0.57±0.01 0.85

Fig. 5. Theobserved95%CLupperlimitsonσ(pp→X)×B(X→WZ)asa func-tionofthesignalmassm,whereX standsforthesignalresonance.Theexpected limitsarealsoshowntogetherwiththe±1 and±2 standarddeviationuncertainty bands.BoththeexpectedandobservedupperlimitsassumetheEGM W signal acceptancetimeseﬃciencyaspresentedinTable 4.Theoreticalcrosssectionsfor theEGMWandtheHVTbenchmarkmodelsarealsoshown.Theuncertaintyband aroundtheEGMWcross-sectionlinerepresentsthetheoreticaluncertaintyonthe NNLOcross-sectioncalculationusingZWPROD[32].

lections(lepton pT,lepton η,Z bosonmass,Emiss_T , y(W,Z)and φ (,Emiss

T ))andleptonisolation requirementsasinthenominal selections.Particlelevelreferstoparticlestatesthatstemfromthe hardscatter,includingthosethataretheproductofhadronization, butbeforetheirinteractionwiththedetector.Table 5presentsthe 95%CLexpectedandobservedlowerlimitsontheEGMWboson massforeachdecaychannelandtheircombination.Theobserved (expected)exclusionlimitontheEGMWmassisfoundtobe1.52 (1.49)TeV,andthelimitsineachchannelareshowninTable 5.The simulatedHVT resonances are found to havekinematic distribu-tionssimilartothoseoftheWandthushavesimilaracceptances tothe EGMmodel. Thecorresponding observed (expected)limits forthe A(gV=1),A(gV=3),andB(gV=3)HVTresonancesfrom Ref.[20] are 1.49 (1.45) TeV, 0.76(0.69) TeV,and1.56 (1.53) TeV respectively. InFig. 5, the HVTbenchmark model curves are not shownforlowresonancemasswherethemodelsdonotapply.

9. Conclusion

Asearchforresonant WZ dibosonproductioninthefully lep-tonicchannel hasbeenperformedwiththeATLASdetector,using 20.3 fb−1of pp collisiondatacollectedat√s=8 TeV attheLHC.

Fig. 6. Observed 95% CL exclusion contours in the HVT parameter space {(g2_/_g

V)cF,gVcH}forresonancesofmass1 TeV,1.5 TeVand2 TeV.Alsoshownare

thebenchmarkmodelparametersA(gV=1)(circle)andA(gV=3)(square)andB(gV=3)

(triangle).

Table 5

Expectedandobservedlowermasslimitsat95%CLin TeVfortheEGMWboson intheeνee,eνμμ,μνee,μνμμchannelsaswellasthefourchannelscombined.

Excluded EGM Wlower mass [TeV]

eνee μνee eνμμ μνμμ combined

Expected 1.21 1.16 1.17 1.16 1.49

Observed 1.20 1.19 1.06 1.17 1.52

NoexcessisfoundindatacomparedtotheSMexpectations. Strin-gent limitson the production cross section times WZ branching

ratio areobtained asa function ofthe resonance massfora W

arisingfromanextendedgaugemodelanddecayingtoWZ.A cor-responding observed (expected) mass limit of 1.52 (1.49) TeV is derivedfortheW.

Acknowledgements

We thank CERN forthe very successfuloperation of the LHC, aswell as thesupport staff fromour institutionswithout whom ATLAScouldnotbeoperatedeﬃciently.

(8)

We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia;ARC,Australia;BMWFandFWF,Austria;ANAS, Azerbai-jan;SSTC,Belarus; CNPqandFAPESP,Brazil;NSERC, NRCandCFI, Canada;CERN;CONICYT,Chile;CAS,MOSTandNSFC,China; COL-CIENCIAS,Colombia;MSMTCR,MPOCRandVSCCR,Czech Repub-lic; DNRF, DNSRC and Lundbeck Foundation, Denmark; EPLANET, ERC and NSRF, European Union; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, DFG, HGF, MPG and AvH Founda-tion,Germany;GSRTandNSRF,Greece;ISF,MINERVA,GIF,I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST,Morocco;FOMandNWO, Netherlands;BRFandRCN, Nor-way;MNiSWandNCN,Poland;GRICESandFCT,Portugal;MNE/IFA, Romania; MESofRussiaandROSATOM, RussianFederation;JINR; MSTD,Serbia;MSSR,Slovakia; ARRSandMIZŠ,Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SER, SNSF and Cantons of Bern and Geneva, Switzer-land; NSC, Taiwan; TAEK, Turkey; STFC, the Royal Society and Leverhulme Trust, United Kingdom; DOE and NSF, United States ofAmerica.

The crucial computingsupport fromall WLCG partners is ac-knowledged gratefully, in particular from CERN and the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy),NL-T1(Netherlands),PIC(Spain),ASGC (Taiwan),RAL(UK) andBNL(USA)andintheTier-2facilitiesworldwide.

References

[1] Observation ofanew particle inthe searchfor the Standard ModelHiggs boson with theATLAS detector at theLHC, Phys.Lett. B716(2012)1–29,

http://dx.doi.org/10.1016/j.physletb.2012.08.020,arXiv:1207.7214.

[2] Observation ofanew boson at amass of125GeV with the CMS experi-ment atthe LHC,Phys. Lett.B716(2012)30–61, http://dx.doi.org/10.1016/ j.physletb.2012.08.021,arXiv:1207.7235.

[3] Evidence for thespin-0natureofthe Higgsboson usingATLAS data,Phys. Lett. B726(2013) 120–144, http://dx.doi.org/10.1016/j.physletb.2013.08.026, arXiv:1307.1432.

[4] Studyofthemassandspin-parityoftheHiggsbosoncandidateviaitsdecays toZbosonpairs,Phys.Rev.Lett.110(2013)081803,http://dx.doi.org/10.1103/ PhysRevLett.110.081803,arXiv:1212.6639.

[5] P. Langacker, R.W. Robinett, J.L. Rosner, New heavy gauge bosons in pp

and pp collisions,¯ Phys. Rev.D 30 (1984) 1470, http://dx.doi.org/10.1103/ PhysRevD.30.1470.

[6]N.Arkani-Hamed,A.G.Cohen,E.Katz,A.E.Nelson,ThelittlestHiggs,J.High EnergyPhys.07(2002)034,arXiv:hep-ph/0206021.

[7] K.Lane,S.Mrenna,Thecollider phenomenologyoftechnihadronsinthe tech-nicolorstraw manmodel,Phys. Rev.D67 (2003)115011, http://dx.doi.org/ 10.1103/PhysRevD.67.115011,arXiv:hep-ph/0210299.

[8] E. Eichten, K. Lane, Low-scaletechnicolor at the Tevatron and LHC, Phys. Lett. B669(2008) 235–238, http://dx.doi.org/10.1016/j.physletb.2008.09.047, arXiv:0706.2339.

[9] F.Sannino,K.Tuominen,Orientifoldtheorydynamicsandsymmetrybreaking, Phys.Rev.D71(2005)051901,http://dx.doi.org/10.1103/PhysRevD.71.051901, arXiv:hep-ph/0405209.

[10] A.Belyaev,etal.,TechnicolorwalksattheLHC,Phys.Rev.D79(2009)035006,

http://dx.doi.org/10.1103/PhysRevD.79.035006,arXiv:0809.0793.

[11] K.Agashe,R.Contino,A.Pomarol,TheminimalcompositeHiggsmodel,Nucl. Phys.B719(2005)165–187,http://dx.doi.org/10.1016/j.nuclphysb.2005.04.035, arXiv:hep-ph/0412089.

[12] G. Giudice, C. Grojean, A. Pomarol, R. Rattazzi, The strongly-interacting lightHiggs,J.HighEnergy Phys.0706(2007)045,http://dx.doi.org/10.1088/ 1126-6708/2007/06/045,arXiv:hep-ph/0703164.

[13] L.Randall,R.Sundrum,Alargemasshierarchyfromasmallextradimension, Phys. Rev. Lett.83 (1999) 3370–3373,http://dx.doi.org/10.1103/PhysRevLett. 83.3370,arXiv:hep-ph/9905221.

[14] H. Davoudiasl, J.L. Hewett, T.G. Rizzo, Bulk gauge ﬁelds in the Randall– Sundrum model, Phys. Lett. B 473(2000) 43–49, http://dx.doi.org/10.1016/ S0370-2693(99)01430-6,arXiv:hep-ph/9911262.

[15] C.Csaki,C.Grojean,H.Murayama,L.Pilo,J.Terning,Gaugetheoriesonan in-terval:unitaritywithoutaHiggs,Phys.Rev.D69(2004)055006,http://dx.doi. org/10.1103/PhysRevD.69.055006,arXiv:hep-ph/0305237.

[16] G.Altarelli,B.Mele,M.Ruiz-Altaba,Searchingfornewheavyvectorbosonsin

pp colliders,¯ Z.Phys.C45(1989)109,http://dx.doi.org/10.1007/BF01556677.

[17] K. Babu, C.F. Kolda, J. March-Russell, Leptophobic U(1)’s and the R(b)− R(c) crisis, Phys. Rev. D 54 (1996) 4635–4647, http://dx.doi.org/10.1103/ PhysRevD.54.4635,arXiv:hep-ph/9603212.

[18] T.G. Rizzo, Gauge kinetic mixing and leptophobic Z in E(6) and SO(10), Phys.Rev.D59(1999)015020,http://dx.doi.org/10.1103/PhysRevD.59.015020, arXiv:hep-ph/9806397.

[19]J.Hewett,T.Rizzo,DissectingtheWjjanomaly:diagnostictestsofa leptopho-bicZ,arXiv:1106.0294.

[20]D.Pappadopulo,A.Thamm,R.Torre,A.Wulzer,Heavyvectortriplets:bridging theoryanddata,arXiv:1402.4431.

[21] V.D.Barger,W.-Y.Keung,E.Ma,AgaugemodelwithlightW andZ bosons,

Phys.Rev.D22(1980)727,http://dx.doi.org/10.1103/PhysRevD.22.727. [22] R.Contino,D.Marzocca,D.Pappadopulo,R.Rattazzi, Onthe effectof

reso-nancesincompositeHiggsphenomenology,J.HighEnergyPhys.1110(2011) 081,http://dx.doi.org/10.1007/JHEP10(2011)081,arXiv:1109.1570.

[23] Search for resonant W Z productioninthe W Z→ ν channelin√s= 7 TeV pp collisionswiththeATLASdetector,Phys.Rev.D85(2012)112012,

[24] Search forresonant dibosonproductioninthelvjjdecaychannelswith the ATLAS detector, Phys. Rev. D 87 (2013) 112006, http://dx.doi.org/10.1103/ PhysRevD.87.112006,arXiv:1305.0125.

[25]Searchformassiveresonancesdecayingintopairsofboostedbosonsin semi-leptonicﬁnalstatesat√s=8 TeV,arXiv:1405.3447.

[26]SearchformassiveresonancesindijetsystemscontainingjetstaggedasWor Zbosondecaysinppcollisionsat√s=8 TeV,arXiv:1405.1994.

[27] SearchforaWortechni-ρdecayingintoW Z inpp collisionsat√s=7 TeV, Phys.Rev.Lett.109(2012)141801,http://dx.doi.org/10.1103/PhysRevLett.109. 141801,arXiv:1206.0433.

[28] ATLASCollaboration,TheATLASexperimentattheCERNlargehadroncollider, J.Instrum.3(2008)S08003,http://dx.doi.org/10.1088/1748-0221/3/08/S08003. [29] Improvedluminositydeterminationinpp collisionsat √s=7 TeV usingthe ATLAS detector at the LHC, Eur. Phys. J. C 73 (2013) 2518, http://dx.doi. org/10.1140/epjc/s10052-013-2518-3,arXiv:1302.4393.

[30] T. Sjostrand, S. Mrenna, P.Z. Skands, A brief introduction to PYTHIA 8.1, Comput.Phys.Commun.178(2008)852–867,http://dx.doi.org/10.1016/j.cpc. 2008.01.036,arXiv:0710.3820.

[31] A. Martin,W.Stirling,R.Thorne, G.Watt,Partondistributionsfor theLHC, Eur.Phys.J.C63(2009)189–285, http://dx.doi.org/10.1140/epjc/s10052-009-1072-5,arXiv:0901.0002.

[32] R.Hamberg,W.vanNeerven,T.Matsuura,Acompletecalculationoftheorder

α−s2_correction_to_the_Drell–Yan_{K factor,}_Nucl._Phys._B₃₅₉₍₁₉₉₁₎_343–405,

http://dx.doi.org/10.1016/0550-3213(91)90064-5.

[33] S. Alioli, P.Nason, C.Oleari, E.Re,A general framework for implementing NLOcalculationsinshowerMonteCarloprograms:thePOWHEGBOX,J.High Energy Phys. 1006 (2010) 043, http://dx.doi.org/10.1007/JHEP06(2010)043, arXiv:1002.2581.

[34] T.Melia,P.Nason, R.Rontsch,G.Zanderighi,W+W−, W Z and Z Z

produc-tioninthePOWHEGBOX,JHEP 1111(2011)078,http://dx.doi.org/10.1007/ JHEP11(2011)078,arXiv:1107.5051.

[35] P. Nason, A new method for combining NLO QCD with shower Monte Carloalgorithms,JHEP0411(2004)040,http://dx.doi.org/10.1088/1126-6708/ 2004/11/040,arXiv:hep-ph/0409146.

[36] S. Frixione, P. Nason, C. Oleari, Matching NLO QCD computations with Parton Shower simulations: the POWHEG method, JHEP 0711 (2007) 070,

http://dx.doi.org/10.1088/1126-6708/2007/11/070,arXiv:0709.2092.

[37] H.-L. Lai, M. Guzzi, J. Huston, Z.Li, P.M. Nadolsky, J. Pumplin, C.-P. Yuan, Newpartondistributionsforcolliderphysics,Phys.Rev.D82(2010)074024,

[38] J.Alwall, M. Herquet,F.Maltoni, O.Mattelaer, T. Stelzer,MadGraph5: go-ingbeyond,J.HighEnergy Phys.1106(2011)128,http://dx.doi.org/10.1007/ JHEP06(2011)128,arXiv:1106.0522.

[39] P.M.Nadolsky,H.-L.Lai,Q.-H.Cao,J.Huston,J.Pumplin,etal.,Implicationsof CTEQglobalanalysisforcolliderobservables,Phys.Rev.D78(2008)013004,

[40] SummaryofATLASPythia8tunes,Tech.Rep.ATL-PHYS-PUB-2012-003,CERN, Geneva,August2012.

[41] J.Archibald,etal.,Simulationofphoton–photoninteractionsinhadron colli-sionswithSHERPA,Nucl.Phys.Proc.Suppl.179–180(2008)218–225,http://dx. doi.org/10.1016/j.nuclphysbps.2008.07.027.

[42] TheATLASsimulationinfrastructure,Eur.Phys.J.C70(2010)823–874,http:// dx.doi.org/10.1140/epjc/s10052-010-1429-9,arXiv:1005.4568.

[43] S.Agostinelli,etal.,GEANT4:asimulationtoolkit,Nucl.Instrum.Meth.A506 (2003)250–303,http://dx.doi.org/10.1016/S0168-9002(03)01368-8.

[44]Electronreconstruction andidentiﬁcation eﬃciencymeasurementswith the ATLASdetectorusingthe2011LHCproton–protoncollisiondata,arXiv:1404. 2240.

[45] Performanceofmissingtransversemomentumreconstructioninproton–proton collisionsat 7 TeVwith ATLAS,Eur.Phys.J.C72(2012)1844,http://dx.doi. org/10.1140/epjc/s10052-011-1844-6,arXiv:1108.5602.

(9)

[46] T. Aaltonen, et al., Combination of CDF and D0 W -boson mass measure-ments,Phys.Rev.D88 (5)(2013)052018,http://dx.doi.org/10.1103/PhysRevD. 88.052018,arXiv:1307.7627.

[47] S.Schael,etal.,PrecisionelectroweakmeasurementsontheZ resonance,Phys. Rep. 427 (2006) 257–454, http://dx.doi.org/10.1016/j.physrep.2005.12.006, arXiv:hep-ex/0509008.

[48] T.Aaltonen,etal.,FirstmeasurementofinclusiveWandZcrosssectionsfrom run IIofthe FermilabTevatroncollider,Phys. Rev.Lett.94 (2005)091803,

http://dx.doi.org/10.1103/PhysRevLett.94.091803,arXiv:hep-ex/0406078. [49] V.M.Abazov,etal.,Measurementoftheshapeofthebosonrapidity

distribu-tionforp¯p→Z/γ∗→e+e−+X eventsproducedat√s of1.96 TeV,Phys.Rev. D76(2007)012003,http://dx.doi.org/10.1103/PhysRevD.76.012003, arXiv:hep-ex/0702025.

[50] M.L.Mangano,M.Moretti,F.Piccinini,R.Pittau,A.D.Polosa,ALPGEN,a gener-atorforhardmultipartonprocessesinhadroniccollisions,J.HighEnergyPhys. 0307(2003)001,http://dx.doi.org/10.1088/1126-6708/2003/07/001, arXiv:hep-ph/0206293.

[51] S.Frixione,B.R.Webber,MatchingNLOQCDcomputationsandpartonshower simulations,J.HighEnergyPhys.0206(2002)029,http://dx.doi.org/10.1088/ 1126-6708/2002/06/029,arXiv:hep-ph/0204244.

[52] G.Corcella,I.Knowles,G.Marchesini,S.Moretti,K. Odagiri,et al.,HERWIG 6:aneventgenerator forhadronemissionreactionswithinterferinggluons

(includingsupersymmetricprocesses),J.HighEnergyPhys.0101(2001)010,

http://dx.doi.org/10.1088/1126-6708/2001/01/010,arXiv:hep-ph/0011363. [53] J.Butterworth,J.R. Forshaw,M.Seymour,Multipartoninteractions in

photo-productionatHERA,Z.Phys.C72(1996)637–646,http://dx.doi.org/10.1007/ s002880050286,arXiv:hep-ph/9601371.

[54] M. Cacciari, G.P. Salam, G. Soyez, The anti-k(t) jet clustering algorithm, J. High Energy Phys. 0804 (2008) 063,http://dx.doi.org/10.1088/1126-6708/ 2008/04/063,arXiv:0802.1189.

[55] J.M. Campbell, R.K. Ellis, C. Williams, Vector boson pair production at the LHC, J. High Energy Phys. 1107 (2011) 018, http://dx.doi.org/10.1007/ JHEP07(2011)018,arXiv:1105.0020.

[56] F. Campanario, S. Sapeta, WZ production beyond NLOfor high-pT observ-ables, Phys.Lett. B718(2012)100–104,http://dx.doi.org/10.1016/j.physletb. 2012.10.013,arXiv:1209.4595.

[57]W.Verkerke,D.P.Kirkby,TheRooFittoolkitfordatamodeling,eConfC0303241 (2003)MOLT007,arXiv:physics/0306116.

[58]M.G.Kendall,A.Stuart,TheAdvancedTheoryofStatistics,CharlesGriﬃnand CompanyLimited,London,1967.

[59] A.L.Read,Presentation ofsearchresults:the CL(s)technique,J.Phys. G28 (2002)2693–2704,http://dx.doi.org/10.1088/0954-3899/28/10/313.

[60] D.Pappadopulo,A.Thamm,R.Torre,A.Wulzer,http://rtorre.web.cern.ch/rtorre/ Riccardotorre/vector_triplet_t.html.

ATLASCollaboration

G. Aad84,B. Abbott112, J. Abdallah152, S. Abdel Khalek116, O. Abdinov11,R. Aben106,B. Abi113, M. Abolins89, O.S. AbouZeid159,H. Abramowicz154, H. Abreu153, R. Abreu30, Y. Abulaiti147a,147b, B.S. Acharya165a,165b,a, L. Adamczyk38a, D.L. Adams25, J. Adelman177, S. Adomeit99, T. Adye130, T. Agatonovic-Jovin13a,J.A. Aguilar-Saavedra125a,125f,M. Agustoni17,S.P. Ahlen22,F. Ahmadov64,b, G. Aielli134a,134b, H. Akerstedt147a,147b, T.P.A. Åkesson80,G. Akimoto156, A.V. Akimov95,

G.L. Alberghi20a,20b, J. Albert170,S. Albrand55,M.J. Alconada Verzini70, M. Aleksa30, I.N. Aleksandrov64, C. Alexa26a,G. Alexander154, G. Alexandre49,T. Alexopoulos10, M. Alhroob165a,165c, G. Alimonti90a, L. Alio84,J. Alison31,B.M.M. Allbrooke18, L.J. Allison71,P.P. Allport73,J. Almond83,A. Aloisio103a,103b, A. Alonso36, F. Alonso70,C. Alpigiani75, A. Altheimer35,B. Alvarez Gonzalez89, M.G. Alviggi103a,103b, K. Amako65,Y. Amaral Coutinho24a,C. Amelung23,D. Amidei88,S.P. Amor Dos Santos125a,125c, A. Amorim125a,125b,S. Amoroso48, N. Amram154,G. Amundsen23, C. Anastopoulos140,L.S. Ancu49, N. Andari30, T. Andeen35, C.F. Anders58b,G. Anders30,K.J. Anderson31, A. Andreazza90a,90b,

V. Andrei58a, X.S. Anduaga70, S. Angelidakis9,I. Angelozzi106, P. Anger44, A. Angerami35, F. Anghinolﬁ30,A.V. Anisenkov108, N. Anjos125a,A. Annovi47,A. Antonaki9, M. Antonelli47,

A. Antonov97, J. Antos145b, F. Anulli133a,M. Aoki65,L. Aperio Bella18, R. Apolle119,c, G. Arabidze89, I. Aracena144, Y. Arai65, J.P. Araque125a,A.T.H. Arce45,J-F. Arguin94, S. Argyropoulos42, M. Arik19a, A.J. Armbruster30, O. Arnaez30, V. Arnal81,H. Arnold48,M. Arratia28,O. Arslan21, A. Artamonov96, G. Artoni23,S. Asai156, N. Asbah42,A. Ashkenazi154,B. Åsman147a,147b, L. Asquith6, K. Assamagan25, R. Astalos145a,M. Atkinson166, N.B. Atlay142,B. Auerbach6,K. Augsten127,M. Aurousseau146b,

G. Avolio30, G. Azuelos94,d, Y. Azuma156, M.A. Baak30,C. Bacci135a,135b, H. Bachacou137,K. Bachas155, M. Backes30, M. Backhaus30,J. Backus Mayes144,E. Badescu26a,P. Bagiacchi133a,133b,P. Bagnaia133a,133b, Y. Bai33a, T. Bain35,J.T. Baines130, O.K. Baker177, S. Baker77, P. Balek128, F. Balli137,E. Banas39,

Sw. Banerjee174,A.A.E. Bannoura176,V. Bansal170, H.S. Bansil18,L. Barak173, S.P. Baranov95, E.L. Barberio87, D. Barberis50a,50b, M. Barbero84,T. Barillari100,M. Barisonzi176,T. Barklow144,

N. Barlow28, B.M. Barnett130,R.M. Barnett15,Z. Barnovska5, A. Baroncelli135a,G. Barone49, A.J. Barr119, F. Barreiro81,J. Barreiro Guimarães da Costa57, R. Bartoldus144, A.E. Barton71,P. Bartos145a,

V. Bartsch150, A. Bassalat116,A. Basye166, R.L. Bates53, L. Batkova145a, J.R. Batley28,M. Battaglia138, M. Battistin30,F. Bauer137,H.S. Bawa144,e,T. Beau79,P.H. Beauchemin162, R. Beccherle123a,123b, P. Bechtle21,H.P. Beck17,K. Becker176, S. Becker99,M. Beckingham139,C. Becot116,A.J. Beddall19c, A. Beddall19c,S. Bedikian177, V.A. Bednyakov64,C.P. Bee149, L.J. Beemster106,T.A. Beermann176,

M. Begel25,K. Behr119,C. Belanger-Champagne86,P.J. Bell49, W.H. Bell49, G. Bella154, L. Bellagamba20a, A. Bellerive29,M. Bellomo85, K. Belotskiy97,O. Beltramello30,O. Benary154,D. Benchekroun136a, K. Bendtz147a,147b, N. Benekos166,Y. Benhammou154, E. Benhar Noccioli49, J.A. Benitez Garcia160b, D.P. Benjamin45,J.R. Bensinger23,K. Benslama131, S. Bentvelsen106,D. Berge106,

(10)

E. Bergeaas Kuutmann16,N. Berger5,F. Berghaus170, E. Berglund106,J. Beringer15, C. Bernard22, P. Bernat77,C. Bernius78,F.U. Bernlochner170, T. Berry76, P. Berta128,C. Bertella84, G. Bertoli147a,147b, F. Bertolucci123a,123b,D. Bertsche112, M.I. Besana90a,G.J. Besjes105, O. Bessidskaia147a,147b,

M.F. Bessner42,N. Besson137,C. Betancourt48,S. Bethke100,W. Bhimji46, R.M. Bianchi124,

L. Bianchini23, M. Bianco30, O. Biebel99, S.P. Bieniek77, K. Bierwagen54, J. Biesiada15,M. Biglietti135a, J. Bilbao De Mendizabal49,H. Bilokon47, M. Bindi54,S. Binet116,A. Bingul19c,C. Bini133a,133b,

C.W. Black151, J.E. Black144, K.M. Black22, D. Blackburn139,R.E. Blair6, J.-B. Blanchard137,T. Blazek145a, I. Bloch42, C. Blocker23, W. Blum82,∗, U. Blumenschein54,G.J. Bobbink106, V.S. Bobrovnikov108,

S.S. Bocchetta80,A. Bocci45, C. Bock99, C.R. Boddy119,M. Boehler48, J. Boek176, T.T. Boek176, J.A. Bogaerts30, A.G. Bogdanchikov108,A. Bogouch91,∗,C. Bohm147a,J. Bohm126, V. Boisvert76,

T. Bold38a,V. Boldea26a, A.S. Boldyrev98, M. Bomben79, M. Bona75,M. Boonekamp137,A. Borisov129, G. Borissov71, M. Borri83, S. Borroni42,J. Bortfeldt99,V. Bortolotto135a,135b, K. Bos106,D. Boscherini20a, M. Bosman12,H. Boterenbrood106,J. Boudreau124,J. Bouffard2,E.V. Bouhova-Thacker71,

D. Boumediene34,C. Bourdarios116, N. Bousson113, S. Boutouil136d, A. Boveia31, J. Boyd30, I.R. Boyko64, I. Bozovic-Jelisavcic13b, J. Bracinik18, A. Brandt8,G. Brandt15, O. Brandt58a, U. Bratzler157,B. Brau85, J.E. Brau115,H.M. Braun176,∗, S.F. Brazzale165a,165c, B. Brelier159,K. Brendlinger121, A.J. Brennan87, R. Brenner167,S. Bressler173,K. Bristow146c,T.M. Bristow46,D. Britton53,F.M. Brochu28, I. Brock21, R. Brock89,C. Bromberg89,J. Bronner100, G. Brooijmans35, T. Brooks76,W.K. Brooks32b,J. Brosamer15, E. Brost115,G. Brown83,J. Brown55, P.A. Bruckman de Renstrom39, D. Bruncko145b, R. Bruneliere48, S. Brunet60,A. Bruni20a,G. Bruni20a,M. Bruschi20a,L. Bryngemark80, T. Buanes14, Q. Buat143, F. Bucci49, P. Buchholz142, R.M. Buckingham119,A.G. Buckley53,S.I. Buda26a, I.A. Budagov64,

F. Buehrer48, L. Bugge118,M.K. Bugge118,O. Bulekov97,A.C. Bundock73,H. Burckhart30,S. Burdin73, B. Burghgrave107,S. Burke130,I. Burmeister43,E. Busato34,D. Büscher48,V. Büscher82,P. Bussey53, C.P. Buszello167, B. Butler57, J.M. Butler22,A.I. Butt3,C.M. Buttar53,J.M. Butterworth77,P. Butti106, W. Buttinger28,A. Buzatu53,M. Byszewski10, S. Cabrera Urbán168, D. Caforio20a,20b, O. Cakir4a, P. Calaﬁura15,A. Calandri137, G. Calderini79,P. Calfayan99,R. Calkins107,L.P. Caloba24a, D. Calvet34, S. Calvet34,R. Camacho Toro49,S. Camarda42, D. Cameron118,L.M. Caminada15,

R. Caminal Armadans12, S. Campana30,M. Campanelli77,A. Campoverde149, V. Canale103a,103b, A. Canepa160a, M. Cano Bret75,J. Cantero81,R. Cantrill76, T. Cao40, M.D.M. Capeans Garrido30, I. Caprini26a,M. Caprini26a, M. Capua37a,37b, R. Caputo82,R. Cardarelli134a,T. Carli30,G. Carlino103a, L. Carminati90a,90b,S. Caron105,E. Carquin32a,G.D. Carrillo-Montoya146c,J.R. Carter28,

J. Carvalho125a,125c, D. Casadei77,M.P. Casado12,M. Casolino12,E. Castaneda-Miranda146b,

A. Castelli106,V. Castillo Gimenez168,N.F. Castro125a,P. Catastini57,A. Catinaccio30, J.R. Catmore118, A. Cattai30, G. Cattani134a,134b, S. Caughron89, V. Cavaliere166,D. Cavalli90a,M. Cavalli-Sforza12, V. Cavasinni123a,123b,F. Ceradini135a,135b,B. Cerio45,K. Cerny128,A.S. Cerqueira24b, A. Cerri150, L. Cerrito75, F. Cerutti15, M. Cerv30,A. Cervelli17, S.A. Cetin19b,A. Chafaq136a, D. Chakraborty107, I. Chalupkova128,K. Chan3,P. Chang166,B. Chapleau86,J.D. Chapman28,D. Charfeddine116,

D.G. Charlton18,C.C. Chau159,C.A. Chavez Barajas150,S. Cheatham86, A. Chegwidden89,S. Chekanov6, S.V. Chekulaev160a, G.A. Chelkov64,f, M.A. Chelstowska88, C. Chen63, H. Chen25,K. Chen149,

L. Chen33d,g,S. Chen33c,X. Chen146c,Y. Chen35,H.C. Cheng88, Y. Cheng31, A. Cheplakov64, R. Cherkaoui El Moursli136e,V. Chernyatin25,∗,E. Cheu7, L. Chevalier137,V. Chiarella47,

G. Chiefari103a,103b, J.T. Childers6, A. Chilingarov71,G. Chiodini72a, A.S. Chisholm18,R.T. Chislett77, A. Chitan26a, M.V. Chizhov64,S. Chouridou9,B.K.B. Chow99, D. Chromek-Burckhart30,M.L. Chu152, J. Chudoba126, J.J. Chwastowski39, L. Chytka114,G. Ciapetti133a,133b,A.K. Ciftci4a,R. Ciftci4a, D. Cinca62, V. Cindro74, A. Ciocio15,P. Cirkovic13b,Z.H. Citron173,M. Citterio90a,M. Ciubancan26a,A. Clark49, P.J. Clark46,R.N. Clarke15, W. Cleland124,J.C. Clemens84,C. Clement147a,147b,Y. Coadou84,

M. Cobal165a,165c,A. Coccaro139, J. Cochran63, L. Coffey23,J.G. Cogan144,J. Coggeshall166, B. Cole35, S. Cole107,A.P. Colijn106, J. Collot55, T. Colombo58c,G. Colon85, G. Compostella100,

P. Conde Muiño125a,125b, E. Coniavitis167,M.C. Conidi12, S.H. Connell146b, I.A. Connelly76,

S.M. Consonni90a,90b, V. Consorti48,S. Constantinescu26a,C. Conta120a,120b, G. Conti57,F. Conventi103a,h, M. Cooke15, B.D. Cooper77, A.M. Cooper-Sarkar119,N.J. Cooper-Smith76, K. Copic15, T. Cornelissen176, M. Corradi20a,F. Corriveau86,i, A. Corso-Radu164, A. Cortes-Gonzalez12, G. Cortiana100,G. Costa90a,

(11)

M.J. Costa168,D. Costanzo140, D. Côté8, G. Cottin28, G. Cowan76, B.E. Cox83,K. Cranmer109,G. Cree29, S. Crépé-Renaudin55, F. Crescioli79, W.A. Cribbs147a,147b, M. Crispin Ortuzar119, M. Cristinziani21, V. Croft105, G. Crosetti37a,37b, C.-M. Cuciuc26a, T. Cuhadar Donszelmann140, J. Cummings177,

M. Curatolo47, C. Cuthbert151, H. Czirr142,P. Czodrowski3,Z. Czyczula177,S. D’Auria53,M. D’Onofrio73, M.J. Da Cunha Sargedas De Sousa125a,125b_,_{C. Da Via}83_,_{W. Dabrowski}38a_,_{A. Daﬁnca}119_,_{T. Dai}88_,

O. Dale14,F. Dallaire94,C. Dallapiccola85,M. Dam36, A.C. Daniells18,M. Dano Hoffmann137, V. Dao105, G. Darbo50a, S. Darmora8, J.A. Dassoulas42,A. Dattagupta60,W. Davey21, C. David170, T. Davidek128, E. Davies119,c, M. Davies154,O. Davignon79,A.R. Davison77,P. Davison77,Y. Davygora58a, E. Dawe143, I. Dawson140,R.K. Daya-Ishmukhametova85, K. De8,R. de Asmundis103a,S. De Castro20a,20b,

S. De Cecco79, N. De Groot105, P. de Jong106,H. De la Torre81, F. De Lorenzi63, L. De Nooij106, D. De Pedis133a, A. De Salvo133a,U. De Sanctis165a,165b, A. De Santo150,J.B. De Vivie De Regie116, W.J. Dearnaley71,R. Debbe25,C. Debenedetti46, B. Dechenaux55, D.V. Dedovich64,I. Deigaard106, J. Del Peso81,T. Del Prete123a,123b,F. Deliot137,C.M. Delitzsch49,M. Deliyergiyev74,A. Dell’Acqua30, L. Dell’Asta22,M. Dell’Orso123a,123b,M. Della Pietra103a,h,D. della Volpe49,M. Delmastro5,

P.A. Delsart55,C. Deluca106,S. Demers177,M. Demichev64,A. Demilly79, S.P. Denisov129,

D. Derendarz39,J.E. Derkaoui136d,F. Derue79, P. Dervan73,K. Desch21, C. Deterre42,P.O. Deviveiros106, A. Dewhurst130,S. Dhaliwal106,A. Di Ciaccio134a,134b,L. Di Ciaccio5, A. Di Domenico133a,133b,

C. Di Donato103a,103b, A. Di Girolamo30, B. Di Girolamo30, A. Di Mattia153,B. Di Micco135a,135b, R. Di Nardo47,A. Di Simone48,R. Di Sipio20a,20b,D. Di Valentino29,M.A. Diaz32a, E.B. Diehl88, J. Dietrich42, T.A. Dietzsch58a, S. Diglio84,A. Dimitrievska13a,J. Dingfelder21,C. Dionisi133a,133b, P. Dita26a,S. Dita26a,F. Dittus30,F. Djama84,T. Djobava51b,M.A.B. do Vale24c,

A. Do Valle Wemans125a,125g,T.K.O. Doan5, D. Dobos30,C. Doglioni49,T. Doherty53, T. Dohmae156, J. Dolejsi128,Z. Dolezal128, B.A. Dolgoshein97,∗, M. Donadelli24d,S. Donati123a,123b, P. Dondero120a,120b, J. Donini34,J. Dopke30,A. Doria103a, M.T. Dova70,A.T. Doyle53, M. Dris10, J. Dubbert88,S. Dube15, E. Dubreuil34, E. Duchovni173, G. Duckeck99, O.A. Ducu26a,D. Duda176, A. Dudarev30, F. Dudziak63, L. Duﬂot116,L. Duguid76,M. Dührssen30, M. Dunford58a,H. Duran Yildiz4a,M. Düren52,

A. Durglishvili51b, M. Dwuznik38a, M. Dyndal38a,J. Ebke99,W. Edson2,N.C. Edwards46,W. Ehrenfeld21, T. Eifert144, G. Eigen14,K. Einsweiler15,T. Ekelof167, M. El Kacimi136c, M. Ellert167,S. Elles5,

F. Ellinghaus82, N. Ellis30,J. Elmsheuser99,M. Elsing30,D. Emeliyanov130,Y. Enari156,O.C. Endner82, M. Endo117, R. Engelmann149,J. Erdmann177,A. Ereditato17,D. Eriksson147a,G. Ernis176, J. Ernst2, M. Ernst25, J. Ernwein137, D. Errede166, S. Errede166,E. Ertel82,M. Escalier116, H. Esch43, C. Escobar124, B. Esposito47, A.I. Etienvre137,E. Etzion154, H. Evans60, A. Ezhilov122,L. Fabbri20a,20b, G. Facini31, R.M. Fakhrutdinov129, S. Falciano133a,R.J. Falla77, J. Faltova128,Y. Fang33a, M. Fanti90a,90b, A. Farbin8, A. Farilla135a, T. Farooque12, S. Farrell164,S.M. Farrington171, P. Farthouat30, F. Fassi168,P. Fassnacht30, D. Fassouliotis9, A. Favareto50a,50b, L. Fayard116, P. Federic145a, O.L. Fedin122,j,W. Fedorko169,

M. Fehling-Kaschek48, S. Feigl30, L. Feligioni84, C. Feng33d,E.J. Feng6, H. Feng88, A.B. Fenyuk129, S. Fernandez Perez30, S. Ferrag53,J. Ferrando53,A. Ferrari167, P. Ferrari106,R. Ferrari120a,

D.E. Ferreira de Lima53, A. Ferrer168, D. Ferrere49, C. Ferretti88, A. Ferretto Parodi50a,50b,M. Fiascaris31, F. Fiedler82,A. Filipˇciˇc74,M. Filipuzzi42,F. Filthaut105,M. Fincke-Keeler170, K.D. Finelli151,

M.C.N. Fiolhais125a,125c, L. Fiorini168, A. Firan40, J. Fischer176, W.C. Fisher89,E.A. Fitzgerald23,

M. Flechl48, I. Fleck142, P. Fleischmann88, S. Fleischmann176, G.T. Fletcher140, G. Fletcher75,T. Flick176, A. Floderus80, L.R. Flores Castillo174,k,A.C. Florez Bustos160b,M.J. Flowerdew100,A. Formica137,

A. Forti83,D. Fortin160a, D. Fournier116, H. Fox71,S. Fracchia12, P. Francavilla79,M. Franchini20a,20b, S. Franchino30, D. Francis30, M. Franklin57, S. Franz61,M. Fraternali120a,120b,S.T. French28,

C. Friedrich42, F. Friedrich44, D. Froidevaux30,J.A. Frost28,C. Fukunaga157, E. Fullana Torregrosa82, B.G. Fulsom144,J. Fuster168, C. Gabaldon55,O. Gabizon173, A. Gabrielli20a,20b,A. Gabrielli133a,133b, S. Gadatsch106,S. Gadomski49,G. Gagliardi50a,50b, P. Gagnon60, C. Galea105, B. Galhardo125a,125c, E.J. Gallas119, V. Gallo17, B.J. Gallop130, P. Gallus127,G. Galster36,K.K. Gan110,R.P. Gandrajula62, J. Gao33b,g,Y.S. Gao144,e,F.M. Garay Walls46, F. Garberson177,C. García168,J.E. García Navarro168, M. Garcia-Sciveres15,R.W. Gardner31,N. Garelli144, V. Garonne30,C. Gatti47,G. Gaudio120a, B. Gaur142, L. Gauthier94, P. Gauzzi133a,133b, I.L. Gavrilenko95, C. Gay169, G. Gaycken21, E.N. Gazis10, P. Ge33d, Z. Gecse169, C.N.P. Gee130, D.A.A. Geerts106,Ch. Geich-Gimbel21, K. Gellerstedt147a,147b,C. Gemme50a,