Search for W' decaying to tau lepton and neutrino in proton-proton collisions at s=√8 TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

W



decaying

to

tau

lepton

and

neutrino

in

proton–proton

collisions

at

√

s

=

8 TeV

Receivedinrevisedform20December2015 Accepted1February2016

Availableonline3February2016 Editor:M.Doser

Keywords: CMS Physics Wdecays

The firstsearchforaheavy chargedvectorbosoninthe finalstatewith atau leptonand aneutrino isreported, using19.7 fb−1ofLHCdataat√s=8 TeV.A signalwouldappearasan excessofevents withhightransversemass,wherethestandardmodelbackgroundislow.Noexcessisobserved.Limits are set on amodel inwhichthe W decayspreferentially tofermions ofthe third generation.These resultssubstantiallyextendpreviousconstraintsonthismodel.Massesbelow2.0to2.7 TeVareexcluded, dependingonthe modelparameters.Inaddition,the existenceofaW bosonwithuniversal fermion couplingsisexcludedat95%confidencelevel,forWmassesbelow2.7 TeV.Forfurtherreinterpretation amodel-independentlimitonpotentialsignalsforvarioustransversemassthresholdsisalsopresented.

©2016CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.Thisisanopenaccess articleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Newheavygaugebosonsarepredictedbyvariousextensionsof thestandardmodel(SM).Charged heavygaugebosons are gener-ally referred to as W [1]. Non-universal gauge interaction mod-els (NUGIM) [2–5] predict a larger W-boson branching fraction tothe third generationof fermions.Searches fora W boson de-cayingto a tau lepton andneutrino have never been performed before,while theelectron andmuonchannels havebeenstudied extensivelyat the Tevatron[6,7] and by the ATLAS andCMS ex-periments at the LHC [8,9]. This Letter describes a search for a W boson decayingto a tauleptonanda neutrinowiththe CMS detector[10]attheCERNLHC,usingproton–protoncollisions col-lected in2012at acenter-of-massenergy of8 TeV.The dataset corresponds to an integrated luminosity of 19.7±0.5 fb−1. The results are interpreted in the context of the sequential standard model (SSM) W boson [1]as well asan extended gauge group NUGIM[2,11,12].Thesignature ofaW-bosoneventissimilarto that ofa W-boson eventinwhich theW boson is produced“off shell”withahighmass.Eventsofinterestare thoseinwhichthe only detectable products ofthe W decay forma single hadron-ically decaying tau (τh). The hadronic decays of the tau lepton are experimentallydistinctive because theyresultin low charged hadronmultiplicity,unlikeQCDjets,whichhavehighhadron mul-tiplicity,orotherleptonicWdecays,whichhavenone.Incontrast, thedecaysW→τ ντ→eνeντντ andW→τ ντ→μνμντντ

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

not be distinguished from W→eνe and W→μνμ, thus they suffer fromlow significanceand are notselected in thisanalysis butratherinthecorrespondingleptonic(e, μ)Wsearches. 2. Physicsmodels

IntheSSM,theWbosonisaheavyanalogueoftheWboson.It isanarrowresonancewithfermionicdecaymodesandbranching fractionssimilartothoseoftheSMWboson,withtheadditionof thedecayW→tb, whichbecomesrelevantforW-bosonmasses largerthan180 GeV.IftheWbosonisheavy enoughtodecayto top andbottomquarks,theSSMbranching fractionforthedecay W→τ ν is 8.5%.Under these assumptions, thetotal width of a 1 TeVWbosonisabout33 GeV.DecaysoftheW bosonintoWZ bosonsdependonthespecificmodelassumptionsandareusually considered to be suppressedin theSSM,asassumedby the cur-rentsearchandbyprevioussearchesinotherfinalstates[9,13].If theWinteractswithleft-handedparticlesandright-handed anti-particles (V−A coupling), interferencewiththe SM W boson is expected[14–16].

Models with non-universal couplings predict an enhanced branchingfractiontothethirdgenerationoffermionsandexplain the large mass of the top quark. In the other model studied in this analysis, NUGIM [2,11,12], the weak SM SU(2)W group is a low-energylimit oftwogauge groups,a lightSU(2)l andaheavy SU(2)h, which coupleonly to the light fermions of the first two generationsandtotheheavyfermionsofthethirdgeneration, re-spectively. These two groups mix such that an SM-like SU(2)W andanextendedgroupSU(2)E exist.ThesecondSU(2)E extended

http://dx.doi.org/10.1016/j.physletb.2016.02.002

0370-2693/©2016CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

Fig. 1. Branchingfractions(left-handscaleandsolidlines)andtotalwidth (right-handscaleanddottedlines)forWdecaysintheNUGIM,ascalculatedinRefs.[2, 11,12].ForcotθE=1 thevaluesarethesameasthoseintheSSM,rescaledto

ac-commodatetheWH decaychannel.

gauge group gives riseto additional gauge bosons such asa W. Themixingofthetwogaugegroupsisdescribedbyamixing an-gleoftheextendedgroup θE,whichmodifiesthecouplingtothe heavybosons.Hencethemixingchangestheproductioncross sec-tion and, as illustrated in Fig. 1, the branching fractions of the W.For cotθE3 theW boson decays to fermions ofthe third generationonly,whereasatcotθE=1 the branchingfractionsare identicaltothose oftheSSM,andthe W couples democratically toall fermions.For cotθE<1 thedecays into light fermions are dominant. Inthe NUGIM, thedecayinto WZ bosons isnegligible byconstruction.IneithertheSSMortheNUGIM,thepresenceofa W-bosonsignalovertheW-bosonbackgroundcould beobserved inthedistributionofthetransversemass(MT)ofthe τhandthe missingtransverseenergy(Emiss_T ):

MT=



2 pτ_TE_Tmiss[1−cosφ (τ,pmiss_T )], (1)

wherepτ_TdenotesthepTofthe τhandEmissT = |p miss

T |,wherep miss T isdefinedas−pTofallreconstructedparticles.Theangleinthe transverseplane betweenpmiss

T andthedirectionof τhisdenoted φ (τ,pmiss

T ).

3. Generationofbackgroundandsignalsamples

The major SM backgrounds are dominated by W and Z+jets productionand are generated using MadGraph 5.1 [17] (for on-shellW andZ+jetsbackgrounds), pythia 6.426 [18] (foroff-shell W,WW,WZ,andZZ backgrounds)and powheg 1.0[19–23](fort¯t andsingle t+jets).The tau decayis simulatedby tauola[24] for all samples.Forthe hadronization ofthe MadGraph background, pythiais used. The response of these events in the CMS detec-torissimulatedusing Geant4[25].Thebackgroundsareproduced at leading-order (LO), but reweighted to higher order cross sec-tions. For the main W+jets background, a differential cross sec-tion as a function of the mass of the W-boson decay products isreweighted,incorporatingnext-to-next-to-leading-order(NNLO) QCDandnext-to-leading-order(NLO)electroweakcorrections.The effectwithrespecttotheLOcalculationcorrespondstoaK-factor of 1.3 at a mass of 0.3 TeV and drops for higher masses to 1.1

for a mass of 1 TeV. The calculation uses Monte Carlo genera-tors mcsanc 1.01 [26] and fewz 3.1 [27], following the recom-mended combination from Ref. [28]. For the Z+jets background, theinclusiveNNLOQCDcrosssectioniscalculatedusing fewz.For t¯t events, the inclusive NNLO calculation from [29] is used. For the diboson (VV) backgrounds, inclusiveNLO QCD cross sections are calculated using mcfm 6.6[30].The background contribution from multijet events is estimated from control samples in data. Thesignal eventsfortheSSMW aregeneratedwith pythia with NNLOcrosssectionsfrom fewz. TheNUGIMsignalsaregenerated with MadGraph 4.5.1[17] andhadronized with pythia.The par-ton distributionfunctions(PDFs)usedareCTEQ6L1 [31] for lead-ingordersimulationandCTEQ10[32] for(N)NLO simulation.The electroweak NLO calculation NNPDF 2.3 at NNLO QCD with and withoutQEDcontributions[33]areused.

4. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ing solenoidof6 m internal diameter,providinga magneticfield of3.8 T.Withinthesolenoidvolume area siliconpixelandstrip tracker,aleadtungstatecrystalelectromagneticcalorimeter(ECAL), andabrass andscintillatorhadroncalorimeter(HCAL),each com-posed of a barrel and two endcap sections. Muons are mea-suredingas-ionizationdetectorsembeddedinthesteelflux-return yokeoutsidethesolenoid. Extensive forwardcalorimetry comple-ments thecoverage provided bythe barrelandendcapdetectors. A particle-flow(PF)eventalgorithm[34]isusedtoreconstructthe events,identifythetaucandidatesanddeterminethemissingET. The algorithmreconstructs andidentifiessingle particles withan optimizedcombinationofall subdetectorinformation.The events are triggered by theCMS trigger system, which is split into two levels,afirst level(L1)composed ofcustomhardwareprocessors, anda high-level trigger(HLT) processor farm.For thisanalysisa “jetplus Emiss_T ”triggerisused,withthresholdsof pT>80 GeV for the jet and Emiss_T >105 GeV, wherethe latteris seededatL1 in thecalorimeterwith Emiss

T above 40 GeV. Bothobjectsare recon-structedattheHLTlevelusingthePFeventreconstruction.A more detaileddescriptionoftheCMSdetector,togetherwithadefinition ofthecoordinatesystemusedandtherelevantkinematicvariables, canbefoundinRef.[10].

5. Reconstructionandidentificationofphysicsobjects

TaureconstructioninCMS[35]isappliedtojetsclusteredfrom PFobjects,usingtheanti-kT algorithmwithaparameter R=0.5. Tau candidates must be distinguished from quark or gluon jets (QCD jetsin the following). The hadronic taudecays, τh, are re-constructedusingthe“hadron-plus-strips”(HPS)algorithm,which isbasedondecaymodesproceedingviaspecificintermediate res-onances,withacombinedbranchingfractionof 65%.Theyinclude modeswith eitherone orthree chargedhadrons, and up totwo neutralpions.Neutralpionsarereconstructedviatheirdecayinto pairs ofphotonsdetected intheECAL.The patternofenergy de-positionintheECALtypicallyoccursin“strips”,elongatedintheφ

directionasaresultofinteractionsinthetrackermaterialandthe effectoftheaxialmagneticfield.The τhcandidateisreconstructed from stripsand chargedhadrons, which are combined using the mass ranges expectedfromthe intermediate resonances. A more detailed discussion of the HPS algorithm can be found in [35]. Thereconstruction ofhadronictaudecayshasbeenoptimizedfor tauleptonswithlargepT wheredifferenttrackspotentiallymerge. Thisoccursbecauseeitherthetrackreconstructionseedcannotbe resolvedorthetrackssharesomanyhitsthatonetrackcannot be reconstructed.Thisleads toreconstructeddecaymodeswithonly

twochargedhadrons(instead ofthree) beingacceptedto accom-modate the boostedtopology. The energy measurement of these high-pTobjectsisdominatedbythecalorimeterandthereforehas agood pTresolution.Theallowedmassrangefortheintermediate statereconstructionisbroadenedforhigh-pT tauleptons,to com-pensate for the mass resolution. With these adaptations the tau reconstructionefficiencyisconstantat60%±6% for pT>80 GeV, ashasbeencheckedinsimulationsuptopT=3 TeV.Hadronictau decaysidentified bythe HPSalgorithm arerequired tobe within thetrackingacceptance,|η|<2.3,andthetaupTisrequiredtobe largerthan50 GeVtoreducethecontaminationfromQCDjets. Ad-ditionally the pT oftheleading chargedhadron isrequired tobe larger than 20 GeV.Subsequently, τh isdistinguished fromother objectsthat could mimica taucandidate,such asQCD jets, elec-trons, or muons. The discriminator against QCD jets is the most important,sincetherateofQCDjetsattheLHCisseveralorders ofmagnitude larger than thetau productionrate. Discrimination is based on isolation criteria: no additional PF charged hadrons orphotonswith |pT|above 2 GeV are allowed inan isolation cone of R=(φ)2_{+ (η)}2_{=0.3 (where φ is the azimuthal} angleinradians and η isthe pseudorapidity)around the τh can-didatedirection. Particle-flow objects are correctedfor additional collisions in the same bunch crossing (pileup). Charged hadrons areidentifiedaspileupobjectsbyvertexassociation.Neutral par-ticlecandidatesare corrected by usingan average pT subtraction fromthechargedhadronsidentifiedaspileupinaR=0.6 cone. Details can be found in Ref. [35]. Discrimination against elec-tronsisobtainedusingamultivariatetechnique, basedonvarious tau, photon, trackandelectron properties.The muon discrimina-torsearchesforhitsinthemuonsystemassociatedwiththetrack ofthe τh candidate.Both discriminatorssuppresslightleptons by threeorders ofmagnitude, without a significantreduction ofthe tauefficiency.Eventsofinterest forthisanalysisarerequirednot tocontainidentifiedelectrons ormuons.Electronsarerequiredto satisfy shape and isolation criteria aswell as pT>20 GeV, and

|η|<1.44 or1.56<|η|<2.50.Muonsarerequiredtobeisolated andtohave pT>20 GeV and|η|<2.4.

6. Analysisstrategy

Thestrategy ofthisanalysisis toselecta heavyboson decay-ingalmostatrestinto τhandEmiss_T .Inthetauchannel,theimpact ofthe interference betweenW andW bosons is expectedto be substantiallylowerthanthatpreviouslyfoundintheelectronand muonchannels [9].This occursbecausethesignal shapeof aW bosonwithhadronicallydecayingtauleptonsdoesnotshowa Ja-cobianpeakstructure,becauseofthepresenceoftwoneutrinosin thefinalstate.Theinterferenceeffecthasthereforenotbeen con-sideredinthisanalysis.Forthe“jet+Emiss_T ”trigger,analysis thresh-oldsofpT>100 GeV fortheleadingjetand Emiss_T >140 GeV are appliedtoaccountfordifferencesoftriggerandreconstructed en-ergydefinitions.TheseanalysisthresholdsonthetaupTandEmissT , alongwiththekinematicselectionontheratioof pτ_T/Emiss_T ,yield an implicitlower threshold on thetransverse mass.The eventis requiredto contain one isolatedtau lepton.Twokinematic crite-ria are applied to select signal events: the ratio ofthe τh pT to the Emiss_T isrequiredtosatisfy0.7<pτ_T/Emiss_T <1.5 andtheangle

φ (τ,pmiss_T )hastobe greaterthan2.4radians.Thisevent selec-tionmainlyreducesthe backgroundinthelow-MT region, which hasthelargestbackground,whilethesignalefficiencyathighW massesisonlyreducedbyabout 5%.Theefficiencyandacceptance for a W→τ ν event depend on the mass. For MW=2.2 TeV, 21% oftheeventspassallidentificationandselectioncriteria.This reduces to 17% for MW=1 TeV, 7% for MW=0.5 TeV, and, at

Fig. 2. The MT distributionafterthefinalselection.Datapointswitherror bars showLHCdata.Thehorizontalerrorbaroneachpointindicatesthewidthofthe bin,whichis25 GeVforthefirstthreebinsand50 GeVforallotherbins.Thefilled histogramshowsthebackgroundestimatediscussedinthetext,andthehatched areatheuncertaintyinthisestimate.ThesignalshapesfordifferentSSMWboson massesareshownasopenhistograms.ThecrosssectionforSSMMW=500 GeV is scaledby0.2.Intheratioplotthebin-widthisincreasedwhereneededtohaveat leastoneexpectedbackgroundeventineachbin.

higher masses, to 16% at MW=3 TeV. The reduction for lower masses occurs becauseof the change in shape of the MT distri-bution illustrated inFig. 2, while forhigher massesthe off-shell productionbecomes dominantandshiftstheeventsto lower MT. From thesimulationofhadronictaueventswithlarge MT values, above the kinematicturn-on,42% are acceptedonce all selection andidentificationcriteriaare takenintoaccount. Thisacceptance isindependentoftheWmass.FortheexamplecaseofW→τ ν

with MW=2.2 TeV, the cross section calculated in the SSM is 13.5 fb.Thisyields 54.8predictedsignal eventsinthe τh+EmissT final state, with the 21% acceptance quoted above for this MW value. The variation of the predicted SSM cross section with W masscanbeseeninFig. 3.

7. Backgroundestimation

The transverse mass distribution withthe observed data and expected backgroundevents anduncertainties is showninFig. 2 and Table 1. The dominant background,contributing almost two thirds ofthetotal,comesfromtheoff-shelltailoftheSM W bo-son. This background is indistinguishable fromthe signal, and is estimated from simulation.The contributionfrom W→e/μ+ν

events, in which the electron or muon is not identified, is also taken fromsimulation. The background contribution fromevents with one QCD jet falsely identified asa τh is suppressed by the pτ_T/Emiss_T requirement. Nonetheless it is the second largest back-groundforthissearchandisestimatedfromdatausingreference regions, separated fromthe signal region using the uncorrelated quantities, pτ_T/Emiss_T and τh isolation. The shape of the QCD jet backgroundisestimatedusingdataeventswithajetidentifiedas a τh, fulfilling all kinematic criteriadescribed earlier,apart from the isolation requirement. Its normalizationisbased on theratio

Table 1

Theeventyieldsforobserveddataandestimatedbackgrounds,andtheproductofacceptanceandefficiencyforthesignal(W→τ ν)fordifferentthresholdvaluesMmin T . Mmin

T [GeV] Data VV DY Top QCD jets W Sum of backgrounds Efficiencyfor

MW=2.2 TeV 200 1990 10 10 54 620 1380 2080±34(stat)±250(syst) 0.21 400 364 2.3 2.9 7.6 151 234 398±5.5(stat)±63(syst) 0.19 600 41 0.61 0.37 0.34 18.2 32.2 51.7±1.3(stat)±9(syst) 0.16 800 10 0.064 0.072 0 3.6 7.4 11.1±0.49(stat)±2.1(syst) 0.12 1000 4 0.0091 0.027 0 1.07 1.94 3.05±0.19(stat)±0.66(syst) 0.096 1200 1 0.0031 0.016 0 0.31 0.61 0.94±0.095(stat)±0.22(syst) 0.071 1400 0 0.0011 0.0076 0 0.130 0.180 0.319±0.046(stat)±0.081(syst) 0.047

Fig. 3. Limitsontheproductofcrosssectionandbranchingfractionintoτ ν for aSSMWboson.Thesolidlineshowsthelimitobservedwith19.7 fb−1_ofdata whilethedashedlinecorrespondstotheexpectedlimit.Theshadedbandsindicate the68%and95%confidenceintervalsoftheexpectedlimit.Thedottedandthe long-dashedlinesshowthecrosssectionpredictionintheSSMasafunctionofthe Wbosonmass,inNNLOandLO,respectively.

ofthenumbersofeventswithan isolated τh (Niso)tothose con-taining a non-isolated τh (Nnon-iso), determined in a signal-free reference region with pτ_T/Emiss_T >1.5. This ratio is evaluated as a function of the hadronic decay modes of the tau lepton. The meanratioofisolatedtonon-isolatedeventsisR=Niso/Nnon-iso= 0.0066±0.12%(stat)±0.16%(syst).Here the contributionof non-QCD events is subtracted. It amounts to 24% for Niso and 11%

for Nnon-iso. The systematic uncertainty is estimated by

chang-ing the pτ_T/Emiss

T threshold and the variable in which the ratio R is binned. The number ofQCD jet events inthe signal region is estimated, using this method,to be 620±124 after subtract-ingthecontaminationof32%fromelectroweakbackgroundevents. An additional systematic uncertainty of 20% is included, derived fromthenormalizationuncertaintyintheelectroweakbackground. Other sources of background considered include top quark pro-duction,either inpairs orsingly; Drell–Yan(DY) events;and tau leptons produced indiboson (WW, WZ, ZZ) events.A large frac-tionof theseare suppressedby requiringthe back-to-backdecay topology.Thesebackgrounds are showninFig. 2 asTop, DY, and Diboson, respectively. They contribute a total of 3% to the back-ground.

8. Systematicuncertainties

Mostofthe systematicuncertainties inthisanalysisaffectthe shapeoftheMT distributionbychangingthebackgroundand

sig-nal predictions.Others influence theoverall normalization; these includethe uncertaintyof2.6% [36] inthe integratedluminosity. Simulated event samples are used to evaluate shape-dependent uncertainties arising from the measurement of individual parti-cles and jets in the events. The kinematic variables of the indi-vidual objects are varied and the effect of the changes on the final MT distribution is evaluated. In the following, the shape-dependent uncertainties are listed in decreasing order of their importance for the high-MT region. The main uncertainty in the backgroundyield for MT≥1 TeV isdueto themomentum mea-surementofthetaulepton[37],importantforestimatingthe con-tributionfromoff-shellSM W-bosondecays.UsingZ→τ τ events andtau-mass fits,the uncertaintyin the momentum scaleis es-timated to be 3% of the tau pT.This estimation is confirmedby comparing energymeasurements fromtauandjet reconstruction algorithms for high-pT taus. This results in a 15% scale uncer-tainty in the background event yield, primarily from the tail of off-shell SM W bosons, which iscorrelated with the uncertainty in the signal prediction.There isan 8% uncertainty inthe event yieldfromthetheoreticalpredictionofthebackground.One con-tribution to this theory uncertainty comes from the NNLO QCD and NLO electroweak calculationsand isevaluated following the prescription described in Ref. [28]; there is an additional contri-butionfromthePDFs,forwhichtheprescriptionsofRefs. [38,39] are used. The uncertaintyin the eventyield fromthe jet energy calibrationisestimatedtobe 6%.Thecalibrationuncertaintyis de-pendent on thejet η and pT, andis determined using dijetand Z→μμ+jets events [40]. The knowledge ofthe reconstruction efficiency for high-pT tau leptons is a source of uncertainty in-fluencingthe backgroundandsignal normalization.The efficiency is determined by studying Z→τ τ and t¯t processes [37]. The resulting uncertaintyin the normalizationis 6%. There is an un-certainty of 20% in the QCD jet contribution to the background, whichisestimatedfromstatisticaluncertaintiesinthecontrol re-gionsandcrosschecksofthemethod,andwhichresultsina4–6% uncertaintyin theoverall backgroundyield.Other sources of un-certaintyarethejetenergyresolution(ηandpT dependent)[40], pileup modeling (5% on the estimated number of additional in-teractions), and other factors affecting the Emiss_T determination, such as low-energy deposits not associated with a jet (10% un-certainty in the energy of deposits smaller than 10 GeV). The overall impact of these effects is a 6% background uncertainty. Theimpactofalltheseuncertaintiesonthesignalacceptancehas been evaluated using the simulated samples. The size and rela-tiveimportanceoftheeffectsobservedaresimilartothoseforthe background yield, and depend on the shape ofthe MT distribu-tion.

9. Results

The final transverse mass distribution inFig. 2 showsno sig-nificantdeviationsfromthepredictedbackground.A multibin ap-proachisusedtoderivealimitontheW-bosonmass.A likelihood

Fig. 4. LimitsontheNUGIMparameterspaceareshownfromvariousanalyses.The solidlinereferstothisanalysis.Thenon-LHClimits(CKMandLeptonflavor viola-tion)arecalculatedinRef.[11].TheWresultsarefromRef.[13]forthetbfinal stateandRef.[9]foreνasreinterpretedinRef.[12].Thelinescorrespondto95% CL limits.

function is evaluated separately using the numbers of events in each MT bin.Thelikelihoodfunctionsfromallbinsare combined toextract themass limit.Fora moremodel-independent limit,a single-binapproachisused,countingalleventsaboveathreshold Mmin_T and comparing the number with the expected SM back-ground.Theparameterofinterestistheproductofthesignalcross sectionandthebranching fraction, σB(W→τ ν).Limitsare ob-tainedat95%confidencelevel(CL)usingaBayesianapproach[41] withauniformprior.

Thelimiton σB(W→τ ν)asafunctionoftheSSMW-boson mass is shown in Fig. 3. The observed and expected limits are in agreement. The SSM W boson is excluded for masses 0.3<

MW <2.7 TeV at 95% CL in the tau channel. The lower mass limit is dueto the trigger threshold and rising background. The W mass limit obtained at 95% CL is 400 GeV lower for a sig-nal cross section calculated to leading order. In the high mass region,off-shellproductionofWbosonsbecomesdominant, shift-ing thesignal MT distribution tolower MT. Incomparison, anal-yses of the muon and electron channels have set limits of 3.0 and 3.2 TeV on the SSM W mass, respectively [9]. In addition to the limit on the SSMW boson, limitsare seton the param-eterspaceoftheNUGIM. Onlyleading-ordersignal crosssections are available in theNUGIM. A separate crosssection limit is de-rived for each value of the model parameter cotθE, since the signal efficiency dependson this parameter. The actual widthof the W resonance fora given mass, asshown inFig. 1, is taken into account. From these limits, constraints on the mass of the W bosonas afunction of thecoupling parameter cotθE are de-rived in the same way as described previously for the SSM W boson. The resulting constraints from these mass exclusion lim-its on the parameter space can be seen in Fig. 4. The W mass limit is 2.0 TeV for cotθE=5.5, rising to a W boson mass of 2.7 TeVforcotθE=1.This variationisdueinparttothechange incouplingstrengthtothetaulepton,whichaffectsthedecay,as shown in Fig. 1, and in part to the change in coupling to light quarks, which affects the production. For cotθE >5.5 the width of the W becomes very broad, and large virtual corrections are needed.Thissearch setssignificantlybetterlimitsthanthe previ-ousconstraintsfromdirectandindirectsearchesforlargecotθE[9, 11,13]reinterpreted in[12].ForcotθE<1,thelightfamiliesyield

Fig. 5. Modelindependentlimits,ontheeffectivecrosssectionforaW-likesignal aboveathresholdvalueMmin

T ,fordifferentMminT .Thesolidlineshowsthelimit ob-servedwith19.7 fb−1_{ofdatawhilethedashedlinecorrespondstotheexpected} limit.Theshadedbandsindicatethe68%and95%confidenceintervalsofthe ex-pectedlimit.Theregionabovethecurveisexcluded.

a bettersensitivitybecauseoftheir higherefficiencyand branch-ing fraction as shown for the case of the electron channel in Fig. 4.

The multibin approach assumesa certain signal shape in MT. However, new physics processes yielding a tau+Emiss

T final state could cause an excess of a different shape. To be independent of models, a single-bin approach compares the number of ob-served eventsabove a sliding MT threshold,denoted MminT ,with the SMexpectationforthisMT range.Theresultingcross section limit as a function of Mmin_T is shown in Fig. 5. The reconstruc-tionefficiencyisestimatedtobe 42%forW eventssatisfyingthe condition MT>MminT .Itmaybenotedthatthefractionofthe sig-nalthat satisfiesthe Mmin

T requirementdependsontheparticular model, and is mass-dependent. The reconstruction efficiency has an uncertaintycorrespondingtothatofatypicalW-likesignalat different Mmin_T thresholds. This allows a reinterpretation in vari-ousmodelsbyevaluatingthesignalefficiency, εsignal,fortheMTmin threshold, defined as the number of events in the signal region withMT>Mmin_T dividedbythetotalnumberofgeneratedevents:

εsignal=NMT>MminT /Ntotal. 10. Summary

In summary, the first search for an excess in the transverse mass distribution of the tau+Emiss_T channel has been performed. The datasample was collected withtheCMSdetectorinproton– protoncollisions at√s=8 TeV,andcorresponds toanintegrated luminosity of19.7 fb−1_{.No significant excessbeyondtheSM} ex-pectation isobserved.An SSMW bosonisexcluded inthe mass range 0.3 TeV<MW<2.7 TeV at95% confidence level. Within theNUGIMthelowerlimitontheW-bosonmassdependsonthe couplingconstantcotθEandvariesfrom2.0to2.7 TeVat95% con-fidencelevel.

Acknowledgements

We congratulate our colleagues in the CERN accelerator de-partments for the excellent performance of the LHC and thank

thetechnicalandadministrativestaffsatCERN andatotherCMS institutes for their contributions to the success of the CMS ef-fort.Inaddition,wegratefullyacknowledgethecomputingcenters and personnel of the Worldwide LHC Computing Grid for de-livering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detec-tor provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, andFAPESP(Brazil); MES(Bulgaria); CERN;CAS,MOST, andNSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER, ERC IUT and ERDF (Estonia); Academy of Fin-land, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP andNRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASUand SFFR(Ukraine); STFC (United Kingdom);DOE andNSF (USA).

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V. Khachatryan,A.M. Sirunyan, A. Tumasyan YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, E. Asilar,T. Bergauer, J. Brandstetter, E. Brondolin,M. Dragicevic, J. Erö,M. Flechl, M. Friedl, R. Frühwirth1,V.M. Ghete, C. Hartl, N. Hörmann, J. Hrubec, M. Jeitler1, V. Knünz,A. König,

M. Krammer1,I. Krätschmer, D. Liko,T. Matsushita, I. Mikulec,D. Rabady2, B. Rahbaran,H. Rohringer, J. Schieck1,R. Schöfbeck, J. Strauss, W. Treberer-Treberspurg,W. Waltenberger, C.-E. Wulz1

InstitutfürHochenergiephysikderOeAW,Wien,Austria

V. Mossolov,N. Shumeiko, J. Suarez Gonzalez NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus

S. Alderweireldt, T. Cornelis,E.A. De Wolf, X. Janssen,A. Knutsson, J. Lauwers,S. Luyckx, S. Ochesanu, R. Rougny, 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, N. Heracleous,J. Keaveney, S. Lowette,L. Moreels, A. Olbrechts,Q. Python, D. Strom, S. Tavernier, W. Van Doninck, P. Van Mulders, G.P. Van Onsem,I. Van Parijs

VrijeUniversiteitBrussel,Brussel,Belgium

P. Barria, C. Caillol, B. Clerbaux, G. De Lentdecker, H. Delannoy, G. Fasanella, L. Favart, A.P.R. Gay,

A. Grebenyuk,T. Lenzi, A. Léonard, T. Maerschalk,A. Marinov, L. Perniè, A. Randle-conde, T. Reis,T. Seva, C. Vander Velde, P. Vanlaer, R. Yonamine,F. Zenoni, F. Zhang3

UniversitéLibredeBruxelles,Bruxelles,Belgium

K. Beernaert,L. Benucci, A. Cimmino, S. Crucy, D. Dobur, A. Fagot,G. Garcia,M. Gul, J. Mccartin, A.A. Ocampo Rios, D. Poyraz,D. Ryckbosch, S. Salva, M. Sigamani, N. Strobbe,M. Tytgat,

W. Van Driessche, E. Yazgan, N. Zaganidis GhentUniversity,Ghent,Belgium

S. Basegmez, C. Beluffi4,O. Bondu,S. Brochet, G. Bruno, R. Castello, A. Caudron, L. Ceard,

G.G. Da Silveira,C. Delaere, D. Favart,L. Forthomme,A. Giammanco5,J. Hollar, A. Jafari,P. Jez,M. Komm, V. Lemaitre, A. Mertens, C. Nuttens, L. Perrini, A. Pin, K. Piotrzkowski,A. Popov6,L. Quertenmont,

M. Selvaggi,M. Vidal Marono UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium N. Beliy, G.H. Hammad

UniversitédeMons,Mons,Belgium

W.L. Aldá Júnior, G.A. Alves,L. Brito, M. Correa Martins Junior,C. Hensel,C. Mora Herrera, A. Moraes, M.E. Pol, P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato7,A. Custódio, E.M. Da Costa,

D. De Jesus Damiao,C. De Oliveira Martins, S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson, D. Matos Figueiredo, L. Mundim,H. Nogima, W.L. Prado Da Silva, A. Santoro, A. Sznajder,

E.J. Tonelli Manganote7,A. Vilela Pereira UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahujaa,C.A. Bernardesb,A. De Souza Santosb, S. Dograa,T.R. Fernandez Perez Tomeia,

E.M. Gregoresb,P.G. Mercadanteb, C.S. Moona,8,S.F. Novaesa,Sandra S. Padulaa, D. Romero Abad, J.C. Ruiz Vargas

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

A. Aleksandrov, V. Genchev†,R. Hadjiiska, P. Iaydjiev, S. Piperov,M. Rodozov, S. Stoykova, G. Sultanov, M. Vutova

InstituteforNuclearResearchandNuclearEnergy,Sofia,Bulgaria

A. Dimitrov,I. Glushkov, L. Litov, B. Pavlov,P. Petkov UniversityofSofia,Sofia,Bulgaria

M. Ahmad, J.G. Bian, G.M. Chen,H.S. Chen, M. Chen, T. Cheng,R. Du, C.H. Jiang, R. Plestina9, F. Romeo, S.M. Shaheen,J. Tao, C. Wang, Z. Wang, H. Zhang

InstituteofHighEnergyPhysics,Beijing,China

C. Asawatangtrakuldee, Y. Ban,Q. Li, S. Liu, Y. Mao,S.J. Qian, D. Wang, Z. Xu,W. Zou StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

C. Avila,A. Cabrera, L.F. Chaparro Sierra, C. Florez,J.P. Gomez, B. Gomez Moreno, J.C. Sanabria UniversidaddeLosAndes,Bogota,Colombia

N. Godinovic, D. Lelas,D. Polic, I. Puljak, P.M. Ribeiro Cipriano UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia Z. Antunovic,M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,K. Kadija, J. Luetic,S. Micanovic, L. Sudic InstituteRudjerBoskovic,Zagreb,Croatia

A. Attikis, G. Mavromanolakis,J. Mousa, C. Nicolaou, F. Ptochos,P.A. Razis, H. Rykaczewski UniversityofCyprus,Nicosia,Cyprus

M. Bodlak,M. Finger10, M. Finger Jr.10 CharlesUniversity,Prague,CzechRepublic

Y. Assran11,S. Elgammal12, M.A. Mahmoud13

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt B. Calpas,M. Kadastik, M. Murumaa, M. Raidal, A. Tiko,C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia P. Eerola,J. Pekkanen, M. Voutilainen DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Härkönen,V. Karimäki, R. Kinnunen, T. Lampén, K. Lassila-Perini,S. Lehti, T. Lindén,P. Luukka, T. Mäenpää,T. Peltola, E. Tuominen, 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, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry,E. Locci, M. Machet, J. Malcles,J. Rander, A. Rosowsky, M. Titov, A. Zghiche

DSM/IRFU,CEA/Saclay,Gif-sur-Yvette,France

I. Antropov, S. Baffioni, F. Beaudette, P. Busson, L. Cadamuro, E. Chapon, C. Charlot, T. Dahms, O. Davignon,N. Filipovic, A. Florent, R. Granier de Cassagnac, S. Lisniak,L. Mastrolorenzo, P. Miné, I.N. Naranjo, M. Nguyen,C. Ochando, G. Ortona, P. Paganini, S. Regnard, R. Salerno,J.B. Sauvan, Y. Sirois, T. Strebler, Y. Yilmaz, A. Zabi

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

J.-L. Agram14, J. Andrea, A. Aubin, D. Bloch,J.-M. Brom, M. Buttignol,E.C. Chabert, N. Chanon, C. Collard, E. Conte14, X. Coubez, J.-C. Fontaine14,D. Gelé, U. Goerlach,C. Goetzmann, A.-C. Le Bihan, J.A. Merlin2, K. Skovpen, P. Van Hove

InstitutPluridisciplinaireHubertCurien,UniversitédeStrasbourg,UniversitédeHauteAlsaceMulhouse,CNRS/IN2P3,Strasbourg,France S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,C. Bernet, G. Boudoul, E. Bouvier, C.A. Carrillo Montoya, J. Chasserat, R. Chierici, D. Contardo, B. Courbon, P. Depasse, H. El Mamouni, J. Fan, J. Fay, S. Gascon, M. Gouzevitch, B. Ille, F. Lagarde, I.B. Laktineh,M. Lethuillier, L. Mirabito,A.L. Pequegnot, S. Perries, J.D. Ruiz Alvarez,D. Sabes, L. Sgandurra,V. Sordini, M. Vander Donckt, P. Verdier, S. Viret,H. Xiao

UniversitédeLyon,UniversitéClaudeBernardLyon1,CNRS-IN2P3,InstitutdePhysiqueNucléairedeLyon,Villeurbanne,France T. Toriashvili15

GeorgianTechnicalUniversity,Tbilisi,Georgia Z. Tsamalaidze10

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann, S. Beranek,M. Edelhoff,L. Feld, A. Heister, M.K. Kiesel, K. Klein, M. Lipinski, A. Ostapchuk, M. Preuten,F. Raupach, S. Schael,J.F. Schulte, T. Verlage,H. Weber, B. Wittmer, V. Zhukov6

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

M. Ata, M. Brodski,E. Dietz-Laursonn, D. Duchardt, L. Edelhäuser, M. Endres,M. Erdmann, S. Erdweg, T. Esch, R. Fischer,A. Güth, T. Hebbeker,C. Heidemann, K. Hoepfner,D. Klingebiel,A. Knochel,

S. Knutzen,P. Kreuzer, M. Merschmeyer,A. Meyer, P. Millet,M. Olschewski, K. Padeken, P. Papacz, T. Pook,M. Radziej, H. Reithler, M. Rieger, F. Scheuch, L. Sonnenschein, D. Teyssier,S. Thüer RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

V. Cherepanov, Y. Erdogan,G. Flügge, H. Geenen, M. Geisler, F. Hoehle, B. Kargoll, T. Kress, Y. Kuessel, A. Künsken, J. Lingemann2,A. Nehrkorn, A. Nowack,I.M. Nugent,C. Pistone, O. Pooth,A. Stahl

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,I. Asin, N. Bartosik, O. Behnke, U. Behrens,A.J. Bell, K. Borras, A. Burgmeier,A. Cakir, L. Calligaris, A. Campbell,S. Choudhury, F. Costanza, C. Diez Pardos, G. Dolinska,S. Dooling,T. Dorland, G. Eckerlin, D. Eckstein, T. Eichhorn, G. Flucke,E. Gallo, J. Garay Garcia, A. Geiser, A. Gizhko,

P. Gunnellini, J. Hauk, M. Hempel16,H. Jung, A. Kalogeropoulos, O. Karacheban16, M. Kasemann, P. Katsas, J. Kieseler, C. Kleinwort,I. Korol, W. Lange, J. Leonard,K. Lipka, A. Lobanov, W. Lohmann16, R. Mankel, I. Marfin16,I.-A. Melzer-Pellmann, A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller,

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DeutschesElektronen-Synchrotron,Hamburg,Germany

V. Blobel, M. Centis Vignali, A.R. Draeger,J. Erfle, E. Garutti,K. Goebel, D. Gonzalez, M. Görner,J. Haller, M. Hoffmann,R.S. Höing,A. Junkes, R. Klanner, R. Kogler, T. Lapsien, T. Lenz, I. Marchesini,D. Marconi, D. Nowatschin, J. Ott, F. Pantaleo2,T. Peiffer, A. Perieanu, N. Pietsch,J. Poehlsen, D. Rathjens,C. Sander, H. Schettler,P. Schleper, E. Schlieckau, A. Schmidt, J. Schwandt, M. Seidel,V. Sola, H. Stadie,

G. Steinbrück, H. Tholen,D. Troendle, E. Usai, L. Vanelderen,A. Vanhoefer UniversityofHamburg,Hamburg,Germany

M. Akbiyik, C. Barth, C. Baus,J. Berger,C. Böser, E. Butz, T. Chwalek, F. Colombo, W. De Boer, A. Descroix, A. Dierlamm,S. Fink, F. Frensch, M. Giffels,A. Gilbert, F. Hartmann2, S.M. Heindl,U. Husemann,

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InstitutfürExperimentelleKernphysik,Karlsruhe,Germany

G. Anagnostou,G. Daskalakis, T. Geralis,V.A. Giakoumopoulou, A. Kyriakis, D. Loukas,A. Psallidas, I. Topsis-Giotis

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

A. Agapitos,S. Kesisoglou, A. Panagiotou,N. Saoulidou, E. Tziaferi UniversityofAthens,Athens,Greece

I. Evangelou,G. Flouris, C. Foudas, P. Kokkas, N. Loukas, N. Manthos,I. Papadopoulos, E. Paradas, J. Strologas

UniversityofIoánnina,Ioánnina,Greece

G. Bencze,C. Hajdu, A. Hazi,P. Hidas, D. Horvath17, F. Sikler,V. Veszpremi, G. Vesztergombi18, A.J. Zsigmond

WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni,S. Czellar, J. Karancsi19,J. Molnar, Z. Szillasi InstituteofNuclearResearchATOMKI,Debrecen,Hungary

M. Bartók20, A. Makovec,P. Raics, Z.L. Trocsanyi, B. Ujvari UniversityofDebrecen,Debrecen,Hungary

P. Mal, K. Mandal, N. Sahoo, S.K. Swain NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

S. Bansal,S.B. Beri, V. Bhatnagar, R. Chawla, R. Gupta,U. Bhawandeep, A.K. Kalsi, A. Kaur, M. Kaur, R. Kumar,A. Mehta,M. Mittal, J.B. Singh, G. Walia

Ashok Kumar, Arun Kumar, A. Bhardwaj,B.C. Choudhary, R.B. Garg,A. Kumar, S. Malhotra, M. Naimuddin,N. Nishu, K. Ranjan,R. Sharma, V. Sharma

UniversityofDelhi,Delhi,India

S. Banerjee, S. Bhattacharya, K. Chatterjee,S. Dey, S. Dutta, Sa. Jain, N. Majumdar, A. Modak, K. Mondal, S. Mukherjee,S. Mukhopadhyay, A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar, M. Sharan

SahaInstituteofNuclearPhysics,Kolkata,India

A. Abdulsalam, R. Chudasama, D. Dutta, V. Jha, V. Kumar, A.K. Mohanty2, L.M. Pant,P. Shukla, A. Topkar BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz, S. Banerjee, S. Bhowmik21,R.M. Chatterjee, R.K. Dewanjee, S. Dugad, S. Ganguly,S. Ghosh, M. Guchait,A. Gurtu22,G. Kole, S. Kumar, B. Mahakud, M. Maity21, G. Majumder, K. Mazumdar, S. Mitra, G.B. Mohanty, B. Parida, T. Sarkar21,K. Sudhakar, N. Sur, B. Sutar, N. Wickramage23 TataInstituteofFundamentalResearch,Mumbai,India

S. Chauhan,S. Dube, S. Sharma

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

H. Bakhshiansohi,H. Behnamian, S.M. Etesami24, A. Fahim25, R. Goldouzian, M. Khakzad,

M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi, F. Rezaei Hosseinabadi, B. Safarzadeh26, M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b, C. Calabriaa,b,C. Caputoa,b,S.S. Chhibraa,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,c, S. Nuzzoa,b,A. Pompilia,b,G. Pugliesea,c, R. Radognaa,b, A. Ranieria,G. Selvaggia,b,L. Silvestrisa,2, R. Vendittia,b,P. Verwilligena

a_{INFNSezionediBari,Bari,Italy} b_{UniversitàdiBari,Bari,Italy} c_{PolitecnicodiBari,Bari,Italy}

G. Abbiendia,C. Battilana2, A.C. Benvenutia,D. Bonacorsia,b,S. Braibant-Giacomellia,b, L. Brigliadoria,b, R. Campaninia,b, P. Capiluppia,b,A. Castroa,b,F.R. Cavalloa, 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. Tosi}a,b_{, R. Travaglini}a,b

a_{INFNSezionediBologna,Bologna,Italy} b_{UniversitàdiBologna,Bologna,Italy}

G. Cappelloa,M. Chiorbolia,b,S. Costaa,b,F. Giordanoa,c,R. Potenzaa,b,A. Tricomia,b,C. Tuvea,b a_{INFNSezionediCatania,Catania,Italy}

b_{UniversitàdiCatania,Catania,Italy} c_{CSFNSM,Catania,Italy}

G. Barbaglia, V. Ciullia,b,C. Civininia, R. D’Alessandroa,b,E. Focardia,b,S. Gonzia,b,V. Goria,b, P. Lenzia,b,M. Meschinia,S. Paolettia, G. Sguazzonia,A. Tropianoa,b,L. Viliania,b

a_{INFNSezionediFirenze,Firenze,Italy} b_{UniversitàdiFirenze,Firenze,Italy}

L. Benussi,S. Bianco, F. Fabbri, D. Piccolo INFNLaboratoriNazionalidiFrascati,Frascati,Italy

V. Calvellia,b, F. Ferroa, M. Lo Veterea,b, M.R. Mongea,b,E. Robuttia, S. Tosia,b a_{INFNSezionediGenova,Genova,Italy}

b_{UniversitàdiGenova,Genova,Italy}

L. Brianza,M.E. Dinardoa,b,S. Fiorendia,b,S. Gennaia, R. Gerosaa,b,A. Ghezzia,b, P. Govonia,b,

S. Malvezzia, R.A. Manzonia,b, B. Marzocchia,b,2,D. Menascea,L. Moronia,M. Paganonia,b, D. Pedrinia, S. Ragazzia,b_{,N. Redaelli}a_{,T. Tabarelli de Fatis}a,b

a_{INFNSezionediMilano-Bicocca,Milano,Italy} b_{UniversitàdiMilano-Bicocca,Milano,Italy}

S. Buontempoa, N. Cavalloa,c,S. Di Guidaa,d,2, M. Espositoa,b, F. Fabozzia,c,A.O.M. Iorioa,b, G. Lanzaa, L. Listaa,S. Meolaa,d,2,M. Merolaa,P. Paoluccia,2,C. Sciaccaa,b,F. Thyssen

a_{INFNSezionediNapoli,Napoli,Italy} b_{UniversitàdiNapoli’FedericoII’,Napoli,Italy} c_{UniversitàdellaBasilicata,Potenza,Italy} d_{UniversitàG.Marconi,Roma,Italy}

P. Azzia,2,N. Bacchettaa,L. Benatoa,b, D. Biselloa,b, A. Bolettia,b, A. Brancaa,b,R. Carlina,b,P. Checchiaa, M. Dall’Ossoa,b,2,T. Dorigoa, F. Gasparinia,b, U. Gasparinia,b, A. Gozzelinoa, K. Kanishcheva,c,

S. Lacapraraa,M. Margonia,b,A.T. Meneguzzoa,b, F. Montecassianoa, M. Passaseoa, J. Pazzinia,b, N. Pozzobona,b, P. Ronchesea,b,F. Simonettoa,b, E. Torassaa,M. Tosia,b, M. Zanetti,P. Zottoa,b, A. Zucchettaa,b,2,G. Zumerlea,b

a_{INFNSezionediPadova,Padova,Italy} b_{UniversitàdiPadova,Padova,Italy} c_{UniversitàdiTrento,Trento,Italy}

A. Braghieria, A. Magnania,P. Montagnaa,b, S.P. Rattia,b,V. Rea,C. Riccardia,b,P. Salvinia, I. Vaia, P. Vituloa,b

a_{INFNSezionediPavia,Pavia,Italy} b_{UniversitàdiPavia,Pavia,Italy}

L. Alunni Solestizia,b, M. Biasinia,b, G.M. Bileia,D. Ciangottinia,b,2,L. Fanòa,b, P. Laricciaa,b, G. Mantovania,b, M. Menichellia,A. Sahaa,A. Santocchiaa,b, A. Spieziaa,b

a_{INFNSezionediPerugia,Perugia,Italy} b_{UniversitàdiPerugia,Perugia,Italy}

K. Androsova,27,P. Azzurria,G. Bagliesia,J. Bernardinia,T. Boccalia,G. Broccoloa,c,R. Castaldia, M.A. Cioccia,27,R. Dell’Orsoa, S. Donatoa,c,2,G. Fedi, L. Foàa,c,†,A. Giassia, M.T. Grippoa,27,

F. Ligabuea,c,T. Lomtadzea,L. Martinia,b, A. Messineoa,b, F. Pallaa,A. Rizzia,b,A. Savoy-Navarroa,28, A.T. Serbana, P. Spagnoloa,P. Squillaciotia,27, R. Tenchinia,G. Tonellia,b, A. Venturia, P.G. Verdinia a_{INFNSezionediPisa,Pisa,Italy}

b_{UniversitàdiPisa,Pisa,Italy}

c_{ScuolaNormaleSuperiorediPisa,Pisa,Italy}

L. Baronea,b, F. Cavallaria,G. D’imperioa,b,2, D. Del Rea,b,M. Diemoza, S. Gellia,b,C. Jordaa,E. Longoa,b, F. Margarolia,b, P. Meridiania,F. Michelia,b, G. Organtinia,b,R. Paramattia, F. Preiatoa,b,S. Rahatloua,b, C. Rovellia,F. Santanastasioa,b,P. Traczyka,b,2

a_{INFNSezionediRoma,Roma,Italy} b_{UniversitàdiRoma,Roma,Italy}

N. Amapanea,b_{,R. Arcidiacono}a,c,2_{,S. Argiro}a,b_{,M. Arneodo}a,c_{,R. Bellan}a,b_{, C. Biino}a_{, N. Cartiglia}a_, M. Costaa,b,R. Covarellia,b, P. De Remigisa,A. Deganoa,b,N. Demariaa, L. Fincoa,b,2,C. Mariottia, S. Masellia,E. Migliorea,b, V. Monacoa,b, E. Monteila,b, M. Musicha, 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, A. Solanoa,b, A. Staianoa, U. Tamponia

a_{INFNSezionediTorino,Torino,Italy} b_{UniversitàdiTorino,Torino,Italy}

c_{UniversitàdelPiemonteOrientale,Novara,Italy}

S. Belfortea,V. Candelisea,b,2, M. Casarsaa,F. Cossuttia, G. Della Riccaa,b,B. Gobboa,C. La Licataa,b, M. Maronea,b,A. Schizzia,b, T. Umera,b,A. Zanettia

a_{INFNSezionediTrieste,Trieste,Italy} b_{UniversitàdiTrieste,Trieste,Italy}

S. Chang, A. Kropivnitskaya,S.K. Nam KangwonNationalUniversity,Chunchon,RepublicofKorea

D.H. Kim,G.N. Kim, M.S. Kim,D.J. Kong, S. Lee, Y.D. Oh,A. Sakharov, D.C. Son KyungpookNationalUniversity,Daegu,RepublicofKorea

J.A. Brochero Cifuentes, H. Kim,T.J. Kim, M.S. Ryu ChonbukNationalUniversity,Jeonju,RepublicofKorea

S. Song

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

S. Choi, Y. Go, D. Gyun,B. Hong,M. Jo, H. Kim, Y. Kim,B. Lee, K. Lee, K.S. Lee, S. Lee,S.K. Park, Y. Roh KoreaUniversity,Seoul,RepublicofKorea

H.D. Yoo

SeoulNationalUniversity,Seoul,RepublicofKorea

M. Choi,H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park, G. Ryu UniversityofSeoul,Seoul,RepublicofKorea

Y. Choi,Y.K. Choi, J. Goh,D. Kim, E. Kwon, J. Lee, I. Yu SungkyunkwanUniversity,Suwon,RepublicofKorea

A. Juodagalvis,J. Vaitkus VilniusUniversity,Vilnius,Lithuania

I. Ahmed,Z.A. Ibrahim, J.R. Komaragiri, M.A.B. Md Ali29,F. Mohamad Idris30,W.A.T. Wan Abdullah, M.N. Yusli

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

E. Casimiro Linares, H. Castilla-Valdez, E. De La Cruz-Burelo,I. Heredia-de La Cruz31, A. Hernandez-Almada,R. Lopez-Fernandez, A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico S. Carrillo Moreno, F. Vazquez Valencia UniversidadIberoamericana,MexicoCity,Mexico

S. Carpinteyro, I. Pedraza, H.A. Salazar Ibarguen BenemeritaUniversidadAutonomadePuebla,Puebla,Mexico

A. Morelos Pineda

UniversidadAutónomadeSanLuisPotosí,SanLuisPotosí,Mexico D. Krofcheck

UniversityofAuckland,Auckland,NewZealand P.H. Butler,S. Reucroft

UniversityofCanterbury,Christchurch,NewZealand

A. Ahmad, M. Ahmad, Q. Hassan,H.R. Hoorani, W.A. Khan,T. Khurshid, M. Shoaib 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

G. Brona,K. Bunkowski, 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, A. Di Francesco, P. Faccioli,P.G. Ferreira Parracho, M. Gallinaro, N. Leonardo,L. Lloret Iglesias, F. Nguyen, 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, V. Konoplyanikov, A. Lanev,A. Malakhov,V. Matveev32, P. Moisenz, V. Palichik,V. Perelygin, S. Shmatov, S. Shulha,

N. Skatchkov,V. Smirnov, A. Zarubin JointInstituteforNuclearResearch,Dubna,Russia

V. Golovtsov,Y. Ivanov, V. Kim33,E. Kuznetsova, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov,L. Uvarov, S. Vavilov, 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, E. Vlasov, A. Zhokin

InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia A. Bylinkin

NationalResearchNuclearUniversity‘MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

V. Andreev,M. Azarkin34,I. Dremin34, M. Kirakosyan, A. Leonidov34,G. Mesyats, S.V. Rusakov, A. Vinogradov

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Baskakov,A. Belyaev, E. Boos,V. Bunichev, M. Dubinin35, L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova,I. Lokhtin, I. Myagkov,S. Obraztsov, M. Perfilov, V. Savrin

I. Azhgirey,I. Bayshev,S. Bitioukov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine, V. Petrov, R. Ryutin, A. Sobol, L. Tourtchanovitch,S. Troshin, N. Tyurin, A. Uzunian,A. Volkov

StateResearchCenterofRussianFederation,InstituteforHighEnergyPhysics,Protvino,Russia P. Adzic36, M. Ekmedzic,J. Milosevic,V. Rekovic UniversityofBelgrade,FacultyofPhysicsandVincaInstituteofNuclearSciences,Belgrade,Serbia

J. Alcaraz Maestre, E. Calvo,M. Cerrada,M. Chamizo Llatas, N. Colino, B. De La Cruz,A. Delgado Peris, D. Domínguez Vázquez, 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 C. Albajar, J.F. de Trocóniz, M. Missiroli, D. Moran UniversidadAutónomadeMadrid,Madrid,Spain

H. Brun, J. Cuevas,J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, E. Palencia Cortezon, J.M. Vizan Garcia

UniversidaddeOviedo,Oviedo,Spain

I.J. Cabrillo, A. Calderon, J.R. Castiñeiras De Saa, P. De Castro Manzano, J. Duarte Campderros,

M. Fernandez,G. Gomez, A. Graziano,A. Lopez Virto, J. Marco, R. Marco,C. Martinez Rivero, F. Matorras, F.J. Munoz Sanchez, J. Piedra Gomez,T. Rodrigo, A.Y. Rodríguez-Marrero, A. Ruiz-Jimeno, L. Scodellaro, I. Vila, R. Vilar Cortabitarte

InstitutodeFísicadeCantabria(IFCA),CSIC-UniversidaddeCantabria,Santander,Spain

D. Abbaneo, E. Auffray, G. Auzinger, M. Bachtis,P. Baillon, A.H. Ball, D. Barney, A. Benaglia, J. Bendavid, L. Benhabib,J.F. Benitez, G.M. Berruti, P. Bloch,A. Bocci, A. Bonato,C. Botta, H. Breuker, T. Camporesi, G. Cerminara, S. Colafranceschi37,M. D’Alfonso, D. d’Enterria, A. Dabrowski, V. Daponte, A. David,

M. De Gruttola, F. De Guio, A. De Roeck, S. De Visscher, E. Di Marco,M. Dobson, M. Dordevic, T. du Pree, N. Dupont,A. Elliott-Peisert, G. Franzoni, W. Funk, D. Gigi, K. Gill,D. Giordano, M. Girone, F. Glege, R. Guida, S. Gundacker, M. Guthoff,J. Hammer, M. Hansen, P. Harris,J. Hegeman, V. Innocente, P. Janot, H. Kirschenmann,M.J. Kortelainen, K. Kousouris, K. Krajczar,P. Lecoq, C. Lourenço,M.T. Lucchini, N. Magini,L. Malgeri, M. Mannelli,A. Martelli, L. Masetti,F. Meijers, S. Mersi, E. Meschi, F. Moortgat, S. Morovic, M. Mulders, M.V. Nemallapudi,H. Neugebauer, S. Orfanelli38,L. Orsini, L. Pape, E. Perez, A. Petrilli, G. Petrucciani,A. Pfeiffer, D. Piparo, A. Racz,G. Rolandi39, M. Rovere, M. Ruan, H. Sakulin, C. Schäfer, C. Schwick,A. Sharma, P. Silva,M. Simon, P. Sphicas40,D. Spiga, J. Steggemann,B. Stieger, M. Stoye, Y. Takahashi, D. Treille, A. Triossi,A. Tsirou,G.I. Veres18,N. Wardle,H.K. Wöhri,

A. Zagozdzinska41,W.D. Zeuner

CERN,EuropeanOrganizationforNuclearResearch,Geneva,Switzerland

W. Bertl,K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, D. Kotlinski,U. Langenegger, D. Renker, T. Rohe

PaulScherrerInstitut,Villigen,Switzerland

F. Bachmair, L. Bäni, L. Bianchini, M.A. Buchmann,B. Casal, G. Dissertori, M. Dittmar, M. Donegà, M. Dünser,P. Eller, C. Grab,C. Heidegger, D. Hits, J. Hoss, G. Kasieczka, W. Lustermann,B. Mangano, A.C. Marini,M. Marionneau, P. Martinez Ruiz del Arbol,M. Masciovecchio, D. Meister, P. Musella, F. Nessi-Tedaldi, F. Pandolfi, J. Pata, F. Pauss,L. Perrozzi,M. Peruzzi, M. Quittnat, M. Rossini, A. Starodumov42,M. Takahashi, V.R. Tavolaro, K. Theofilatos,R. Wallny

T.K. Aarrestad, C. Amsler43, L. Caminada,M.F. Canelli,V. Chiochia, A. De Cosa, C. Galloni,A. Hinzmann, T. Hreus,B. Kilminster, C. Lange, J. Ngadiuba,D. Pinna, P. Robmann, F.J. Ronga,D. Salerno, Y. Yang UniversitätZürich,Zurich,Switzerland

M. Cardaci,K.H. Chen, T.H. Doan, C. Ferro,Sh. Jain, R. Khurana,M. Konyushikhin, C.M. Kuo, W. Lin, Y.J. Lu,R. Volpe, S.S. Yu

NationalCentralUniversity,Chung-Li,Taiwan

R. Bartek,P. Chang, Y.H. Chang, Y.W. Chang,Y. Chao, K.F. Chen, P.H. Chen, C. Dietz, F. Fiori, U. Grundler, W.-S. Hou,Y. Hsiung, Y.F. Liu,R.-S. Lu, M. Miñano Moya, E. Petrakou,J.F. Tsai, Y.M. Tzeng

NationalTaiwanUniversity(NTU),Taipei,Taiwan

B. Asavapibhop,K. Kovitanggoon, G. Singh, N. Srimanobhas, N. Suwonjandee ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand

A. Adiguzel, M.N. Bakirci44,C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut, Y. Guler,

E. Gurpinar,I. Hos, E.E. Kangal45,G. Onengut46,K. Ozdemir47, S. Ozturk44, A. Polatoz, D. Sunar Cerci48, M. Vergili,C. Zorbilmez

CukurovaUniversity,Adana,Turkey

I.V. Akin,B. Bilin, S. Bilmis, B. Isildak49,G. Karapinar50,U.E. Surat, M. Yalvac, M. Zeyrek MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

E.A. Albayrak51, E. Gülmez,M. Kaya52,O. Kaya53, T. Yetkin54 BogaziciUniversity,Istanbul,Turkey

K. Cankocak,S. Sen55, F.I. Vardarlı 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, E. Clement, D. Cussans,H. Flacher, J. Goldstein,M. Grimes, G.P. Heath, H.F. Heath,J. Jacob, L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold56, S. Paramesvaran,A. Poll, T. Sakuma,S. Seif El Nasr-storey, S. Senkin, D. Smith,V.J. Smith

UniversityofBristol,Bristol,UnitedKingdom

K.W. Bell,A. Belyaev57,C. Brew, R.M. Brown, D.J.A. Cockerill, J.A. Coughlan, K. Harder,S. Harper, E. Olaiya,D. Petyt, C.H. Shepherd-Themistocleous, A. Thea,L. Thomas, I.R. Tomalin, T. Williams, W.J. Womersley, S.D. Worm

RutherfordAppletonLaboratory,Didcot,UnitedKingdom

M. Baber,R. Bainbridge, O. Buchmuller, A. Bundock,D. Burton, S. Casasso,M. Citron, D. Colling, L. Corpe, N. Cripps,P. Dauncey,G. Davies, A. De Wit, M. Della Negra,P. Dunne, A. Elwood, W. Ferguson, J. Fulcher, D. Futyan,G. Hall, G. Iles, G. Karapostoli,M. Kenzie, R. Lane, R. Lucas56,L. Lyons, A.-M. Magnan,

S. Malik,J. Nash, A. Nikitenko42, J. Pela, M. Pesaresi,K. Petridis, D.M. Raymond, A. Richards,A. Rose, C. Seez,A. Tapper, K. Uchida, M. Vazquez Acosta58, T. Virdee,S.C. Zenz

J.E. Cole, P.R. Hobson, A. Khan,P. Kyberd, D. Leggat,D. Leslie, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner

BrunelUniversity,Uxbridge,UnitedKingdom

A. Borzou,K. Call,J. Dittmann, K. Hatakeyama, A. Kasmi, H. Liu,N. Pastika BaylorUniversity,Waco,USA

O. Charaf,S.I. Cooper, C. Henderson, P. Rumerio TheUniversityofAlabama,Tuscaloosa,USA

A. Avetisyan, T. Bose,C. Fantasia, D. Gastler, P. Lawson, D. Rankin, C. Richardson,J. Rohlf, J. St. John, L. Sulak,D. Zou

BostonUniversity,Boston,USA

J. Alimena,E. Berry, S. Bhattacharya, D. Cutts, N. Dhingra, A. Ferapontov, A. Garabedian,U. Heintz, E. Laird,G. Landsberg, Z. Mao, M. Narain, S. Sagir, T. Sinthuprasith

BrownUniversity,Providence,USA

R. Breedon,G. Breto, M. Calderon De La Barca Sanchez, S. Chauhan,M. Chertok, J. Conway,R. Conway, P.T. Cox, R. Erbacher,M. Gardner, W. Ko, R. Lander,M. Mulhearn, D. Pellett, J. Pilot, F. Ricci-Tam, S. Shalhout, J. Smith, M. Squires, D. Stolp, M. Tripathi, S. Wilbur,R. Yohay

UniversityofCalifornia,Davis,Davis,USA

R. Cousins,P. Everaerts,C. Farrell, J. Hauser, M. Ignatenko, D. Saltzberg, E. Takasugi, V. Valuev,M. Weber UniversityofCalifornia,LosAngeles,USA

K. Burt, R. Clare,J. Ellison, J.W. Gary, G. Hanson,J. Heilman, M. Ivova PANEVA, P. Jandir, E. Kennedy, F. Lacroix,O.R. Long, A. Luthra, M. Malberti, M. Olmedo Negrete, A. Shrinivas,H. Wei, S. Wimpenny UniversityofCalifornia,Riverside,Riverside,USA

J.G. Branson, G.B. Cerati,S. Cittolin, R.T. D’Agnolo, A. Holzner, R. Kelley, D. Klein, J. Letts, I. Macneill, D. Olivito, S. Padhi, M. Pieri, M. Sani,V. Sharma, S. Simon, M. Tadel,A. Vartak, S. Wasserbaech59, C. Welke,F. Würthwein,A. Yagil, G. Zevi Della Porta

UniversityofCalifornia,SanDiego,LaJolla,USA

D. Barge, J. Bradmiller-Feld, C. Campagnari, A. Dishaw, V. Dutta,K. Flowers, M. Franco Sevilla, P. Geffert, C. George, F. Golf, L. Gouskos,J. Gran, J. Incandela, C. Justus,N. Mccoll, S.D. Mullin, J. Richman, D. Stuart, I. Suarez,W. To, C. West,J. Yoo

UniversityofCalifornia,SantaBarbara,SantaBarbara,USA

D. Anderson,A. Apresyan, A. Bornheim,J. Bunn, Y. Chen, J. Duarte, A. Mott, H.B. Newman,C. Pena, M. Pierini,M. Spiropulu, J.R. Vlimant, S. Xie, R.Y. Zhu

CaliforniaInstituteofTechnology,Pasadena,USA

V. Azzolini,A. Calamba, B. Carlson, T. Ferguson, Y. Iiyama, M. Paulini,J. Russ, M. Sun, H. Vogel, I. Vorobiev

CarnegieMellonUniversity,Pittsburgh,USA

J.P. Cumalat, W.T. Ford,A. Gaz, F. Jensen, A. Johnson, M. Krohn,T. Mulholland, U. Nauenberg, J.G. Smith, K. Stenson,S.R. Wagner