Study of Excited Λ0 b States Decaying to Λ0 bπ+π− in proton-proton Collisions at √s = 13 TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Study

of

excited

Λ

states

decaying

to

Λ

π

+

π

−

in

proton-proton

collisions

at

√

s

=

13

TeV

Receivedinrevisedform18February2020 Accepted26February2020

Availableonline2March2020 Editor:M.Doser Keywords: CMS Physics Beautybaryon Heavybaryon Heavyflavor Flavorspectroscopy Experimentalresults

A studyof excitedΛ0_bbaryons isreported, basedonadata samplecollectedin2016–2018with the CMSdetectorattheLHCinproton-protoncollisionsatacenter-of-massenergyof13 TeV,corresponding to an integrated luminosity of up to 140 fb−1.The existence of four excitedΛ0_b states: Λ0_b(5912)0_,

Λ0_b(5920)0,Λ_b0(6146)0,andΛ0_b(6152)0intheΛ0_bπ+π−massspectrumisconfirmed,andtheirmasses are measured. The Λ0_bπ+π− mass distribution exhibits a broad excess of events in the region of 6040–6100 MeV,whoseorigincannotbediscernedwiththepresentdata.

©2020TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Studies of excited baryonic states are an important aspect of hadron spectroscopy and help to shed light on the mechanisms responsiblefordynamicsofquarksandbaryon formation.In par-ticular,spectroscopyofbaryonsthat containaheavy-flavorquark, such as the Λ0_b baryon, can test predictions of heavy-quark ef-fective theory [1]. A number of theoretical calculations exist for variousorbital andradial excitationsof thegroundstate baryons containingab quark [2–16],includingthoseoftheΛ0_b baryon.In general,thereareanumberofexcited Λ0_b baryonstatespredicted inthe 5.9–6.4 GeV massrange.However, predictions are very di-verse in terms of the specific mass spectrum and do not point toanycommonnarrowmassregionin whichtosearch forthese excited states.As an additionalcomplication, thewidths andthe production cross sections of various excited states are generally unknown.This situationmakes experimental searches forexcited heavy-quark baryons both challenging and important for testing varioustheoreticalmodels.

The existence of two narrow excited Λ_b0 states, Λ0_b(5912)0

and Λ0_b(5920)0, in the Λ0_bπ+π− invariant mass spectrum near the kinematic threshold was reported by the LHCb Collabora-tionin2012 [17] (charge-conjugatestatesareimpliedthroughout

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

thisLetter). Themeasuredmassesare M(Λ_b0(5912)0)=5911.97± 0.67MeV and M(Λ0_b(5920)0)=5919.77±0.67MeV, and the re-spectivenaturalwidthswerefoundtobebelow0.83and0.75 MeV at95%confidencelevel.ThelatterstatewasconfirmedbytheCDF Collaboration [18] soonthereafterwiththe massmeasured tobe M(Λ0_b(5920)0)=5919.22±0.76MeV.Theprecisionofthese mea-surements was limited by the large uncertainty in the Λ0_b mass at the time; the current world-average values M(Λ0_b(5912)0)=

5912.20±0.21MeV andM(Λ0_b(5920)0)=5919.92±0.19MeV [19] are based on the updated Λ0_b mass measurement [20,21]. Re-cently, the LHCb experiment has also presented an observation oftwonarrowhigher-massstatesintheΛ0_bπ+π−spectrum,with thefollowingmassesandwidths [22]:M(Λ_b0(6146)0)=6146.17± 0.43MeV, (Λ0_b(6146)0)=2.9±1.3MeV, and M(Λ0_b(6152)0)=

6152.51±0.38MeV,(Λ0_b(6152)0)=2.1±0.9MeV.

In this Letter, a study of the Λ0_bπ+π− invariant mass dis-tribution in the 5900–6400 GeV range by the CMS Collaboration is reported. Both the Λ0_b(5912)0 and Λ0_b(5920)0 states near the kinematic threshold are confirmed and their masses are mea-sured.Inaddition,theΛ0_bπ+π−distributionisinvestigatedinthe higher-massregionandsignalsconsistentwiththeΛ0_b(6146)0_and

Λ0_b(6152)0 statesareobserved.Thegroundstatebaryon Λ0_b is re-constructed via its decays into the J/ψ and ψ(2S) channels. The analysis uses the proton-proton (pp) collision data recorded

https://doi.org/10.1016/j.physletb.2020.135345

0370-2693/©2020TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

withtheCMSdetectorin2016–2018,duringtheCERNLHCRun2 at√s=13TeV,correspondingtoanintegratedluminosityofupto 140 fb−1.

2. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ing solenoidof 6 m internal diameter, providinga magnetic field of3.8 T. Withinthe solenoidvolume area siliconpixel andstrip tracker, a lead tungstate crystal electromagnetic calorimeter, and a brass and scintillator hadron calorimeter, each composed of a barrelandtwo endcapsections.Forward calorimetersextendthe pseudorapiditycoverageprovidedbythebarrelandendcap detec-tors.Muonsaredetectedingas-ionizationchambersembeddedin the steel flux-return yoke outside the solenoid. A more detailed descriptionoftheCMSdetector,together withadefinitionofthe coordinatesystemused andtherelevantkinematic variables,can befoundinRef. [23].

Events of interest are selected using a two-tiered trigger sys-tem [24]. Thefirstlevel (L1),composedofcustom hardware pro-cessors, usesinformationfromthe calorimetersandmuon detec-torstoselecteventsatarateofaround100 kHz withinatime in-tervaloflessthan4 μs.TheL1triggerusedintheanalysisrequired at least two muons. The second level, known as the high-level trigger (HLT), consistsof a farm of processors running a version of the full event reconstruction software optimized for fast pro-cessing, andreduces the event rateto around 1 kHz before data storage. The set of HLT algorithms used in the analysis requires twoopposite-sign(OS)muonswithvariouspseudorapidity η and transversemomentum pT thresholds,compatiblewithbeing

pro-ducedinthedimuondecaysofJ/ψ orψ(2S)mesons.Giventhat nosingle triggeralgorithm isdedicatedto thedecaysignature of interest,the analysisuses a combinationofseveraltriggers, with integratedluminositiesupto140 fb−1.

3. Eventselection

The event selection begins by requiring two OS muons pass-ingtheCMSsoft-muonidentificationcriteria [25] with pT>3GeV

and|η|<2.2.Themuonsmustforma commonvertexwitha χ2

fitprobability ( Pvtx) greater than1%. The dimuon invariantmass

isrequiredtosatisfy 2.90<M(μ+μ−)<3.95GeV.IfM(μ+μ−)is below3.4 GeV, thedimuonsystemisconsideredtobeaJ/ψ can-didate,oraψ(2S)candidateotherwise.

Anotherψ(2S)decaychannelisalsousedtoincreasethesignal yield: ψ(2S)→J/ψπ+π−→ μ+μ−π+π−. Two additional, high purity [26], OS tracks, assumed to be pions and labeled π_ψ(2S), are required to have pT>0.35GeV. They are fit to a common

vertex with a J/ψ candidate, using a world-average J/ψ me-son mass [19] constraint. The invariant mass of the J/ψ candi-date and the two tracks must satisfy the requirement 3672< M(J/ψπ+π−)<3700MeV, corresponding to a window centered ontheworld-averageψ(2S)mesonmass,withahalf-widthof ap-proximatelythreetimesthecorrespondingmassresolution.

A  candidateis formed from a displaced two-prong vertex, assumingthedecay→pπ−,asdescribedinRef. [27].Thepπ− invariant mass is required to be within ±10MeV of the world-average baryonmassmPDG_ [19],whichcorresponds to approx-imately three times the  candidate mass resolution. The two tracksare refittedwiththeir invariant massconstrainedtomPDG_ , andtheobtainedcandidateisrequiredtohavePvtx>1%.

ToformtheΛ0_bcandidates,theJ/ψorψ(2S)candidateandthe

candidatearefittoacommonvertexwithPvtx>1%,wherethe

world-averageJ/ψorψ(2S)mass [19] constraintisappliedtothe muon pair.In thecaseof theψ(2S)→J/ψπ+π− decaychannel, onlytheJ/ψ→ μ+μ− massconstraintisused.

Theprimaryvertex(PV)associatedwiththeΛ0_bcandidateis se-lectedamongallthereconstructedverticesbyrequiringthe small-estanglebetweenthereconstructedΛ0_bcandidatemomentumand the vector pointingfromthisvertexto the Λ0_b decayvertex. The PVisthenrefittedafterremovingthetracksassociatedwiththe

andeither theJ/ψ orψ(2S) candidates.The decaylength ofthe Λ0_bcandidateinthetransverseplane,Lxy,iscomputedasthe two-dimensional distance between the PV and the Λ0_b decay vertex, and isrequired to exceedthree timesits uncertainty. This selec-tion helpstosuppressthecombinatorial background.Inaddition, the transverse momentum ofthe Λ0_b candidate isrequired to be wellalignedwiththetransversedisplacementvector:cosα>0.99, where α istheanglebetweentheprojectionsontheplane trans-verse to the beams of the Λ0_b candidate momentum and of the vector connecting the PV with the Λ0_b decay vertex. The num-bers of Λ0_b signal candidates after these requirements are about 39 000, 3400, and4300forthe J/ψ, ψ(2S)(ψ(2S)→ μ+μ−), andψ(2S)(ψ(2S)→J/ψπ+π−)channels,respectively.

TheΛ0_bπ+π−candidatesareformedbycombiningtheselected Λ0_b candidates withtwo OStracks originatingfromthe PV, asin Refs. [28–30], since the lifetimeof excited Λ0_b statesis expected to be negligible, resulting in prompt decays. Combinations of a Λ0_b candidate withtwo promptsame-sign (SS) pions are usedas a control channel and formthe SScontrol region, asopposed to the OS signal region. The higher-pT pion of the pair is labeled

π±₁ and the lower-pT pion π±₂. To improve the Λ0_bπ+π−

invari-antmassresolution,alltracksformingthePVandtheselectedΛ0_b candidate, takenasa single “pseudo-track”withthe momentum, its uncertainty, andthe assigned mass equal to those of the Λ0_b candidate, are refit to a common vertex. The Λ0_bπ+π− invariant mass m_Λ0

bπ+π− is then calculated using the momenta of parti-cles returned by this vertexfit through the relationm_Λ0

bπ+π− = M(Λ0_bπ+π−)−M(Λ0_b)+mPDG

Λ0_b,wherem

PDG

Λ0_b =5619.60±0.17MeV istheworld-averageΛ0_b baryonmass [19].ThePVrefitting proce-dureimprovestheΛ0_bπ+π−massresolutionbyupto50%.Unless specified otherwise, multiple Λ0_bπ+π− candidates found in the sameeventarenotdiscarded.

4. Simulatedsamplesandselectionoptimization

Several simulatedsignal samples withdifferentmasses of ex-cited Λ0_b statesare usedin the analysis. The pythia 8.230 pack-age [31] is used to simulate the production of the excited Λ0_b states. The 0_b baryon, witha modified mass value, is usedas a proxy for an excited Λ0_b baryon. The decays are described with evtgen 1.6.0 [32].Final-state photonradiation isincludedin evt-gen using photos [33,34]. Generatedeventsare thenpassed to a detailed Geant4-based simulation [35] of the CMS detector, fol-lowedbythesametriggerandreconstructionalgorithmsusedfor collisiondata.Thesimulationincludeseffectsfrommultiplepp in-teractionsinthesameornearbybunchcrossings(pileup)withthe multiplicitydistributionmatchingthatobservedindata.

Simulated samples are used to optimize the selection criteria using the Punzifigure of merit [36], i.e., optimizingthe value of S/(5₂+√B),whereS isthesimulatedsignalyieldandB isthe ex-pectedbackground,asestimatedusingtheSScontrolregion.This optimizationschemeisindependentofthesignalnormalization.

The selection requirements are optimized separately for the low-massm_Λ0

bπ+π−<5950MeV andhigh-mass5950<mΛ 0 bπ+π−

<6400MeV regions, using the Λ0_b(5912)0 and Λ0_b(6150)0 simu-latedsignalsamples,respectively.Forthelow-massregion,the op-timizedcriteriaare:pT(π±₂)>0.3GeV,pT(π₁±)>0.35GeV,cosα>

Fig. 1. InvariantmassdistributionoftheselectedΛ0

bπ+π−candidatesnear

thresh-old.Theverticalbarsonthedatapointsdisplaythestatisticaluncertaintiesinthe data.Theoverallfitresultisshownbythethicksolidline,withthethinanddashed linesrepresentingthesignaland combinatorialbackgroundcomponents, respec-tively.

0.995, cosα3D_{>0.995, and p}

T(πψ(2S))>0.4GeV, where α3D is

a three-dimensional analog of the angle α. For the high-mass region, the optimized requirements are found to be pT(π±₂)>

0.7GeV, pT(π1±)>1.4GeV, pT(Λ0_b)>16GeV, Pvtx(Λ0_b)>2%, and

Pvtx(Λ0_bπ+π−)>8%. Inthehigh-massregion,duetohigher

back-grounds, ifmultiple excited Λ0_b candidates in an event pass the aboverequirements,onlythehighest pT candidateiskept.Inthe

low-mass region the average number of candidates per event is veryclosetoone,whileinthehigh-massregionitisaroundtwo.

5. Observed0_bπ+π−invariantmassspectra Theobserved invariant massdistribution m_Λ0

bπ+π− ofthe se-lectedsignalcandidatesnearthethresholdisshowninFig.1.The twonarrowpeakscorrespondingtotheΛ0_b(5912)0andΛ0_b(5920)0

baryonsaremodeledwithdouble-Gaussianfunctionswiththe res-olutionparametersfixedtothoseobtainedinsimulation(effective resolutions are about 0.6and 0.8 MeV). The background is mod-eled with a threshold function (x−x0)β, where x0 is the mass

thresholdvalue. The value of β, as well asthe masses and nor-malizations of the two signal functions, are free parameters of an unbinned maximum-likelihood fit to data. The best-fit signal yields are 28.4±5.8 and 159±14 events, and the measured massesare 5912.32±0.12MeV and 5920.16±0.07MeV, respec-tively,wheretheuncertaintiesarestatisticalonly.Thepresenceof eachofthepeaksisestablishedwithastatisticalsignificanceof5.7 andwell over 6 standard deviations (σ), forthe Λ0_b(5912)0 and Λ0_b(5920)0 states, respectively, thereby confirming the existence ofthesetwobaryon states.The significanceshavebeenevaluated withthelikelihood-ratiotechniquebyapplyingtheone- and two-peak signal hypotheses.The likelihood ratios are evaluated using anasymptotic formula [37,38].The meansandresolution param-eters ofthe two peaks are allowed to vary in the fit within the GaussianconstraintsfromRef. [19] andthesimulation.The signifi-canceoftheΛ0_b(5912)0_{statevariesbetween5.4and5.7σ withthe}

variationsinthefitmodelusedtoestimatethesystematic uncer-tainties,asdetailedinSection6;thesignificanceoftheΛ0_b(5920)0

stateremainswellabove6σ. Highermassesinthem_Λ0

bπ+π− distributionarestudiedaswell, as shown in Fig. 2. A narrow peak at approximately 6150 MeV is evident, consistent with an overlap of the Λ0_b(6146)0 and Λ0_b(6152)0 signals, aswell asabroadenhancement intheregion below6100 MeV.NoneofthesefeaturesarepresentintheSS

con-Fig. 2. InvariantmassdistributionoftheselectedΛ0

bπ+π−candidatesinthe

high-massregion.Theverticalbarsonthedatapointsrepresentthestatistical uncertain-tiesinthedata.Theoverallfitresultisshownbythethicksolidline.Thethinlines presentthecontributionsfromthetwosignalpeaksandthebroadenhancement. Thedashedlinedisplaysthecombinatorialbackground.

trol region, asshown inthe supplemental material [URL will be insertedbypublisher].

Anumberofcross-checkshavebeenperformedto understand ifthebroadenhancement canbetheresultofakinematic reflec-tion orproducedby a backgroundprocess. Itwas found that the enhancement is not compatible with the partially reconstructed decaysofΛ0_b(6146)0 orΛ0_b(6152)0 statesintoΛ0_bπ+π−π0(where the π0 islost). Tocheckifitcan be dueto some otherstate de-cayingintotheΛ0_bK±π∓channels,theΛ0_bKπinvariantmass distri-butionsareobtainedbysubstitutingthepionmasswiththekaon mass. No significant enhancements over the smooth background are found. The m_Λ0

bπ+π− background distributionis found to be in agreement between the SS and OS regions in the simulation anddoesnotshowanyenhancementinthe6000–6100 MeV mass region. The two-dimensional distributions of the Λ0_bπ+π− mass versus the Λ0_bπ+ and Λ_b0π− massesfromdata are shownin the supplemental material [URL willbe inserted by publisher]. If the Λ0_bπ± invariant massranges correspondingto the−_b,+_b,∗−_b , and∗+_b baryonsare vetoed,theSSandOSmassdistributions in dataarefound tobeinagreement inthe regionbelow6100 MeV anddonotexhibitabroadenhancement,asshowninthe supple-mentalmaterial[URLwillbeinsertedbypublisher].Thissuggests thatthebroadexcessmightberelatedtotheintermediate±_b and

∗_b± baryonstates,althoughthecurrentsizeofthedatasetdoes notallowthishypothesistobetested.

The observed m_Λ0

bπ+π− distribution in the high-mass region is fit with a sum of three signal functions and a smooth back-ground function obtained by multiplying the threshold function

(x−x0)β by afirst-orderpolynomial.Thesignal function

describ-ing thebroadstructure below6100 MeV is a single Breit–Wigner functionconvolvedwithadouble-Gaussianresolutionfunction ob-tained from simulation. The narrow peak around 6150 MeV is modeled withthe sumoftwo Breit–Wigner functions, each con-volved witha double-Gaussianresolution function obtainedfrom simulation,having an effectivemass resolutionofabout3.8 MeV. Thenaturalwidthsofthetwosignalsarefixedtothosemeasured by the LHCbCollaboration [22]. Thefit resultsforthe yields and masses,respectively,are301±72 and6073±5MeV forthebroad enhancement, 70±35 and 6146.5±1.9MeV for the Λ0_b(6146)0, and113±35 and6152.7±1.1MeV fortheΛ0_b(6152)0.The mea-surednaturalwidthofthebroadexcessis55±11(stat) MeV.While thisworkwasunderthejournalreview,asimilarstructure, consis-tentwiththeonereportedhereandpossiblyanewbaryonstate, hasbeenobservedbytheLHCbCollaboration [39].

Usingthe likelihood-ratiotechnique andthe one- versus two-peakhypotheses,thepresenceoftwopeakshasastatistical signif-icanceof0.4σ,indicating thatthedataarealsoconsistent witha singlepeakat6150 MeV.Forthedouble-peakhypothesis,the nat-uralwidthsofthetwostatesareallowedtovaryinthefitwithin theGaussianconstraintsfromtheLHCbmeasurement [22].Inthe single-peakhypothesis,themassandthenaturalwidthofthe sig-nal peak are free parameters of the fit. In both cases, the mass resolutionisallowed tofloatinthefitwithinits Gaussian uncer-tainty estimatedfromsimulation. Thelocalstatisticalsignificance ofthesingle-peakhypothesiswithrespecttothebackground-only hypothesis is foundto be over 6σ inthe baseline fit, andvaries between5.4and6.5σ withthe changes inthefit rangeandthe model used to estimate the systematic uncertainties, as detailed inSection6.Thebroadenhancementhasalocalstatistical signif-icance of about4σ. Resonances with massesbetween 6200 and 6400 MeV havebeenalsoconsideredinthefitmodelandno sig-nificant excess was found. The present amount of datadoes not allowustoperformconclusivestudiesof_b∗±→ Λ0_bπ±decay con-tributionstotheresonancesdecayingintoΛ0_bπ+π−.

6. Systematicuncertainties

Several sources of systematic uncertainties in the measured masses are considered. To evaluate the systematic uncertainties related to the choice of the fit model, several alternative signal andbackgroundfunctionsare tested. Uncertaintiesrelated tothe choice of the signal and background models are evaluated sepa-rately.The systematicuncertainty in each measurementis calcu-latedasthemaximumdeviationoftheobservedmassvalue from thebaseline fitresult.Thealternativesignalmodelcorrespondsto a single-Gaussian resolutionfunction; the alternativebackground modelsforthelow- andhigh-massregions arefirst- and second-orderpolynomials, respectively,multipliedby thesame threshold functionasinthebaselinefit.

Forthe high-mass region, the nature ofthe broad excess be-low 6100 MeV isunclear, thereforean additionalfitis performed intheregionm_Λ0

bπ+π−>6100MeV,andtheobserveddeviations fromthebaseline fit resultinthe measured massesaretaken as thesystematicuncertaintiesrelatedtothepossiblepresenceofthe broadresonance.

The systematicuncertaintyfromthe choice ofthe fitrangeis evaluated by extending the rangeup to6650 MeV. The observed deviationsinthemeasuredmassesaretakenasthesystematic un-certainties.Thesystematicuncertaintiesduetofitrangevariations arenegligiblefortheΛ0_b(5912)0andΛ0_b(5920)0 states.

In the baseline fits of the m_Λ0

bπ+π− distributions, the mass resolutionsarefixedtothoseestimatedfromsimulatedevent sam-ples.Thesystematicuncertaintyassociatedwitha possible differ-encesbetweendataandsimulationiscalculatedusingthe follow-ing procedure. The mass resolutions are compared betweendata andsimulation for the copiousΛ0_b→J/ψ signal:they are, re-spectively, 15.25 and15.78 MeV,corresponding to a difference of 3.5%. This difference is considered to be the uncertainty in the resolution dueto the data-simulationdifference. To estimate the effectofthisuncertaintyonthemeasuredmasses,thebaselinefits are redone with the resolutions increased or decreased by 3.5%, andthelargestdeviationinthemeasured massesfromthe base-linefitresults isconsidered asthesystematicuncertaintydueto themassresolution.

Themeasured massesofthe Λ0_b(6146)0 _andΛ0

b(6152)0 states

haveanadditionalsystematicuncertaintyduetothefactthattheir naturalwidthswerefixedinthenominalfittothevaluesreported byLHCb.Toestimatetherespectiveuncertainty,thenominalfitis repeatedwith the naturalwidths fixed to the central values

ob-tainedby LHCbplusorminus thecorrespondinguncertainties (in total8additionalfitsareperformed).

A potential bias in the mass measurement due to a possible misalignmentofthetrackerdetectorshasbeenevaluatedby com-paringdistributionsobtainedin2016,2017,and2018running pe-riods, which isa reasonablecomparison,given thatan important fraction of the CMS tracking detector was replaced between the 2016and2017datataking.Asexpected,thealignmentofthe de-tector leads to a negligible systematic uncertainty in the results reportedinthisLetter.

ThevarioussystematicuncertaintiesaresummarizedinTable1, together with the total uncertainties calculated as the quadratic sumoftheindividualsources.

7. Summary

In summary, using the pp collision data recorded with the CMS detectorat √s=13TeV, corresponding toan integrated lu-minosity of up to 140 fb−1, the existence of the Λ0_b(5912)0 and Λ0_b(5920)0 baryons is confirmed. Their masses, with respect to the Λ0_b mass, are measured to be 292.72±0.12±0.01MeV and 300.56±0.07±0.01MeV,respectively,wherethefirstuncertainty is statistical andthe second is systematic. By adding the known Λ0_b mass of 5619.60±0.17MeV [19], we report the mass mea-surements

M(Λ0_b(5912)0)=5912.32±0.12±0.01±0.17 MeV, M(Λ0_b(5920)0)=5920.16±0.07±0.01±0.17 MeV,

wherethethirduncertaintyistheuncertaintyintheworld-average Λ0_b mass. The obtained values are consistent with the world-averagevaluesandhavesimilarprecision.

In addition, the Λ0_bπ+π− invariant mass spectrum is investi-gated in the mass range up to 6400 MeV. A narrow peak is ob-served with a mass close to 6150 MeV, with a significance over 5 standard deviations, consistent with the superposition of the Λ0_b(6146)0 andΛ_b0(6152)0 baryonsrecentlyobservedbytheLHCb Collaboration [22].Themassesofthesestatesaremeasuredtobe

M(Λ0_b(6146)0)=6146.5±1.9±0.8±0.2 MeV, M(Λ0_b(6152)0)=6152.7±1.1±0.4±0.2 MeV,

wherethe firstuncertaintyisstatistical,the secondissystematic, and the third is the uncertainty in the world-average Λ0_b mass value. Thecorrespondingmassdifferenceswithrespecttothe Λ0_b massare

M(Λ0_b(6146)0)−M(Λ_b0)=526.9±1.9±0.8 MeV, M(Λ0_b(6152)0)−M(Λ_b0)=533.1±1.1±0.4 MeV.

Thesemeasurementsare notaspreciseas, butareingood agree-mentwiththeLHCbresults [22].

Inaddition,a broadexcess ofeventsisobserved intheregion 6040–6100 MeV, not presentinthe same-sign Λ0_bπ±π± distribu-tion. Ifit is fit witha single Breit-Wigner function, the returned mass and width are 6073±5(stat) MeV and 55±11(stat) MeV. However, it isnot excluded that this enhancement is an overlap ofmorethanonestatewithclosemassesoriscreatedbythe par-tially reconstructed decays of higher-mass states. More data are neededtoelucidatethenatureofthisexcess.

Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the

Table 1

Systematicuncertainties(inMeV)inthemeasuredmasses.Adashmeansthatthecorrespondinguncertaintyisnegligible,and“N/A”meansthatitdoesnotapply. Source M(Λ0b(5912) 0 ) M(Λ0b(5920) 0 ) M(Λ0b(6146) 0 ) M(Λ0b(6152) 0 ) Signal model 0.005 0.011 0.21 0.23 Background model 0.004 — 0.16 0.14

Inclusion of the broad excess region N/A N/A 0.35 0.14

Fit range — — 0.40 0.02

Mass resolution 0.007 0.001 0.01 0.09

Knowledge of N/A N/A 0.43 0.26

Total 0.009 0.011 0.77 0.41

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: BMBWFandFWF(Austria);FNRS andFWO (Belgium); CNPq, CAPES, FAPERJ,FAPERGS, andFAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, PUT and ERDF (Estonia); AcademyofFinland,MEC,andHIP(Finland);CEAandCNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); NK-FIA (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN(Italy);MSIPandNRF(RepublicofKorea);MES(Latvia);LAS (Lithuania);MOEandUM(Malaysia); BUAP,CINVESTAV,CONACYT, LNS,SEP,andUASLP-FAI(Mexico);MOS(Montenegro);MBIE(New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portu-gal);JINR(Dubna);MON,ROSATOM, RAS,RFBR,andNRCKI (Rus-sia);MESTD(Serbia);SEIDI,CPAN,PCTI,andFEDER(Spain);MoSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter,IPST,STAR, andNSTDA(Thailand);TUBITAKandTAEK (Turkey);NASU (Ukraine); STFC (United Kingdom); DOE andNSF (USA).

Individuals have received support from the Marie-Curie pro-gramandtheEuropeanResearchCouncilandHorizon2020Grant, contract Nos. 675440, 752730, and 765710 (European Union); the Leventis Foundation; the A.P. Sloan Foundation; the Alexan-der von Humboldt Foundation; the Belgian Federal Science Pol-icy 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 Technologie (IWT-Belgium); theF.R.S.-FNRS andFWO (Belgium)under the “Excellenceof Sci-ence – EOS” – be.h project n. 30820817; the Beijing Municipal Science & Technology Commission, No. Z191100007219010; the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic;theDeutscheForschungsgemeinschaft(DFG)under Ger-many’s Excellence Strategy – EXC 2121 “Quantum Universe” – 390833306; the Lendület (“Momentum”) Program and the János Bolyai Research Scholarship of the Hungarian Academy of Sci-ences, the New National Excellence Program ÚNKP, the NK-FIA research grants 123842, 123959, 124845, 124850, 125105, 128713, 128786, and 129058 (Hungary); the Council of Science andIndustrial Research,India;the HOMING PLUSprogramofthe Foundation for Polish Science, cofinanced from European Union, Regional 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 Ministry ofScience andEducation, grantno. 14.W03.31.0026(Russia); the ProgramaEstataldeFomento de laInvestigación Científicay Téc-nicade ExcelenciaMaría de Maeztu, grant MDM-2015-0509 and

theProgramaSeveroOchoadelPrincipadode Asturias;theThalis andAristeiaprogramscofinancedbyEU-ESF andtheGreek NSRF; theRachadapisekSompotFundforPostdoctoralFellowship, Chula-longkornUniversityandtheChulalongkornAcademic intoIts2nd Century Project Advancement Project (Thailand); The Kavli Foun-dation; theNvidia Corporation; the SuperMicro Corporation;The WelchFoundation,contractC-1845;andtheWestonHavens Foun-dation(USA).

Appendix A. Supplementarymaterial

Supplementarymaterialrelatedtothisarticlecanbefound on-lineathttps://doi.org/10.1016/j.physletb.2020.135345.

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TheCMSCollaboration

A.M. Sirunyan†, A. Tumasyan YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, F. Ambrogi, T. Bergauer, M. Dragicevic,J. Erö, A. Escalante Del Valle,M. Flechl, R. Frühwirth1, M. Jeitler1, N. Krammer,I. Krätschmer, D. Liko,T. Madlener, I. Mikulec,N. Rad, J. Schieck1, R. Schöfbeck, M. Spanring, W. Waltenberger, C.-E. Wulz1,M. Zarucki

InstitutfürHochenergiephysik,Wien,Austria

V. Drugakov,V. Mossolov, J. Suarez Gonzalez InstituteforNuclearProblems,Minsk,Belarus

M.R. Darwish,E.A. De Wolf, D. Di Croce, X. Janssen,T. Kello2,A. Lelek, M. Pieters,H. Rejeb Sfar, H. Van Haevermaet,P. Van Mechelen, S. Van Putte, N. Van Remortel

UniversiteitAntwerpen,Antwerpen,Belgium

F. Blekman, E.S. Bols,S.S. Chhibra, J. D’Hondt,J. De Clercq, D. Lontkovskyi, S. Lowette,I. Marchesini, S. Moortgat, Q. Python, S. Tavernier,W. Van Doninck, P. Van Mulders

VrijeUniversiteitBrussel,Brussel,Belgium

D. Beghin, B. Bilin,B. Clerbaux, G. De Lentdecker, H. Delannoy, B. Dorney,L. Favart, A. Grebenyuk, A.K. Kalsi, L. Moureaux, A. Popov, N. Postiau,E. Starling, L. Thomas, C. Vander Velde, P. Vanlaer, D. Vannerom

UniversitéLibredeBruxelles,Bruxelles,Belgium

T. Cornelis,D. Dobur, I. Khvastunov3,M. Niedziela, C. Roskas, K. Skovpen, M. Tytgat, W. Verbeke, B. Vermassen, M. Vit

GhentUniversity,Ghent,Belgium

G. Bruno,C. Caputo, P. David,C. Delaere, M. Delcourt, A. Giammanco,V. Lemaitre, J. Prisciandaro, A. Saggio, P. Vischia,J. Zobec

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

G.A. Alves,G. Correia Silva,C. Hensel, A. Moraes CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato4, E. Coelho, E.M. Da Costa, G.G. Da Silveira5, D. De Jesus Damiao,C. De Oliveira Martins, S. Fonseca De Souza, H. Malbouisson, J. Martins6,

D. Matos Figueiredo,M. Medina Jaime7, M. Melo De Almeida,C. Mora Herrera,L. Mundim, H. Nogima, W.L. Prado Da Silva, P. Rebello Teles,L.J. Sanchez Rosas,A. Santoro, A. Sznajder, M. Thiel,

E.J. Tonelli Manganote4,F. Torres Da Silva De Araujo, A. Vilela Pereira UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

C.A. Bernardesa, L. Calligarisa,T.R. Fernandez Perez Tomeia,E.M. Gregoresb,D.S. Lemos, P.G. Mercadanteb,S.F. Novaesa,Sandra S. Padulaa

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

A. Aleksandrov, G. Antchev, R. Hadjiiska,P. Iaydjiev, M. Misheva, M. Rodozov,M. Shopova, G. Sultanov InstituteforNuclearResearchandNuclearEnergy,BulgarianAcademyofSciences,Sofia,Bulgaria

M. Bonchev,A. Dimitrov, T. Ivanov, L. Litov, B. Pavlov,P. Petkov, A. Petrov UniversityofSofia,Sofia,Bulgaria

W. Fang2, X. Gao2,L. Yuan BeihangUniversity,Beijing,China

M. Ahmad, Z. Hu, Y. Wang DepartmentofPhysics,TsinghuaUniversity,Beijing,China

G.M. Chen8, H.S. Chen8,M. Chen, C.H. Jiang, D. Leggat, H. Liao, Z. Liu, A. Spiezia,J. Tao, E. Yazgan, H. Zhang,S. Zhang8,J. Zhao

InstituteofHighEnergyPhysics,Beijing,China

A. Agapitos,Y. Ban, G. Chen, A. Levin,J. Li, L. Li,Q. Li, Y. Mao, S.J. Qian, D. Wang,Q. Wang StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

M. Xiao

ZhejiangUniversity,Hangzhou,China

C. Avila,A. Cabrera, C. Florez, C.F. González Hernández,M.A. Segura Delgado UniversidaddeLosAndes,Bogota,Colombia

J. Mejia Guisao,J.D. Ruiz Alvarez,C.A. Salazar González, N. Vanegas Arbelaez UniversidaddeAntioquia,Medellin,Colombia

D. Giljanovi ´c, N. Godinovic, D. Lelas,I. Puljak, T. Sculac

Z. Antunovic, M. Kovac UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,D. Ferencek, K. Kadija,D. Majumder, B. Mesic, M. Roguljic, A. Starodumov9,T. Susa InstituteRudjerBoskovic,Zagreb,Croatia

M.W. Ather,A. Attikis, E. Erodotou, A. Ioannou,M. Kolosova, S. Konstantinou, G. Mavromanolakis, J. Mousa,C. Nicolaou, F. Ptochos, P.A. Razis, H. Rykaczewski,H. Saka, D. Tsiakkouri

UniversityofCyprus,Nicosia,Cyprus

M. Finger10, M. Finger Jr.10, A. Kveton,J. Tomsa CharlesUniversity,Prague,CzechRepublic

E. Ayala

EscuelaPolitecnicaNacional,Quito,Ecuador E. Carrera Jarrin

UniversidadSanFranciscodeQuito,Quito,Ecuador Y. Assran11,12,S. Elgammal12

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

S. Bhowmik, A. Carvalho Antunes De Oliveira,R.K. Dewanjee, K. Ehataht, M. Kadastik, M. Raidal, C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola, L. Forthomme,H. Kirschenmann, K. Osterberg,M. Voutilainen DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

E. Brücken,F. Garcia, J. Havukainen, J.K. Heikkilä, V. Karimäki,M.S. Kim, R. Kinnunen, T. Lampén, K. Lassila-Perini,S. Laurila, S. Lehti, T. Lindén,H. Siikonen, E. Tuominen, J. Tuominiemi

HelsinkiInstituteofPhysics,Helsinki,Finland P. Luukka, T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon, F. Couderc,M. Dejardin, D. Denegri, B. Fabbro,J.L. Faure, F. Ferri, S. Ganjour, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry,C. Leloup,B. Lenzi, E. Locci, J. Malcles,J. Rander,

A. Rosowsky, M.Ö. Sahin,A. Savoy-Navarro13,M. Titov, G.B. Yu IRFU,CEA,UniversitéParis-Saclay,Gif-sur-Yvette,France

S. Ahuja, C. Amendola, F. Beaudette, M. Bonanomi, P. Busson, C. Charlot, B. Diab, G. Falmagne, R. Granier de Cassagnac, I. Kucher, A. Lobanov, C. Martin Perez,M. Nguyen, C. Ochando, P. Paganini, J. Rembser,R. Salerno, J.B. Sauvan, Y. Sirois, A. Zabi,A. Zghiche

LaboratoireLeprince-Ringuet,CNRS/IN2P3,EcolePolytechnique,InstitutPolytechniquedeParis,France

J.-L. Agram14, J. Andrea, D. Bloch,G. Bourgatte, J.-M. Brom,E.C. Chabert, C. Collard,E. Conte14, J.-C. Fontaine14,D. Gelé, U. Goerlach, C. Grimault,A.-C. Le Bihan, N. Tonon, P. Van Hove

UniversitédeStrasbourg,CNRS,IPHCUMR7178,Strasbourg,France S. Gadrat

S. Beauceron,C. Bernet, G. Boudoul,C. Camen, A. Carle, N. Chanon, R. Chierici, D. Contardo, P. Depasse, H. El Mamouni,J. Fay, S. Gascon, M. Gouzevitch, B. Ille, Sa. Jain, I.B. Laktineh,H. Lattaud, A. Lesauvage, M. Lethuillier,L. Mirabito, S. Perries,V. Sordini, L. Torterotot, G. Touquet, M. Vander Donckt, S. Viret UniversitédeLyon,UniversitéClaudeBernardLyon1,CNRS-IN2P3,InstitutdePhysiqueNucléairedeLyon,Villeurbanne,France

T. Toriashvili15

GeorgianTechnicalUniversity,Tbilisi,Georgia Z. Tsamalaidze10

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann,L. Feld, K. Klein, M. Lipinski, D. Meuser, A. Pauls, M. Preuten,M.P. Rauch, J. Schulz, M. Teroerde

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

M. Erdmann,B. Fischer, S. Ghosh, T. Hebbeker,K. Hoepfner, H. Keller, L. Mastrolorenzo,

M. Merschmeyer,A. Meyer, P. Millet,G. Mocellin, S. Mondal, S. Mukherjee,D. Noll, A. Novak, T. Pook, A. Pozdnyakov,T. Quast, M. Radziej, Y. Rath, H. Reithler,J. Roemer, A. Schmidt, S.C. Schuler, A. Sharma, S. Wiedenbeck, S. Zaleski

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

G. Flügge,W. Haj Ahmad16,O. Hlushchenko, T. Kress,T. Müller, A. Nowack,C. Pistone, O. Pooth,D. Roy, H. Sert,A. Stahl17

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,P. Asmuss,I. Babounikau, H. Bakhshiansohi, K. Beernaert,O. Behnke,

A. Bermúdez Martínez, A.A. Bin Anuar, K. Borras18,V. Botta, A. Campbell,A. Cardini, P. Connor,

S. Consuegra Rodríguez,C. Contreras-Campana, V. Danilov,A. De Wit, M.M. Defranchis, C. Diez Pardos, D. Domínguez Damiani,G. Eckerlin, D. Eckstein, T. Eichhorn, A. Elwood, E. Eren, L.I. Estevez Banos, E. Gallo19, A. Geiser, A. Grohsjean, M. Guthoff,M. Haranko, A. Harb,A. Jafari,N.Z. Jomhari, H. Jung, A. Kasem18,M. Kasemann, H. Kaveh, J. Keaveney, C. Kleinwort, J. Knolle,D. Krücker, W. Lange, T. Lenz, J. Lidrych,K. Lipka, W. Lohmann20,R. Mankel, I.-A. Melzer-Pellmann, A.B. Meyer, M. Meyer, M. Missiroli, J. Mnich, A. Mussgiller,V. Myronenko, D. Pérez Adán,S.K. Pflitsch, D. Pitzl,A. Raspereza, A. Saibel, M. Savitskyi,V. Scheurer, P. Schütze,C. Schwanenberger, R. Shevchenko, A. Singh, R.E. Sosa Ricardo, H. Tholen,O. Turkot, A. Vagnerini, M. Van De Klundert, R. Walsh, Y. Wen,K. Wichmann,C. Wissing, O. Zenaiev, R. Zlebcik

DeutschesElektronen-Synchrotron,Hamburg,Germany

R. Aggleton,S. Bein, L. Benato,A. Benecke, T. Dreyer, A. Ebrahimi, F. Feindt,A. Fröhlich, C. Garbers, E. Garutti,D. Gonzalez, P. Gunnellini, J. Haller, A. Hinzmann, A. Karavdina, G. Kasieczka, R. Klanner, R. Kogler,N. Kovalchuk, S. Kurz, V. Kutzner, J. Lange,T. Lange, A. Malara, J. Multhaup,C.E.N. Niemeyer, A. Reimers,O. Rieger, P. Schleper, S. Schumann,J. Schwandt, J. Sonneveld,H. Stadie,G. Steinbrück, B. Vormwald, I. Zoi

UniversityofHamburg,Hamburg,Germany

M. Akbiyik, M. Baselga,S. Baur, T. Berger,E. Butz, R. Caspart, T. Chwalek, W. De Boer,A. Dierlamm, K. El Morabit,N. Faltermann, M. Giffels,A. Gottmann, F. Hartmann17,C. Heidecker, U. Husemann, M.A. Iqbal,S. Kudella, S. Maier, S. Mitra, M.U. Mozer, D. Müller, Th. Müller, M. Musich, A. Nürnberg, G. Quast, K. Rabbertz,D. Savoiu, D. Schäfer, M. Schnepf, M. Schröder, I. Shvetsov,H.J. Simonis, R. Ulrich, M. Wassmer,M. Weber, C. Wöhrmann, R. Wolf,S. Wozniewski

G. Anagnostou, P. Asenov, G. Daskalakis,T. Geralis,A. Kyriakis, D. Loukas, G. Paspalaki,A. Stakia InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

M. Diamantopoulou,G. Karathanasis, P. Kontaxakis,A. Manousakis-katsikakis, A. Panagiotou, I. Papavergou, N. Saoulidou, K. Theofilatos,K. Vellidis, E. Vourliotis

NationalandKapodistrianUniversityofAthens,Athens,Greece

G. Bakas, K. Kousouris,I. Papakrivopoulos, G. Tsipolitis,A. Zacharopoulou NationalTechnicalUniversityofAthens,Athens,Greece

I. Evangelou, C. Foudas,P. Gianneios, P. Katsoulis, P. Kokkas, S. Mallios,K. Manitara, N. Manthos, I. Papadopoulos, J. Strologas,F.A. Triantis, D. Tsitsonis

UniversityofIoánnina,Ioánnina,Greece

M. Bartók21,R. Chudasama, M. Csanad, P. Major, K. Mandal, A. Mehta,G. Pasztor, O. Surányi, G.I. Veres MTA-ELTELendületCMSParticleandNuclearPhysicsGroup,EötvösLorándUniversity,Budapest,Hungary

G. Bencze,C. Hajdu, D. Horvath22,F. Sikler, V. Veszpremi,G. Vesztergombi† WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni, S. Czellar, J. Karancsi21,J. Molnar, Z. Szillasi InstituteofNuclearResearchATOMKI,Debrecen,Hungary

P. Raics, D. Teyssier,Z.L. Trocsanyi, G. Zilizi InstituteofPhysics,UniversityofDebrecen,Debrecen,Hungary

T. Csorgo, S. Lökös, W.J. Metzger, F. Nemes, T. Novak EszterhazyKarolyUniversity,KarolyRobertCampus,Gyongyos,Hungary

S. Choudhury, J.R. Komaragiri, L. Panwar, P.C. Tiwari IndianInstituteofScience(IISc),Bangalore,India

S. Bahinipati23, C. Kar,G. Kole, P. Mal, V.K. Muraleedharan Nair Bindhu, A. Nayak24,D.K. Sahoo23, S.K. Swain

NationalInstituteofScienceEducationandResearch,HBNI,Bhubaneswar,India

S. Bansal, S.B. Beri,V. Bhatnagar, S. Chauhan,N. Dhingra25, R. Gupta, A. Kaur, M. Kaur, S. Kaur, P. Kumari, M. Lohan, M. Meena, K. Sandeep, S. Sharma,J.B. Singh, A.K. Virdi

PanjabUniversity,Chandigarh,India

A. Bhardwaj,B.C. Choudhary, R.B. Garg, M. Gola,S. Keshri, A. Kumar,M. Naimuddin, P. Priyanka, K. Ranjan,A. Shah, R. Sharma

UniversityofDelhi,Delhi,India

R. Bhardwaj26,M. Bharti26,R. Bhattacharya,S. Bhattacharya, U. Bhawandeep26,D. Bhowmik, S. Dutta, S. Ghosh, B. Gomber27, M. Maity28,K. Mondal, S. Nandan, A. Purohit, P.K. Rout, G. Saha,S. Sarkar, M. Sharan, B. Singh26, S. Thakur26

SahaInstituteofNuclearPhysics,HBNI,Kolkata,India

P.K. Behera, S.C. Behera,P. Kalbhor, A. Muhammad, R. Pradhan, P.R. Pujahari, A. Sharma, A.K. Sikdar IndianInstituteofTechnologyMadras,Madras,India

D. Dutta, V. Jha, D.K. Mishra, P.K. Netrakanti, L.M. Pant,P. Shukla BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz,M.A. Bhat, S. Dugad, R. Kumar Verma, G.B. Mohanty, N. Sur TataInstituteofFundamentalResearch-A,Mumbai,India

S. Banerjee, S. Bhattacharya, S. Chatterjee,P. Das, M. Guchait,S. Karmakar, S. Kumar, G. Majumder, K. Mazumdar,N. Sahoo, S. Sawant

TataInstituteofFundamentalResearch-B,Mumbai,India

S. Dube,B. Kansal, A. Kapoor, K. Kothekar, S. Pandey, A. Rane, A. Rastogi, S. Sharma IndianInstituteofScienceEducationandResearch(IISER),Pune,India

S. Chenarani,S.M. Etesami,M. Khakzad, M. Mohammadi Najafabadi,M. Naseri, F. Rezaei Hosseinabadi InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b, R. Alya,b,29, C. Aruta, C. Calabriaa,b, A. Colaleoa, D. Creanzaa,c,L. Cristellaa,b,

N. De Filippisa,c, M. De Palmaa,b, A. Di Florioa,b, W. Elmetenaweea,b,L. Fiorea,A. Gelmia,b,G. Iasellia,c, M. Incea,b,S. Lezkia,b,G. Maggia,c,M. Maggia,J.A. Merlina, G. Minielloa,b, S. Mya,b,S. Nuzzoa,b,

A. Pompilia,b, G. Pugliesea,c,R. Radognaa, A. Ranieria,G. Selvaggia,b,L. Silvestrisa, F.M. Simonea,b, R. Vendittia,P. Verwilligena

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

G. Abbiendia,C. Battilanaa,b,D. Bonacorsia,b, L. Borgonovia,b,S. Braibant-Giacomellia,b,

R. Campaninia,b,P. Capiluppia,b,A. Castroa,b, F.R. Cavalloa, C. Cioccaa, G. Codispotia,b, M. Cuffiania,b, G.M. Dallavallea,F. Fabbria,A. Fanfania,b,E. Fontanesia,b, P. Giacomellia,C. Grandia, L. Guiduccia,b, F. Iemmia,b,S. Lo Meoa,30, S. Marcellinia, G. Masettia,F.L. Navarriaa,b,A. Perrottaa,F. Primaveraa,b, A.M. Rossia,b,T. Rovellia,b, G.P. Sirolia,b,N. Tosia

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

S. Albergoa,b,31,S. Costaa,b,A. Di Mattiaa,R. Potenzaa,b, A. Tricomia,b,31, C. Tuvea,b a_{INFNSezionediCatania,Catania,Italy}

b_{UniversitàdiCatania,Catania,Italy}

G. Barbaglia,A. Cassese, R. Ceccarelli,V. Ciullia,b,C. Civininia, R. D’Alessandroa,b, F. Fioria,b,

E. Focardia,b, G. Latinoa,b, P. Lenzia,b, M. Lizzo, M. Meschinia,S. Paolettia, R. Seidita,G. Sguazzonia, L. Viliania

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

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

M. Bozzoa,b,F. Ferroa, R. Mulargiaa,b,E. Robuttia, S. Tosia,b a_{INFNSezionediGenova,Genova,Italy}

A. Benagliaa, A. Beschia,b,F. Brivioa,b,V. Cirioloa,b,17, M.E. Dinardoa,b,P. Dinia, S. Gennaia,

A. Ghezzia,b, P. Govonia,b, L. Guzzia,b,M. Malbertia,S. Malvezzia,D. Menascea, F. Montia,b, L. Moronia, M. Paganonia,b,D. Pedrinia,S. Ragazzia,b, T. Tabarelli de Fatisa,b,D. Valsecchia,b,17,D. Zuoloa,b

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

S. Buontempoa, N. Cavalloa,c, A. De Iorioa,b,A. Di Crescenzoa,b, F. Fabozzia,c,F. Fiengaa, G. Galatia, A.O.M. Iorioa,b, L. Layera,b, L. Listaa,b, S. Meolaa,d,17, P. Paoluccia,17, B. Rossia,C. Sciaccaa,b,

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

P. Azzia,N. Bacchettaa,D. Biselloa,b,A. Bolettia,b,A. Bragagnoloa,b, R. Carlina,b, P. Checchiaa, P. De Castro Manzanoa, T. Dorigoa,U. Dossellia, F. Gasparinia,b, U. Gasparinia,b,A. Gozzelinoa, S.Y. Hoha,b,M. Margonia,b,A.T. Meneguzzoa,b, J. Pazzinia,b,M. Presillab,P. Ronchesea,b, R. Rossina,b, F. Simonettoa,b_{,A. Tiko}a_{,M. Tosi}a,b_{, M. Zanetti}a,b_{,P. Zotto}a,b_{,A. Zucchetta}a,b_{, G. Zumerle}a,b

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

A. Braghieria,D. Fiorinaa,b,P. Montagnaa,b, S.P. Rattia,b,V. Rea, M. Ressegottia,b,C. Riccardia,b, P. Salvinia, I. Vaia,P. Vituloa,b

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

M. Biasinia,b, G.M. Bileia,D. Ciangottinia,b,L. Fanòa,b,P. Laricciaa,b, R. Leonardia,b,E. Manonia, G. Mantovania,b,V. Mariania,b, M. Menichellia,A. Rossia,b, A. Santocchiaa,b,D. Spigaa

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

K. Androsova,P. Azzurria,G. Bagliesia,V. Bertacchia,c,L. Bianchinia,T. Boccalia, R. Castaldia, M.A. Cioccia,b, R. Dell’Orsoa,S. Donatoa,L. Gianninia,c,A. Giassia,M.T. Grippoa, F. Ligabuea,c,

E. Mancaa,c,G. Mandorlia,c,A. Messineoa,b,F. Pallaa, A. Rizzia,b, G. Rolandia,c,S. Roy Chowdhurya,c, A. Scribanoa, P. Spagnoloa, R. Tenchinia,G. Tonellia,b, N. Turini,A. Venturia, P.G. Verdinia

a_{INFNSezionediPisa,Pisa,Italy} b_{UniversitàdiPisa,Pisa,Italy}

c_{ScuolaNormaleSuperiorediPisa,Pisa,Italy}

F. Cavallaria,M. Cipriania,b,D. Del Rea,b, E. Di Marcoa,M. Diemoza, E. Longoa,b, P. Meridiania, G. Organtinia,b,F. Pandolfia, R. Paramattia,b, C. Quarantaa,b, S. Rahatloua,b,C. Rovellia,

F. Santanastasioa,b, L. Soffia,b,R. Tramontanoa,b a_{INFNSezionediRoma,Rome,Italy}

b_{SapienzaUniversitàdiRoma,Rome,Italy}

N. Amapanea,b, R. Arcidiaconoa,c,S. Argiroa,b,M. Arneodoa,c,N. Bartosika,R. Bellana,b, A. Belloraa,b, C. Biinoa, A. Cappatia,b_{,N. Cartiglia}a_{,S. Cometti}a_{,M. Costa}a,b_{, R. Covarelli}a,b_{,N. Demaria}a_,

J.R. González Fernándeza, B. Kiania,b,F. Leggera,C. Mariottia,S. Masellia, E. Migliorea,b,V. Monacoa,b, E. Monteila,b,M. Montenoa, M.M. Obertinoa,b,G. Ortonaa,L. Pachera,b,N. Pastronea, M. Pelliccionia, G.L. Pinna Angionia,b,A. Romeroa,b,M. Ruspaa,c, R. Salvaticoa,b, V. Solaa,A. Solanoa,b,D. Soldia,b, A. Staianoa,D. Trocinoa,b

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

S. Belfortea,V. Candelisea,b, M. Casarsaa,F. Cossuttia,A. Da Rolda,b,G. Della Riccaa,b,F. Vazzolera,b, A. Zanettia

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

B. Kim, D.H. Kim,G.N. Kim, J. Lee, S.W. Lee, C.S. Moon, Y.D. Oh,S.I. Pak, S. Sekmen, D.C. Son,Y.C. Yang KyungpookNationalUniversity,Daegu,RepublicofKorea

H. Kim,D.H. Moon

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea B. Francois,T.J. Kim, J. Park

HanyangUniversity,Seoul,RepublicofKorea

S. Cho,S. Choi, Y. Go, S. Ha,B. Hong, K. Lee,K.S. Lee, J. Lim, J. Park, S.K. Park, Y. Roh,J. Yoo KoreaUniversity,Seoul,RepublicofKorea

J. Goh

KyungHeeUniversity,DepartmentofPhysics,RepublicofKorea H.S. Kim

SejongUniversity,Seoul,RepublicofKorea

J. Almond,J.H. Bhyun, J. Choi, S. Jeon, J. Kim, J.S. Kim,H. Lee, K. Lee,S. Lee, K. Nam, M. Oh,S.B. Oh, B.C. Radburn-Smith, U.K. Yang,H.D. Yoo, I. Yoon

SeoulNationalUniversity,Seoul,RepublicofKorea

D. Jeon, J.H. Kim, J.S.H. Lee, I.C. Park, I.J. Watson UniversityofSeoul,Seoul,RepublicofKorea

Y. Choi,C. Hwang, Y. Jeong, J. Lee,Y. Lee, I. Yu SungkyunkwanUniversity,Suwon,RepublicofKorea

V. Veckalns32

RigaTechnicalUniversity,Riga,Latvia

V. Dudenas, A. Juodagalvis,A. Rinkevicius, G. Tamulaitis, J. Vaitkus VilniusUniversity,Vilnius,Lithuania

F. Mohamad Idris33, W.A.T. Wan Abdullah,M.N. Yusli,Z. Zolkapli NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

J.F. Benitez, A. Castaneda Hernandez,J.A. Murillo Quijada, L. Valencia Palomo UniversidaddeSonora(UNISON),Hermosillo,Mexico

H. Castilla-Valdez,E. De La Cruz-Burelo, I. Heredia-De La Cruz34,R. Lopez-Fernandez, A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

S. Carrillo Moreno, C. Oropeza Barrera, M. Ramirez-Garcia,F. Vazquez Valencia UniversidadIberoamericana,MexicoCity,Mexico

J. Eysermans, I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada BenemeritaUniversidadAutonomadePuebla,Puebla,Mexico

A. Morelos Pineda

UniversidadAutónomadeSanLuisPotosí,SanLuisPotosí,Mexico J. Mijuskovic3,N. Raicevic

UniversityofMontenegro,Podgorica,Montenegro D. Krofcheck

UniversityofAuckland,Auckland,NewZealand S. Bheesette,P.H. Butler, P. Lujan UniversityofCanterbury,Christchurch,NewZealand

A. Ahmad, M. Ahmad, M.I.M. Awan,Q. Hassan, H.R. Hoorani,W.A. Khan, M.A. Shah, M. Shoaib,M. Waqas NationalCentreforPhysics,Quaid-I-AzamUniversity,Islamabad,Pakistan

V. Avati,L. Grzanka, M. Malawski

AGHUniversityofScienceandTechnologyFacultyofComputerScience,ElectronicsandTelecommunications,Krakow,Poland

H. Bialkowska, M. Bluj,B. Boimska, M. Górski, M. Kazana, M. Szleper,P. Zalewski NationalCentreforNuclearResearch,Swierk,Poland

K. Bunkowski, A. Byszuk35, K. Doroba, A. Kalinowski, M. Konecki,J. Krolikowski, M. Olszewski, M. Walczak

InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland

M. Araujo, P. Bargassa,D. Bastos, A. Di Francesco, P. Faccioli,B. Galinhas, M. Gallinaro, J. Hollar, N. Leonardo,T. Niknejad, J. Seixas,K. Shchelina, G. Strong,O. Toldaiev, J. Varela

LaboratóriodeInstrumentaçãoeFísicaExperimentaldePartículas,Lisboa,Portugal

S. Afanasiev,P. Bunin, M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev,V. Karjavine, A. Lanev, A. Malakhov,V. Matveev36,37_{,P. Moisenz, V. Palichik,V. Perelygin, M. Savina, S. Shmatov, S. Shulha,}

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

L. Chtchipounov,V. Golovtcov, Y. Ivanov, V. Kim38,E. Kuznetsova39, P. Levchenko,V. Murzin, V. Oreshkin,I. Smirnov, D. Sosnov, V. Sulimov,L. Uvarov, 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,A. Nikitenko40, V. Popov, I. Pozdnyakov,G. Safronov, A. Spiridonov, A. Stepennov, M. Toms,E. Vlasov, A. Zhokin

InstituteforTheoreticalandExperimentalPhysicsnamedbyA.I.AlikhanovofNRC‘KurchatovInstitute’,Moscow,Russia T. Aushev

O. Bychkova, R. Chistov41, M. Danilov41,S. Polikarpov41,E. Tarkovskii NationalResearchNuclearUniversity‘MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

V. Andreev,M. Azarkin, I. Dremin, M. Kirakosyan, A. Terkulov P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Belyaev,E. Boos,M. Dubinin42, L. Dudko,A. Ershov, A. Gribushin,V. Klyukhin, O. Kodolova,I. Lokhtin, S. Obraztsov,S. Petrushanko,V. Savrin, A. Snigirev

SkobeltsynInstituteofNuclearPhysics,LomonosovMoscowStateUniversity,Moscow,Russia

A. Barnyakov43, V. Blinov43, T. Dimova43,L. Kardapoltsev43, I. Ovtin43, Y. Skovpen43 NovosibirskStateUniversity(NSU),Novosibirsk,Russia

I. Azhgirey,I. Bayshev,S. Bitioukov, V. Kachanov, D. Konstantinov, P. Mandrik,V. Petrov, R. Ryutin, S. Slabospitskii, A. Sobol, S. Troshin, N. Tyurin,A. Uzunian, A. Volkov

InstituteforHighEnergyPhysicsofNationalResearchCentre‘KurchatovInstitute’,Protvino,Russia A. Babaev,A. Iuzhakov, V. Okhotnikov

NationalResearchTomskPolytechnicUniversity,Tomsk,Russia V. Borchsh, V. Ivanchenko, E. Tcherniaev TomskStateUniversity,Tomsk,Russia

P. Adzic44,P. Cirkovic, M. Dordevic, P. Milenovic, J. Milosevic,M. Stojanovic UniversityofBelgrade,FacultyofPhysicsandVINCAInstituteofNuclearSciences,Serbia

M. Aguilar-Benitez,J. Alcaraz Maestre, A. Álvarez Fernández,I. Bachiller, M. Barrio Luna,Cristina

F. Bedoya,J.A. Brochero Cifuentes, C.A. Carrillo Montoya,M. Cepeda, M. Cerrada, N. Colino, B. De La Cruz, A. Delgado Peris,J.P. Fernández Ramos,J. Flix, M.C. Fouz,O. Gonzalez Lopez,S. Goy Lopez,

J.M. Hernandez, M.I. Josa,D. Moran, Á. Navarro Tobar, A. Pérez-Calero Yzquierdo, J. Puerta Pelayo, I. Redondo, L. Romero,S. Sánchez Navas, M.S. Soares, A. Triossi,C. Willmott

CentrodeInvestigacionesEnergéticasMedioambientalesyTecnológicas(CIEMAT),Madrid,Spain C. Albajar, J.F. de Trocóniz,R. Reyes-Almanza

UniversidadAutónomadeMadrid,Madrid,Spain

B. Alvarez Gonzalez, J. Cuevas,C. Erice, J. Fernandez Menendez, S. Folgueras,I. Gonzalez Caballero, E. Palencia Cortezon,C. Ramón Álvarez, V. Rodríguez Bouza,S. Sanchez Cruz

UniversidaddeOviedo,InstitutoUniversitariodeCienciasyTecnologíasEspacialesdeAsturias(ICTEA),Oviedo,Spain

I.J. Cabrillo, A. Calderon, B. Chazin Quero,J. Duarte Campderros, M. Fernandez,P.J. Fernández Manteca, A. García Alonso,G. Gomez, C. Martinez Rivero, P. Martinez Ruiz del Arbol,F. Matorras, J. Piedra Gomez, C. Prieels, F. Ricci-Tam, T. Rodrigo, A. Ruiz-Jimeno,L. Russo45, L. Scodellaro,I. Vila, J.M. Vizan Garcia InstitutodeFísicadeCantabria(IFCA),CSIC-UniversidaddeCantabria,Santander,Spain

K. Malagalage

UniversityofColombo,Colombo,SriLanka

W.G.D. Dharmaratna, N. Wickramage UniversityofRuhuna,DepartmentofPhysics,Matara,SriLanka

T.K. Aarrestad, D. Abbaneo, B. Akgun, E. Auffray, G. Auzinger, J. Baechler,P. Baillon, A.H. Ball, D. Barney, J. Bendavid,M. Bianco, A. Bocci, P. Bortignon, E. Bossini,E. Brondolin, T. Camporesi, A. Caratelli,

G. Cerminara, E. Chapon,G. Cucciati, D. d’Enterria, A. Dabrowski, N. Daci,V. Daponte, A. David, O. Davignon,A. De Roeck, M. Deile, R. Di Maria, M. Dobson, M. Dünser, N. Dupont,A. Elliott-Peisert, N. Emriskova,F. Fallavollita46,D. Fasanella, S. Fiorendi, G. Franzoni, J. Fulcher, W. Funk, S. Giani,D. Gigi, K. Gill,F. Glege, L. Gouskos, M. Gruchala, M. Guilbaud, D. Gulhan, J. Hegeman, C. Heidegger, Y. Iiyama, V. Innocente, T. James, P. Janot, O. Karacheban20, J. Kaspar, J. Kieseler, M. Krammer1,N. Kratochwil, C. Lange, P. Lecoq,K. Long, C. Lourenço,L. Malgeri,M. Mannelli, A. Massironi,F. Meijers, S. Mersi, E. Meschi, F. Moortgat, M. Mulders, J. Ngadiuba,J. Niedziela, S. Nourbakhsh,S. Orfanelli, L. Orsini, F. Pantaleo17,L. Pape, E. Perez,M. Peruzzi, A. Petrilli, G. Petrucciani,A. Pfeiffer, M. Pierini,F.M. Pitters, D. Rabady, A. Racz,M. Rieger, M. Rovere, H. Sakulin, J. Salfeld-Nebgen,S. Scarfi, C. Schäfer, C. Schwick, M. Selvaggi,A. Sharma,P. Silva, W. Snoeys, P. Sphicas47, J. Steggemann,S. Summers, V.R. Tavolaro, D. Treille, A. Tsirou,G.P. Van Onsem, A. Vartak,M. Verzetti, K.A. Wozniak, W.D. Zeuner

CERN,EuropeanOrganizationforNuclearResearch,Geneva,Switzerland

L. Caminada48, K. Deiters,W. Erdmann, R. Horisberger, Q. Ingram,H.C. Kaestli, D. Kotlinski, U. Langenegger, T. Rohe

PaulScherrerInstitut,Villigen,Switzerland

M. Backhaus, P. Berger, A. Calandri,N. Chernyavskaya, G. Dissertori, M. Dittmar, M. Donegà, C. Dorfer, T.A. Gómez Espinosa, C. Grab, D. Hits, W. Lustermann, R.A. Manzoni, M.T. Meinhard,F. Micheli,

P. Musella, F. Nessi-Tedaldi, F. Pauss,V. Perovic, G. Perrin,L. Perrozzi, S. Pigazzini,M.G. Ratti, M. Reichmann,C. Reissel, T. Reitenspiess, B. Ristic, D. Ruini, D.A. Sanz Becerra,M. Schönenberger, L. Shchutska,M.L. Vesterbacka Olsson, R. Wallny, D.H. Zhu

ETHZurich–InstituteforParticlePhysicsandAstrophysics(IPA),Zurich,Switzerland

C. Amsler49, C. Botta,D. Brzhechko, M.F. Canelli, A. De Cosa, R. Del Burgo,B. Kilminster, S. Leontsinis, V.M. Mikuni,I. Neutelings, G. Rauco, P. Robmann, K. Schweiger, Y. Takahashi,S. Wertz

UniversitätZürich,Zurich,Switzerland

C.M. Kuo,W. Lin, A. Roy,T. Sarkar28,S.S. Yu NationalCentralUniversity,Chung-Li,Taiwan

P. Chang, Y. Chao, K.F. Chen, P.H. Chen, W.-S. Hou,Y.y. Li, R.-S. Lu, E. Paganis, A. Psallidas,A. Steen NationalTaiwanUniversity(NTU),Taipei,Taiwan

B. Asavapibhop, C. Asawatangtrakuldee, N. Srimanobhas,N. Suwonjandee ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand

A. Bat,F. Boran, A. Celik50,S. Damarseckin51,Z.S. Demiroglu,F. Dolek, C. Dozen52, I. Dumanoglu53, G. Gokbulut, Y. Guler, E. Gurpinar Guler54, I. Hos55,C. Isik, E.E. Kangal56, O. Kara, A. Kayis Topaksu, U. Kiminsu,G. Onengut, K. Ozdemir57, A.E. Simsek,U.G. Tok, S. Turkcapar, I.S. Zorbakir, C. Zorbilmez ÇukurovaUniversity,PhysicsDepartment,ScienceandArtFaculty,Adana,Turkey

B. Isildak58, G. Karapinar59,M. Yalvac60 MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

I.O. Atakisi,E. Gülmez, M. Kaya61, O. Kaya62,Ö. Özçelik, S. Tekten63,E.A. Yetkin64 BogaziciUniversity,Istanbul,Turkey

A. Cakir,K. Cankocak53, Y. Komurcu, S. Sen65 IstanbulTechnicalUniversity,Istanbul,Turkey

S. Cerci66, B. Kaynak, S. Ozkorucuklu,D. Sunar Cerci66 IstanbulUniversity,Istanbul,Turkey

B. Grynyov

InstituteforScintillationMaterialsofNationalAcademyofScienceofUkraine,Kharkov,Ukraine L. Levchuk

NationalScientificCenter,KharkovInstituteofPhysicsandTechnology,Kharkov,Ukraine

E. Bhal, S. Bologna,J.J. Brooke, D. Burns67,E. Clement, D. Cussans,H. Flacher, J. Goldstein,G.P. Heath, H.F. Heath,L. Kreczko, B. Krikler,S. Paramesvaran, T. Sakuma,S. Seif El Nasr-Storey, V.J. Smith,J. Taylor, A. Titterton

UniversityofBristol,Bristol,UnitedKingdom

K.W. Bell,A. Belyaev68,C. Brew, R.M. Brown, D.J.A. Cockerill, J.A. Coughlan, K. Harder,S. Harper, J. Linacre,K. Manolopoulos, D.M. Newbold, E. Olaiya,D. Petyt, T. Reis,T. Schuh,

C.H. Shepherd-Themistocleous, A. Thea,I.R. Tomalin, T. Williams RutherfordAppletonLaboratory,Didcot,UnitedKingdom

R. Bainbridge,P. Bloch, S. Bonomally,J. Borg,S. Breeze, O. Buchmuller, A. Bundock, G.S. Chahal69, D. Colling, P. Dauncey,G. Davies, M. Della Negra, P. Everaerts,G. Hall, G. Iles, M. Komm, J. Langford, L. Lyons, A.-M. Magnan,S. Malik,A. Martelli,V. Milosevic, A. Morton, J. Nash70,V. Palladino, M. Pesaresi, D.M. Raymond, A. Richards,A. Rose,E. Scott, C. Seez,A. Shtipliyski, M. Stoye,T. Strebler, A. Tapper, K. Uchida, T. Virdee17, N. Wardle,S.N. Webb, D. Winterbottom, A.G. Zecchinelli,S.C. Zenz

ImperialCollege,London,UnitedKingdom

J.E. Cole, P.R. Hobson,A. Khan, P. Kyberd,C.K. Mackay, I.D. Reid, L. Teodorescu, S. Zahid BrunelUniversity,Uxbridge,UnitedKingdom

A. Brinkerhoff,K. Call, B. Caraway, J. Dittmann, K. Hatakeyama,C. Madrid, B. McMaster,N. Pastika, C. Smith

BaylorUniversity,Waco,USA

R. Bartek,A. Dominguez, R. Uniyal,A.M. Vargas Hernandez CatholicUniversityofAmerica,Washington,DC,USA

A. Buccilli, S.I. Cooper,S.V. Gleyzer, C. Henderson, P. Rumerio, C. West TheUniversityofAlabama,Tuscaloosa,USA

A. Albert, D. Arcaro, Z. Demiragli,D. Gastler, C. Richardson, J. Rohlf, D. Sperka, D. Spitzbart,I. Suarez, L. Sulak,D. Zou

BostonUniversity,Boston,USA

G. Benelli, B. Burkle,X. Coubez18,D. Cutts, Y.t. Duh, M. Hadley, U. Heintz, J.M. Hogan71, K.H.M. Kwok, E. Laird, G. Landsberg,K.T. Lau, J. Lee, M. Narain,S. Sagir72,R. Syarif, E. Usai,W.Y. Wong, D. Yu,W. Zhang BrownUniversity,Providence,USA

R. Band,C. Brainerd, R. Breedon,M. Calderon De La Barca Sanchez, M. Chertok, J. Conway,R. Conway, P.T. Cox,R. Erbacher, C. Flores, G. Funk, F. Jensen,W. Ko†, O. Kukral,R. Lander, M. Mulhearn, D. Pellett, J. Pilot, M. Shi,D. Taylor, K. Tos, M. Tripathi,Z. Wang, F. Zhang