Contents lists available atScienceDirect
Physics
Letters
B
www.elsevier.com/locate/physletb
Search
for
single
production
of
vector-like
quarks
decaying
into
a b quark
and
a
W boson
in
proton–proton
collisions
at
√
s
=
13
TeV
.TheCMS Collaboration
CERN,Switzerland
a r t i c l e i n f o a b s t ra c t
Articlehistory:
Received28January2017
Receivedinrevisedform21June2017 Accepted10July2017
Availableonline15July2017 Editor:M.Doser
Keywords:
CMS Physics
A searchispresented foraheavy vector-likequark,decayingintoab quarkand aWboson,whichis producedsinglyinassociationwithalightflavorquarkandabquark.Theanalysisisperformedusinga datasampleofproton–protoncollisionsatacenter-of-massenergyof√s=13TeV collectedattheLHCin 2015.Thedatasetusedintheanalysiscorrespondstoanintegratedluminosityof2.3 fb−1.Thesearchis
carriedoutusingeventscontainingoneelectronormuon,atleastoneb-taggedjetwithlargetransverse momentum,atleastonejetintheforwardregionofthedetector,andmissingtransversemomentum.No excessoverthestandardmodelpredictionisobserved.Upperlimitsareplacedontheproductioncross sectionofheavyexoticquarks:aTquarkwithachargeof2/3,andaYquarkwithachargeof−4/3.For Yquarkswithcouplingof0.5andB(Y→bW)=100%,theobserved(expected)lowermasslimits are 1.40(1.0) TeV.ThisisthemoststringentlimittodateonthesingleproductionoftheYvector-likequark. ©2017TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3.
1. Introduction
The standard model (SM) of particle physics has been ex-ceptionallysuccessful in describing phenomena atthe subatomic scale. The observationof a Higgs boson witha mass of 125 GeV and with properties consistent with the SM expectations [1–3] completed the SM. However, in the absence of enormous order-dependent cancellations, also known as fine-tuning, large SM quantumcorrectionswouldshiftthebareHiggsbosonmassto val-uesfar beyondtheelectroweak scale.New physics isrequiredto stabilizetheHiggsbosonmassnaturallyattheelectroweakscale, i.e.withoutinvokingfine-tuning.
ManynaturalextensionsoftheSM havebeenproposedin re-cent decades. Some of these models postulate the existence of vector-like quarks (VLQs)[4–6], whichare colored fermions with left- andright-handedchiralstatesbothtransforminginthesame way under the gauge group SU(3)C×SU(2)L×U(1)Y. The VLQs
donotacquire massesthroughtheYukawacouplingtothe Higgs field,andcouldcancelloopcorrectionsfromtheSM topquarkto theHiggsbosonmass.
SearchesforVLQshavealreadybeenperformedinvarious de-cay modes using proton–proton collisions at √s=8TeV. These searches were primarily focused on the pair production mecha-nism andthey ruled out VLQs withmassesup to approximately
E-mailaddress:cms-publication-committee-chair@cern.ch.
0.90 TeV[7–10].TheVLQsingleproductionmechanismis coupling-dependent,anditcouldbecomethedominantcontributiontothe cross section at high VLQ masses. The strength of the VLQ-b-W coupling can be approximately characterized by a single dimen-sionlessparameterthatvariesfrom0to√2[11],wherethelatter wouldcorrespondtoacouplingoffullelectroweakstrength.
Inthispaper,wepresentasearchforthesingleproductionofa heavyvector-like quarkthatdecaysintoabquarkandaW boson usingthe 2015LHC dataset.Thissignaturecan arisefromeither a YoraTquarkwithacharge of−4/3 or2/3,respectively, pro-ducedinassociation witha lightflavor quark anda bquark. The leading orderFeynman diagram for Y andT quark production is shown in Fig. 1. The outgoing light flavor quark q inthe upper part of the diagram produces a jet in the forward region of the detector,whichisadistinctsignatureofsingleproduction.
TheYquarkisexpectedtodecaywithabranchingfraction(B) of 100% into a b quark anda W boson [12], while the Tquark canalsodecayintotHandtZviaaflavorchangingneutralcurrent. Searches with the 2015 LHC data set for single production of a vector-likeTquarkdecayingtotHandtZhavebeenperformedby theCMSCollaboration[13–15].Ifthe Tquark isasinglet,then it isexpectedtodecayintobW50%ofthetime.
The ATLASCollaboration publisheda search forsingle produc-tionofYandTquarksdecayingintobWusing8 TeV proton–proton collisions [16].Theanalysispresentedhereisthefirstsuchsearch using13 TeV proton–protondata,andsetsthemoststringentlimits to dateontheproductioncrosssectionfora singleY orTquark.
http://dx.doi.org/10.1016/j.physletb.2017.07.022
0370-2693/©2017TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3.
Fig. 1. Leading order Feynman diagram for singly produced Y or T quarks. Thesearchiscarriedoutbasedoneventscontaining oneelectron ormuon,atleastoneb-taggedjet withlargetransverse momen-tum(pT),atleastonejetintheforwardregionofthedetector,and
missingtransversemomentum.
2. CMSdetectorandeventsamples
TheessentialfeatureoftheCMSdetectoristhe superconduct-ingsolenoid,6 m indiameterand13 m inlength,whichprovides an axial magnetic field of 3.8 T. Within the solenoid volume a multi-layeredsiliconpixelandstriptrackerisusedtomeasurethe trajectoriesofchargedparticleswithpseudorapidity|η|<2.5. Out-sideofthe trackersystem, anelectromagnetic calorimeter(ECAL) madeoflead tungstatecrystals andahadron calorimeter(HCAL) made of brass and scintillators cover the region |η|<3.0. The region3.0<|η|<5.0 iscoveredbytheforwardhadronic calorime-ter,whichismadeprimarilyofsteelandquartzfibers.Muonsare measuredingas-ionization detectorsembedded inthe steel flux-return yoke of the solenoid, and covering the region |η|<2.4. A moredetaileddescriptionof theCMSdetector,together witha definition of the coordinate system used and the relevant kine-maticvariables,canbefoundinRef.[17].
Thedatausedforthisanalysiswererecordedduringthe2015 datatakingperiodinproton–protoncollisions ata center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 2.3 fb−1. The electron data sample was collected using a trigger thatrequiredatleastoneisolatedelectron with|η|< 2.5and pT
> 27 GeV. The muon data sample was collected using a trigger thatrequiredatleastoneisolatedmuon with|η|<2.1and pT >
20 GeV.
The VLQ signal efficiencies and background contributions are estimated using Monte Carlo (MC) samples. They are validated using background enriched data samples. The tt+jets, t- and tW-channel single top-quark production and the WW processes are simulated using powheg v2 [18–20]. Single top quark pro-duction via s-channel and the WZ process are simulated with MadGraph5_amc@nlo v2[21].Inclusivebosonproduction(W+jets andZ+jets)issimulatedwith MadGraph v5[22]. pythia 8.212[23, 24]isusedforpartonshowerdevelopmentandhadronizationand tosimulateQCDmultijetevents.
TheVLQprocessesconsideredinthispaperaregeneratedusing thetree-levelMCeventgenerator MadGraph v5forVLQmassesin therangefrom0.70to1.80 TeV,instepsof100 GeV.TheVLQwidth issetto10 GeV forallmasses.TheNNPDF3.0[25]parton distribu-tionfunctions(PDFs)areusedforbothsignalandSMMCprocesses tomodelthe momentumdistributionof thecollidingpartons in-sidetheprotons.
The cross sections used to normalize the SM processes are calculated to next-to-leading order (NLO) or to next-to-next-to-leadingorder(NNLO),wherethelatterisavailable[26–28].Forthe
signal,theNLOcrosssectionsaretakenfromRefs.[29,30].Forthe tt+jets,tW-channelsingletop-quark,andWW SMprocesses,NNLO crosssectionsareused,whileNLOcrosssectionsareappliedtothe remainingprocesses.
All generated events are processed through the CMS detec-tor simulation based on Geant4 [31]. Additional minimum bias events, generated with pythia 8.212, are superimposed on the hard-scatteringeventstosimulatemultipleproton–proton interac-tions (pileup) within the neighboring bunch crossings. The sim-ulated events are weighted to reproduce the distribution of the numberofpileupinteractions,20onaverage,observedindata.
3. Eventreconstruction
All physics objects in the event are reconstructed using a particle-flow(PF)algorithm [32,33],whichuses informationfrom all subsystems to reconstruct photons, electrons, muons, and chargedand neutralhadrons. Charged particletracks are usedto reconstruct the interaction vertices. The vertex with the highest sumofsquaredpT ofallassociatedtracksistakenastheprimary
vertex of the hard collision. Filters are applied to reject events whereelectronicnoiseorproton-beambackgroundsmimicenergy depositsinthedetector.
Electroncandidates are reconstructedby combiningthe track-ing information with energy deposits in the ECAL in the range |η|<2.5 (excluding the range 1.4442<|η|<1.566, which is a transition region between endcapand barrel calorimeters). Tight identificationcriteriaareappliedtoselectwell-reconstructed elec-tron candidates. Candidates are identified [34] using information onthe shower-shape,thetrackqualityandthespatial match be-tween the track and the electromagnetic cluster, the fraction of total clusterenergyin theHCAL,andthe resultinglevelof activ-ityinthesurroundingtrackerandcalorimeterregions.Theenergy resolutionforelectronswith pT>40GeV,measuredusingZ→ee
decays,isonaverage1.7%intheECALcentralregionofthe detec-tor[34].
Muon candidates are identified using track segments recon-structedseparatelyfromhitsinthesilicontrackingsystemandin themuonsystem.Toidentifymuoncandidates,thetracksegments mustbeconsistentwithmuonsoriginatingfromtheprimary ver-texandsatisfyingtight identificationrequirements.The matching ofthemuonandsilicontracksegmentsresultsinarelativepT
res-olutionof1.3–2.0%inthecentralregionofthedetectorformuons with20<pT<100GeV, andformuonswith pT upto 1 TeV the
resolutionis10%orbetter[35].
Lepton(electron ormuon)reconstruction and trigger efficien-cies are evaluated asa function of pT and |η| in both data and
simulation, using a “tag-and-probe” method [36] with recorded andsimulatedsamplesofdileptonicZevents.
An isolation variable is employed to suppress leptons origi-nating fromQCD processes. We define a relative isolation as the sum of the pT of particle tracks found in the tracker and
en-ergy deposits found in the calorimeters within a cone R= √
(η)2+ (φ)2= 0.3(0.4) aroundthetrajectory ofthe electron
(muon), divided by the lepton pT. Relative isolation is corrected
forthe effects ofpileup, andisrequired to be lessthan 0.15for muons,andlessthan0.4(0.6)forelectronsinthebarrel(endcap) region.
Particles reconstructed by the PF algorithm are clustered into jetsbyusing thedirectionofeachparticleattheinteraction ver-tex.ChargedhadronsfoundbythePFalgorithmthatareassociated withpileupverticesarenotconsidered.Particlesthatareidentified asisolatedleptons areremovedfromthejetclustering procedure. Jets are reconstructed with the anti-kT algorithm [37,38] witha
distance parameter of 0.4. An event-by-event jet-area-based cor-rection[39,40]isappliedtoremove,on astatisticalbasis, neutral pileup contribution that is not already removed by the charged-hadron subtractionproceduredescribed above. Jet energy correc-tionsareappliedtoeachjet,asafunctionof pT and η,tocorrect
forthecalorimeterresponse[41].
The missingtransverse momentum is defined asthe negative vector sumof the transverse momenta ofall the particles found by the PF algorithm, and its magnitude is referred to as ETmiss. Thedecayofaheavy quark intoaleptonicallydecaying W boson anda b quark is expectedto exhibit genuine missingtransverse momentum because ofthe undetected neutrino fromthe W de-cay. A missing transverse momentum thresholdis appliedto the selected events,andthe missingtransverse momentum vector is usedinthemassreconstruction.
Toidentifyjetsoriginatingfroma bquark (b-taggedjets),the combined secondary vertex(CSV) algorithm is used [42,43]. This taggingalgorithmcombinesvariablesthatcandistinguishbquark jets from those originating from light flavors, such as informa-tionontrackimpactparameter significanceandsecondary vertex properties. The variables are combined using a likelihood ratio technique to compute ab taggingdiscriminator. We use theCSV mediumoperatingpoint[42],whichachievesabtaggingefficiency ofapproximately70% anda mistagrateof1%.Data-to-Simulation efficiencyandmistagratescalefactorsaccountforthesmall differ-encesobservedbetweendata andsimulation.We usethesescale factors as a function of jet pT and η [42] to correct simulated
events.
4. Eventselectionandsearchstrategy
The signal event selection requires exactly one lepton with pT>40GeV and |η|<2.1.Events withadditionalleptons having
pT>10GeV and |η|<2.5 and passing relatively loose isolation
andidentificationrequirementsarerejectedtosuppressdileptonic events.
Eventsarerequiredtohaveatleasttwojets,oneinthecentral andoneintheforwardregionofthedetector.Thecentraljetis re-quiredtohavepT>200GeV and|η|<2.4 andbeb-tagged.When
thereismorethanonecentraljetsatisfyingtheabovecriteria,the leadingcentraljetisusedtoreconstructthemassoftheVLQ.The forwardjet(2.4<|η|<5.0)musthavepT>30GeV.
InthedecayofasinglyproducedVLQ,thebquark andtheW boson tend to be produced with the transverse momenta point-inginoppositedirections.Hence,theazimuthalanglebetweenthe centralb jetandthe lepton isrequired tosatisfy φ (,b)>2. In addition,the lepton is requiredto be separated fromany jets with pT>40GeV producedinthe event. When ahadronic jetis
found within R(,jet)<1.5, theeventisrejected. Since W bo-son originating from heavy VLQ decayhas significant pT, events
are requiredto havesubstantial EmissT (>50GeV)due tothe un-detected neutrinofromthe Wboson decay.The transverse mass, MT,formedby the leptonand EmissT systemisrequiredto satisfy
MT<130GeV tosuppresstt dileptonevents,whichcanmimicthe
signalwhenoneoftheleptonsescapesdetection.
Finally,eventsarerequiredto have ST>500GeV,where ST is
definedasthescalar sumofthetransverse momentaof the lep-ton,theleadingcentraljet,andthemissingtransversemomentum. Thisrequirementreducesthesignalefficiencybylessthan10%for theVLQmassrangeconsideredinthispaper.
Theinvariantmassoftheheavyquarkcandidate,Minv,is
recon-structed from its decay products: the lepton, the leading central jet, and the neutrino, where the x,y-components of the neu-trino momentum are given by the missing transverse momen-tum, while the z-component is determined by constraining the
invariant massof the lepton andneutrino to the W boson mass value. The solution with the smallest value is considered as the
z-component.Thismethodisused onlywhenthe solutionofthe
relevant quadraticequation isreal,otherwisethe z-component is settozero.
The single VLQ productionY/T→bW would resultin a peak intheMinvdistributionatthemassoftheVLQ.Theexperimental
massresolutionis12–15%andisindependentoftheVLQmass.
5. Backgroundmodeling
Thedominantbackgroundprocessesinthissearcharethe pro-ductionoftt andW+jetsevents.Themodelingoftheseprocesses isvalidatedbystudyingbackground-enrichedsamples.
Toverifythemodelingofthett process,weselecteventswith the lepton and EmissT fulfilling the signal selection criteria, and at least 2 b-tagged jetswith the leading (sub-leading) jet satis-fying the requirement of pT>70(30)GeV. We also remove the
R(,jet), φ (,b) and forward jet requirements to enrich the
samplewithtt events.
The top quark pT spectrum from the tt simulation is known
to bemismodeledandisreweightedusingtheempiricalfunction describedinRef.[44].Afterthiscorrection,thedatapointsatlarge valuesofallrelevantkinematicdistributionsareconsistentwithin systematicuncertainties.DistributionsofSTandtheinvariantmass
ofthebWsysteminthett sampleareshowninFig. 2.
TheW+jets-enrichedcontrolsamplerequirementisidenticalto the signal event selection except that events with b-tagged jets are vetoed.We observethatin theW+jetssimulatedsample, the numberofeventsatlarge jet pT distributions isoverestimatedas
compared with the distributions measured in data. We derive a correction fortheW+jetssimulationasafunctionofthe HT
vari-able, definedasthescalar sumofthe transversemomenta ofall jetswithpT>30GeV.ThedatatosimulationratiooftheHT
distri-butioniswelldescribedbya2-parameterlinearfitwithanegative slope. A correction to the modeling of the W+jets HT spectrum
is made using the results of the fit. After the correction is ap-plied, goodagreement inthe modeling ofall kinematicvariables isobserved.DistributionsofST andtheinvariantmassofthebW
systemintheW+jetssampleareshowninFig. 3.
6. Systematicuncertainties
Wedividethesystematicuncertaintiesintotwocategories: un-certaintiesthatimpactonlytherateofbackgroundandsignal pre-dictions,anduncertaintiesthat affectboththerateandtheshape of the fitted Minv spectra. The shape uncertainties affecting the
Minv distributionaremodeledbyvaryingthenuisanceparameters
thatcharacterizetheassociatedsystematiceffectsupanddownby onestandarddeviation.
The uncertainty in the integratedluminosity is2.7% [45]. We assign the uncertainties for the normalization of the SM back-groundprocessesastheuncertaintiesoncorrespondingCMScross section measurementsat13 TeV,whichare5.6%fortt[46],14.7% for single top quark [47], and 9.2% for W+jets [48], where in the last casewe also account separately foruncertainties in the W+heavy-flavorcontributions[49,50].
To account for the MC mismodeling correction in the W+jets sample,wederiveatwo-sideduncertaintybandusingtheHT
cor-rectionprocedure. Toaccountforthe MCmismodeling correction inthett sample,wederiveatwo-sideduncertaintybandusingthe top pTreweightingprocedure.Onesideofthebandisobtainedby
removing thecorrection,andtheotherside isobtainedby apply-ingtheproceduretwice.Theuncertaintiesduetothesecorrections increasewiththeriseofthetopquark pT andHT,whichleadsto
Fig. 2. Kinematicdistributionsinthett-enrichedcontrolsample:ST(top)andMinv
(bottom).Thelastbinincludesoverflowevents.Thestatisticalandsystematic un-certaintiesarerepresentedbythehatchedbandontheratioplot.
thewideningoftheuncertaintybandatlarge STandMinv,ascan
beseeninFigs. 2 and 3.
In addition, the reconstruction efficiency of forward jets has beenobservedtobelargerinthesimulationthaninthedata.The efficiencyasa functionof ηis correctedtomatchthedatausing theW+jets-enrichedsamplewith0b-taggedjets,andvalidated us-ingthett-enrichedsamplewithtwob-taggedjets.Anuniformrate uncertaintyof±15% isassignedtocovertheforwardjet mismod-elinginsimulation.
Triggerand lepton identification efficiencies in simulation are correctedasfunctionsofleptonpTand ηusingdecaysofZ bosons
toleptons indata. Theassociated uncertainty ofabout2% is the statisticaluncertaintyinthedata.
Theshapeuncertaintiesincludeuncertaintiesinthejetenergy scale,jet energy resolution,b tagging efficiency, pileup, PDFs, as wellasfactorizationandrenormalizationscales. These uncertain-tiesaretreatedasuncorrelated.
The uncertainty related to the modeling of pileup is evalu-atedbyvarying theinelasticcross sectionby ±5% relative tothe nominalvalueof69 mb[51].Uncertaintiesinrenormalizationand
Fig. 3. KinematicdistributionsintheW+jets-enrichedcontrolsample:ST(top)and
Minv(bottom).Thelastbinincludesoverflowevents.Thestatisticalandsystematic
uncertaintiesarerepresentedbythehatchedbandontheratioplot.
factorizationscales are takenintoaccount by varying bothscales simultaneouslyupanddownbyafactoroftwo.Uncertainties aris-ing from thechoice of PDFs are takeninto account accordingto thePDF4LHCprocedure[52].
ThesystematicuncertaintiesaresummarizedinTable 1.
7. Limitcalculationandresults
Good agreement betweenthe eventyields in the dataand in the SM prediction is observed within uncertainties, as shown in Table 2.ThesumoftheSMbackgroundsandahypothesizedsignal forthecombinedelectronandmuonchannelsisfittedtothe ob-servedspectrumofMinv.Thefitusesabinnedlikelihoodmethod,
wherethebinningofthedistributionsischoseninsuchawaythat thestatisticaluncertaintyintheMCestimationoftotalbackground per bin isalways lessthan 20%.Contributions fromthe SM pro-cesses are allowed tofloat independentlywithin their systematic uncertainties, using log-normal priors [53,54]. The nuisance pa-rametersdescribingthe shapeuncertaintiesare constrainedusing Gaussian priors. The shapes of the Minv distributions for
Table 1
Summaryofthesystematicuncertaintiesassociatedwiththesimulatedbackgroundsandthesignalevents.Thevaluequotedrepresentstheexpectedchangeintheevent yieldinthesignalregionduetothesystematicuncertainty.
Source W+jets tt Single top Signal
Integrated luminosity rate 2.7% 2.7 % 2.7 % 2.7 %
Jet energy scale shape 5% 6% 5% 3%
Jet energy resolution shape 2% 1% 1% 2%
b tagging efficiency shape 3% 5% 5% 5%
Multiple interactions shape 1% 1% 1% 1%
Lepton efficiency rate 2% 2% 2% 2%
Trigger efficiency rate 2% 2% 2% 2%
Cross section rate 9.2% 5.6% 14.7% —
Top quark pTreweighting shape — 28% — —
W+jets HTreweighting shape 5.3% — — —
Renormalization/factorization scales shape 14% 16% 16% —
PDF shape 5.5% 2.3% 8.5% 6.7%
Forward jet reweighting rate 15% 15% 15% 15%
Table 2
Data,background,andpossiblesignalpre-fiteventyieldscorrespondingto2.3 fb−1ofintegratedluminosity.ThesignalsampleistheM(Y)=1.0TeV masspointusingthe NLOcross section[30].Thepercentageinthesignalcolumnindicatesthesignalefficiency.Thebackgrounduncertaintiesincludeboththestatisticalandthesystematicpre-fit components.
Channel W+jets tt Single t QCD Z+jets Diboson Y (1.0 TeV) Total bkg. Data Electron 44±12 28±11 20±5 <1 1.5±1.5 1.3±0.5 54(1.3%) 95±17 78 Muon 52±14 34±13 27±6 <1 <1 1.7±0.6 60(1.4%) 115±20 95
nuisanceparameters.Thepost-fitMinvdistribution,withtheshape
and background normalizations corresponding to the maximum likelihood values, is presented in Fig. 4. All corrections derived fromthe background-enrichedregions are propagated to the sig-nalregionandappropriatesystematicuncertaintiesareassigned.
Upper limits at 95% confidence level (CL) on the production cross section of the Y/T→bW process are computed using a Bayesianapproach[55],wherethelikelihoodismarginalizedwith respecttothenuisanceparametersrepresentingsystematic uncer-tainties. The expected limit is calculated by resamplingthe data from the background distribution. The 95% CL expected and ob-servedupperlimitsare listedinTable 3andshowninFig. 5.The observed limits at high VLQ mass reflect a 2σ deficit of events above1.0TeV inthe Minv distribution.The limitsare derived
as-suming a narrow width for the VLQ. The VLQ width is propor-tional to the square of the coupling,and is negligible compared to the experimental resolution for couplings below 0.5, for the rangeof VLQ masses considered inthis paper.In the framework of the model considered, Y quarks with a coupling of 0.5 and
B(Y→bW)=100% areexcluded inthe massrangefrom0.85to 1.40 TeV.This result may be compared with the expectedregion ofexcludedmasses, whichextendsupto1.0 TeV.InthecaseofT quarkswithacouplingof0.5,thetheoreticalcrosssection,the se-lectionefficiencyandthe Minv distributionare thesameasthose
fortheproductionanddecayofYquarks,buttheexpecteddecay branchingfractionB(T→bW)is50%,onlyhalfthat expectedfor
B(Y→bW).Thusmassexclusionlimitssimilartothose achieved fortheYquarkwouldonlybeobtainedforB(T→bW)=100%.
8. Summary
Asearchhasbeenperformedforsingleproductionofa vector-like quark decaying into a b quark and a W boson in the elec-tron/muon + jets channels. The mass of the vector-like quark is reconstructed by forming the invariant mass of the leading b-taggedjet,electronormuon,andmissingtransversemomentumin theevent, anda fittothe invariantmassspectrum isperformed. No evidenceof an excessdue tonew physics isobserved.Upper limitsat 95% CL are set on the crosssections forsingle produc-tion of vector-like Y and T quarks in the mass range from 0.70
Fig. 4. TheinvariantmassMinvdistributionofheavyquarkcandidates,reconstructed
fromtheirdecayproducts:thelepton,theleadingcentraljet,andtheneutrino.The distributionisobtainedafterthefit,assumingthebackground-onlyhypothesis.The dashedhistogramsshowtheeventdistributionsexpectedforaYquarkwithmasses of1.0 TeV and1.4 TeV,couplingof0.5andB(Y→bW)=100%.Thestatisticaland systematicuncertaintiesarerepresentedbythehatchedbandontheratioplot.In thelastbinthedataoverfloweventisanelectronchanneleventwithamassof 2.22 TeV.
to 1.80 TeV. Inthe framework ofthe model considered, Y quarks withacouplingof0.5andB(Y→bW)=100% areexcludedinthe mass range from0.85 to 1.40 TeV. This result may be compared withtheexpectedregionofexcludedmasses,whichextendsupto 1.0 TeV. These resultsrepresent the moststringent limitsto date onthesingle productionofavector-like Yquark.InthecaseofT quarkswithacouplingof0.5,thetheoreticalcrosssection,the se-lectionefficiencyandthe Minv distributionarethesameasthose
fortheproductionanddecayofYquarks,buttheexpecteddecay branching fractionB(T→bW)is50%, onlyhalfthatexpectedfor
Fig. 5. ExpectedandobservedlimitsonthesingleVLQproduction(pp→Ybq and pp→Tbq)crosssectiontogetherwiththeoneandtwostandarddeviation uncer-taintybands.
Table 3
The95%CLexpectedandobservedupperlimits(UL)onthesingleVLQproduction crosssection,assumingB(VLQ→bW)=100%.
VLQ mass (TeV) Expected UL (pb) Observed UL (pb) 0.70 1.16+0−0..6837 2.03 0.80 0.91+0.43 −0.30 1.20 0.90 0.65+0.29 −0.21 0.54 1.0 0.49+0−0..2415 0.26 1.10 0.37+0−0..1912 0.20 1.20 0.28+0.14 −0.09 0.18 1.30 0.27+0−0..1109 0.16 1.40 0.26+0−0..1108 0.13 1.50 0.24+0.11 −0.08 0.11 1.60 0.21+0.11 −0.06 0.10 1.70 0.20+0−0..1006 0.10 1.80 0.19+0.09 −0.05 0.11
B(Y→bW).Thusmassexclusionlimitssimilartothoseachieved fortheYquarkwouldonlybeobtainedforB(T→bW)=100%.
Acknowledgements
WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrativestaffs atCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentersand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythecomputinginfrastructure essential toour analyses. Finally, we acknowledge the enduring support for the construc-tionandoperationofthe LHCandtheCMSdetectorprovided by thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIEN-CIAS(Colombia);MSESandCSF(Croatia);RPF(Cyprus);SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Fin-land,MEC,andHIP(Finland);CEAandCNRS/IN2P3(France);BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hun-gary);DAEandDST (India);IPM(Iran);SFI(Ireland);INFN (Italy); MSIPandNRF (RepublicofKorea);LAS(Lithuania);MOE andUM (Malaysia); BUAP,CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI
(Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland);FCT(Portugal);JINR(Dubna);MON,ROSATOM,RAS,RFBR andRAEP(Russia);MESTD (Serbia);SEIDI,CPAN, PCTIandFEDER (Spain);SwissFundingAgencies(Switzerland);MST(Taipei); ThEP-Center, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey);NASUandSFFR(Ukraine); STFC(United Kingdom);DOE andNSF(USA).
Individuals have received support from the Marie-Curie pro-gram and the European Research Council and EPLANET (Euro-pean Union); the Leventis Foundation; the A.P. Sloan Founda-tion; the Alexander von Humboldt Foundation; the Belgian Fed-eral Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technolo-gie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) ofthe Czech Republic;the Council ofScience and Indus-trial Research, India; the HOMING PLUS program of the Foun-dation for Polish Science, cofinanced from European Union, Re-gional Development Fund, the Mobility Plus program of the Ministry of Science and Higher Education, the National Science Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/ 02861,Sonata-bis2012/07/E/ST2/01406;theNationalPriorities Re-search Program by Qatar National Research Fund; the Programa Clarín-COFUNDdelPrincipadode Asturias;theThalisandAristeia programscofinancedbyEU-ESFandtheGreekNSRF;the Rachada-pisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University and theChulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); and the Welch Founda-tion,contractC-1845.
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TheCMSCollaboration
A.M. Sirunyan,A. Tumasyan YerevanPhysicsInstitute,Yerevan,Armenia
W. Adam, E. Asilar,T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, J. Erö,M. Flechl, M. Friedl, R. Frühwirth1, V.M. Ghete, C. Hartl, N. Hörmann, J. Hrubec,M. Jeitler1,A. König, I. Krätschmer, D. Liko, T. Matsushita,I. Mikulec, D. Rabady, N. Rad, B. Rahbaran,H. Rohringer, J. Schieck1,J. Strauss,
W. Waltenberger, C.-E. Wulz1 InstitutfürHochenergiephysik,Wien,Austria
O. Dvornikov,V. Makarenko, V. Mossolov,J. Suarez Gonzalez, V. Zykunov InstituteforNuclearProblems,Minsk,Belarus
N. Shumeiko
NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus
S. Alderweireldt, E.A. De Wolf,X. Janssen,J. Lauwers, M. Van De Klundert, H. Van Haevermaet, P. Van Mechelen,N. Van Remortel, A. Van Spilbeeck
UniversiteitAntwerpen,Antwerpen,Belgium
S. Abu Zeid,F. Blekman, J. D’Hondt, N. Daci,I. De Bruyn, K. Deroover, S. Lowette,S. Moortgat, L. Moreels, A. Olbrechts,Q. Python, K. Skovpen, S. Tavernier,W. Van Doninck, P. Van Mulders, I. Van Parijs
VrijeUniversiteitBrussel,Brussel,Belgium
H. Brun, B. Clerbaux, G. De Lentdecker, H. Delannoy, G. Fasanella,L. Favart, R. Goldouzian, A. Grebenyuk, G. Karapostoli,T. Lenzi,A. Léonard, J. Luetic, T. Maerschalk,A. Marinov, A. Randle-conde,T. Seva,
C. Vander Velde, P. Vanlaer,D. Vannerom, R. Yonamine,F. Zenoni, F. Zhang2 UniversitéLibredeBruxelles,Bruxelles,Belgium
A. Cimmino,T. Cornelis, D. Dobur,A. Fagot, M. Gul, I. Khvastunov,D. Poyraz, S. Salva, R. Schöfbeck, M. Tytgat,W. Van Driessche, E. Yazgan, N. Zaganidis
GhentUniversity,Ghent,Belgium
H. Bakhshiansohi,C. Beluffi3,O. Bondu, S. Brochet,G. Bruno, A. Caudron, S. De Visscher, C. Delaere, M. Delcourt,B. Francois, A. Giammanco, A. Jafari,M. Komm, G. Krintiras,V. Lemaitre, A. Magitteri, A. Mertens, M. Musich, K. Piotrzkowski,L. Quertenmont,M. Selvaggi, M. Vidal Marono, S. Wertz UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium
N. Beliy
UniversitédeMons,Mons,Belgium
W.L. Aldá Júnior, F.L. Alves,G.A. Alves,L. Brito, C. Hensel,A. Moraes, M.E. Pol,P. Rebello Teles CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil
E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato4, A. Custódio, E.M. Da Costa, G.G. Da Silveira5, D. De Jesus Damiao,C. De Oliveira Martins, S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson, D. Matos Figueiredo,C. Mora Herrera, L. Mundim,H. Nogima, W.L. Prado Da Silva, A. Santoro,
A. Sznajder,E.J. Tonelli Manganote4,F. Torres Da Silva De Araujo, A. Vilela Pereira UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil
S. Ahujaa,C.A. Bernardesa, S. Dograa,T.R. Fernandez Perez Tomeia, E.M. Gregoresb, P.G. Mercadanteb, C.S. Moona,S.F. Novaesa,Sandra S. Padulaa,D. Romero Abadb, J.C. Ruiz Vargasa
aUniversidadeEstadualPaulista,SãoPaulo,Brazil bUniversidadeFederaldoABC,SãoPaulo,Brazil
A. Aleksandrov, R. Hadjiiska, P. Iaydjiev,M. Rodozov, S. Stoykova, G. Sultanov, M. Vutova InstituteforNuclearResearchandNuclearEnergy,Sofia,Bulgaria
A. Dimitrov, I. Glushkov,L. Litov, B. Pavlov,P. Petkov UniversityofSofia,Sofia,Bulgaria
W. Fang6
BeihangUniversity,Beijing,China
M. Ahmad, J.G. Bian, G.M. Chen, H.S. Chen,M. Chen, Y. Chen7,T. Cheng, C.H. Jiang, D. Leggat, Z. Liu, F. Romeo,M. Ruan, S.M. Shaheen, A. Spiezia,J. Tao, C. Wang, Z. Wang, H. Zhang,J. Zhao
InstituteofHighEnergyPhysics,Beijing,China
Y. Ban, G. Chen, Q. Li, S. Liu,Y. Mao, S.J. Qian, D. Wang,Z. Xu StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China
C. Avila,A. Cabrera, L.F. Chaparro Sierra, C. Florez, J.P. Gomez, C.F. González Hernández,J.D. Ruiz Alvarez, J.C. Sanabria
UniversidaddeLosAndes,Bogota,Colombia
N. Godinovic, D. Lelas, I. Puljak,P.M. Ribeiro Cipriano, T. Sculac UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia Z. Antunovic, M. Kovac
UniversityofSplit,FacultyofScience,Split,Croatia
V. Brigljevic,D. Ferencek, K. Kadija,B. Mesic, T. Susa InstituteRudjerBoskovic,Zagreb,Croatia
A. Attikis, G. Mavromanolakis, J. Mousa,C. Nicolaou, F. Ptochos, P.A. Razis,H. Rykaczewski, D. Tsiakkouri UniversityofCyprus,Nicosia,Cyprus
M. Finger8, M. Finger Jr.8 CharlesUniversity,Prague,CzechRepublic E. Carrera Jarrin
UniversidadSanFranciscodeQuito,Quito,Ecuador
E. El-khateeb9, S. Elgammal10,A. Mohamed11
AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt M. Kadastik, L. Perrini, M. Raidal, A. Tiko, C. Veelken
NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia P. Eerola, J. Pekkanen,M. Voutilainen DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland
J. Härkönen,T. Järvinen, V. Karimäki, R. Kinnunen, T. Lampén,K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, J. Tuominiemi, E. Tuovinen,L. Wendland
J. Talvitie,T. Tuuva
LappeenrantaUniversityofTechnology,Lappeenranta,Finland
M. Besancon,F. Couderc, M. Dejardin, D. Denegri,B. Fabbro, J.L. Faure, C. Favaro, F. Ferri, S. Ganjour, S. Ghosh,A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, I. Kucher, E. Locci,M. Machet, J. Malcles,J. Rander, A. Rosowsky, M. Titov
IRFU,CEA,UniversitéParis-Saclay,Gif-sur-Yvette,France
A. Abdulsalam,I. Antropov, S. Baffioni, F. Beaudette, P. Busson, L. Cadamuro, E. Chapon,C. Charlot, O. Davignon,R. Granier de Cassagnac, M. Jo, S. Lisniak,P. Miné, M. Nguyen, C. Ochando, G. Ortona, P. Paganini,P. Pigard, S. Regnard, R. Salerno,Y. Sirois, T. Strebler, Y. Yilmaz, A. Zabi, A. Zghiche LaboratoireLeprince-Ringuet,EcolePolytechnique,IN2P3-CNRS,Palaiseau,France
J.-L. Agram12,J. Andrea, A. Aubin,D. Bloch, J.-M. Brom,M. Buttignol, E.C. Chabert,N. Chanon, C. Collard, E. Conte12,X. Coubez, J.-C. Fontaine12, D. Gelé, U. Goerlach,A.-C. Le Bihan, P. Van Hove
InstitutPluridisciplinaireHubertCurien(IPHC),UniversitédeStrasbourg,CNRS-IN2P3,France S. Gadrat
CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France
S. Beauceron,C. Bernet, G. Boudoul,C.A. Carrillo Montoya, R. Chierici,D. Contardo, B. Courbon,
P. Depasse,H. El Mamouni, J. Fay, S. Gascon,M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde, I.B. Laktineh, M. Lethuillier,L. Mirabito, A.L. Pequegnot, S. Perries,A. Popov13,D. Sabes, V. Sordini,M. Vander Donckt, P. Verdier,S. Viret
UniversitédeLyon,UniversitéClaudeBernardLyon1,CNRS-IN2P3,InstitutdePhysiqueNucléairedeLyon,Villeurbanne,France T. Toriashvili14
GeorgianTechnicalUniversity,Tbilisi,Georgia Z. Tsamalaidze8
TbilisiStateUniversity,Tbilisi,Georgia
C. Autermann,S. Beranek, L. Feld, M.K. Kiesel, K. Klein, M. Lipinski, M. Preuten,C. Schomakers, J. Schulz, T. Verlage
RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany
A. Albert, M. Brodski,E. Dietz-Laursonn, D. Duchardt, M. Endres,M. Erdmann, S. Erdweg, T. Esch, R. Fischer,A. Güth, M. Hamer,T. Hebbeker, C. Heidemann, K. Hoepfner,S. Knutzen, M. Merschmeyer, A. Meyer,P. Millet, S. Mukherjee,M. Olschewski, K. Padeken, T. Pook,M. Radziej, H. Reithler, M. Rieger, F. Scheuch,L. Sonnenschein, D. Teyssier,S. Thüer
RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany
V. Cherepanov, G. Flügge, B. Kargoll, T. Kress, A. Künsken,J. Lingemann, T. Müller, A. Nehrkorn, A. Nowack,C. Pistone, O. Pooth,A. Stahl15
RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany
M. Aldaya Martin,T. Arndt, C. Asawatangtrakuldee, K. Beernaert,O. Behnke, U. Behrens,A.A. Bin Anuar, K. Borras16,A. Campbell, P. Connor,C. Contreras-Campana, F. Costanza, C. Diez Pardos, G. Dolinska, G. Eckerlin,D. Eckstein, T. Eichhorn, E. Eren,E. Gallo17, J. Garay Garcia, A. Geiser, A. Gizhko,
J.M. Grados Luyando, A. Grohsjean, P. Gunnellini, A. Harb,J. Hauk, M. Hempel18, H. Jung,
W. Lange, A. Lelek, T. Lenz,J. Leonard, K. Lipka,A. Lobanov, W. Lohmann18, R. Mankel,
I.-A. Melzer-Pellmann,A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, D. Pitzl,R. Placakyte, A. Raspereza, B. Roland, M.Ö. Sahin,P. Saxena, T. Schoerner-Sadenius,S. Spannagel, N. Stefaniuk,G.P. Van Onsem, R. Walsh, C. Wissing
DeutschesElektronen-Synchrotron,Hamburg,Germany
V. Blobel, M. Centis Vignali, A.R. Draeger,T. Dreyer, E. Garutti, D. Gonzalez, J. Haller, M. Hoffmann, A. Junkes, R. Klanner, R. Kogler,N. Kovalchuk, T. Lapsien, I. Marchesini, D. Marconi,M. Meyer, M. Niedziela, D. Nowatschin, F. Pantaleo15,T. Peiffer, A. Perieanu, J. Poehlsen, C. Scharf,P. Schleper, A. Schmidt, S. Schumann,J. Schwandt, H. Stadie,G. Steinbrück, F.M. Stober,M. Stöver, H. Tholen, D. Troendle,E. Usai, L. Vanelderen,A. Vanhoefer, B. Vormwald
UniversityofHamburg,Hamburg,Germany
M. Akbiyik, C. Barth,S. Baur, C. Baus, J. Berger,E. Butz, R. Caspart, T. Chwalek, F. Colombo, W. De Boer, A. Dierlamm, S. Fink,B. Freund,R. Friese, M. Giffels,A. Gilbert, P. Goldenzweig,D. Haitz, F. Hartmann15, S.M. Heindl,U. Husemann, I. Katkov13, S. Kudella, H. Mildner,M.U. Mozer, Th. Müller, M. Plagge,
G. Quast, K. Rabbertz,S. Röcker, F. Roscher, M. Schröder,I. Shvetsov, G. Sieber, H.J. Simonis,R. Ulrich, S. Wayand,M. Weber, T. Weiler, S. Williamson, C. Wöhrmann, R. Wolf
InstitutfürExperimentelleKernphysik,Karlsruhe,Germany
G. Anagnostou, G. Daskalakis,T. Geralis,V.A. Giakoumopoulou, A. Kyriakis, D. Loukas, I. Topsis-Giotis InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece
S. Kesisoglou, A. Panagiotou, N. Saoulidou, E. Tziaferi NationalandKapodistrianUniversityofAthens,Athens,Greece
I. Evangelou, G. Flouris,C. Foudas, P. Kokkas, N. Loukas, N. Manthos, I. Papadopoulos,E. Paradas UniversityofIoánnina,Ioánnina,Greece
N. Filipovic, G. Pasztor
MTA-ELTELendületCMSParticleandNuclearPhysicsGroup,EötvösLorándUniversity,Budapest,Hungary
G. Bencze,C. Hajdu, D. Horvath19,F. Sikler, V. Veszpremi,G. Vesztergombi20,A.J. Zsigmond WignerResearchCentreforPhysics,Budapest,Hungary
N. Beni, S. Czellar, J. Karancsi21,A. Makovec, J. Molnar,Z. Szillasi InstituteofNuclearResearchATOMKI,Debrecen,Hungary
M. Bartók20,P. Raics, Z.L. Trocsanyi, B. Ujvari InstituteofPhysics,UniversityofDebrecen,Hungary
J.R. Komaragiri IndianInstituteofScience(IISc),India
S. Bahinipati22, S. Bhowmik23,S. Choudhury24, P. Mal, K. Mandal, A. Nayak25, D.K. Sahoo22, N. Sahoo, S.K. Swain
NationalInstituteofScienceEducationandResearch,Bhubaneswar,India
S. Bansal, S.B. Beri,V. Bhatnagar, R. Chawla, U. Bhawandeep, A.K. Kalsi, A. Kaur, M. Kaur, R. Kumar, P. Kumari, A. Mehta,M. Mittal, J.B. Singh, G. Walia
Ashok Kumar,A. Bhardwaj, B.C. Choudhary, R.B. Garg,S. Keshri, S. Malhotra,M. Naimuddin, N. Nishu, K. Ranjan,R. Sharma, V. Sharma
UniversityofDelhi,Delhi,India
R. Bhattacharya,S. Bhattacharya, K. Chatterjee, S. Dey,S. Dutt, S. Dutta, S. Ghosh, N. Majumdar, A. Modak, K. Mondal,S. Mukhopadhyay, S. Nandan,A. Purohit, A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar,M. Sharan, S. Thakur
SahaInstituteofNuclearPhysics,Kolkata,India P.K. Behera
IndianInstituteofTechnologyMadras,Madras,India
R. Chudasama,D. Dutta, V. Jha, V. Kumar, A.K. Mohanty15, P.K. Netrakanti,L.M. Pant, P. Shukla,A. Topkar BhabhaAtomicResearchCentre,Mumbai,India
T. Aziz,S. Dugad, G. Kole, B. Mahakud, S. Mitra, G.B. Mohanty, B. Parida,N. Sur, B. Sutar TataInstituteofFundamentalResearch-A,Mumbai,India
S. Banerjee, R.K. Dewanjee,S. Ganguly, M. Guchait,Sa. Jain, S. Kumar, M. Maity23, G. Majumder, K. Mazumdar,T. Sarkar23, N. Wickramage26
TataInstituteofFundamentalResearch-B,Mumbai,India
S. Chauhan,S. Dube, V. Hegde, A. Kapoor, K. Kothekar, S. Pandey, A. Rane, S. Sharma IndianInstituteofScienceEducationandResearch(IISER),Pune,India
S. Chenarani27, E. Eskandari Tadavani,S.M. Etesami27, M. Khakzad, M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi28,F. Rezaei Hosseinabadi, B. Safarzadeh29,M. Zeinali
InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran M. Felcini,M. Grunewald
UniversityCollegeDublin,Dublin,Ireland
M. Abbresciaa,b, C. Calabriaa,b, C. Caputoa,b, A. Colaleoa,D. Creanzaa,c, L. Cristellaa,b,N. De Filippisa,c, M. De Palmaa,b, L. Fiorea, G. Iasellia,c, G. Maggia,c, M. Maggia,G. Minielloa,b,S. Mya,b,S. Nuzzoa,b, A. Pompilia,b, G. Pugliesea,c,R. Radognaa,b,A. Ranieria, G. Selvaggia,b, A. Sharmaa, L. Silvestrisa,15, R. Vendittia,b, P. Verwilligena
aINFNSezionediBari,Bari,Italy bUniversitàdiBari,Bari,Italy cPolitecnicodiBari,Bari,Italy
G. Abbiendia,C. Battilana, D. Bonacorsia,b, S. Braibant-Giacomellia,b,L. Brigliadoria,b,R. Campaninia,b, P. Capiluppia,b,A. Castroa,b,F.R. Cavalloa, S.S. Chhibraa,b, G. Codispotia,b, M. Cuffiania,b,
G.M. Dallavallea,F. Fabbria,A. Fanfania,b,D. Fasanellaa,b, P. Giacomellia, C. Grandia, L. Guiduccia,b, S. Marcellinia, G. Masettia,A. Montanaria,F.L. Navarriaa,b,A. Perrottaa,A.M. Rossia,b,T. Rovellia,b, G.P. Sirolia,b,N. Tosia,b,15
aINFNSezionediBologna,Bologna,Italy bUniversitàdiBologna,Bologna,Italy
S. Albergoa,b, S. Costaa,b, A. Di Mattiaa,F. Giordanoa,b, R. Potenzaa,b,A. Tricomia,b, C. Tuvea,b aINFNSezionediCatania,Catania,Italy
G. Barbaglia, V. Ciullia,b,C. Civininia, R. D’Alessandroa,b,E. Focardia,b,P. Lenzia,b, M. Meschinia, S. Paolettia,L. Russoa,30, G. Sguazzonia, D. Stroma, L. Viliania,b,15
aINFNSezionediFirenze,Firenze,Italy bUniversitàdiFirenze,Firenze,Italy
L. Benussi, S. Bianco, F. Fabbri,D. Piccolo, F. Primavera15 INFNLaboratoriNazionalidiFrascati,Frascati,Italy
V. Calvellia,b, F. Ferroa, M.R. Mongea,b,E. Robuttia, S. Tosia,b aINFNSezionediGenova,Genova,Italy
bUniversitàdiGenova,Genova,Italy
L. Brianzaa,b,15,F. Brivioa,b,V. Ciriolo, M.E. Dinardoa,b,S. Fiorendia,b,15,S. Gennaia,A. Ghezzia,b, P. Govonia,b,M. Malbertia,b, S. Malvezzia, R.A. Manzonia,b,D. Menascea,L. Moronia,M. Paganonia,b, D. Pedrinia,S. Pigazzinia,b,S. Ragazzia,b,T. Tabarelli de Fatisa,b
aINFNSezionediMilano-Bicocca,Milano,Italy bUniversitàdiMilano-Bicocca,Milano,Italy
S. Buontempoa, N. Cavalloa,c, G. De Nardo, S. Di Guidaa,d,15, M. Espositoa,b, F. Fabozzia,c,F. Fiengaa,b, A.O.M. Iorioa,b, G. Lanzaa,L. Listaa, S. Meolaa,d,15,P. Paoluccia,15, C. Sciaccaa,b, F. Thyssena
aINFNSezionediNapoli,Napoli,Italy bUniversitàdiNapoli‘FedericoII’,Napoli,Italy cUniversitàdellaBasilicata,Potenza,Italy dUniversitàG.Marconi,Roma,Italy
P. Azzia,15, L. Benatoa,b,D. Biselloa,b, A. Bolettia,b, R. Carlina,b,A. Carvalho Antunes De Oliveiraa,b, P. Checchiaa,M. Dall’Ossoa,b,P. De Castro Manzanoa,T. Dorigoa, U. Dossellia,S. Fantinela,F. Fanzagoa, F. Gasparinia,b, U. Gasparinia,b, F. Gonellaa,S. Lacapraraa, M. Margonia,b, A.T. Meneguzzoa,b,
J. Pazzinia,b, N. Pozzobona,b,P. Ronchesea,b, E. Torassaa,M. Zanettia,b, P. Zottoa,b, G. Zumerlea,b aINFNSezionediPadova,Padova,Italy
bUniversitàdiPadova,Padova,Italy cUniversitàdiTrento,Trento,Italy
A. Braghieria,F. Fallavollitaa,b, A. Magnania,b, P. Montagnaa,b,S.P. Rattia,b, V. Rea, C. Riccardia,b, P. Salvinia, I. Vaia,b, P. Vituloa,b
aINFNSezionediPavia,Pavia,Italy bUniversitàdiPavia,Pavia,Italy
L. Alunni Solestizia,b,G.M. Bileia, D. Ciangottinia,b,L. Fanòa,b, P. Laricciaa,b,R. Leonardia,b, G. Mantovania,b,M. Menichellia, A. Sahaa, A. Santocchiaa,b
aINFNSezionediPerugia,Perugia,Italy bUniversitàdiPerugia,Perugia,Italy
K. Androsova,30,P. Azzurria,15, G. Bagliesia, J. Bernardinia, T. Boccalia, R. Castaldia,M.A. Cioccia,30, R. Dell’Orsoa,S. Donatoa,c,G. Fedi, A. Giassia, M.T. Grippoa,30, F. Ligabuea,c,T. Lomtadzea,L. Martinia,b, A. Messineoa,b, F. Pallaa,A. Rizzia,b, A. Savoy-Navarroa,31,P. Spagnoloa,R. Tenchinia,G. Tonellia,b, A. Venturia, P.G. Verdinia
aINFNSezionediPisa,Pisa,Italy bUniversitàdiPisa,Pisa,Italy
cScuolaNormaleSuperiorediPisa,Pisa,Italy
L. Baronea,b,F. Cavallaria, M. Cipriania,b,D. Del Rea,b,15,M. Diemoza, S. Gellia,b,E. Longoa,b, F. Margarolia,b,B. Marzocchia,b, P. Meridiania,G. Organtinia,b,R. Paramattia,F. Preiatoa,b, S. Rahatloua,b,C. Rovellia,F. Santanastasioa,b
aINFNSezionediRoma,Roma,Italy bUniversitàdiRoma,Roma,Italy
N. Amapanea,b,R. Arcidiaconoa,c,15,S. Argiroa,b,M. Arneodoa,c,N. Bartosika,R. Bellana,b, C. Biinoa, N. Cartigliaa,F. Cennaa,b, M. Costaa,b,R. Covarellia,b,A. Deganoa,b,N. Demariaa, L. Fincoa,b, B. Kiania,b, C. Mariottia, S. Masellia,E. Migliorea,b, V. Monacoa,b, E. Monteila,b, M. Montenoa,M.M. Obertinoa,b, L. Pachera,b,N. Pastronea, M. Pelliccionia, G.L. Pinna Angionia,b,F. Raveraa,b,A. Romeroa,b, M. Ruspaa,c, R. Sacchia,b, K. Shchelinaa,b, V. Solaa,A. Solanoa,b,A. Staianoa,P. Traczyka,b
aINFNSezionediTorino,Torino,Italy bUniversitàdiTorino,Torino,Italy
cUniversitàdelPiemonteOrientale,Novara,Italy
S. Belfortea,M. Casarsaa, F. Cossuttia,G. Della Riccaa,b, A. Zanettia aINFNSezionediTrieste,Trieste,Italy
bUniversitàdiTrieste,Trieste,Italy
D.H. Kim,G.N. Kim, M.S. Kim, S. Lee, S.W. Lee, Y.D. Oh,S. Sekmen, D.C. Son,Y.C. Yang KyungpookNationalUniversity,Daegu,RepublicofKorea
A. Lee
ChonbukNationalUniversity,Jeonju,RepublicofKorea H. Kim
ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea J.A. Brochero Cifuentes,T.J. Kim
HanyangUniversity,Seoul,RepublicofKorea
S. Cho,S. Choi, Y. Go,D. Gyun, S. Ha,B. Hong, Y. Jo, Y. Kim, K. Lee,K.S. Lee,S. Lee,J. Lim, S.K. Park, Y. Roh KoreaUniversity,Seoul,RepublicofKorea
J. Almond,J. Kim, H. Lee,S.B. Oh, B.C. Radburn-Smith, S.h. Seo, U.K. Yang,H.D. Yoo, G.B. Yu SeoulNationalUniversity,Seoul,RepublicofKorea
M. Choi,H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park, G. Ryu, M.S. Ryu UniversityofSeoul,Seoul,RepublicofKorea
Y. Choi,J. Goh, C. Hwang, J. Lee,I. Yu SungkyunkwanUniversity,Suwon,RepublicofKorea
V. Dudenas, A. Juodagalvis,J. Vaitkus VilniusUniversity,Vilnius,Lithuania
I. Ahmed,Z.A. Ibrahim, M.A.B. Md Ali32,F. Mohamad Idris33,W.A.T. Wan Abdullah, M.N. Yusli, Z. Zolkapli
NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia
H. Castilla-Valdez,E. De La Cruz-Burelo, I. Heredia-De La Cruz34,A. Hernandez-Almada, R. Lopez-Fernandez,R. Magaña Villalba, J. Mejia Guisao, A. Sanchez-Hernandez
CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico
S. Carrillo Moreno, C. Oropeza Barrera, F. Vazquez Valencia UniversidadIberoamericana,MexicoCity,Mexico
S. Carpinteyro, I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada BenemeritaUniversidadAutonomadePuebla,Puebla,Mexico
A. Morelos Pineda
UniversidadAutónomadeSanLuisPotosí,SanLuisPotosí,Mexico D. Krofcheck
UniversityofAuckland,Auckland,NewZealand P.H. Butler
UniversityofCanterbury,Christchurch,NewZealand
A. Ahmad, M. Ahmad, Q. Hassan,H.R. Hoorani, W.A. Khan, A. Saddique,M.A. Shah, M. Shoaib, M. Waqas NationalCentreforPhysics,Quaid-I-AzamUniversity,Islamabad,Pakistan
H. Bialkowska, M. Bluj,B. Boimska, T. Frueboes,M. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper,P. Zalewski
NationalCentreforNuclearResearch,Swierk,Poland
K. Bunkowski,A. Byszuk35, K. Doroba,A. Kalinowski, M. Konecki,J. Krolikowski, M. Misiura, M. Olszewski, M. Walczak
InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland
P. Bargassa,C. Beirão Da Cruz E Silva, B. Calpas, A. Di Francesco, P. Faccioli,P.G. Ferreira Parracho, M. Gallinaro,J. Hollar, N. Leonardo,L. Lloret Iglesias, M.V. Nemallapudi,J. Rodrigues Antunes, J. Seixas, O. Toldaiev, D. Vadruccio,J. Varela, P. Vischia
LaboratóriodeInstrumentaçãoeFísicaExperimentaldePartículas,Lisboa,Portugal
S. Afanasiev,P. Bunin, M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev,V. Karjavin, A. Lanev, A. Malakhov,V. Matveev36,37,V. Palichik, V. Perelygin, M. Savina, S. Shmatov, S. Shulha,N. Skatchkov, V. Smirnov, A. Zarubin
JointInstituteforNuclearResearch,Dubna,Russia
L. Chtchipounov,V. Golovtsov, Y. Ivanov, V. Kim38, E. Kuznetsova39,V. Murzin, V. Oreshkin, V. Sulimov, A. Vorobyev
PetersburgNuclearPhysicsInstitute,Gatchina(St.Petersburg),Russia
Yu. Andreev,A. Dermenev, S. Gninenko, N. Golubev, A. Karneyeu,M. Kirsanov, N. Krasnikov, A. Pashenkov,D. Tlisov, A. Toropin
InstituteforNuclearResearch,Moscow,Russia
V. Epshteyn, V. Gavrilov, N. Lychkovskaya,V. Popov, I. Pozdnyakov, G. Safronov, A. Spiridonov,M. Toms, E. Vlasov, A. Zhokin
InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia A. Bylinkin37
MoscowInstituteofPhysicsandTechnology,Moscow,Russia
R. Chistov40,M. Danilov40,S. Polikarpov
V. Andreev,M. Azarkin37,I. Dremin37, M. Kirakosyan, A. Leonidov37,A. Terkulov P.N.LebedevPhysicalInstitute,Moscow,Russia
A. Baskakov,A. Belyaev, E. Boos,V. Bunichev, M. Dubinin41, L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, I. Lokhtin,I. Miagkov, S. Obraztsov, M. Perfilov, S. Petrushanko,V. Savrin
SkobeltsynInstituteofNuclearPhysics,LomonosovMoscowStateUniversity,Moscow,Russia V. Blinov42, Y. Skovpen42,D. Shtol42
NovosibirskStateUniversity(NSU),Novosibirsk,Russia
I. Azhgirey,I. Bayshev,S. Bitioukov, D. Elumakhov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine, V. Petrov, R. Ryutin, A. Sobol,S. Troshin, N. Tyurin,A. Uzunian, A. Volkov StateResearchCenterofRussianFederation,InstituteforHighEnergyPhysics,Protvino,Russia
P. Adzic43,P. Cirkovic, D. Devetak,M. Dordevic, J. Milosevic,V. Rekovic UniversityofBelgrade,FacultyofPhysicsandVincaInstituteofNuclearSciences,Belgrade,Serbia
J. Alcaraz Maestre,M. Barrio Luna, E. Calvo,M. Cerrada,M. Chamizo Llatas, N. Colino, B. De La Cruz, A. Delgado Peris,A. Escalante Del Valle, C. Fernandez Bedoya,J.P. Fernández Ramos, J. Flix, M.C. Fouz, P. Garcia-Abia,O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa,E. Navarro De Martino, A. Pérez-Calero Yzquierdo,J. Puerta Pelayo, A. Quintario Olmeda,I. Redondo, L. Romero,M.S. Soares CentrodeInvestigacionesEnergéticasMedioambientalesyTecnológicas(CIEMAT),Madrid,Spain
J.F. de Trocóniz,M. Missiroli, D. Moran UniversidadAutónomadeMadrid,Madrid,Spain
J. Cuevas,J. Fernandez Menendez, I. Gonzalez Caballero, J.R. González Fernández,E. Palencia Cortezon, S. Sanchez Cruz,I. Suárez Andrés, J.M. Vizan Garcia
UniversidaddeOviedo,Oviedo,Spain
I.J. Cabrillo, A. Calderon, E. Curras, M. Fernandez,J. Garcia-Ferrero,G. Gomez, A. Lopez Virto, J. Marco, C. Martinez Rivero,F. Matorras, J. Piedra Gomez, T. Rodrigo,A. Ruiz-Jimeno, L. Scodellaro,N. Trevisani, I. Vila, R. Vilar Cortabitarte
InstitutodeFísicadeCantabria(IFCA),CSIC-UniversidaddeCantabria,Santander,Spain
D. Abbaneo, E. Auffray, G. Auzinger, P. Baillon, A.H. Ball,D. Barney, P. Bloch, A. Bocci, C. Botta, T. Camporesi, R. Castello,M. Cepeda, G. Cerminara, Y. Chen,D. d’Enterria, A. Dabrowski,V. Daponte, A. David,M. De Gruttola, A. De Roeck, E. Di Marco44,M. Dobson, B. Dorney, T. du Pree,D. Duggan, M. Dünser, N. Dupont, A. Elliott-Peisert,P. Everaerts, S. Fartoukh, G. Franzoni, J. Fulcher,W. Funk, D. Gigi, K. Gill,M. Girone, F. Glege, D. Gulhan, S. Gundacker, M. Guthoff, P. Harris,J. Hegeman, V. Innocente, P. Janot,J. Kieseler, H. Kirschenmann,V. Knünz,A. Kornmayer15,M.J. Kortelainen, K. Kousouris, M. Krammer1, C. Lange, P. Lecoq,C. Lourenço, M.T. Lucchini,L. Malgeri, M. Mannelli,A. Martelli, F. Meijers, J.A. Merlin, S. Mersi,E. Meschi, P. Milenovic45,F. Moortgat, S. Morovic, M. Mulders,
H. Neugebauer,S. Orfanelli, L. Orsini,L. Pape, E. Perez, M. Peruzzi,A. Petrilli, G. Petrucciani,A. Pfeiffer, M. Pierini,A. Racz,T. Reis, G. Rolandi46,M. Rovere, H. Sakulin,J.B. Sauvan, C. Schäfer, C. Schwick, M. Seidel,A. Sharma,P. Silva, P. Sphicas47, J. Steggemann,M. Stoye, Y. Takahashi, M. Tosi,D. Treille, A. Triossi,A. Tsirou,V. Veckalns48,G.I. Veres20, M. Verweij, N. Wardle, H.K. Wöhri, A. Zagozdzinska35, W.D. Zeuner
W. Bertl,K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, D. Kotlinski,U. Langenegger, T. Rohe
PaulScherrerInstitut,Villigen,Switzerland
F. Bachmair, L. Bäni, L. Bianchini, B. Casal, G. Dissertori, M. Dittmar, M. Donegà, C. Grab, C. Heidegger, D. Hits, J. Hoss,G. Kasieczka, W. Lustermann,B. Mangano,M. Marionneau, P. Martinez Ruiz del Arbol, M. Masciovecchio, M.T. Meinhard,D. Meister, F. Micheli,P. Musella, F. Nessi-Tedaldi, F. Pandolfi, J. Pata, F. Pauss,G. Perrin, L. Perrozzi,M. Quittnat, M. Rossini, M. Schönenberger, A. Starodumov49,
V.R. Tavolaro, K. Theofilatos, R. Wallny InstituteforParticlePhysics,ETHZurich,Zurich,Switzerland
T.K. Aarrestad, C. Amsler50, L. Caminada,M.F. Canelli, A. De Cosa, C. Galloni,A. Hinzmann, T. Hreus, B. Kilminster, J. Ngadiuba,D. Pinna,G. Rauco, P. Robmann, D. Salerno, C. Seitz,Y. Yang, A. Zucchetta UniversitätZürich,Zurich,Switzerland
V. Candelise,T.H. Doan, Sh. Jain,R. Khurana, M. Konyushikhin, C.M. Kuo, W. Lin, A. Pozdnyakov,S.S. Yu NationalCentralUniversity,Chung-Li,Taiwan
Arun Kumar, P. Chang, Y.H. Chang,Y. Chao, K.F. Chen, P.H. Chen, F. Fiori, W.-S. Hou, Y. Hsiung, Y.F. Liu, R.-S. Lu, M. Miñano Moya,E. Paganis, A. Psallidas, J.f. Tsai
NationalTaiwanUniversity(NTU),Taipei,Taiwan
B. Asavapibhop, G. Singh, N. Srimanobhas,N. Suwonjandee ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand
A. Adiguzel, S. Damarseckin, Z.S. Demiroglu, C. Dozen, E. Eskut, S. Girgis, G. Gokbulut, Y. Guler, I. Hos51, E.E. Kangal52,O. Kara, A. Kayis Topaksu,U. Kiminsu,M. Oglakci, G. Onengut53, K. Ozdemir54,
S. Ozturk55, A. Polatoz, B. Tali56,S. Turkcapar, I.S. Zorbakir,C. Zorbilmez CukurovaUniversity–PhysicsDepartment,ScienceandArtFaculty,Turkey
B. Bilin, S. Bilmis, B. Isildak57, G. Karapinar58, M. Yalvac, M. Zeyrek MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey
E. Gülmez,M. Kaya59,O. Kaya60, E.A. Yetkin61, T. Yetkin62 BogaziciUniversity,Istanbul,Turkey
A. Cakir,K. Cankocak, S. Sen63 IstanbulTechnicalUniversity,Istanbul,Turkey B. Grynyov
InstituteforScintillationMaterialsofNationalAcademyofScienceofUkraine,Kharkov,Ukraine L. Levchuk,P. Sorokin
NationalScientificCenter,KharkovInstituteofPhysicsandTechnology,Kharkov,Ukraine
R. Aggleton,F. Ball, L. Beck, J.J. Brooke,D. Burns, E. Clement, D. Cussans,H. Flacher,J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath, J. Jacob,L. Kreczko, C. Lucas, D.M. Newbold64, S. Paramesvaran, A. Poll, T. Sakuma,S. Seif El Nasr-storey, D. Smith, V.J. Smith
