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Study of Vector Boson Scattering and Search for New Physics in Events with Two Same-Sign Leptons and Two Jets V. K hachatryan et al.* (CMS Collaboration) (Received 23 October 2014; revised manuscript received 11 December 2014; published 2 February 2015) A study of vector boson scattering in p p collisions at a center-of-mass energy of 8 TeV is presented. The data sample corresponds to an integrated luminosity of 19.4 fb_1 collected with the CMS detector. Candidate events are selected with exactly two leptons of the same charge, two jets with large rapidity separation and high dijet mass, and moderate missing transverse energy. The signal region is expected to be dominated by electroweak same-sign VF-boson pair production. The observation agrees with the standard model prediction. The observed significance is 2.0 standard deviations, where a significance of 3.1 standard deviations is expected based on the standard model. Cross section measurements for W±W± and WZ processes in the fiducial region are reported. Bounds on the structure of quartic vector-boson interactions are given in the framework of dimension-eight effective field theory operators, as well as limits on the production of doubly charged Higgs bosons. DOI: 10.1103/PhysRevLett. 114.051801

PACS numbers: 14.70.Fm, 12.60.Cn, 13.38.-b, 13.85.Qk

Vector boson scattering (VBS) and quartic boson cou­ plings are features o f the standard m odel (SM ) that remain largely unexplored by the LHC experiments. The obser­ vation o f a Higgs boson [1-3], in accordance with a key prediction o f the SM, motivates further study o f the m echanism o f electrow eak symmetry breaking through m easurem ents o f VBS processes. In the absence o f the SM Higgs boson, the amplitudes for these processes would increase as a function o f center-of-mass energy and ultim ately violate unitarity [4,5], The Higgs boson actually observed by the LHC experim ents m ay restore the unitarity, although som e scenarios o f physics beyond the SM predict enhancem ents for VBS through m odifications to the Higgs sector or the presence o f additional resonances [6,7]. This Letter presents a study o f VBS in p p collisions at \ / s = 8 TeV. The data sample corresponds to an integrated lum inosity o f 19.4 ± 0 .5 fb_1 collected with the CMS detector [8] at the LHC in 2012. The aim o f the analysis is to find evidence for the electroweak production of same-sign W -boson pair events. The strong production cross section is reduced by the sam e-sign requirement, m aking the experim ental signature o f same-sign dilepton events with two jets an ideal topology for VBS studies. Candidate events have exactly tw o identified leptons o f the same charge, tw o jets w ith large rapidity separation and dijet mass, and m oderate m issing transverse energy. The final states considered are p ^ p ~ v ^ v ^ jj, e +e +v evej j , e +fj+i/ei/fij j , and their charge conjugates and r-lepton

decays to electrons and muons. Figure 1 shows represen­ tative Feynm an diagrams for the electroweak and QCD induced production. The study o f VBS presented here leads to measurements o f the production cross sections for W ± W ± and W Z in a fiducial region. Evidence for electroweak production has been reported by the ATLAS Collaboration [9]. Various extensions o f the SM alter the couplings o f vector bosons. An excess o f events could signal the presence o f anomalous quartic gauge couplings (AQGCs) [10], Doubly charged Higgs bosons are predicted in Higgs sectors beyond the SM where weak isotriplet scalars are included [11,12]; they can be produced via weak vector-boson fusion (VBF) and decay to pairs o f same-sign W bosons [13],

* Full author list given at the end of the article. Published, by the American Physical Society under the terms o f the Creative Commons Attribution 3.0 License. Further distri­ bution o f this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI. 0 0 3 1 -9 0 0 7 /1 5 /1 14(5)/051801(16)

FIG. 1. Representative Feynman diagrams for the electroweak and QCD induced same-sign W-boson pair production.

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The central feature of the CMS apparatus is a super­ conducting solenoid, of 6 m internal diameter, providing a magnetic field of 3.8 T. Within the field volume are a silicon pixel and strip tracker, a crystal electromagnetic calorimeter, and a brass or scintillator hadron calorimeter. Muons are measured in gas-ionization detectors embedded in the steel flux-return yoke of the magnet. The first level of the CMS trigger system, composed of custom hardware processors, is designed to select the most interesting events within 3 /zs, using information from the calorimeters and muon detectors. The high level trigger processor farm further reduces the event rate to a few hundred hertz before data storage. Details of the CMS detector and its perfor­ mance can be found elsewhere [8]. Several Monte Carlo (MC) event generators are used to simulate the signal and background processes. The leadingorder event generator MadGraph 5.2 [14] is used to produce event samples of diboson production via diagrams with two or fewer powers of as and up to six electroweak vertices. This includes two categories of diagrams: those with exactly two powers of as which we refer to as quantum chromodynamic (QCD) production and those with no powers of as, which we refer to as electroweak (EW) production. The EW category includes diagrams with WWWW quaitic interactions and diagrams where two same-sign W bosons scatter through the exchange of a Higgs boson, a Z boson, or a photon. Double-parton scattering, triboson production, and doubly charged Higgs boson production samples are also generated using MadGraph 5.2. Top-quark background processes are gen­ erated with the next-to-leading-order event generator powheg 1.0 [15-18]. The set of parton distribution functions (PDFs) used is CTEQ6L [19] for M adGraph and CT10 [20] for powheg. All event generators are interfaced to pythia 6.4 [21] for the showering of the partons and subsequent hadronization. The pythia parameters for the underlying event were set according to the Z2* tune [22], The detector response is simulated by the Geant4 package [23] using a detailed description of the CMS detector. The average number of simultaneous proton-proton interactions per bunch crossing in the 8 TeV data is approximately 21; additional p p interactions overlapping with the event of interest are included in the simulated samples. Collision events are selected by the trigger system requiring the presence of one or two high transverse momentum (p T) muons or electrons. The trigger efficiency is greater than 99% for events that pass all other selection criteria explained below. A particle-flow algorithm [24,25] is used to recon­ struct all observable particles in the event. It combines all the subdetector information to reconstruct individual particles and identify them as charged hadrons, neutral hadrons, photons, and leptons. The missing transverse energy £™ss is defined as the magnitude of the negative vector sum of the transverse momenta of all reconstructed particles (charged and neutral) in the event.

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The selection of events aims to single out same-sign dilepton events with the VBS topology while reducing the top quark, Drell-Yan, and WZ background processes. All objects are selected following the methods described in Ref. [26], To avoid bias, the number of events passing the selection was not evaluated until the analysis was complete. Two same-sign lepton candidates, muons or electrons, with p T > 20 GeV and \rj\ < 2.4(2.5) for muons (electrons) are required to be isolated from other reconstructed particles in a cone of AR = 0.3, where AR = \J Ay2 + A(f>2. Jets are reconstructed using the anti-k7 clustering algorithm [27] with a distance parameter R = 0.5, as implemented in the f a s t je t package [28,29]. Events are required to have at least two selected jets with ET > 30 GeV and \rj\ < 4.7. The VBS topology is targeted by requiring that the two jets with leading p T have large dijet mass, ntjj > 500 GeV, and large pseudorapidity separation, A ^ j >2. 5. To suppress top-quark backgrounds (ft and tW), a topquark veto technique is used; it is based on the presence of a soft muon in the event from the semileptonic decay of the bottom quark and on bottom-quark jet tagging criteria based on the impact parameters of the constituent tracks [30]. A minimum dilepton mass, > 50 GeV, is required to reduce the W + jets and top-quark background processes. To reduce the background from WZ production, events with a third, loosely identified lepton with p T > 10 GeV are rejected. Drell-Yan events can be selected if the charge of one lepton is measured incorrectly. To reduce this background, \ m ^ - mz | > 1 5 GeV is required for e±e± events. The charge confusion in dimuon events is negli­ gible. The Drell-Yan background is further reduced by requiring E f 'ss > 40 GeV. The nonprompt lepton background originating from leptonic decays of heavy quarks, hadrons misidentified as leptons, and electrons from photon conversions, is suppressed by the identification and isolation requirements imposed on muons and electrons. The remaining contri­ bution from the nonprompt lepton background is estimated directly from data. The efficiency for a predefined loose leptonlike object to pass the full lepton selection, typically called the “tight-to-loose ratio” (ATI ), is estimated in a control sample with one additional lepton candidate that passes the standard lepton selection criteria. To account for the dependence on kinematic observables, this ratio is parameterized as a function of p T and rj. Systematic uncertainties are obtained by the application of RTL to other control samples, accounting for the sample depend­ ence in the estimation of i?XL. The WZ —> 3tfv process is normalized in a data control region by requiring a third fully identified lepton with p T > 10 GeV. The contribution of opposite-sign dilepton events to the signal region is estimated by applying data-to-simulation charge misidentification scale factors to simulated events with two opposite-sign leptons. The charge-misidentification fraction is estimated using Z boson events and is found to be between

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TABLE I. Signal and background yields after the full selection. Only statistical uncertainties are reported. The signal, W± W±j j, includes EW and QCD processes and their interference.

W+W+

w~w~ w±w±

Nonprompt

WZ

VVV

Wrong sign

WW DPS

Total bkg.

W± W±j j

Data

2.1 ± 0 .6 2.1 ± 0 .5 4.2 ± 0 .8

0.6 ± 0 .1 0.4 ±0.1 1.0 ± 0.1

0.2 ± 0 .1 0.1 ± 0.1 0.3 ± 0 .1

0.1 ± 0.1

0.1 ± 0.1

0.1 ± 0.1

0.1 ± 0.1

3.1 ± 0 .6 2.6 ± 0 .5 5.7 ± 0 .8

7.1 ± 0.1 1.8 ± 0.1 8.9 ± 0.1

10 2 12

0.1% and 0.3% for electrons, while it is negligible for muons. After the full selection, about 15% of the background is due to the WZ -*■ 3€v process and about 75% to nonprompt leptons. Backgrounds from opposite-sign lepton pairs misreconstructed as same-sign (“wrong-sign background”), WW production via double parton scattering (DPS), and triboson production (VVV), which includes top-pair plus boson processes, contribute less than 10%. The expected signal and background yields are shown in Table I for positive and negative pairs separately and for their sum. The signal corresponds to W± W± production, including EW and QCD contributions, and their interfer­ ence, which amounts to approximately 10%. The EW processes constitute 85%-90% of the total signal contri­ bution. The nijj and leading-lepton p T distributions for the signal and background processes are shown in Fig. 2. In order to quantify the significance of the observation of the production via VBS, a statistical analysis of the event yields is performed in eight bins: four bins in m;/ with two bins in the lepton charge. The signal efficiencies are estimated using simulated samples. In the statistical analysis, shape and normalization uncertainties are considered. The shape uncertainties are estimated by remaking the distribution of a given observ­ able after considering the systematic variations for each source of uncertainty. The lepton trigger, reconstruction, and selection efficiencies are measured using Z/y* -> events that provide an unbiased sample with high purity. The estimated uncertainty is 2% per lepton. The uncertainties due to the momentum scale for electrons and muons are also taken into account and contribute 2%. The jet energy scale and resolution uncertainties give rise to an uncertainty in the yields of about 5%. The uncertainty in the event selection efficiency for events with neutrinos yielding genuine £™ss in the final state is assessed and leads to an uncertainty of 2%. The uncertainty in the estimated event yields, which is related to the top-quark veto, is evaluated by using a Z/y* -»• Z+Z~ sample with at least two reconstructed jets and is found to be about 2%. The statistical uncertainty in the yield of each bin and for each process is also taken into account. The uncertainty of 2.6% in the integrated luminosity [31] is considered for all simulated processes. The normalization of the processes with misidentified leptons has a 36% systematic uncer­ tainty [26], which has two sources: the dependence on the

sample composition and the method used to estimate it. The WZ normalization uncertainty is 35%, dominated by the small number of events in the trilepton control region. Theoretical uncertainties are estimated by varying the

19.4 fb '1 (8 TeV)

CMS

Data

VWW’jj Other Bkgs. Nonprompt

c

!o

w

c >

LLI

0

500

1000

1500

2000

mjj (GeV) CMS

19.4 fb'1 (8 TeV) Data

W±W±jj

15 ■ ■

•“

w

Other Bkgs. Nonprompt

10

c 0)

5

0

0

100

200

300

400

500

p lm a x ( G e V )

FIG. 2 (color online). The distributions of (top) and leading lepton pT, p£'max, in the signal region (bottom). The hatched bars include statistical and systematic uncertainties. The W+W + and W~W~ candidates are combined in these distributions. The signal, W± W±j j, includes EW and QCD processes and their interference. The histograms for other backgrounds include the contributions from wrong-sign events, DPS, and VVV processes.

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renormalization and factorization scales up and down by a factor of two from their nominal value in the event, and found to be 5% for the signal normalization and 50% for the triboson background normalization. A PDF uncertainty of 6%-8% in the normalization of the signal and WZ processes is included. The systematic uncertainties of the background normalizations are taken into account using log-normal distributions. The cross section is extracted for a fiducial signal region. The fiducial region is defined by requiring two same-sign leptons with p / > 10 GeV and \rjf \ < 2.5, two jets with p TJ > 20 GeV and j^j < 5.0, mn > 300 GeV, and \krjjj\ > 2.5 and is less stringent than the event selection for our signal region. The measured cross section is corrected for the acceptance in this region using the MadGraph MC generator, which is also used to estimate the theoretical cross section. The acceptance ratio between the selected signal region and the fiducial region is 36% considering generator-level jet and lepton properties only. The overall acceptance times efficiency is 7.9%. The M adGraph prediction of the same-sign W-boson pair cross section is corrected by a next-to-leading order to leading-order cross section ratio estimated using vbfnlo [32-34], The fiducial cross section is found to be Ofi W±W ±) are derived as shown in Fig. 4. The experimental results are overlaid with theoretical cross sections for three values of the vacuum expectation value. In summary, a study of vector boson scattering in pp collisions at y's = 8 TeV has been presented based on a

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data sample corresponding to an integrated luminosity of 19.4 fb-1. Candidate events are selected with exactly two leptons of the same charge, two jets with large rapidity separation and dijet mass, and moderate missing transverse energy. The signal region is expected to be dominated by electroweak same-sign W-boson pair production. The observation agrees with the standard model prediction. The observed significance is 2.0 standard deviations, where a significance of 3.1 standard deviations is expected based on the standard model. Cross section measurements for W± W± and WZ processes in the fiducial region are reported. Bounds on the structure of quartic vector-boson interactions are given in the framework of dimension-eight effective field theory operators, as well as limits on the production of doubly charged Higgs bosons. We congratulate our colleagues in the CERN accel­ erator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centers and personnel of the Worldwide LHC Computing Grid for delivering so effec­ tively the computing infrastructure essential to our analy­ ses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER, ERC IUT and ERDF (Estonia); Academy of Finland, 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); NRF and WCU (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); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA).

m^,, (GeV)

FIG. 4 (color online). Expected and observed 95% C.L. upper limits on the cross section times branching fraction, ffH±±B{H±zk W±W±). Theoretical cross sections for three values of the vacuum expectation value (vev) are overlaid.

[1] [2] [3] [4]

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V. K h ac h atry an ,1 A. M . S iru n y a n ,1 A. T u m a sy an ,1 W. A d am ,2 T. B erg au er,2 M . D rag icev ic,2 J. E rd ,2 M . F rie d l,2 R. F riih w id h ,2b V. M. G h ete,2 C. H a rd ,2 N. H o rm an n ,2 J. H ru b ec,2 M . Jeitler,2'6 W. K iesenhofer,2 V. K niinz,2 M . K ram m er,2'b I. K ratschm er,2 D. L ik o ,2 I. M ik u lec,2 D. R ab ad y ,2’c B. R ah b aran ,2 H. R o h rin g er,2 R. S ch o fb eck ,2 J. S trauss,2 W. T reberer-T reberspurg,2 W. W altenberger,2 C .-E. W ulz,2 b V. M o sso lo v ,3 N. S h u m eik o ,3 J. S uarez G o n zalez,3 S. A lderw eireldt,4 M . B ansal,4 S. B ansal,4 T. C ornells 4 E. A. D e W olf,4 X . Jan ssen 4 A . K n u tsso n ,4 J. L au w ers,4 S. L u y ck x ,4 S. O ch esan u ,4 R. R o ugny 4 M . Van D e K lundert,4 H. Van H aev erm aet,4 P. Van M ech elen ,4 N. Van R e m o d e l,4 A. Van S pilbeeck,4 F. B lek m an ,5 S. B ly w e e d ,6 J. D ’H o n d t,5 N. D aci,5 N. H eracleo u s,3 J. K eaveney,5 S. L o w ette,5 M . M aes,5 A. O lbrech ts,5 Q. P y th o n ,5 D. S trom ,5 S. T avernier,5 W. Van D o n in ck ,5 P. Van M u ld ers.5 G. P. Van O n sem ,6 I. V illella,5 C. C aillol,6 B. C lerb au x ,6 G. D e L entdecker,6 D. D o b u r,6 L. F a v a d ,6 A. P. R. G ay,6 A. G reb en y u k ,6 A. L eo n ard ,6 A. M o h am m ad i,6 L. P em ie ,6'1’ T. R eis,6 T. Seva,6 L. T h o m as,6 C. V ander V elde,6 P. V anlaer,6 J. W ang,6 F. Z en o n i,6 V. A d ler,7 K. B e e m a e d ,7 L. B en u cci,7 A. C im m in o ,7 S. C o stan tin i,7 S. C rucy,7 S. D ild ick ,7 A. F ag o t,7 G. G arcia,7 J. M c c a d in ,7 A. A. O cam po R io s,7 D. R y c k b o sch ,7 S. Salva D iblen ,7 M . S ig am an i,7 N. S tro b b e,7 F. T h y sse n ,7 M . T ytgat,7 E. Y azgan.7 N. Z ag an id is,7 S. B a seg m ez,8 C. B eluffi,80 G. B ru n o .8 R. C astello ,8 A. C a u d ro n ,8 L. C eard ,8 G. G. D a S ilv eira,8 C. D elaere,8 T.

du P ree,8 D. F a v a d ,8 L. F o d h o m m e ,8 A. G iam m an co ,8'6 J. H ollar,8 A. Jafari,8 P. Je z,8 M . K o m m ,8 V. L em aitre,8 C. N u tte n s,8 D. P ag an o ,8 L. P errini,8 A. P in ,8 K. P io trzk o w sk i,8 A. P o p o v ,8,f L. Q u e d e n m o n t,8 M . S elv ag g i,8

M . V idal M a ro n o ,8 J. M . V izan G arcia,8 N. B eliy,9 T. C aeb erg s,9 E. D au b ie,9 G. H. H am m ad ,9 W. L. A ld a Ju n io r,10 G. A. A lv e s,10 L. B rito ,10 M. Cornea M a d in s Ju n io r,10 T. D os R eis M a d in s ,10 C. M o ra H e m e ra ,10 M . E. P o l,10 W. C a rv a lh o ,11 J. C h in ellato ,11’8 A. C u sto d io ,11 E. M . D a C o s ta ,11 D. D e Jesus D am iao ,11 C. D e O liveira M a d in s ,11 S. F o n seca D e S o u z a ,11 H. M a lb o u isso n ,11 D. M atos F ig u e ire d o ,11 L. M u n d im ," H. N o g im a ,11 W. L. P rado D a S ilv a ,11 J. S an ta o lalla,11 A. S a n to ro ,11 A. S zn ajd er,11 E. J. Tonelli M a n g a n o te ,11,8 A. V ilela P ereira,11 C. A. B e rn a rd es,121’ S. D o g ra ,l2a

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T. R. Fernandez Perez Tom ei,12a E. M. G regores,12b P. G. M ercadante,l2b S.F. N ovaes,I2a Sandra S. Padula,12a A.

Aleksandrov,13 V. G enchev,13’0 P. Iaydjiev,13 A. M arinov,13 S. Piperov,13 M. Rodozov,13 G. Sultanov,13 M. Vutova,13

A. D im itrov,14 I. G lushkov,14 R. H adjiiska,14 L. Litov,14 B. Pavlov,14 P. Petkov,14 J. G. B ian,15 G. M. C hen,15 H. S. C hen,15 M. C hen,15 T. C heng,15 R. D u ,15 C. H. Jiang,15 R. Plestina,15’h F. R om eo,15 J. Tao,15 Z. W ang,15 C. A saw atangtrakuldee,16 Y. B an,16 Q. L i,16 S. L iu ,16 Y. M ao,16 S. J. Q ian,16 D. W ang,16 W. Z ou,16 C. A vila,17 A. C abrera,17 L. F. Chaparro Sierra,17 C. Florez,17 J. P. G om ez,17 B. Gom ez M oreno,17 J. C. Sanabria,17 N. G odinovic,18 D. Lelas,18 D. Polic,18 I. Puljak,18 Z. A ntunovic,19 M. K ovac,19 V. Brigljevic,20 K. Kadija,20 J. Luetic,20 D. M ekterovic,20 L. Sudic,20 A. Attikis,21 G. M avrom anolakis,21 J. M ousa,21 C. N icolaou,21 F. Ptochos,21 P. A. Razis,21 M. Bodlak,22 M. Finger,22 M. Finger Jr.,22’1 Y. A ssran,23’j A. Ellithi Kam el,23’k M. A. M ahm oud,23’1A. Radi,23’m’n M. Kadastik,24 M. M urum aa,24 M. Raidal,24 A. Tiko,24 P. Eerola,25 G. Fedi,25 M. Voutilainen,25 J. H arkonen,26 V. Karim aki,26 R. K innunen,26 M. J. Kortelainen,26 T. Lam pen,26 K.

Lassila-Perini,26 S. Lehti,26 T. Linden,26 P. Luukka,26 T. M aenpaa,26 T. Peltola,26 E. Tuom inen,26 J. Tuom iniem i,26

E. Tuovinen,26 L. W endland,26 J. Talvitie,27 T. Tuuva,27 M. Besancon,28 F. Couderc,28 M. D ejardin,28 D. Denegri,28 B. Fabbro,28 J. L. Faure,28 C. Favaro,28 F. Ferri,28 S. Ganjour,28 A. G ivem aud,28 P. Gras,28 G. Hamel de M onchenault,28 P. Jarry,28 E. Locci,28 J. M alcles,28 J. Rander,28 A. Rosowsky,28 M. Titov,28 S. Baffioni,29 F. Beaudette,29 P. Busson,29 C. Chariot,29 T. D ahm s,29 M. D alchenko,29 L. D obrzynski,29 N. Filipovic,29 A. Florent,29 R. Granier de Cassagnac,29 L. M astrolorenzo,29 P. M ine,29 C. M ironov,29 I. N. N aranjo,29 M. N guyen,29 C. O chando,29 P. Paganini,29 S. Regnard,29 R. Salerno,29 J. B. Sauvan,29 Y. Sirois,29 C. Veelken,29 Y. Yilmaz,29 A. Zabi,29 J.-L. Agram ,30,0 J. A ndrea,30 A. A ubin,30 D. Bloch,30 J.-M . B rom ,30 E. C. Chabert,30 C. Collard,30 E. Conte,30’0 J.-C. Fontaine,30’0 D. Gele,30 U. G oerlach,30 C. G oetzm ann,30 A.-C. Le Bihan,30 P. Van H ove,30 S. G adrat,31 S. Beauceron,32 N. Beaupere,32 G. Boudoul,32’0 E. Bouvier,32 S. Brochet,32 C. A. Carrillo M ontoya,32 J. Chasserat,32 R. Chierici,32 D. C ontardo,32'0 P. D epasse,32 H. El M am ouni,32 J. Fan,32 J. Fay,32 S. G ascon,32 M. G ouzevitch,32 B. Ille,32 T. Kurca,32 M. Lethuillier,32 L. M irabito,32 S. Perries,32 J. D. Ruiz Alvarez,32 D. Sabes,32 L. Sgandurra,32 V. Sordini,32 M. Vander D onckt,32 P. Verdier,32 S. Viret,32 H. X iao,32 Z. Tsam alaidze,33’1 C. A uterm ann,34 S. Beranek,34 M. Bontenackels,34 M. Edelhoff,34 L. Feld,34 A. Heister,34 O. H indrichs,34 K. Klein,34 A. O stapchuk,34 F. Raupach,34 J. Sam m et,34 S. Schael,34 H. Weber,34 B. W ittmer,34 V. Zhukov,34’1 M. A ta,35 M. B rodski,35 E. D ietz-Laursonn,35 D. D uchardt,35 M. Erdm ann,35 R. Fischer,35 A. Giith,35 T. Hebbeker,35 C. H eidem ann,35 K. Hoepfner,35 D. Klingebiel,35 S. K nutzen,35 P. Kreuzer,35 M. M erschmeyer,35 A. M eyer,35 P. M illet,35 M. Olschew ski,35 K. Padeken,35 P. Papacz,35 H. Reithler,35 S. A. Schm itz,35 L. Sonnenschein,35 D. Teyssier,35 S. Thiier,35 M. Weber,35 V. Cherepanov,36 Y. Erdogan,36 G. Fliigge,36 H. Geenen,36 M. Geisler,36 W. Haj A hm ad,36 F. H oehle,36 B. Kargoll,36 T. Kress,36 Y. K uessel,36 A. Kiinsken,36 J. Lingem ann,36’0 A. N ow ack,36 I. M. N ugent,36 L. Perchalla,36 O. Pooth,36 A. Stahl,36 I. A sin,37 N. Bartosik,37 J. Behr,37 U. Behrens,37 A. J. Bell,37 A. Bethani,37 K. Borras,37 A. Burgmeier,37 A. Cakir,37 L. Calligaris,37 A. Cam pbell,37 S. Choudhury,37 F. Costanza,37 C. Diez Pardos,37 G. D olinska,37 S. D ooling,37 T. D orland,37 G. Eckerlin,37 D. Eckstein,37 T. Eichhom ,37 G. Flucke,37 J. Garay G arcia,37 A. Geiser,37 P. G unnellini,37 J. H auk,37 M. H em pel,37,p H. Jung,37 A. Kalogeropoulos,37 M. Kasem ann,37 P. Katsas,37 J. Kieseler,37 C.

Kleinw ort,371. Korol,37 D. Kriicker,37 W. Lange,37 J. Leonard,37 K. Lipka,37 A. Lobanov,37 W. Lohm ann,37 p B. Lutz,37 R.

M ankel,37 I. M arfm ,37’p I.-A. M elzer-Pellm ann,37 A. B. M eyer,37 G. M ittag,37 J. M nich,37 A. M ussgiller,37 S.

N aum ann-Em m e,37 A. N ayak,37 E. N tom ari,37 H. Perrey,37 D. Pitzl,37 R. Placakyte,37 A. Raspereza,37

P. M. Ribeiro C ipriano,37 B. R oland,37 E. R on,37 M. 6 . Sahin,37 J. Salfeld-Nebgen,37 P. Saxena,37 T. Schoem er-Sadenius,37 M. Schroder,37 C. Seitz,37 S. Spannagel,37 A. D. R. Vargas Trevino,37 R. W alsh,37 C. W issing,37 M. Aldaya M artin,38 V. Blobel,38 M. Centis Vignali,38 A. R. Draeger,38 J. Erfle,38 E. Garutti,38 K. G oebel,38 M. G om er,38 J. Haller,38 M. Hoffm ann,38 R. S. H oing,38 A. Junkes,38 H. Kirschenm ann,38 R. Klanner,38 R. Kogler,38 J. Lange,38 T. Lapsien,38 T. Lenz,38 I. M archesini,38 J. Ott,38 T. Peiffer,38 A. Perieanu,38 N. Pietsch,38 J. Poehlsen,38 T. Poehlsen,38 D. Rathjens,38 C. Sander,38 H. Schetder,38 P. Schleper,38 E. Schlieckau,38 A. Schm idt,38 M. Seidel,38 V. Sola,38 H. Stadie,38 G. Steinbruck,38 D. Troendle,38 E. U sai,38 L. Vanelderen,38 A. Vanhoefer,38 C. Barth,39 C. Baus,39 J. Berger,39 C. Boser,39 E. Butz,39 T. C hw alek,39 W. De Boer,39 A. D escroix,39 A. D ierlam m ,39 M. Feindt,39 F. Frensch,39 M. Giffels,39 A. G ilbert,39 F. H artm ann,39’0 T. H auth,39’0 U. H usem ann,39 I. Katkov,391 A. Kom m ayer,39’0 E. Kuznetsova,39 P. Lobelle Pardo,39 M. U. M ozer,39 T. M uller,39 Th. M uller,39 A. N um berg,39 G. Quast,39 K. Rabbertz,39 S. Rocker,39 H. J. Sim onis,39 F. M. Stober,39 R. U lrich,39 J. W agner-Kuhr,39 S. W ayand,39 T. Weiler,39 R. W olf,39 G. A nagnostou,40 G. Daskalakis,40 T. I.

G eralis,40 V. A. G iakoum opoulou,40 A. Kyriakis,40 D. Loukas,40 A. M arkou,40 C. M arkou,40 A. Psallidas,40

Topsis-Giotis,40 A. Agapitos,41 S. K esisoglou,41 A. Panagiotou,41 N. Saoulidou,41 E. Stiliaris,41 X. A slanoglou,42

051801-7

PHYSICAL

PRL 114, 051801 (2015)

REVIEW

42

. 42

week ending

LETTERS

42

6 FEBRUARY 2015

42

42

42

42

I. Evangelou,42 G. F lo u ris h C. Foudas,‘tz P. K okkas,^ N. M anthos,4Z I. Papadopoulos,4Z E. Paradas,4Z J. Strologas,'

G. Bencze,43 C. H ajdu,43 P. H idas,43 D. Horvath,43,q F. Sikler,43 V. V eszprem i43 G. Vesztergombi,43’r A. J. Zsigm ond,43 .44

44,s

.44

44

44 .

. 45 ,

45 N. Beni,44 S. Czellar,44 J. Karancsi,44 S J. M olnar,44 J. Palinkas,44 Z. Szillasi,44 A. M akovec. 43 P. Raics,45 Z. L. Trocsanyi,i,45 46 ,

47 ,

47

47 i

47

■ 47 i

.47 ,

.4 7

B. Ujvari,45 S. K. Swain,40 S. B. Beri,4' V. Bhatnagar,4' R. Gupta,4' U. Bhaw andeep,4' A. K. Kalsi,4' M. Kaur,4' R. Kumar, 47

, 47

.48

48

48

.48

M. M ittal,47 N. N ishu,4' J. B. Singh,4' A shok Kumar,46 Arun Kumar,48 S. A huja,48 A. Bhardwaj,48 B .C . Choudhary,'

A. Kumar,48 S. M alhotra,48 M. N aim uddin,48 K. R anjan,48 V. Sharma,48 S. Banerjee,49 S. Bhattacharya,49 K. Chatterjee,49 49

49

49

49

49

.49

S. D utta,49 B. Gom ber,44 Sa. Jain,44 Sh. Jain,44 R. Khurana,44 A. M odak,44 S. M ukherjee,44 D. Roy,44 S. Sarkar,'

M. Sharan,49 A. A bdulsalam ,50 D. Dutta,50 S. Kailas,50 V. Kumar,50 A. K. M ohanty,50’3 L. M. Pant,50 P. Shukla,50 A. Topkar,50 T. A ziz,51 S. B anerjee,51 S. B how m ik,511 R. M. Chatterjee,51 R. K. Dewanjee,51 S. D ugad,5' S. Ganguly,51 S. G hosh,51 M. G uchait,51 A. G urtu,51’u G. Kole,51 S. Kumar,51 M. Maity,51’1 G. M ajum der,51 K. M azum dar,51 G. B. M ohanty,51 B. Parida,51 K. Sudhakar,51 N. W ickram age,5l v H. Bakhshiansohi,52 H. B ehnam ian,52 S. M. Etesam i,52’" A. Fahim ,52* R. G oldouzian,52 M. K hakzad,52 M. M oham m adi N ajafabadi,52 M. Naseri,52 S. Paktinat M ehdiabadi,52 F. Rezaei H osseinabadi,52 B. Safarzadeh,52y M. Zeinali,52 M. Felcini,53 M. G runewald,53 M. Abbrescia,543’546 C. Calabria,54a’54b S. S. Chhibra,54a’54b A. C olaleo,54a D. Creanza,54a’54c N. De Filippis,54a’54c M. De Palm a,54a’54b L. Fiore,543 G. Iaselli,54a’54c G. M aggi,54a’54c M. M aggi,543 S. My,54a’54c S. Nuzzo,54a’54b A. Pompili,54a’54b G. Pugliese,54a’54c R. R adogna,54a'54b c G. Selvaggi,54a 54b A. Sharm a,543 L. Silvestris,5430 R. Venditti,543'546 G. A bbiendi,553 A. C. Benvenuti,

55a

D. Bonacorsi,55a,55b S. B raibant-G iacom elli,55a,55b L. Brigliadori,553’556 R. Cam panini,55a,55b P. Capiluppi,55a’55b A. Castro,55a’55b F. R. Cavallo,553 G. C odispoti,55a'55b M. Cuffiani,55a’55b G. M. Dallavalle,553 F. Fabbri,55a A. Fanfani,

55a,55b

D. Fasanella,55a,55b P. Giacom elli,553 C. G randi,553 L. G uiducci,55a'55b S. M arcellini,553 G. M asetti,553 A. M ontanari,553 F. L. Navarria,553’55b A. Perrotta,553 F. Prim avera,55a’55b A. M. Rossi,55a’55b T. Rovelli,55a’55b G. P. Siroli,55a'55b N. Tosi,55a'55b R. Travaglini,553’556 S. A lbergo,

56a,56b

G. Cappello,563 M. Chiorboli,56a’56b S. Costa,56a’56b F. Giordano,56a’c R. Potenza,56a’56b

A. Tricom i,56a’56b C. Tuve,56a’56b G. Barbagli,573 V. Ciulli,57a’57b C. Civinini,573 R. D ’Alessandro,573'576 E. Focardi,57a’57b 57a,57b ,

E. G allo,573 S. G onzi,5' 3’5' 0 V. Gori,

57a,57b,c

P. Lenzi,57a 57b M. M eschini,573 S. Paoletti,573 G. Sguazzoni,573 A. Tropiano,573'576 L. B enussi,58 S. Bianco,58 F. Fabbri,58 D. Piccolo,58 R. Ferretti, 59a’59b F. Ferro,593 M. Lo Vetere,59a’59b E. Robutti,593 • 60a,60b

S. Tosi,59a,59b M. E. D inardo,60a’60b S. Fiorendi,'

S. G ennai,60a c R. Gerosa,

60a,60b,c

A. G hezzi,60a’60b P. Govoni,

60a,60b 60a

M. T. Lucchini,60a,60b’c S. M alvezzi,603 R. A. M anzoni,603,606 A. M artelli,60a’60b B. M arzocchi,60a’60b’c D. Menasce,' 60a,60b 61a L. M oroni,603 M. Paganoni, D. Pedrini,603 S. Ragazzi,; 60a,60b N R e d a e l l i ) 60aT T a b a r e l l i d e F a t i s ,60a'60b s . Buontempo,' 61a,6id,c

61a,61d,c

N. Cavallo,61a’61c S. Di G uida,61a'61d’c F. Fabozzi,61a’61c A. O. M. lorio,6' 3’616 L. Lista,613 S. M eola,013’010’0 M. Merola, 61a,c 62a 62a P. Paolucci, P. Azzi,623 N. Bacchetta,623 M. Bellato,623 D. Bisello,623’626 R. Carlin,62a’62b P. Checchia,623

61a

M. DaH’Osso,62a’62b T. D origo,623 M. Galanti,623’626 F. Gasparini,623'626 U. G asparini,62a’62b P. Giubilato,62a’62b A. G ozzelino,623 K. Kanishchev,62a62c S. Lacaprara,623 M. Margoni,

62a,62b

A. T. M eneguzzo,62a,62b J. Pazzini,62a’62b

M. Pegoraro,623 N. Pozzobon,62a’62b P. Ronchese,62a’62b F. Sim onetto,62a’62b E. Torassa,623 M. Tosi,62a'62b P. Zotto,62a’62b 62a,62b

63a,63b

A. Zucchetta,62a,62b G. Zum erle,62a’62b M. G abusi,63a'63b S. P. Ratti,63a’63b V. Re,63a C. Riccardi,63a’63b P. Salvini,633 P. Vitulo,63a’63b M. Biasini,643,646 G. M. Bilei,643 D. Ciangottini,64a'64b’c L. Fano,64a'64b P. Lariccia,64a’64b G. M antovani,643,646 M. M enichelli,643 A. Saha,64,1 A. Santocchia,643’646 A. Spiezia,64a’64bc K. Androsov,1553 2 P. A zzurri,653 G. Bagliesi,653 J. B em ardini,653 T. Boccali,653 G. Broccolo,65a'65c R. Castaldi,653 M. A. Ciocci,65a’z R. D ell’Orso,653 S. D onato,65a’65c’c F. Fieri,653'650 L. Foa,65a,65c A. G iassi,653 M .T . Grippo,653’2 F. Ligabue,653’650 T. Lom tadze,653 L. M artini,65a’65b A. M essineo,653,656 C. S. M oon,653133 F. Palla,65a’c A. Rizzi,65a’65b A. Savoy-Navarro,65a’bb A. T. Serban,653 P. Spagnolo,653 66a,66b

P. Squillacioti,653’2 R. Tenchini,653 G. Tonelli,653’656 A. Venturi,653 P. G. Verdini,653 C. Vemieri,65a’65c’c L. Barone,1 F. Cavallari,663 G. D ’im perio,663,666 D. Del Re,'66a,66b P. M eridiani,663 F. Micheli,

jyj

D i e m o z 66a C

J o r d a 66a R

L o n g o > 66466b R M a r g a r o l i ; 66a,66b

66a,66b,c

S. N ourbakhsh,66a 66b G. Organtini,66a 66b R. Param atti,663 S. Rahatlou,663’666 C. Rovelli, 67a,67b F. Santanastasio,66d’66b L. Soffi,66a'66b’c P. Traczyk,66a,66b'c N. A m apane,673'676 R. Arcidiacono,673’670 S. Argiro,’

66a

67a,67b

M. A rneodo,673'670 R. B ellan,67a’67b C. Biino,673 N. Cartiglia,673 S. Casasso,67a’67b'c M. Costa,67a’67b A. Degano,' 67a,67b,c 67a 67a N. D em aria,673 L. Finco, C. M ariotti,673 S. M aselli,673 E. M igliore,67a'67b V. M onaco,673’676 M. M usich,

67a,67b

M. M. O bertino,67a’67cx G. O rtona,673’676 L. Pacher,673’676 N. Pastrone,673 M. Pelliccioni,673 G. L. Pinna Angioni,'

A. Potenza,673'676 A. Rom ero,67a'67b M. Ruspa,67a’67c R. Sacchi,673’676 A. Solano,67a'67b A. Staiano,673 U. Tamponi,673 68a,68b,c 68a,68b S. Belforte,683 V. Candelise,' M. Casarsa,683 F. Cossutti,683 G. Della Ricca,' B. G obbo,683 C. La Licata,683’686 M. M arone,683’686 A. Schizzi,683'686 T. Um er,68a’68b A. Zanetti,683 S. Chang,69 A. Kropivnitskaya,69 S. K. N am ,69 D. H. Kim,70 70 ,

. 70 ,

70 ,

70

70

,70 ,

70 r

71

G. N. Kim ,70 M. S. K im ,,u D. J. K ong,'u S. L e e ,'u Y. D. O h ,'u H. Park.'" A. Sakharov,,u D. C. S on,,u T. J. K im ,'1J. Y. Kim,

051801-8

72

PRL 114, 051801 (2015)

PHYSICAL

REVIEW

LETTERS

week ending

6 FEBRUARY 2015

S. Song,72 S. C hoi,73 D. G yun,73 B. H ong,73 M. Jo,73 H. Kim,73 Y. Kim,73 B. Lee,73 K. S. Lee,73 S. K. Park,73 Y. Roh,73 M. Choi,74 J. H. Kim ,741. C. Park,74 G. Ryu,74 M. S. R yu,74 Y. Choi,75 Y. K. Choi,75 J. Goh,75 D. Kim,75 E. K won,75 J. Lee,75 H. Seo,75 I. Yu,73 A. Juodagalvis,76 J. R. Kom aragiri,77 M. A. B. M d Ali,77 E. Casim iro Linares,78 H. Castilla-Valdez,78 E. D e L a Cruz-Burelo,78 I. H eredia-de L a Cruz,78 cc A. H em andez-A lm ada,78 R. Lopez-Fem andez,78 A. Sanchez-H em andez,

S. Carrillo M oreno,

F. Vazquez Valencia,

I. Pedraza,

H. A. Salazar Ibarguen,

A. M orelos Pineda,81 D. K rofcheck,82 P. H. Butler,83 S. R eucroft,83 A. A hm ad,84 M. A hm ad,84 Q. H assan,84 H. R. H oorani,84 W. A. K han,84 T. K hurshid,84 M. Shoaib,84 H. Bialkowska,85 M. B luj,85 B. Boim ska,85 T. Frueboes,85 M. G orski,85 M. K azana,85 K. N aw rocki,85 K. Rom anow ska-Rybinska,85 M. Szleper,8 P. Zalew ski,85 G. B rona,86 K. B unkow ski,86 M. C w iok,86 W. D om inik,86 K. D oroba,86 A. Kalinow ski,86 M. Konecki,86 J. K rolikowski,86 M. M isiura,86 M. O lszew ski,86 W. W olszczak,86 P. Bargassa,87 C. Beirao D a Cruz E Silva,87 P. Faccioli,87 P. G. Ferreira Parracho,87 M. G allinaro,87 L. Lloret Iglesias,87 F. N guyen,87 J. Rodrigues A ntunes,87 J. Seixas,87 J. Varela,87 P. Vischia,87 S. Afanasiev,88 P. B unin,88 M. Gavrilenko,88 I. G olutvin,88 I. Gorbunov,88 A. Kamenev,88 V. K arjavin,88 V. Konoplyanikov,88 A. Lanev,88 A. M alakhov,88 V. M atveev,88'dd P. M oisenz,88 V. Palichik,88 V. Perelygin,88 S. Shmatov,88 N. Skatchkov,88 V. Smirnov,88 A. Zarubin,88 V. Golovtsov,89 Y. Ivanov,89 V. Kim ,89 ee P. Levchenko,89 V. M urzin,89 V. Oreshkin,89 I. Smirnov,89 V. Sulimov,89 L. Uvarov,89 S. Vavilov,89 A. Vorobyev,89 An. Vorobyev,89 Yu. Andreev,90 A. Dermenev,90 S. G ninenko,90 N. Golubev,90 M. Kirsanov,90 N. Krasnikov,90 A. Pashenkov,90 D. Tlisov,90 A. Toropin,90 V. Epshteyn,91 V. Gavrilov,91 N. Lychkovskaya,91 V. Popov,91 I. Pozdnyakov,91 G. Safronov,91 S. Semenov,91 A. Spiridonov,91 V. Stolin,91 E. Vlasov,91 A. Zhokin,91 V. Andreev,92 M. A zarkin,92 I. D rem in,92 M. Kirakosyan,92 A. Leonidov,92 G. M esyats,92 S. V. Rusakov,92 A. Vinogradov,92 A. Belyaev,93 E. Boos,93 V. Bunichev,9’ M. Dubinin,9311 L. D udko,93 A. Ershov,93 A. Gribushin,93 V. K lyukhin,93 O. Kodolova,93 I. Lokhtin,93 S. Obraztsov,93 V. Savrin,93 A. Snigirev,93 I. Azhgirey,94 I. Bayshev,94 S. Bitioukov,94 V. Kachanov,94 A. Kalinin,94 D. Konstantinov,94 V. Krychkine,94 V. Petrov,94 R. R yutin,94 A. Sobol,94 L. Tourtchanovitch,94 S. Troshin,94 N. Tyurin,94 A. U zunian,94 A. Volkov,94 P. Adzic,95,88 M. Ekm edzic,93 J. M ilosevic,95 V. Rekovic,93 J. Alcaraz M aestre,96 C. Battilana,96 E. Calvo,96 M. Cerrada,96 M. Cham izo Llatas,96 N. C olino,96 B. De L a Cruz,96 A. Delgado Peris,96 D. D om inguez V azquez,96 A. Escalante Del Valle,96 C. Fernandez Bedoya,96 J. P. Fernandez Ram os,96 J. Flix,96 M. C. Fouz,96 P. Garcia-Abia,96 O. Gonzalez Lopez,96 S. Goy Lopez,96 J. M. H ernandez,96 M. I. Josa,96 E. Navarro De M artino,96 A. Perez-Calero Yzquierdo,96 J. Puerta Pelayo,96 A. Quintario O lm eda,96 I. Redondo,96 L. Rom ero,96 M. S. Soares,96 C. Albajar,97 J. F. de Troconiz,97 M. M issiroli,97 D. M oran,97 H. B run,98 J. Cuevas,98 J. Fernandez M enendez,98 S. Folgueras,98 I. Gonzalez Caballero,98 J. A. Brochero Cifuentes,99 I. J. Cabrillo,99 A. C alderon,99 J. Duarte C am pderros," M. F ernandez," G. G o m ez," A. G razian o ," A. Lopez V irto ," J. M a rc o ," R. M a rc o ," C. M artinez R iv ero ," F. M atorras," F. J. M unoz S anchez," J. Piedra G o m ez," T. R o d rig o ," A. Y. R odnguez-M arrero," A. R uiz-Jim eno," L. Scodellaro," I. V ila," R. Vilar C o rtabitarte," D. A bbaneo,100 E. Auffray,100 G. A uzinger,100 M. B achtis,100 P. B aillon,100 A. H. B all,100 D. Barney,100 A. B enaglia,100 J. B endavid,100 L. B enhabib,100 J.F . B enitez,100 C. B em et,100,h P. B loch,100 A. B occi,100 A. B onato,100 O. B ondu,100 C. B otta,100 H. B reuker,100 T. C am poresi,100 G. Cerm inara,100 S. C olafranceschi,100 hh M. D ’A lfonso,100 D. d ’Enterria,100 A. D abrow ski,100 A. D avid,100 F. De G uio,100 A. De R oeck,100 S. D e Visscher,100 E. Di M arco,100 M. D obson,100 M. D ordevic,100 N. D upont-Sagorin,100 A. Elliott-Peisert,100 J. Eugster,100 G. Franzoni,100 W. F unk,100 D. G igi,100 K. G ill,100 D. G iordano,100 M. G irone,100 F. G lege,100 R. G uida,100 S. G undacker,100 M. G uthoff,100 J. H am m er,100 M. H ansen,100 P. H arris,100 J. H egem an,100 V. Innocente,100 P. Janot,100 K. K ousouris,100 K. K rajczar,100 P. L ecoq,100 C. Lourengo,100 N. M agini,100 L. M algeri,100 M. M annelli,100 J. M arrouche,100 L. M asetti,100 F. M eijers,100 S. M ersi,100 E. M eschi,100 F. M oortgat,100 S. M orovic,100 M. M ulders,100 P. M usella,100 L. O rsini,100 L. P ape,100 E. Perez,100 L. Perrozzi,100 A. P etrilli,100 G. Petrucciani,100 A. Pfeiffer,100 M. Pierini,100 M. Pim ia,100 D. Piparo,100 M. Plagge,100 A. R acz,100 G. R olandi,100,11 M. R overe,100 H. Sakulin,100 C. Schafer,100 C. Schw ick,100 A. Sharm a,100 P. Siegrist,100 P. Silva,100 M. Sim on,100 P. Sphicas,100,jj D. Spiga,100 J. Steggem ann,100 B. Stieger,100 M. Stoye,100 Y. Takahashi,100 D. Treille,100 A. T sirou,100 G. I. Veres,100,1 N. W ardle,100 H. K. W ohri,100 H. W ollny,100 W. D. Zeuner,100 W. B ertl,101 K. D eiters,101 W. E rdm ann,101 R. H orisberger,101 Q. Ingram ,101 H. C. K aestli,101 D. Kotlinski,101 U. L angenegger,101 D. R enker,101 T. R ohe,101 F. Bachm air,102 L. B ani,102 L. Bianchini,102 M. A. B uchm ann,102 B. C asal,102 N. C hanon,102 G. D issertori,102 M. D ittm ar,102 M. D onega,102 M. Diinser,102 P. Eller,102 C. G rab,102 D. H its,102 J. H oss,102 W. Lusterm ann,102 B. M angano,102 A. C. M arini,102 P. M artinez Ruiz del A rbol,102 M. M asciovecchio,102 D. M eister,102 N. M ohr,102 C. N ageli,102,kk F. N essi-Tedaldi,102 F. Pandolfi,102 F. Pauss,102 M. Peruzzi,102 M. Q uittnat,102 L. R ebane,102

051801-9

PHYSICAL

PRL 114, 051801 (2015)

REVIEW

week ending 6 FEBRUARY 2015

LETTERS

M. R ossini,102 A. Starodum ov,102’11 M. Takahashi,102 K. Theofilatos,102 R. W allny,102 H. A. W eber,102 C. A m sler,'03mm M. F. C anelli,103 V. C hiochia,103 A. De C osa,103 A. H inzm ann,103 T. H reus,103 B. K ilm inster,103 C. L ange,103 B. M illan M ejias,103 J. N gadiuba,103 D. P inna,103 P. R obm ann,103 F. J. R onga,103 S. Taroni,103 M. Verzetti,103 Y. Yang,103 M. C ardaci,104 K. H. C hen,104 C. F erro,104 C. M. K uo,104 W. L in,104 Y. J. L u ,104 R. Volpe,104 S. S. Y u,104 P. C hang,105 Y. H. C hang,105 Y. W. C hang,105 Y. C hao,105 K. F. C hen,105 P. H. C hen,105 C. D ietz,105 U. G rundler,105 W.-S. H ou,105 K. Y. K ao,105 Y. F. L iu,105 R.-S. L u ,105 D. M ajum der,105 E. Petrakou,105 Y. M. Tzeng,105 R. W ilken,105 B. A savapibhop,106 G. Singh,106 N. Srim anobhas,106 N. Suw onjandee,106 A. A diguzel,107 M. N. B akirci,107’nn S. C erci,107,00 C. D ozen,107 I. D um anoglu,107 E. E sk u t,107 S. G irgis,107 G. G okbulut,107 E. Gurpinar,1071. H os,107 E. E. K angal,107 A. Kayis Topaksu,107 G. Onengut,

107,pp

K. O zdem ir,107 S. O zturk,107,nn A. Polatoz,107 D. Sunar Cerci,107,00 B. Tali,107,00 H. Topakli,107,nn

M. V ergili,1071. V. A k in ,"18 B. B ilin,108 S. B ilm is,108 H. Gamsizkan,

108,qq

S. Sekm en,108 U. E. Surat,108 M. Yalvac,108 M. Z eyrek,108 E. A. Albayrak,

B. Isildak,108,rr G. K arapinar,108,55 K. O calan,108’" 109,uu

109,vv

E. Giilm ez,109 M. K aya,lu'J'vv O. K aya

109, ww

T. Y etkin,l09’xx K. C ankocak,110 F. I. V ardarh,110 L. L evchuk,111 P. Sorokin,111 J. J. B rooke,1P E. C lem ent,112 D. C ussans,112 H. F lacher,112 J. G oldstein,112 M. G rim es,112 G .P H eath,112 H .F . H eath,112 J. Jacob,112 L. K reczko,112 C. Lucas,112 Z. M eng,112 D. M. Newbold, H 2,yy S. Param esvaran,112 A. Poll,112 T. Sakum a,112 S. Senkin,112 V. J. Sm ith,112 T. W illiam s,112 K .W . B ell,113 A. B elyaev,ll3,zz C. Brew,113 R .M . B row n,113 D .J .A . C ockerill,113 J. A. C oughlan,113 K. Harder,113 S. H arper,113 E. O laiya,113 D. P etyt,113 C. H. Shepherd-Them istocleous,113 A. Thea,1131. R. Tom alin,113 W. J. W omersley,113 S. D. W orm ,113 M. B aber,114 R. B ainbridge,114 O. Buchm uller,114 D. B urton,114 D. Colling,114 N. C ripps,114 P. D auncey,114 G. D avies,114M. D ellaN eg ra,114P. D unne,114 W. Ferguson,114 J. Fulcher,114D. Futyan,114G. H all,l14G. Iles,114M. Jarvis,114 G. K arapostoli,114 M. K enzie,114 R. L ane,114 R. Lucas, 114,yy L. Lyons,114 A.-M. M agnan,114 S. M alik,114 B. M athias,114 114,11 J. N ash,114 A. Nikitenko, J. P ela,114 M. Pesaresi,114 K. Petridis,114 D. M. R aym ond,114 S. R ogerson,114 A. R ose,114 C. Seez,114 P. Sharp,114,3 A. Tapper,114 M. Vazquez A costa,114 T. V irdee,114 S. C. Z enz,114 J. E. C ole,115 P R . H obson,115 A. K han,115 P. K yberd,115 D. L eggat,115 D. L eslie,115 I. D. R eid,115 P. Sym onds,115 L. Teodorescu,115 M. Turner,115 J. D ittm ann,116 K. H atakeyam a,116 A. K asm i,116 H. L iu,116 T. Scarborough,116 O. C haraf,117 S .I. C ooper,117 C. H enderson,117 P. R um erio,117 A. A vetisyan,118 T. B ose,118 C. Fantasia,118 P. L aw son,118 C. R ichardson,118 J. R ohlf,118 J. St. Jo h n ,118 L. Sulak,118 J. A lim ena,119 E. B erry,119 S. B hattacharya,119 G. Christopher,119 D. C utts,119 Z. D em iragli,119 N. D hingra,119 A. Ferapontov,119 A. G arabedian,119 U. H eintz,119 G. Kukartsev,119 E. L aird,119 G. L andsberg,119 M. L u k ,119 M. N arain,119 M. Segal a ,116 T. Sinthuprasith,119 T. Speer,119 J. Sw anson,119 R. B reedon,120 G. B reto,120 M. Calderon D e La Barca Sanchez,120 S. C hauhan,1Jl M. C hertok,120 J. Conw ay,120 R. Conw ay,120 P. T. C ox,120 R. Erbacher,120 M. G ardner,120 W. K o,120 R. Lander,120 T. M iceli,120 M. M ulheam ,120 D. Pellett,120 J. Pilot,120 F. R icci-Tam ,120 M. Searle,120 S. Shalhout,120 J. Sm ith,120 M. Squires,120 D. Stolp,120 M. Tripathi,120 S. W ilbur,120 R. Yohay,120 R. C ousins,121 P. Everaerts,121 C. Farrell,121 J. H auser,121 M. Ignatenko,121 G. R akness,121 E. Takasugi,121 V. Valuev,121 M. W eber,121 K. B urt,122 R. C lare,122 J. Ellison,122 J.W . G ary,122 G. H anson,122 J. H eilm an,122 M. Ivova R ikova,122 P. Jandir,122 E. K ennedy,122 F. Lacroix,122 O. R. L ong,122 A. L uthra,122 M. M alberti,122 M. Olm edo N egrete,122 A. Shrinivas,122 S. Sum ow idagdo,122 S. W im penny,122 J. G. B ranson,123 G. B. Cerati,123 S. C ittolin,123 R .T . D ’A gnolo,123 A. H olzner,123 R. Kelley,123 D. K lein,123 D. K ovalskyi,123 J. Letts,123 I. M acneill,123 D. O livito,123 S. P adhi,123 C. Palm er,123 M. Pieri,123 M. Sani,123 V. Sharm a,123 S. Sim on,123 E. Sudano,123 Y. T u,123 123

123

123

124

124

• 124

A. Vartak,123 C. W elke,1"5 F. W iirthw ein,1"5 A. Yagil,1" D. B arge,1"4 J. Bradm iller-Feld,1Z4 C. Campagnari,

T. D anielson,124 A. D ishaw ,124 V. D utta,124 K. Flow ers,124 M. Franco Sevilla,124 P. Geffert,124 C. G eorge,124 F. G olf,124 L. G ouskos,124 J. Incandela,124 C. Justus,124 N. M ccoll,124 J. Richm an,124 D. Sm art,124 W. To,124 C. W est,124 J. Yoo,124 A. A presyan,1-5 A. B om heim ,125 J. B unn,125 Y. C hen,125 J. D uarte,125 A. M ott,125 H. B. N ew m an,125 C. P ena,125 C. R ogan,125 M. Spiropulu,125 V. Tim ciuc,125 J .R . V lim ant,125 R. W ilkinson,125 S. X ie,125 R. Y. Z hu,125 V. A zzolini,126 126

126

126

• 126

126

126

. 126

A. C alam ba,126 B. C arlson,1"0 T. Ferguson,1"0 Y. Iiyam a,1"0 M. Paulini,1"0 J. R uss,1"0 H. Vogel,1"0 I. Vorobiev,

J. P. C um alat,127 W. T. F ord,127 A. G az,127 M. K rohn,127 E. Luiggi Lopez,127 U. N auenberg,127 J. G. Sm ith,127 K. Stenson,127 K. A. U lm er,127 S. R. W agner,127 J. A lexander,128 A. C hatteijee,128 J. Chaves,128 J. C hu,128 S. D ittm er,128 N. E ggert,128 N. M irm an,128 G. Nicolas K aufm an,128 J. R. Patterson,128 A. R y d ,128 E. Salvati,128 L. Skinnari,128 W. S un,128 W. D. Teo,128 J. T hom ,128 J. T hom pson,128 J. Tucker,128 Y. W eng,128 L. W instrom ,128 P. W ittich,128 D. W inn,129 S. A bdullin,130 M. A lbrow ,130 J. A nderson,130 G. A pollinari,130 L. A .T . B auerdick,130 A. Beretvas,130 J. Berryhill,130 P C . B hat,130 G. B olla,130 K. B urkett,130 J. N. Butler,130 H. W. K. C heung,130 F. C hlebana,130 S. Cihangir,130 V. D. Elvira,130 I. F isk,130 J. F reem an,130 Y. G ao,130 E. G ottschalk,130 L. G ray,130 D. G reen,130 S. G riinendahl,130 O. G utsche,130 J. H anlon,130

051801-10

114, 051801 (2015)

PRL

PHYSICAL

REVIEW

LETTERS

week ending

6 FEBRUARY 2015

D. H are,130 R. M. H arris,130 J. H irschauer,130 B. H ooberm an,130 S. Jindariani,130 M. Johnson,130 U. Joshi,130 K. K aadze,130 B. K lim a,130 B. K reis,130 S. K w an,130’3 J. Linacre,130 D. L incoln,130 R. L ipton,130 T. L iu,130 R. Lopes De S a,130 J. Lykken,130 K.

M aeshim a,130 J. M. M arraffino,130 V. I. M artinez O utschoom ,130 S. M aruyam a,130 D. M ason,130 P. M cB ride,130

P. M erkel,130 K. M ishra,130 S. M renna,130 Y. M usienko,130’dd S. N ahn,130 C. N ew m an-H olm es,130 V. O ’D ell,130 0 . Prokofyev,130 E. Sexton-K ennedy,130 S. Sharm a,130 A. Soha,130 W. J. Spalding,130 L. Spiegel,130 L. Taylor,130 S. Tkaczyk,130 N. V. T ran,130 L. U plegger,130 E. W. Vaandering,130 R. V idal,130 A. W hitbeck,130 J. W hitm ore,130 F. Y ang,130 D. A costa,131 P. Avery,1’1 P B ortignon,131 D. Bourilkov,131 M. Carver,131 D. C urry,131 S. D as,131 M. De G ruttola,131 G. P. Di G iovanni,131 R. D. F ield,131 M. Fisher,1311. K. Furic,131 J. H ugon,131 J. K onigsberg,131 A. Korytov,131 T. K ypreos,131 J. F. Low ,131 K. M atchev,131 H. M ei,131 P. M ilenovic,131,aaa G. M itselm akher,131 L. M uniz,131 A. Rinkevicius,131 L. Shchutska,131 M. Snow ball,131 D. Sperka,131 J. Yelton,131 M. Zakaria,131 S. H ew am anage,132 S. L inn,132 P. M arkow itz,132 G. M artinez,132 J. L. R odriguez,132 T. A dam s,133 A. A skew ,133 J. B ochenek,133 B. D iam ond,133 J. H aas,133 S. H agopian,133 V. H agopian,13’ K. F. Johnson,133 H. Prosper,133 V. Veeraraghavan,133 M. W einberg,133 M. M. Baarm and,134 M.

H ohlm ann,134 H. K alakhety,134 F. Yumiceva,134 M. R. A dam s,135 L. A panasevich,135 D. Berry,135 R. R. B etts,135

I. Bucinskaite,131 R. C avanaugh,131 O. Evdokim ov,135 L. G authier,135 C. E. Gerber,131 D .J. H ofm an,135 P. K urt,135 D. H. M oon,131 C. O ’B rien,135 I. D. Sandoval G onzalez,135 C. Silkw orth,131 P. Turner,135 N. Varelas,135 B. B ilki,136,bbb W. C larida,136 K. D ilsiz,136 F. D uru,136 M. H aytm yradov,136 J.-P. M erlo,136 H. M erm erkaya,136’ccc A. M estvirishvili,136 A. M oeller,136 J. N achtm an,136 H. O gul,136 Y. O nel,136 F. O zok,136’uu A. P enzo,136 R. R ahm at,136 S. S en,136 P. Tan,136 E. Tiras,136 J. W etzel,136 K. Y i,136 B. A. B arnett,137 B. B lum enfeld,137 S. B olognesi,137 D. Fehling,137 A. V. G ritsan,137 P. M aksim ovic,137 C. M artin,137 M. Sw artz,137 P. Baringer,138 A. B ean,138 G. B enelli,138 C. B runer,138 R. P. Kenny III,138 M. M alek,138 M. M urray,138 D. N oonan,138 S. Sanders,138 J. Sekaric,138 R. Stringer,138 Q. W ang,138 J. S. W ood,138 I. C hakaberia,139 A. Ivanov,139 S. K halil,139 M. M akouski,139 Y. M aravin,139 L. K. Saini,139 S. Shrestha,139 N. Skhirtladze,139 I. Svintradze,139 J. G ronberg,140 D. L ange,140 F. R ebassoo,140 D. W right,140 A. B aden,141 A. B elloni,141 B. C alvert,141 S .C . E n o ,141 J. A. G om ez,141 N .J. H adley,141 R. G. K ellogg,141 T. K olberg,141 Y. L u ,141 M. M arionneau,141 A. C. M ignerey,141 K. Pedro,141 A. Skuja,141 M .B . Tonjes,141 S .C . Tonwar,141 A. A pyan,142 R. Barbieri,142 G. B auer,142 W. B usza,14" I. A. C ali,14" M. C h an ,14' L. Di M atteo,142 G. Gom ez C eballos,142 M. G oncharov,142 D. G ulhan,142 M. K lute,142 Y. S. L ai,142 Y.-J. L ee,142 A. L evin,142 P. D. Luckey,142 T. M a,142 C. Paus,142 D. R alph,142 C. R oland,142 G. R oland,142 G. S. F. Stephans,14" F. Stockli,142 K. Sum orok,142 D. Velicanu,142 J. Veverka,142 B. W yslouch,142 M. Y ang,142 M. Z anetti,142 V. Z hukova,142 B. D ahm es,143 A. G ude,143 S .C . K ao,143 K. K lapoetke,143 Y. K ubota,143 J. M ans,143 N. Pastika,143 R. R usack,143 A. Singovsky,143 N. Tam be,143 J. Turkew itz,143 J. G. A costa,144 S. O liveros,144 E. Avdeeva,145 K. B loom ,145 S. B ose,141 D. R. C laes,141 A. D om inguez,145 R. Gonzalez Suarez,145 J. K eller,141 D. K now lton,145 I. K ravchenko,145 J. Lazo-Flores,145 S. M alik,145 F. M eier,145 F. R atnikov,145 G .R . Snow,145 M. Zvada,145 J. D olen,146 A. G odshalk,146 1. Iashvili,146 A. K harchilava,146 A. K um ar,146 S. R appoccio,146 G. A lverson,147 E. Barberis,147 D. B aum gartel,147 M . C hasco,147 J. H aley,147 A. M assironi,147 D. M. M orse,147 D. N ash,147 T. O rim oto,147 D. Trocino,147 R.-J. W ang,147 D. W ood,147 J. Z hang,147 K. A. H ahn,148 A. K ubik,148 N. M ucia,148 N. O dell,148 B. Pollack,148 A. Pozdnyakov,148 M. Schm itt,148 S. Stoynev,148 K. Sung,148 M. Velasco,148 S. W on,148 A. Brinkerhoff,149 K. M. C han,149 A. D rozdetskiy,149 M. H ildreth,149 C. Jessop,149 D .J. K arm gard,149 N. K ellam s,149 K. L annon,149 S. Lynch,149 N. M arinelli,149 T. Pearson,149 M. Planer,149 R. R uchti,149 N. Vails,149 M. W ayne,149 M. W olf,149 A. W oodard,149 L. A ntonelli,150 J. B rinson,150 B. B ylsm a,150 L. S. D urkin,150 S. Flow ers,150 A. H art,150 C. H ill,150 R. H ughes,150 K. Kotov,150 T. Y. L ing,150 W. L uo,150 D. P uigh,150 M. R odenburg,150 G. Sm ith,150 B .L . W iner,150 H. W olfe,150 H .W . W ulsin,150 O. D riga,151 P. Elm er,151 J. H ardenbrook,151 P. H ebda,151 A. H unt,151 S. A. K oay,151 P. L ujan,151 D. M arlow,151 T. M edvedeva,151 M. M ooney,151 J. O lsen,151 P. Piroue,151 X. Q uan,151 H. Saka,151 D. Stickland,151'c C. Tully,151 J. S. W erner,151 A. Z uranski,151 E. B row nson,152 H. M endez,112 J. E. Ram irez Vargas,152 V. E. B arnes,153 D. B enedetti,153 D. B ortoletto,153 M. De M attia,153 L. G utay,153 Z. H u ,153 M. K. Jh a,153 M. Jones,153 K. Jung,153 M. K ress,153 N. L eonardo,153 D. Lopes P egna,153 V. M aroussov,153 D. H. M iller,153 N. N eum eister,153 B .C . R adbum -Sm ith,153 X. S hi,153 I. Shipsey,153 D. Silvers,153 A. Svyatkovskiy,153 F. W ang,153 W. X ie,153 L. X u ,153 H. D. Yoo,153 J. Zablocki,153 Y. Z heng,153 N. Parashar,154 J. Stupak,154 A. A dair,155 B. A kgun,155 K .M . E cklund,155 F .J .M . G eurts,155 W. L i,155 B. M ichlin,155 B .P. Padley,155 R. R edjim i,155 J. R oberts,155 J. Z abel,155 B. B etchart,156 A. B odek,156 R. C ovarelli,156 P. de B arbara,156 R. D em ina,156 Y. E shaq,156 T. Ferbel,156 A. G arcia-B ellido,156 P. G oldenzw eig,156 J. H an,156 A. H arel,116 A. K hukhunaishvili,156 S. K orjenevski,156 G. Petrillo,156 D. V ishnevskiy,156 R. C iesielski,157 L. D em ortier,157 K. G oulianos,157 G. L ungu,157 C. M esropian,157

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S. A ro ra,'58 A. B arker,138 J. P. C hou,158 C. C ontreras-Cam pana,158 E. C ontreras-C am pana,158 D. D uggan,158 D. Ferencek,158 Y. G ershtein,158 R. G ray,158 E. H alkiadakis,158 D. H idas,158 S. K aplan,158 A. L ath,158 S. Panwalkar,158 M. Park,158 R. Patel,158 S. Salur,158 S. Schnetzer,158 S. Som alw ar,158 R. Stone,158 S. Thom as,158 P. Thom assen,158 M. W alker,158 K. R ose,159 S. Spanier,159 A. York,159 O. B ouhali,160'ddd A. C astaneda H ernandez,160 R. E usebi,160 W. Flanagan,160 J. G ilm ore,160 T. K am on,160,eee V. K hotilovich,160 V. Krutelyov,160 R. M ontalvo,1601. O sipenkov,160 Y. Pakhotin,160 A. Perloff,160 J. R oe,160 A. R ose,160 A. Safonov,160 I. S uarez,160 A. Tatarinov,160 N. A kchurin,161 C. C ow den,161 J. D am gov,161 C. D ragoiu,161 P. R. D udero,161 J. Faulkner,161 K. K ovitanggoon,161 S. K unori,161 S. W. L ee,161 T. Libeiro,161 I. Volobouev,161 E. A ppelt,162 A. G. D elannoy,162 S. G reene,162 A. G urrola,162 W. Johns,162 C. M aguire,162 Y. M ao,162 A. M elo,162 M. Sharm a,162 P. Sheldon,162 B. Snook,162 S. T uo,162 J. V elkovska,162 M. W. A renton,163 S. B outle,163 B. C ox,163 B. Francis,163 J. G oodell,163 R. H irosky,163 A. Ledovskoy,163 H. L i,163 C. L in,163 C. N eu,163 J. W ood,163 C. C larke,164 R. H arr,164 P. E. K archin,164 C. Kottachchi K ankanam ge D o n ,164 P. Lam ichhane,164 J. Sturdy,164 D. A. B elknap,165 D. C arlsm ith,165 M. C epeda,165 S. D asu,165 L. D odd,165 S. D uric,165 E. Friis,165 R. H all-W ilton,165 M. H erndon,165 A. H erve,165 P. K labbers,165 A. L anaro,165 C. L azaridis,165 A. L evine,165 R. L oveless,165 A. M ohapatra,165 I. O jalvo,165 T. Perry,165 G. A. Pierro,165 G. Polese,165 I. R oss,165 T. Sarangi,165 A. Savin,165 W .H . Sm ith,165 D. Taylor,165 P. Verwilligen,165 C. V uosalo,165 and N. W oods165 (CMS Collaboration) 1Yerevan Physics Institute, Yerevan, Armenia 2Institut fu r Hochenergiephysik der OeAW, Wien, Austria 3National Centre fo r Particle and High Energy Physics, Minsk, Belarus 4Universiteit Antwerpen, Antwerpen, Belgium 5Vrije Universiteit Brussel, Brussel, Belgium ^Universite Libre de Bruxelles, Bruxelles, Belgium 1Ghent University, Ghent, Belgium xUniversite Catholique de Louvain, Louvain-la-Neuve, Belgium 9Universite de Mons, Mons, Belgium 10Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil 11 Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil i2dUniversidade Estadual Paulista, Sao Paulo, Brazil 12b Universidade Federal do ABC, Sao Paulo, Brazil 13Institute fo r Nuclear Research and Nuclear Energy, Sofia, Bulgaria 14University o f Sofia, Sofia, Bulgaria 15Institute o f High Energy Physics, Beijing, China 16State Key Laboratory o f Nuclear Physics and Technology, Peking University, Beijing, China 17 Universidad de Los Andes, Bogota, Colombia 18 University o f Split, Faculty o f Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia 19University o f Split, Faculty o f Science, Split, Croatia 20Institute Rudjer Boskovic, Zagreb, Croatia 21 University o f Cyprus, Nicosia, Cyprus 22Charles University, Prague, Czech Republic 23Academy o f Scientific Research and Technology o f the Arab Republic o f Egypt, Egyptian Network o f High Energy Physics, Cairo, Egypt 24National Institute o f Chemical Physics and Biophysics, Tallinn, Estonia 25Department o f Physics, University o f Helsinki, Helsinki, Finland 2bHelsinki Institute o f Physics, Helsinki, Finland 21Lappeenranta University o f Technology, Lappeenranta, Finland 'DSM/IRFU, CEAJSaclay, Gif-sur-Yvette, France 29Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France 30Institut Pluridisciplinaire Hubert Curien, Universite de Strasbourg, Universite de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France 31 Centre de Calcul de Vlnstitut National de Physique Nucleaire et de Physique des Particules, CNRS/1N2P3, Villeurbanne, France 32Universite de Lyon, Universite Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucleaire de Lyon, Villeurbanne, France 33Institute o f High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia 34RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany 35RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany

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36RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany 31Deutsches Elektronen-Synchrotron, Hamburg, Germany 38 University o f Hamburg, Hamburg, Germany 39Institut fiir Experimented Kernphysik, Karlsruhe, Germany 40Institute o f Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece 41University o f Athens, Athens, Greece 42University o f Ioannina, Ioannina, Greece 43 Wigner Research Centre fo r Physics, Budapest, Hungary 44Institute o f Nuclear Research ATOMKI, Debrecen, Hungary 45 University o f Debrecen, Debrecen, Hungary 46National Institute o f Science Education and Research, Bhubaneswar, India 41Punjab University, Chandigarh, India 48 University o f Delhi, Delhi, India 49Saha Institute o f Nuclear Physics, Kolkata, India 50Bhabha Atomic Research Centre, Mumbai, India 51 Tata Institute o f Fundamental Research, Mumbai, India 52Institute fo r Research in Fundamental Sciences (1PM), Tehran, Iran 53 University College Dublin, Dublin, Ireland 54dINFN Sezione di Bari, Bari, Italy 54bUniversita di Bari, Bari, Italy 54cPolitecnico di Bari, Bari, Italy 55jINFN Sezione di Bologna, Bologna, Italy 55bUniversita di Bologna, Bologna, Italy 56aINFN Sezione di Catania, Catania, Italy 56bUniversita di Catania, Catania, Italy 56cCSFNSM, Catania, Italy 51*INFN Sezione di Firenze, Firenze, Italy 51bUniversita di Firenze, Firenze, Italy 58 INFN Laboratori Nazionali di Frascati, Frascati, Italy 3>dINFN Sezione di Genova, Genova, Italy 59bUniversita di Genova, Genova, Italy 60aINFN Sezione di Milano-Bicocca, Milano, Italy 60bUniversita di Milano-Bicocca, Milano, Italy 6UINFN Sezione di Napoli, Napoli, Italy b'bUniversita di Napoli ’Federico TP, Napoli, Italy 6UUniversita della Basilicata (Potenza), Napoli, Italy bldUniversita Guglielmo Marconi (Roma), Napoli, Italy 62liINFN Sezione di Padova, Padova, Italy b2bUniversita di Padova, Padova, Italy b2cUniversita di Trento (Trento), Padova, Italy 63iINFN Sezione di Pavia, Pavia, Italy b3bUniversity di Pavia, Pavia, Italy MdTNFN Sezione di Perugia, Perugia, Italy b4hUniversitd di Perugia, Perugia, Italy 65dINFN Sezione di Pisa, Pisa, Italy 65bUniversita di Pisa, Pisa, Italy 65cScuola Normale Superiore di Pisa, Pisa, Italy bbaINFN Sezione di Roma, Roma, Italy 66bUniversita di Roma, Roma, Italy b7aINFN Sezione di Torino, Torino, Italy 67bUniversity di Torino, Torino, Italy 61cUniversita del Piemonte Orientale (Novara), Torino, Italy 6S*INFN Sezione di Trieste, Trieste, Italy (m University di Trieste, Trieste, Italy 69Kangwon National University, Chunchon, Korea 10Kyungpook National University, Daegu, Korea ll Chonbuk National University, Jeonju, Korea 12Chonnam National University, Institute fo r Universe and Elementary Particles, Kwangju, Korea 13Korea University, Seoul, Korea 14University o f Seoul, Seoul, Korea

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15Sungkyunkwan University, Suwon, Korea 16Vilnius University, Vilnius, Lithuania 11National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia 78Centro de Investigation y de Estudios Avanzados del IPN, Mexico City, Mexico 19Universidad Iberoamericana, Mexico City, Mexico 80 Benemerita Universidad Autonoma de Puebla, Puebla, Mexico 8 1Universidad Autonoma de San Luis Potosi, San Luis Potosi, Mexico 82 University o f Auckland, Auckland, New Zealand 83University o f Canterbury, Christchurch, New Zealand 84National Centre fo r Physics, Quaid-I-Azam University, Islamabad, Pakistan 85National Centre fo r Nuclear Research, Swierk, Poland 86Institute o f Experimental Physics, Faculty o f Physics, University o f Warsaw, Warsaw, Poland 87Laboratorio de Instrumentagao e Fisica Experimental de Partlculas, Lisboa, Portugal 88Joint Institute fo r Nuclear Research, Dubna, Russia 89Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia 90Institute fo r Nuclear Research, Moscow, Russia 91 Institute fo r Theoretical and Experimental Physics, Moscow, Russia 92P.N. Lebedev Physical Institute, Moscow, Russia 93Skobeltsyn Institute o f Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia 94State Research Center o f Russian Federation, Institute fo r High Energy Physics, Protvino, Russia 95 University o f Belgrade, Faculty o f Physics and Vinca Institute o f Nuclear Sciences, Belgrade, Serbia 96Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid, Spain 91 Universidad Autonoma de Madrid, Madrid, Spain 98 Universidad de Oviedo, Oviedo, Spain 99Instituto de Fisica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain l00CERN, European Organization fo r Nuclear Research, Geneva, Switzerland ]0>Paul Scherrer Institut, Villigen, Switzerland '02Institute fo r Particle Physics, ETH Zurich, Zurich, Switzerland m Universitat Zurich, Zurich, Switzerland 104National Central University, Chung-Li, Taiwan m National Taiwan University (NTU), Taipei, Taiwan l06Chulalongkom University, Faculty o f Science, Department o f Physics, Bangkok, Thailand Cukurova University, Adana, Turkey m Middle East Technical University, Physics Department, Ankara, Turkey m Bogazici University, Istanbul, Turkey 110Istanbul Technical University, Istanbul, Turkey 111National Scientific Center, Kharkov Institute o f Physics and Technology, Kharkov, Ukraine 112 University o f Bristol, Bristol, United Kingdom 113Rutherford Appleton Laboratory, Didcot, United Kingdom 114Imperial College, London, United Kingdom U5Brunel University, Uxbridge, United Kingdom 1u'Baylor University, Waco, USA n lThe University o f Alabama, Tuscaloosa, USA 118Boston University, Boston, USA 119Brown University, Providence, USA '"University o f California, Davis, Davis, USA 121 University o f California, Los Angeles, USA m University o f California, Riverside, Riverside, USA University o f California, San Diego, La Jolla, USA l24University o f California, Santa Barbara, Santa Barbara, USA 125 California Institute o f Technology, Pasadena, USA 126Camegie Mellon University, Pittsburgh, USA 127 University o f Colorado at Boulder, Boulder, USA m Cornell University, Ithaca, USA 129Fairfield University, Fairfield, USA 130Fermi National Accelerator Laboratory, Batavia, USA 131 University o f Florida, Gainesville, USA U2Florida International University, Miami, USA 133 Florida State University, Tallahassee, USA 134Florida Institute o f Technology, Melbourne, USA

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135

University o f Illinois at Chicago (UIC), Chicago, USA U6The University o f Iowa, Iowa City, USA 137Johns Hopkins University, Baltimore, USA m The University o f Kansas, Lawrence, USA >39Kansas State University, Manhattan, USA 140Lawrence Livermore National Laboratory, Livermore, USA 141 University o f Maryland, College Park, USA 142Massachusetts Institute o f Technology, Cambridge, USA 143 University o f Minnesota, Minneapolis, USA 144University o f Mississippi, Oxford, USA 145 University o f Nebraska-Lincoln, Lincoln, USA l4bState University o f New York at Buffalo, Buffalo, USA 147Northeastern University, Boston, USA 148Northwestern University, Evanston, USA 149 University o f Notre Dame, Notre Dame, USA m The Ohio State University, Columbus, USA 151 Princeton University, Princeton, USA 152 University o f Puerto Rico, Mayaguez, USA 153Purdue University, West Lafayette, USA 154Purdue University Calumet, Hammond, USA l55Rice University, Houston, USA 156University o f Rochester, Rochester, USA lblThe Rockefeller University, New York, USA 158Rutgers, The State University o f New Jersey, Piscataway, USA 159University o f Tennessee, Knoxville, USA l60Texas A&M University, College Station, USA m Texas Tech University, Lubbock, USA >62Vanderbilt University, Nashville, USA 163 University o f Virginia, Charlottesville, USA IMWayne State University, Detroit, USA 165 University o f Wisconsin, Madison, USA “Deceased. bAlso at Vienna University of Technology, Vienna, Austria. “Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland. dAlso at Institut Pluridisciplinaire Hubert Curien, Universite de Strasbourg, Universite de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France. “Also at National Institute of Chemical Physics and Biophysics, Tallinn, Estonia. fAlso at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia. 8Also at Universidade Estadual de Campinas, Campinas, Brazil. hAlso at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France. ‘Also at Joint Institute for Nuclear Research, Dubna, Russia. JAlso at Suez University, Suez, Egypt. kAlso at Cairo University, Cairo, Egypt. ’Also at Fayoum University, El-Fayoum, Egypt. “ Also at British University in Egypt, Cairo, Egypt. "Also at Sultan Qaboos University, Muscat, Oman. "Also at Universite de Haute Alsace, Mulhouse, France. pAlso at Brandenburg University of Technology, Cottbus, Germany. qAlso at Institute of Nuclear Research ATOMKI, Debrecen, Hungary. ‘Also at Eotvos Lorand University, Budapest, Hungary. “Also at University of Debrecen, Debrecen, Hungary. ‘Also at University of Visva-Bharati, Santiniketan, India. “Also at King Abdulaziz University, Jeddah, Saudi Arabia. vAlso at University of Ruhuna, Matara, Sri Lanka. wAlso at Isfahan University of Technology, Isfahan, Iran. xAlso at University of Tehran, Department of Engineering Science, Tehran, Iran. yAlso at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran. zAlso at Universita degli Studi di Siena, Siena, Italy. aaAlso at Centre National de la Recherche Scientifique (CNRS) - 1N2P3, Paris, France.

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PRL 114, 051801 (2015) bbAlso “ Also ddAlso “ Also ffAlso ggAlso hhAlso “Also Also kkAlso uAlso "““Also ""Also 00Also ppAlso qqAlso "Also ssAlso "Also “"Also vvAlso wwAlso “ Also yyAlso zzAlso “ "Also bbbAlso “ "Also dddAlso eeeAlso

at at at at at at at at at at at at at at at at at at at at at at at at at at at at at at

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week ending 6 FEBRUARY 2015

Purdue University, West Lafayette, USA. Universidad M ichoacana de San Nicolas de Hidalgo, Morelia, Mexico. Institute for Nuclear Research, Moscow, Russia. St. Petersburg State Polytechnical University, St. Petersburg, Russia. California Institute of Technology, Pasadena, USA. Faculty of Physics, University of Belgrade, Belgrade, Serbia. Facolta Ingegneria, Universita di Roma, Roma, Italy. Scuola Normale e Sezione dell’INFN, Pisa, Italy. University of Athens, Athens, Greece. Paul Scherrer Institut, Villigen, Switzerland. Institute for Theoretical and Experimental Physics, Moscow, Russia. Albert Einstein Center for Fundamental Physics, Bern, Switzerland. Gaziosmanpasa University, Tokat, Turkey. Adiyaman University, Adiyaman, Turkey. Cag University, Mersin, Turkey. Anadolu University, Eskisehir, Turkey. Ozyegin University, Istanbul, Turkey. Izmir Institute of Technology, Izmir, Turkey. Necmettin Erbakan University, Konya, Turkey. Mimar Sinan University, Istanbul, Istanbul, Turkey. Marmara University, Istanbul, Turkey. Kafkas University, Kars, Turkey. Yildiz Technical University, Istanbul, Turkey. Rutherford Appleton Laboratory, Didcot, United Kingdom. School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom. University o f Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia. Argonne National Laboratory, Argonne, USA. Erzincan University, Erzincan, Turkey. Texas A&M University at Qatar, Doha, Qatar. Kyungpook National University, Daegu, Korea.

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