Study of \cPZ boson production in PbPb collisions at \sqrt{s_{\rm NN}}=2.76 TeV

Study of \cPZ boson production in PbPb collisions at  TeV


A search for \cPZ bosons in the decay channel has been performed in PbPb collisions at  TeV with the CMS detector at the LHC, in a 7.2 b data sample. The number of opposite-sign muon pairs observed in the 60–120 GeV/ invariant mass range is 39, corresponding to a yield per unit of rapidity () and per minimum bias event of , in the range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.




\RCS \RCS \cmsNoteHeaderHIN-10-003 cern]The CMS Collaboration

The hot and dense matter produced in heavy-ion collisions, often referred to as the quark-gluon plasma (QGP), can be studied in various ways. One approach is to compare measurements made in heavy-ion (AA) collisions to those in proton-proton (\Pp\Pp) and proton- (or deuteron-) nucleus collisions. Another way is to compare in the same AA sample the yields of particles that are modified by the QGP to those of unmodified reference particles. At the Relativistic Heavy Ion Collider (RHIC), direct photons play the reference role [1], although their measurement is complicated by copious background from and other decays, and by the existence of a parton fragmentation component which is potentially modified by the medium [2]. At the Large Hadron Collider (LHC) energies, a new and cleaner reference becomes available: the \cPZ boson, decaying into leptons [3, 4].

Electroweak boson production is an important benchmark process at hadron colliders. At 7 TeV centre-of-mass energy, measurements in \Pp\Pp collisions at the LHC [5, 6] are well described by calculations based on higher-order perturbative Quantum Chromodynamics (pQCD), using recent parton distribution functions (PDFs). In AA collisions, \cPZ boson production can be affected by various initial-state effects, though predictions indicate that these contributions are rather small [3, 7, 8, 9, 10]. Firstly, the mix of protons and neutrons in AA collisions (the so-called isospin effect) is estimated to modify the \cPZ yield by less than 3% compared to \Pp\Pp collisions [9]. Secondly, energy loss and multiple scattering of the initial partons can also alter the \cPZ production, by about 3% [10]. The PDFs however are modified in nuclei and a depletion (shadowing) is expected for \cPZ bosons at the LHC, modifying their yield by as much as 20% [9]. Precise measurements of \cPZ production in heavy-ion collisions can therefore help to constrain nuclear PDFs.

Once produced, \cPZ bosons decay within the medium, with a lifetime of  fm/. Their leptonic decays are of particular interest since leptons pass freely through the produced medium regardless of its nature (partonic or hadronic) and properties. Dileptons from \cPZ bosons can thus serve as a reference to the processes expected to be heavily modified in the QGP, such as quarkonia production, or the production of an opposite-side jet in \cPZ+jet processes [3, 11]. The \cPZ bosons are therefore ideally suited to serve as a standard candle of the initial state in PbPb collisions at the LHC energies.

During the first PbPb LHC run at the end of 2010, at a centre-of-mass energy per nucleon pair of  TeV, \cPZ bosons were observed by the Compact Muon Solenoid (CMS) experiment. The measurement reported in this letter is performed with a 55 million minimum bias (MB) event sample, corresponding to an integrated luminosity of 7.2 b.

A detailed description of the CMS detector can be found in [12]. Its central feature is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Within the field volume are the silicon pixel and strip tracker, the crystal electromagnetic calorimeter, and the brass/scintillator hadron calorimeter. Muons are measured in gas-ionisation detectors embedded in the steel return yoke. In addition, CMS has extensive forward calorimetry, in particular two steel/quartz-fiber Čerenkov, hadron forward (HF) calorimeters, which cover the pseudorapidity range .

In this analysis, \cPZ bosons are measured through their dimuon decays. The silicon pixel and strip tracker measures charged particle trajectories in the range . It consists of 66M pixel and 10M strip detector channels. It provides an impact parameter resolution of  15 m in the transverse plane. Muons are detected in the range, with detection planes based on three technologies: drift tubes, cathode strip chambers, and resistive plate chambers. A matching of the muons to the tracks measured in the silicon tracker results in a resolution between 1 and 2%, for values up to 100 GeV/.

The centrality of AA collisions, i.e. the geometrical overlap of the incoming nuclei, is related to the energy released in the collisions. In CMS, centrality is defined as percentiles of the distribution of the energy deposited in the HFs [13, 14]. The centrality classes used in this analysis are 30–100%, 10–30% and 0–10% (most central), ordered from the lowest to the highest HF energy deposit.

Events are preselected if they contain a reconstructed primary vertex made of at least two tracks, and an offline coincidence of both of the HFs with a total deposited energy of at least 3 GeV. These criteria reduce contributions from single-beam interactions with the environment (e.g. beam-gas and beam halo collisions with the beam pipe), ultra-peripheral electromagnetic collisions, and cosmic-ray muons. The acceptance of this selection is % of the hadronic inelastic cross section [13].

The events are also selected by the two-level trigger of CMS. At the first hardware level, two muon candidates in the muon detectors are required. At the software-based higher-level, two reconstructed tracks in the muon detectors are required, each with a of at least 3 GeV/. In order to study the dimuon trigger efficiency, events are also collected with a single-muon trigger, requiring  GeV/. For \cPZ bosons, the trigger efficiency is estimated to be %.

Muon offline reconstruction is seeded with % efficiency by tracks in the muon detectors, called stand-alone muons. These tracks are then matched to tracks reconstructed in the silicon tracker by means of an algorithm optimised for the heavy-ion environment [15, 14]. For muons from \cPZ decays, the tracking efficiency is  85%, less than in the \Pp\Pp case, as the track reconstruction requires more pixel hits to lower the number of combinations, due to the high multiplicity. Global fits of the muon and tracker tracks, called global muons, are used to obtain the results presented in this letter.

Background muons from cosmic rays and heavy-quark semileptonic decays are rejected by requiring a transverse (longitudinal) impact parameter of less than 0.3 (1.5) mm from the measured vertex. Loose criteria applied on the reconstructed muons result in the dimuon mass spectrum shown in Fig. 1, for muons with  GeV/. No muon isolation criteria are applied, as they are expected to have reduced efficiency in the high particle density of the PbPb environment. The fraction of \cPZ decays removed by the applied selection criteria is estimated to be %, in both data and simulation. Residual background is estimated to be less than 4% by extrapolations from the low mass region, and no correction is applied. Thirty-nine \cPZ candidates are observed in the mass interval 60–120 GeV/. Their distribution is consistent with the one from \Pp\Pp data at 7 TeV [6], scaled down to 39 counts and displayed as an histogram limited to the 60–120 GeV/ mass range in Fig. 1.

Figure 1: Dimuon invariant mass spectra. Full squares are opposite-sign dimuons, while the empty circle shows a unique like-sign dimuon candidate. The histogram shows the corresponding distribution measured in pp collisions at 7 TeV within 60–120 GeV/, scaled to the 39 PbPb candidates.

Muon trigger, reconstruction and selection efficiencies, as well as acceptance, are estimated using the \PYTHIA6.424 simulation [16] with CTEQ6L PDFs [17] and full \GEANTfour [18] detector simulation. To take into account the effect of the higher PbPb underlying-event activity, simulated \cPZ decays are embedded in measured PbPb events at the level of detector hits and with generated vertices matched to the measured ones. These events were processed through the trigger emulation and event reconstruction chain. Track characteristics, such as the number of hits and the of the track fit, have similar distributions in data and simulation. The detector acceptance , defined as the fraction of \cPZ bosons produced at rapidity that decay into muons with and  GeV/, is estimated to be 78%. Within this acceptance, the overall trigger, reconstruction, and identification efficiency averages to 67%, and varies by less than 10% as a function of centrality.

The individual components of this efficiency are also estimated with a technique using data, called tag-and-probe, similar to the one used for the corresponding \Pp\Pp measurement [6]. It consists in counting the \cPZ candidates with and without applying the probed selection on one of the muons: 1) the stand-alone muon reconstruction efficiency is probed with tracker tracks; 2) the silicon tracker reconstruction efficiency is probed with stand-alone muons; 3) the trigger efficiency is probed by testing the trigger response to global muons from a sample triggered by a single-muon requirement. The latter is also checked with high-quality reconstructed muons from MB events. In all cases, these data-driven efficiencies agree with those derived from simulation within the statistical uncertainties.

The total systematic uncertainty on the \cPZ yield is estimated to be 13% by summing in quadrature the following contributions. The largest one is associated with the tracking efficiency and taken as the 9.8% precision of the above-mentioned data-driven efficiency determination. Similarly, the uncertainty associated with the dimuon trigger is 4.5%. The 4% maximum contribution from unsubtracted background is taken as a systematic uncertainty. The uncertainty associated with the selection criteria is considered to be equal to the 2.6% loss of events. The MB trigger efficiency is known at the 3% level. The uncertainty coming from the acceptance correction is estimated to be less than 3%, by varying the underlying generated kinematics (, ) beyond reasonable modifications. Other systematic uncertainties are estimated to sum to less than 1.5%.

The yield of decays per MB event is defined as , where is the number of dimuons counted in the mass window of 60–120 GeV/, is the number of corresponding MB events, corrected for trigger efficiency, and are the acceptance and overall efficiency, and is the rapidity bin width. We find , where the first uncertainty is statistical and the second systematic. The analysis described above is repeated after subdividing the data into three bins for each of the following variables: event centrality and \cPZ boson and . The total systematic uncertainty does not vary significantly with these variables and is considered to be constant and dominantly uncorrelated.

In the absence of in-medium modifications, the yield of perturbative processes such as the \cPZ boson production is supposed to scale with the number of incoherent nucleon-nucleon binary collisions. In order to compare the PbPb measured yields to available \Pp\Pp cross-section calculations, a scaling factor is necessary. This nuclear overlap function is equal to the number of elementary nucleon-nucleon binary collisions divided by the elementary NN cross section, and can be interpreted as the NN equivalent integrated luminosity per AA collision, at a given centrality. In units of mb, the average amounts to , , and , for the centrality ranges 30–100%, 10–30% and 0–10%, respectively, and for MB events. These numbers are computed with a Glauber model calculation [19], using the same parameters as in [13]. The quoted uncertainties are derived by varying within uncertainties the Glauber parameters and the MB trigger and selection efficiency.

The full circles in Fig. 2 (a) show the centrality dependence of the \cPZ yield divided by , while the open square is for MB events. The variable used on the abscissa is the average number of participating nucleons corresponding to the selected centrality intervals, computed in the same Glauber model. No centrality dependence of the binary-scaled \cPZ yields is observed in data. A similar result was recently published by the ATLAS collaboration [20].

The normalised yields are compared to various calculations: 1) using the nucleon CT10 and modified nuclear EPS09 PDFs [21, 9], 2) using MSTW08 PDFs [22] and modelling energy loss [11], and 3) provided by the powheg [23] generator interfaced with the \PYTHIAparton-shower generator and using CTEQ6.6 PDFs [17]. Only a marginal centrality dependence is predicted: the inhomogeneous (i.e. depending on the radial position in nuclei) shadowing is predicted to have negligible impact [7] and the energy-loss prediction drops by 3% from peripheral to central collisions [11].

Figure 2 (b) and (c) show the differential yields, and , as a function of the \cPZ boson and . They are compared to the same theoretical calculations as used for the centrality distribution (when available) multiplied by the minimum bias value. No significant deviations from binary-collision scaling are observed.

Figure 2: The yields of per event: a) divided by the expected nuclear overlap function and as a function of event centrality parameterised as the number of participating nucleons , b) versus the \cPZ boson , c) versus the \cPZ boson . Data points are located horizontally at average values measured within a given bin. Vertical lines (bands) correspond to statistical (systematic) uncertainties. Theoretical predictions are computed within the same bins as the data, and are described in the text.

Nuclear modification factors, , are computed from the AA measured yields , the nuclear overlap function , and the  \cPZ cross sections given by the powheg calculation (solid lines on Fig. 2, e.g.  pb in ). The systematic uncertainty includes uncertainties, but no uncertainty is assigned to the theoretical \Pp\Pp cross section. All values are found compatible with unity. They are reported in Table 1, together with the number of observed \cPZ bosons and their yield per event.

c ()
Centrality ()
% 7
% 14
% 18
Table 1: For each , and centrality interval, number of \cPZ bosons , associated yield per event , and nuclear modification factor derived by using a powheg \Pp\Pp reference. The quantity is given in units of (GeV/. The first uncertainty is statistical and the second systematic.

In conclusion, the \cPZ boson yield in PbPb collisions at  TeV has been measured inclusively and as a function of rapidity, transverse momentum, and centrality. Within uncertainties, no modification is observed with respect to theoretical next-to-leading order pQCD proton-proton cross sections scaled by the number of elementary nucleon-nucleon collisions. This measurement confirms the validity of the Glauber scaling for perturbative cross sections in nucleus-nucleus collisions at the LHC and establishes the feasibility of carrying out detailed \cPZ physics studies in heavy-ion collisions with the CMS detector. With upcoming PbPb collisions at higher luminosity, the \cPZ boson promises to be a powerful reference tool for final-state heavy-ion related signatures as well as providing a means to study the modifications of the parton distribution functions.

We thank Bryon Neufeld, Hannu Paukkunen, Carlos Salgado, Ivan Vitev, and Ramona Vogt for fruitful theoretical inputs on the nuclear effects involved in \cPZ production. We wish to congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine in 2010. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA).

Appendix A The CMS Collaboration

Yerevan Physics Institute, Yerevan, Armenia
S. Chatrchyan, V. Khachatryan, A.M. Sirunyan, A. Tumasyan \cmsinstskipInstitut für Hochenergiephysik der OeAW, Wien, Austria
W. Adam, T. Bergauer, M. Dragicevic, J. Erö, C. Fabjan, M. Friedl, R. Frühwirth, V.M. Ghete, J. Hammer\cmsAuthorMark1, S. Hänsel, C. Hartl, M. Hoch, N. Hörmann, J. Hrubec, M. Jeitler, G. Kasieczka, W. Kiesenhofer, M. Krammer, D. Liko, I. Mikulec, M. Pernicka, H. Rohringer, R. Schöfbeck, J. Strauss, F. Teischinger, P. Wagner, W. Waltenberger, G. Walzel, E. Widl, C.-E. Wulz \cmsinstskipNational Centre for Particle and High Energy Physics, Minsk, Belarus
V. Mossolov, N. Shumeiko, J. Suarez Gonzalez \cmsinstskipUniversiteit Antwerpen, Antwerpen, Belgium
L. Benucci, E.A. De Wolf, X. Janssen, T. Maes, L. Mucibello, S. Ochesanu, B. Roland, R. Rougny, M. Selvaggi, H. Van Haevermaet, P. Van Mechelen, N. Van Remortel \cmsinstskipVrije Universiteit Brussel, Brussel, Belgium
F. Blekman, S. Blyweert, J. D’Hondt, O. Devroede, R. Gonzalez Suarez, A. Kalogeropoulos, J. Maes, M. Maes, W. Van Doninck, P. Van Mulders, G.P. Van Onsem, I. Villella \cmsinstskipUniversité Libre de Bruxelles, Bruxelles, Belgium
O. Charaf, B. Clerbaux, G. De Lentdecker, V. Dero, A.P.R. Gay, G.H. Hammad, T. Hreus, P.E. Marage, L. Thomas, C. Vander Velde, P. Vanlaer, J. Wickens \cmsinstskipGhent University, Ghent, Belgium
V. Adler, S. Costantini, M. Grunewald, B. Klein, A. Marinov, J. Mccartin, D. Ryckbosch, F. Thyssen, M. Tytgat, L. Vanelderen, P. Verwilligen, S. Walsh, N. Zaganidis \cmsinstskipUniversité Catholique de Louvain, Louvain-la-Neuve, Belgium
S. Basegmez, G. Bruno, J. Caudron, L. Ceard, E. Cortina Gil, C. Delaere, D. Favart, A. Giammanco, G. Grégoire, J. Hollar, V. Lemaitre, J. Liao, O. Militaru, S. Ovyn, D. Pagano, A. Pin, K. Piotrzkowski, N. Schul \cmsinstskipUniversité de Mons, Mons, Belgium
N. Beliy, T. Caebergs, E. Daubie \cmsinstskipCentro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil
G.A. Alves, D. De Jesus Damiao, M.E. Pol, M.H.G. Souza \cmsinstskipUniversidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
W. Carvalho, E.M. Da Costa, C. De Oliveira Martins, S. Fonseca De Souza, L. Mundim, H. Nogima, V. Oguri, W.L. Prado Da Silva, A. Santoro, S.M. Silva Do Amaral, A. Sznajder, F. Torres Da Silva De Araujo \cmsinstskipInstituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, Brazil
F.A. Dias, T.R. Fernandez Perez Tomei, E. M. Gregores\cmsAuthorMark2, C. Lagana, F. Marinho, P.G. Mercadante\cmsAuthorMark2, S.F. Novaes, Sandra S. Padula \cmsinstskipInstitute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria
N. Darmenov\cmsAuthorMark1, L. Dimitrov, V. Genchev\cmsAuthorMark1, P. Iaydjiev\cmsAuthorMark1, S. Piperov, M. Rodozov, S. Stoykova, G. Sultanov, V. Tcholakov, R. Trayanov, I. Vankov \cmsinstskipUniversity of Sofia, Sofia, Bulgaria
M. Dyulendarova, R. Hadjiiska, V. Kozhuharov, L. Litov, E. Marinova, M. Mateev, B. Pavlov, P. Petkov \cmsinstskipInstitute of High Energy Physics, Beijing, China
J.G. Bian, G.M. Chen, H.S. Chen, C.H. Jiang, D. Liang, S. Liang, X. Meng, J. Tao, J. Wang, J. Wang, X. Wang, Z. Wang, H. Xiao, M. Xu, J. Zang, Z. Zhang \cmsinstskipState Key Lab. of Nucl. Phys. and Tech.,  Peking University, Beijing, China
Y. Ban, S. Guo, Y. Guo, W. Li, Y. Mao, S.J. Qian, H. Teng, L. Zhang, B. Zhu, W. Zou \cmsinstskipUniversidad de Los Andes, Bogota, Colombia
A. Cabrera, B. Gomez Moreno, A.A. Ocampo Rios, A.F. Osorio Oliveros, J.C. Sanabria \cmsinstskipTechnical University of Split, Split, Croatia
N. Godinovic, D. Lelas, K. Lelas, R. Plestina\cmsAuthorMark3, D. Polic, I. Puljak \cmsinstskipUniversity of Split, Split, Croatia
Z. Antunovic, M. Dzelalija \cmsinstskipInstitute Rudjer Boskovic, Zagreb, Croatia
V. Brigljevic, S. Duric, K. Kadija, S. Morovic \cmsinstskipUniversity of Cyprus, Nicosia, Cyprus
A. Attikis, M. Galanti, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis \cmsinstskipCharles University, Prague, Czech Republic
M. Finger, M. Finger Jr. \cmsinstskipAcademy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt
Y. Assran\cmsAuthorMark4, S. Khalil\cmsAuthorMark5, A. Radi \cmsinstskipNational Institute of Chemical Physics and Biophysics, Tallinn, Estonia
A. Hektor, M. Kadastik, M. Müntel, M. Raidal, L. Rebane \cmsinstskipDepartment of Physics, University of Helsinki, Helsinki, Finland
V. Azzolini, P. Eerola \cmsinstskipHelsinki Institute of Physics, Helsinki, Finland
S. Czellar, J. Härkönen, V. Karimäki, R. Kinnunen, M.J. Kortelainen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, T. Mäenpää, E. Tuominen, J. Tuominiemi, E. Tuovinen, D. Ungaro, L. Wendland \cmsinstskipLappeenranta University of Technology, Lappeenranta, Finland
K. Banzuzi, A. Korpela, T. Tuuva \cmsinstskipLaboratoire d’Annecy-le-Vieux de Physique des Particules, IN2P3-CNRS, Annecy-le-Vieux, France
D. Sillou \cmsinstskipDSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France
M. Besancon, S. Choudhury, M. Dejardin, D. Denegri, B. Fabbro, J.L. Faure, F. Ferri, S. Ganjour, F.X. Gentit, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, E. Locci, J. Malcles, M. Marionneau, L. Millischer, J. Rander, A. Rosowsky, I. Shreyber, M. Titov, P. Verrecchia \cmsinstskipLaboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France
S. Baffioni, F. Beaudette, L. Benhabib, L. Bianchini, M. Bluj\cmsAuthorMark6, C. Broutin, P. Busson, C. Charlot, T. Dahms, L. Dobrzynski, S. Elgammal, R. Granier de Cassagnac, M. Haguenauer, P. Miné, C. Mironov, C. Ochando, P. Paganini, D. Sabes, R. Salerno, Y. Sirois, C. Thiebaux, B. Wyslouch\cmsAuthorMark7, A. Zabi \cmsinstskipInstitut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France
J.-L. Agram\cmsAuthorMark8, J. Andrea, D. Bloch, D. Bodin, J.-M. Brom, M. Cardaci, E.C. Chabert, C. Collard, E. Conte\cmsAuthorMark8, F. Drouhin\cmsAuthorMark8, C. Ferro, J.-C. Fontaine\cmsAuthorMark8, D. Gelé, U. Goerlach, S. Greder, P. Juillot, M. Karim\cmsAuthorMark8, A.-C. Le Bihan, Y. Mikami, P. Van Hove \cmsinstskipCentre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules (IN2P3),  Villeurbanne, France
F. Fassi, D. Mercier \cmsinstskipUniversité de Lyon, Université Claude Bernard Lyon 1,  CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France
C. Baty, S. Beauceron, N. Beaupere, M. Bedjidian, O. Bondu, G. Boudoul, D. Boumediene, H. Brun, N. Chanon, R. Chierici, D. Contardo, P. Depasse, H. El Mamouni, A. Falkiewicz, J. Fay, S. Gascon, B. Ille, T. Kurca, T. Le Grand, M. Lethuillier, L. Mirabito, S. Perries, V. Sordini, S. Tosi, Y. Tschudi, P. Verdier \cmsinstskipE. Andronikashvili Institute of Physics, Academy of Science, Tbilisi, Georgia
V. Roinishvili \cmsinstskipInstitute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia
D. Lomidze \cmsinstskipRWTH Aachen University, I. Physikalisches Institut, Aachen, Germany
G. Anagnostou, M. Edelhoff, L. Feld, N. Heracleous, O. Hindrichs, R. Jussen, K. Klein, J. Merz, N. Mohr, A. Ostapchuk, A. Perieanu, F. Raupach, J. Sammet, S. Schael, D. Sprenger, H. Weber, M. Weber, B. Wittmer \cmsinstskipRWTH Aachen University, III. Physikalisches Institut A,  Aachen, Germany
M. Ata, W. Bender, M. Erdmann, J. Frangenheim, T. Hebbeker, A. Hinzmann, K. Hoepfner, C. Hof, T. Klimkovich, D. Klingebiel, P. Kreuzer, D. Lanske, C. Magass, G. Masetti, M. Merschmeyer, A. Meyer, P. Papacz, H. Pieta, H. Reithler, S.A. Schmitz, L. Sonnenschein, J. Steggemann, D. Teyssier, M. Tonutti \cmsinstskipRWTH Aachen University, III. Physikalisches Institut B,  Aachen, Germany
M. Bontenackels, M. Davids, M. Duda, G. Flügge, H. Geenen, M. Giffels, W. Haj Ahmad, D. Heydhausen, T. Kress, Y. Kuessel, A. Linn, A. Nowack, L. Perchalla, O. Pooth, J. Rennefeld, P. Sauerland, A. Stahl, M. Thomas, D. Tornier, M.H. Zoeller \cmsinstskipDeutsches Elektronen-Synchrotron, Hamburg, Germany
M. Aldaya Martin, W. Behrenhoff, U. Behrens, M. Bergholz\cmsAuthorMark9, K. Borras, A. Cakir, A. Campbell, E. Castro, D. Dammann, G. Eckerlin, D. Eckstein, A. Flossdorf, G. Flucke, A. Geiser, J. Hauk, H. Jung, M. Kasemann, I. Katkov, P. Katsas, C. Kleinwort, H. Kluge, A. Knutsson, M. Krämer, D. Krücker, E. Kuznetsova, W. Lange, W. Lohmann\cmsAuthorMark9, R. Mankel, M. Marienfeld, I.-A. Melzer-Pellmann, A.B. Meyer, J. Mnich, A. Mussgiller, J. Olzem, D. Pitzl, A. Raspereza, A. Raval, M. Rosin, R. Schmidt\cmsAuthorMark9, T. Schoerner-Sadenius, N. Sen, A. Spiridonov, M. Stein, J. Tomaszewska, R. Walsh, C. Wissing \cmsinstskipUniversity of Hamburg, Hamburg, Germany
C. Autermann, S. Bobrovskyi, J. Draeger, H. Enderle, U. Gebbert, K. Kaschube, G. Kaussen, J. Lange, B. Mura, S. Naumann-Emme, F. Nowak, N. Pietsch, C. Sander, H. Schettler, P. Schleper, M. Schröder, T. Schum, J. Schwandt, H. Stadie, G. Steinbrück, J. Thomsen \cmsinstskipInstitut für Experimentelle Kernphysik, Karlsruhe, Germany
C. Barth, J. Bauer, V. Buege, T. Chwalek, W. De Boer, A. Dierlamm, G. Dirkes, M. Feindt, J. Gruschke, C. Hackstein, F. Hartmann, S.M. Heindl, M. Heinrich, H. Held, K.H. Hoffmann, S. Honc, T. Kuhr, D. Martschei, S. Mueller, Th. Müller, M. Niegel, O. Oberst, A. Oehler, J. Ott, T. Peiffer, D. Piparo, G. Quast, K. Rabbertz, F. Ratnikov, N. Ratnikova, M. Renz, C. Saout, A. Scheurer, P. Schieferdecker, F.-P. Schilling, M. Schmanau, G. Schott, H.J. Simonis, F.M. Stober, D. Troendle, J. Wagner-Kuhr, T. Weiler, M. Zeise, V. Zhukov\cmsAuthorMark10, E.B. Ziebarth \cmsinstskipInstitute of Nuclear Physics ”Demokritos”,  Aghia Paraskevi, Greece
G. Daskalakis, T. Geralis, K. Karafasoulis, S. Kesisoglou, A. Kyriakis, D. Loukas, I. Manolakos, A. Markou, C. Markou, C. Mavrommatis, E. Ntomari, E. Petrakou \cmsinstskipUniversity of Athens, Athens, Greece
L. Gouskos, T.J. Mertzimekis, A. Panagiotou \cmsinstskipUniversity of Ioánnina, Ioánnina, Greece
I. Evangelou, C. Foudas, P. Kokkas, N. Manthos, I. Papadopoulos, V. Patras, F.A. Triantis \cmsinstskipKFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary
A. Aranyi, G. Bencze, L. Boldizsar, C. Hajdu\cmsAuthorMark1, P. Hidas, D. Horvath\cmsAuthorMark11, A. Kapusi, K. Krajczar\cmsAuthorMark12, F. Sikler, G.I. Veres\cmsAuthorMark12, G. Vesztergombi\cmsAuthorMark12 \cmsinstskipInstitute of Nuclear Research ATOMKI, Debrecen, Hungary
N. Beni, J. Molnar, J. Palinkas, Z. Szillasi, V. Veszpremi \cmsinstskipUniversity of Debrecen, Debrecen, Hungary
P. Raics, Z.L. Trocsanyi, B. Ujvari \cmsinstskipPanjab University, Chandigarh, India
S. Bansal, S.B. Beri, V. Bhatnagar, N. Dhingra, R. Gupta, M. Jindal, M. Kaur, J.M. Kohli, M.Z. Mehta, N. Nishu, L.K. Saini, A. Sharma, A.P. Singh, J.B. Singh, S.P. Singh \cmsinstskipUniversity of Delhi, Delhi, India
S. Ahuja, S. Bhattacharya, B.C. Choudhary, P. Gupta, S. Jain, S. Jain, A. Kumar, K. Ranjan, R.K. Shivpuri \cmsinstskipBhabha Atomic Research Centre, Mumbai, India
R.K. Choudhury, D. Dutta, S. Kailas, V. Kumar, A.K. Mohanty\cmsAuthorMark1, L.M. Pant, P. Shukla \cmsinstskipTata Institute of Fundamental Research - EHEP, Mumbai, India
T. Aziz, M. Guchait\cmsAuthorMark13, A. Gurtu, M. Maity\cmsAuthorMark14, D. Majumder, G. Majumder, K. Mazumdar, G.B. Mohanty, A. Saha, K. Sudhakar, N. Wickramage \cmsinstskipTata Institute of Fundamental Research - HECR, Mumbai, India
S. Banerjee, S. Dugad, N.K. Mondal \cmsinstskipInstitute for Research and Fundamental Sciences (IPM),  Tehran, Iran
H. Arfaei, H. Bakhshiansohi, S.M. Etesami, A. Fahim, M. Hashemi, A. Jafari, M. Khakzad, A. Mohammadi, M. Mohammadi Najafabadi, S. Paktinat Mehdiabadi, B. Safarzadeh, M. Zeinali \cmsinstskipINFN Sezione di Bari , Università di Bari , Politecnico di Bari ,  Bari, Italy
M. Abbrescia, L. Barbone, C. Calabria, A. Colaleo, D. Creanza, N. De Filippis, M. De Palma, A. Dimitrov, L. Fiore, G. Iaselli, L. Lusito\cmsAuthorMark1, G. Maggi, M. Maggi, N. Manna, B. Marangelli, S. My, S. Nuzzo, N. Pacifico, G.A. Pierro, A. Pompili, G. Pugliese, F. Romano, G. Roselli, G. Selvaggi, L. Silvestris, R. Trentadue, S. Tupputi, G. Zito \cmsinstskipINFN Sezione di Bologna , Università di Bologna ,  Bologna, Italy
G. Abbiendi, A.C. Benvenuti, D. Bonacorsi, S. Braibant-Giacomelli, L. Brigliadori, P. Capiluppi, A. Castro, F.R. Cavallo, M. Cuffiani, G.M. Dallavalle, F. Fabbri, A. Fanfani, D. Fasanella, P. Giacomelli, M. Giunta, S. Marcellini, M. Meneghelli, A. Montanari, F.L. Navarria, F. Odorici, A. Perrotta, F. Primavera, A.M. Rossi, T. Rovelli, G. Siroli, R. Travaglini \cmsinstskipINFN Sezione di Catania , Università di Catania ,  Catania, Italy
S. Albergo, G. Cappello, M. Chiorboli\cmsAuthorMark1, S. Costa, A. Tricomi, C. Tuve \cmsinstskipINFN Sezione di Firenze , Università di Firenze ,  Firenze, Italy
G. Barbagli, V. Ciulli, C. Civinini, R. D’Alessandro, E. Focardi, S. Frosali, E. Gallo, S. Gonzi, P. Lenzi, M. Meschini, S. Paoletti, G. Sguazzoni, A. Tropiano\cmsAuthorMark1 \cmsinstskipINFN Laboratori Nazionali di Frascati, Frascati, Italy
L. Benussi, S. Bianco, S. Colafranceschi\cmsAuthorMark15, F. Fabbri, D. Piccolo \cmsinstskipINFN Sezione di Genova, Genova, Italy
P. Fabbricatore, R. Musenich \cmsinstskipINFN Sezione di Milano-Biccoca , Università di Milano-Bicocca ,  Milano, Italy
A. Benaglia, F. De Guio\cmsAuthorMark1, L. Di Matteo, A. Ghezzi\cmsAuthorMark1, M. Malberti, S. Malvezzi, A. Martelli, A. Massironi, D. Menasce, L. Moroni, M. Paganoni, D. Pedrini, S. Ragazzi, N. Redaelli, S. Sala, T. Tabarelli de Fatis, V. Tancini \cmsinstskipINFN Sezione di Napoli , Università di Napoli ”Federico II” ,  Napoli, Italy
S. Buontempo, C.A. Carrillo Montoya, N. Cavallo\cmsAuthorMark16, A. Cimmino, A. De Cosa, M. De Gruttola, F. Fabozzi\cmsAuthorMark16, A.O.M. Iorio, L. Lista, M. Merola, P. Noli, P. Paolucci \cmsinstskipINFN Sezione di Padova , Università di Padova , Università di Trento (Trento) ,  Padova, Italy
P. Azzi, N. Bacchetta, P. Bellan, D. Bisello, A. Branca, R. Carlin, P. Checchia, M. De Mattia, T. Dorigo, U. Dosselli, F. Fanzago, F. Gasparini, U. Gasparini, S. Lacaprara\cmsAuthorMark17, I. Lazzizzera, M. Margoni, M. Mazzucato, A.T. Meneguzzo, M. Nespolo, L. Perrozzi\cmsAuthorMark1, N. Pozzobon, P. Ronchese, F. Simonetto, E. Torassa, M. Tosi, S. Vanini, P. Zotto, G. Zumerle \cmsinstskipINFN Sezione di Pavia , Università di Pavia ,  Pavia, Italy
P. Baesso, U. Berzano, S.P. Ratti, C. Riccardi, P. Torre, P. Vitulo, C. Viviani \cmsinstskipINFN Sezione di Perugia , Università di Perugia ,  Perugia, Italy
M. Biasini, G.M. Bilei, B. Caponeri, L. Fanò, P. Lariccia, A. Lucaroni\cmsAuthorMark1, G. Mantovani, M. Menichelli, A. Nappi, A. Santocchia, S. Taroni, M. Valdata, R. Volpe\cmsAuthorMark1 \cmsinstskipINFN Sezione di Pisa , Università di Pisa , Scuola Normale Superiore di Pisa ,  Pisa, Italy
P. Azzurri, G. Bagliesi, J. Bernardini, T. Boccali\cmsAuthorMark1, G. Broccolo, R. Castaldi, R.T. D’Agnolo, R. Dell’Orso, F. Fiori, L. Foà, A. Giassi, A. Kraan, F. Ligabue, T. Lomtadze, L. Martini\cmsAuthorMark18, A. Messineo, F. Palla, F. Palmonari, G. Segneri, A.T. Serban, P. Spagnolo, R. Tenchini, G. Tonelli\cmsAuthorMark1, A. Venturi\cmsAuthorMark1, P.G. Verdini \cmsinstskipINFN Sezione di Roma , Università di Roma ”La Sapienza” ,  Roma, Italy
L. Barone, F. Cavallari, D. Del Re, E. Di Marco, M. Diemoz, D. Franci, M. Grassi, E. Longo, S. Nourbakhsh, G. Organtini, A. Palma, F. Pandolfi\cmsAuthorMark1, R. Paramatti, S. Rahatlou \cmsinstskipINFN Sezione di Torino , Università di Torino , Università del Piemonte Orientale (Novara) ,  Torino, Italy
N. Amapane, R. Arcidiacono, S. Argiro, M. Arneodo, C. Biino, C. Botta\cmsAuthorMark1, N. Cartiglia, R. Castello, M. Costa, N. Demaria, A. Graziano\cmsAuthorMark1, C. Mariotti, M. Marone, S. Maselli, E. Migliore, G. Mila, V. Monaco, M. Musich, M.M. Obertino, N. Pastrone, M. Pelliccioni\cmsAuthorMark1, A. Romero, M. Ruspa, R. Sacchi, V. Sola, A. Solano, A. Staiano, D. Trocino, A. Vilela Pereira\cmsAuthorMark1 \cmsinstskipINFN Sezione di Trieste , Università di Trieste ,  Trieste, Italy
S. Belforte, F. Cossutti, G. Della Ricca, B. Gobbo, D. Montanino, A. Penzo \cmsinstskipKangwon National University, Chunchon, Korea
S.G. Heo, S.K. Nam \cmsinstskipKyungpook National University, Daegu, Korea
S. Chang, J. Chung, D.H. Kim, G.N. Kim, J.E. Kim, D.J. Kong, H. Park, S.R. Ro, D. Son, D.C. Son \cmsinstskipChonnam National University, Institute for Universe and Elementary Particles, Kwangju, Korea
Zero Kim, J.Y. Kim, S. Song \cmsinstskipKorea University, Seoul, Korea
S. Choi, B. Hong, M.S. Jeong, M. Jo, H. Kim, J.H. Kim, T.J. Kim, K.S. Lee, D.H. Moon, S.K. Park, H.B. Rhee, E. Seo, S. Shin, K.S. Sim \cmsinstskipUniversity of Seoul, Seoul, Korea
M. Choi, S. Kang, H. Kim, C. Park, I.C. Park, S. Park, G. Ryu \cmsinstskipSungkyunkwan University, Suwon, Korea
Y. Choi, Y.K. Choi, J. Goh, M.S. Kim, J. Lee, S. Lee, H. Seo, I. Yu \cmsinstskipVilnius University, Vilnius, Lithuania
M.J. Bilinskas, I. Grigelionis, M. Janulis, D. Martisiute, P. Petrov, T. Sabonis \cmsinstskipCentro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico
H. Castilla-Valdez, E. De La Cruz-Burelo, R. Lopez-Fernandez, A. Sánchez-Hernández, L.M. Villasenor-Cendejas \cmsinstskipUniversidad Iberoamericana, Mexico City, Mexico
S. Carrillo Moreno, F. Vazquez Valencia \cmsinstskipBenemerita Universidad Autonoma de Puebla, Puebla, Mexico
H.A. Salazar Ibarguen \cmsinstskipUniversidad Autónoma de San Luis Potosí,  San Luis Potosí,  Mexico
E. Casimiro Linares, A. Morelos Pineda, M.A. Reyes-Santos \cmsinstskipUniversity of Auckland, Auckland, New Zealand
D. Krofcheck \cmsinstskipUniversity of Canterbury, Christchurch, New Zealand
P.H. Butler, R. Doesburg, H. Silverwood \cmsinstskipNational Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan
M. Ahmad, I. Ahmed, M.I. Asghar, H.R. Hoorani, W.A. Khan, T. Khurshid, S. Qazi \cmsinstskipInstitute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
M. Cwiok, W. Dominik, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski \cmsinstskipSoltan Institute for Nuclear Studies, Warsaw, Poland
T. Frueboes, R. Gokieli, M. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, G. Wrochna, P. Zalewski \cmsinstskipLaboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal
N. Almeida, P. Bargassa, A. David, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, P. Musella, A. Nayak, J. Seixas, J. Varela \cmsinstskipJoint Institute for Nuclear Research, Dubna, Russia
S. Afanasiev, I. Belotelov, P. Bunin, I. Golutvin, A. Kamenev, V. Karjavin, G. Kozlov, A. Lanev, P. Moisenz, V. Palichik, V. Perelygin, S. Shmatov, V. Smirnov, A. Volodko, A. Zarubin \cmsinstskipPetersburg Nuclear Physics Institute, Gatchina (St Petersburg),  Russia
V. Golovtsov, Y. Ivanov, V. Kim, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev, A. Vorobyev \cmsinstskipInstitute for Nuclear Research, Moscow, Russia
Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, M. Kirsanov, N. Krasnikov, V. Matveev, A. Pashenkov, A. Toropin, S. Troitsky \cmsinstskipInstitute for Theoretical and Experimental Physics, Moscow, Russia
V. Epshteyn, V. Gavrilov, V. Kaftanov, M. Kossov\cmsAuthorMark1, A. Krokhotin, N. Lychkovskaya, V. Popov, G. Safronov, S. Semenov, V. Stolin, E. Vlasov, A. Zhokin \cmsinstskipMoscow State University, Moscow, Russia
E. Boos, A. Demiyanov, A. Ershov, A. Gribushin, O. Kodolova, I. Lokhtin, S. Obraztsov, S. Petrushanko, L. Sarycheva, V. Savrin, A. Snigirev, I. Vardanyan \cmsinstskipP.N. Lebedev Physical Institute, Moscow, Russia
V. Andreev, M. Azarkin, I. Dremin, M. Kirakosyan, A. Leonidov, S.V. Rusakov, A. Vinogradov \cmsinstskipState Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia
I. Azhgirey, S. Bitioukov, V. Grishin\cmsAuthorMark1, V. Kachanov, D. Konstantinov, A. Korablev, V. Krychkine, V. Petrov, R. Ryutin, S. Slabospitsky, A. Sobol, L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov \cmsinstskipUniversity of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia
P. Adzic\cmsAuthorMark19, M. Djordjevic, D. Krpic\cmsAuthorMark19, J. Milosevic \cmsinstskipCentro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT),  Madrid, Spain
M. Aguilar-Benitez, J. Alcaraz Maestre, P. Arce, C. Battilana, E. Calvo, M. Cepeda, M. Cerrada, N. Colino, B. De La Cruz, A. Delgado Peris, C. Diez Pardos, D. Domínguez Vázquez, C. Fernandez Bedoya, J.P. Fernández Ramos, A. Ferrando, J. Flix, M.C. Fouz, P. Garcia-Abia, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, G. Merino, J. Puerta Pelayo, I. Redondo, L. Romero, J. Santaolalla, C. Willmott \cmsinstskipUniversidad Autónoma de Madrid, Madrid, Spain
C. Albajar, G. Codispoti, J.F. de Trocóniz \cmsinstskipUniversidad de Oviedo, Oviedo, Spain
J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, L. Lloret Iglesias, J.M. Vizan Garcia \cmsinstskipInstituto de Física de Cantabria (IFCA),  CSIC-Universidad de Cantabria, Santander, Spain
J.A. Brochero Cifuentes, I.J. Cabrillo, A. Calderon, M. Chamizo Llatas, S.H. Chuang, J. Duarte Campderros, M. Felcini\cmsAuthorMark20, M. Fernandez, G. Gomez, J. Gonzalez Sanchez, C. Jorda, P. Lobelle Pardo, A. Lopez Virto, J. Marco, R. Marco, C. Martinez Rivero, F. Matorras, F.J. Munoz Sanchez, J. Piedra Gomez\cmsAuthorMark21, T. Rodrigo, A.Y. Rodríguez-Marrero, A. Ruiz-Jimeno, L. Scodellaro, M. Sobron Sanudo, I. Vila, R. Vilar Cortabitarte \cmsinstskipCERN, European Organization for Nuclear Research, Geneva, Switzerland
D. Abbaneo, E. Auffray, G. Auzinger, P. Baillon, A.H. Ball, D. Barney, A.J. Bell\cmsAuthorMark22, D. Benedetti, C. Bernet\cmsAuthorMark3, W. Bialas, P. Bloch, A. Bocci, S. Bolognesi, M. Bona, H. Breuker, G. Brona, K. Bunkowski, T. Camporesi, G. Cerminara, J.A. Coarasa Perez, B. Curé, D. D’Enterria, A. De Roeck, S. Di Guida, A. Elliott-Peisert, B. Frisch, W. Funk, A. Gaddi, S. Gennai, G. Georgiou, H. Gerwig, D. Gigi, K. Gill, D. Giordano, F. Glege, R. Gomez-Reino Garrido, M. Gouzevitch, P. Govoni, S. Gowdy, L. Guiducci, M. Hansen, J. Harvey, J. Hegeman, B. Hegner, H.F. Hoffmann, A. Honma, V. Innocente, P. Janot, K. Kaadze, E. Karavakis, P. Lecoq, C. Lourenço, T. Mäki, L. Malgeri, M. Mannelli, L. Masetti, F. Meijers, S. Mersi, E. Meschi, R. Moser, M.U. Mozer, M. Mulders, E. Nesvold\cmsAuthorMark1, M. Nguyen, T. Orimoto, L. Orsini, E. Perez, A. Petrilli, A. Pfeiffer, M. Pierini, M. Pimiä, G. Polese, A. Racz, J. Rodrigues Antunes, G. Rolandi\cmsAuthorMark23, T. Rommerskirchen, C. Rovelli\cmsAuthorMark24, M. Rovere, H. Sakulin, C. Schäfer, C. Schwick, I. Segoni, A. Sharma, P. Siegrist, M. Simon, P. Sphicas\cmsAuthorMark25, M. Spiropulu\cmsAuthorMark26, F. Stöckli, M. Stoye, P. Tropea, A. Tsirou, P. Vichoudis, M. Voutilainen, W.D. Zeuner \cmsinstskipPaul Scherrer Institut, Villigen, Switzerland
W. Bertl, K. Deiters, W. Erdmann, K. Gabathuler, R. Horisberger, Q. Ingram, H.C. Kaestli, S. König, D. Kotlinski, U. Langenegger, F. Meier, D. Renker, T. Rohe, J. Sibille\cmsAuthorMark27, A. Starodumov\cmsAuthorMark28 \cmsinstskipInstitute for Particle Physics, ETH Zurich, Zurich, Switzerland
P. Bortignon, L. Caminada\cmsAuthorMark29, Z. Chen, S. Cittolin, G. Dissertori, M. Dittmar, J. Eugster, K. Freudenreich, C. Grab, A. Hervé, W. Hintz, P. Lecomte, W. Lustermann, C. Marchica\cmsAuthorMark29, P. Martinez Ruiz del Arbol, P. Meridiani, P. Milenovic\cmsAuthorMark30, F. Moortgat, P. Nef, F. Nessi-Tedaldi, L. Pape, F. Pauss, T. Punz, A. Rizzi, F.J. Ronga, M. Rossini, L. Sala, A.K. Sanchez, M.-C. Sawley, B. Stieger, L. Tauscher, A. Thea, K. Theofilatos, D. Treille, C. Urscheler, R. Wallny, M. Weber, L. Wehrli, J. Weng \cmsinstskipUniversität Zürich, Zurich, Switzerland
E. Aguiló, C. Amsler, V. Chiochia, S. De Visscher, C. Favaro, M. Ivova Rikova, B. Millan Mejias, C. Regenfus, P. Robmann, A. Schmidt, H. Snoek \cmsinstskipNational Central University, Chung-Li, Taiwan
Y.H. Chang, E.A. Chen, K.H. Chen, W.T. Chen, S. Dutta, C.M. Kuo, S.W. Li, W. Lin, M.H. Liu, Z.K. Liu, Y.J. Lu, D. Mekterovic, J.H. Wu, S.S. Yu \cmsinstskipNational Taiwan University (NTU),  Taipei, Taiwan
P. Bartalini, P. Chang, Y.H. Chang, Y.W. Chang, Y. Chao, K.F. Chen, W.-S. Hou, Y. Hsiung, K.Y. Kao, Y.J. Lei, R.-S. Lu, J.G. Shiu, Y.M. Tzeng, M. Wang \cmsinstskipCukurova University, Adana, Turkey
A. Adiguzel, M.N. Bakirci\cmsAuthorMark31, S. Cerci\cmsAuthorMark32, Z. Demir, C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut, Y. Guler, E. Gurpinar, I. Hos, E.E. Kangal, T. Karaman, A. Kayis Topaksu, A. Nart, G. Onengut, K. Ozdemir, S. Ozturk, A. Polatoz, K. Sogut\cmsAuthorMark33, D. Sunar Cerci\cmsAuthorMark32, B. Tali, H. Topakli\cmsAuthorMark31, D. Uzun, L.N. Vergili, M. Vergili, C. Zorbilmez \cmsinstskipMiddle East Technical University, Physics Department, Ankara, Turkey
I.V. Akin, T. Aliev, S. Bilmis, M. Deniz, H. Gamsizkan, A.M. Guler, K. Ocalan, A. Ozpineci, M. Serin, R. Sever, U.E. Surat, E. Yildirim, M. Zeyrek \cmsinstskipBogazici University, Istanbul, Turkey
M. Deliomeroglu, D. Demir\cmsAuthorMark34, E. Gülmez, A. Halu, B. Isildak, M. Kaya\cmsAuthorMark35, O. Kaya\cmsAuthorMark35, S. Ozkorucuklu\cmsAuthorMark36, N. Sonmez\cmsAuthorMark37 \cmsinstskipNational Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine
L. Levchuk \cmsinstskipUniversity of Bristol, Bristol, United Kingdom
P. Bell, F. Bostock, J.J. Brooke, T.L. Cheng, E. Clement, D. Cussans, R. Frazier, J. Goldstein, M. Grimes, M. Hansen, D. Hartley, G.P. Heath, H.F. Heath, B. Huckvale, J. Jackson, L. Kreczko, S. Metson, D.M. Newbold\cmsAuthorMark38, K. Nirunpong, A. Poll, S. Senkin, V.J. Smith, S. Ward \cmsinstskipRutherford Appleton Laboratory, Didcot, United Kingdom
L. Basso\cmsAuthorMark39, K.W. Bell, A. Belyaev\cmsAuthorMark39, C. Brew, R.M. Brown, B. Camanzi, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, B.W. Kennedy, E. Olaiya, D. Petyt, B.C. Radburn-Smith, C.H. Shepherd-Themistocleous, I.R. Tomalin, W.J. Womersley, S.D. Worm \cmsinstskipImperial College, London, United Kingdom
R. Bainbridge, G. Ball, J. Ballin, R. Beuselinck, O. Buchmuller, D. Colling, N. Cripps, M. Cutajar, G. Davies, M. Della Negra, J. Fulcher, D. Futyan, A. Guneratne Bryer, G. Hall, Z. Hatherell, J. Hays, G. Iles, G. Karapostoli, B.C. MacEvoy, A.-M. Magnan, J. Marrouche, R. Nandi, J. Nash, A. Nikitenko\cmsAuthorMark28, A. Papageorgiou, M. Pesaresi, K. Petridis, M. Pioppi\cmsAuthorMark40, D.M. Raymond, N. Rompotis, A. Rose, M.J. Ryan, C. Seez, P. Sharp, A. Sparrow, A. Tapper, M. Vazquez Acosta, T. Virdee, S. Wakefield, T. Whyntie \cmsinstskipBrunel University, Uxbridge, United Kingdom
M. Barrett, M. Chadwick, J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, D. Leslie, W. Martin, I.D. Reid, L. Teodorescu \cmsinstskipBaylor University, Waco, USA
K. Hatakeyama \cmsinstskipBoston University, Boston, USA
T. Bose, E. Carrera Jarrin, C. Fantasia, A. Heister, J. St. John, P. Lawson, D. Lazic, J. Rohlf, D. Sperka, L. Sulak \cmsinstskipBrown University, Providence, USA
A. Avetisyan, S. Bhattacharya, J.P. Chou, D. Cutts, A. Ferapontov, U. Heintz, S. Jabeen, G. Kukartsev, G. Landsberg, M. Narain, D. Nguyen, M. Segala, T. Speer, K.V. Tsang \cmsinstskipUniversity of California, Davis, Davis, USA
R. Breedon, M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway, P.T. Cox, J. Dolen, R. Erbacher, E. Friis, W. Ko, A. Kopecky, R. Lander, H. Liu, S. Maruyama, T. Miceli, M. Nikolic, D. Pellett, J. Robles, S. Salur, T. Schwarz, M. Searle, J. Smith, M. Squires, M. Tripathi, R. Vasquez Sierra, C. Veelken \cmsinstskipUniversity of California, Los Angeles, Los Angeles, USA
V. Andreev, K. Arisaka, D. Cline, R. Cousins, A. Deisher, J. Duris, S. Erhan, C. Farrell, J. Hauser, M. Ignatenko, C. Jarvis, C. Plager, G. Rakness, P. Schlein, J. Tucker, V. Valuev \cmsinstskipUniversity of California, Riverside, Riverside, USA
J. Babb, A. Chandra, R. Clare, J. Ellison, J.W. Gary, F. Giordano, G. Hanson, G.Y. Jeng, S.C. Kao, F. Liu, H. Liu, O.R. Long, A. Luthra, H. Nguyen, B.C. Shen, R. Stringer, J. Sturdy, S. Sumowidagdo, R. Wilken, S. Wimpenny \cmsinstskipUniversity of California, San Diego, La Jolla, USA
W. Andrews, J.G. Branson, G.B. Cerati, E. Dusinberre, D. Evans, F. Golf, A. Holzner, R. Kelley, M. Lebourgeois, J. Letts, B. Mangano, S. Padhi, C. Palmer, G. Petrucciani, H. Pi, M. Pieri, R. Ranieri, M. Sani, V. Sharma\cmsAuthorMark1, S. Simon, Y. Tu, A. Vartak, S. Wasserbaech, F. Würthwein, A. Yagil \cmsinstskipUniversity of California, Santa Barbara, Santa Barbara, USA
D. Barge, R. Bellan, C. Campagnari, M. D’Alfonso, T. Danielson, K. Flowers, P. Geffert, J. Incandela, C. Justus, P. Kalavase, S.A. Koay, D. Kovalskyi, V. Krutelyov, S. Lowette, N. Mccoll, V. Pavlunin, F. Rebassoo, J. Ribnik, J. Richman, R. Rossin, D. Stuart, W. To, J.R. Vlimant \cmsinstskipCalifornia Institute of Technology, Pasadena, USA
A. Apresyan, A. Bornheim, J. Bunn, Y. Chen, M. Gataullin, Y. Ma, A. Mott, H.B. Newman, C. Rogan, V. Timciuc, P. Traczyk, J. Veverka, R. Wilkinson, Y. Yang, R.Y. Zhu \cmsinstskipCarnegie Mellon University, Pittsburgh, USA
B. Akgun, R. Carroll, T. Ferguson, Y. Iiyama, D.W. Jang, S.Y. Jun, Y.F. Liu, M. Paulini, J. Russ, H. Vogel, I. Vorobiev \cmsinstskipUniversity of Colorado at Boulder, Boulder, USA
J.P. Cumalat, M.E. Dinardo, B.R. Drell, C.J. Edelmaier, W.T. Ford, A. Gaz, B. Heyburn, E. Luiggi Lopez, U. Nauenberg, J.G. Smith, K. Stenson, K.A. Ulmer, S.R. Wagner, S.L. Zang \cmsinstskipCornell University, Ithaca, USA
L. Agostino, J. Alexander, D. Cassel, A. Chatterjee, S. Das, N. Eggert, L.K. Gibbons, B. Heltsley, W. Hopkins, A. Khukhunaishvili, B. Kreis, G. Nicolas Kaufman, J.R. Patterson, D. Puigh, A. Ryd, X. Shi, W. Sun, W.D. Teo, J. Thom, J. Thompson, J. Vaughan, Y. Weng, L. Winstrom, P. Wittich \cmsinstskipFairfield University, Fairfield, USA
A. Biselli, G. Cirino, D. Winn \cmsinstskipFermi National Accelerator Laboratory, Batavia, USA
S. Abdullin, M. Albrow, J. Anderson, G. Apollinari, M. Atac, J.A. Bakken, S. Banerjee, L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, I. Bloch, F. Borcherding, K. Burkett, J.N. Butler, V. Chetluru, H.W.K. Cheung, F. Chlebana, S. Cihangir, W. Cooper, D.P. Eartly, V.D. Elvira, S. Esen, I. Fisk, J. Freeman, Y. Gao, E. Gottschalk, D. Green, K. Gunthoti, O. Gutsche, J. Hanlon, R.M. Harris, J. Hirschauer, B. Hooberman, H. Jensen, M. Johnson, U. Joshi, R. Khatiwada, B. Klima, K. Kousouris, S. Kunori, S. Kwan, C. Leonidopoulos, P. Limon, D. Lincoln, R. Lipton, J. Lykken, K. Maeshima, J.M. Marraffino, D. Mason, P. McBride, T. Miao, K. Mishra, S. Mrenna, Y. Musienko\cmsAuthorMark41, C. Newman-Holmes, V. O’Dell, R. Pordes, O. Prokofyev, N. Saoulidou, E. Sexton-Kennedy, S. Sharma, W.J. Spalding, L. Spiegel, P. Tan, L. Taylor, S. Tkaczyk, L. Uplegger, E.W. Vaandering, R. Vidal, J. Whitmore, W. Wu, F. Yang, F. Yumiceva, J.C. Yun \cmsinstskipUniversity of Florida, Gainesville, USA
D. Acosta, P. Avery, D. Bourilkov, M. Chen, G.P. Di Giovanni, D. Dobur, A. Drozdetskiy, R.D. Field, M. Fisher, Y. Fu, I.K. Furic, J. Gartner, S. Goldberg, B. Kim, J. Konigsberg, A. Korytov, A. Kropivnitskaya, T. Kypreos, K. Matchev, G. Mitselmakher, L. Muniz, Y. Pakhotin, C. Prescott, R. Remington, M. Schmitt, B. Scurlock, P. Sellers, N. Skhirtladze, D. Wang, J. Yelton, M. Zakaria \cmsinstskipFlorida International University, Miami, USA
C. Ceron, V. Gaultney, L. Kramer, L.M. Lebolo, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez \cmsinstskipFlorida State University, Tallahassee, USA
T. Adams, A. Askew, D. Bandurin, J. Bochenek, J. Chen, B. Diamond, S.V. Gleyzer, J. Haas, V. Hagopian, M. Jenkins, K.F. Johnson, H. Prosper, L. Quertenmont, S. Sekmen, V. Veeraraghavan \cmsinstskipFlorida Institute of Technology, Melbourne, USA
M.M. Baarmand, B. Dorney, S. Guragain, M. Hohlmann, H. Kalakhety, R. Ralich, I. Vodopiyanov \cmsinstskipUniversity of Illinois at Chicago (UIC),  Chicago, USA
M.R. Adams, I.M. Anghel, L. Apanasevich, Y. Bai, V.E. Bazterra, R.R. Betts, J. Callner, R. Cavanaugh, C. Dragoiu, L. Gauthier, C.E. Gerber, D.J. Hofman, S. Khalatyan, G.J. Kunde\cmsAuthorMark42, F. Lacroix, M. Malek, C. O’Brien, C. Silvestre, A. Smoron, D. Strom, N. Varelas \cmsinstskipThe University of Iowa, Iowa City, USA
U. Akgun, E.A. Albayrak, B. Bilki, W. Clarida, F. Duru, C.K. Lae, E. McCliment, J.-P. Merlo, H. Mermerkaya, A. Mestvirishvili, A. Moeller, J. Nachtman, C.R. Newsom, E. Norbeck, J. Olson, Y. Onel, F. Ozok, S. Sen, J. Wetzel, T. Yetkin, K. Yi \cmsinstskipJohns Hopkins University, Baltimore, USA
B.A. Barnett, B. Blumenfeld, A. Bonato, C. Eskew, D. Fehling, G. Giurgiu, A.V. Gritsan, G. Hu, P. Maksimovic, S. Rappoccio, M. Swartz, N.V. Tran, A. Whitbeck \cmsinstskipThe University of Kansas, Lawrence, USA
P. Baringer, A. Bean, G. Benelli, O. Grachov, M. Murray, D. Noonan, S. Sanders, J.S. Wood, V. Zhukova \cmsinstskipKansas State University, Manhattan, USA
A.F. Barfuss, T. Bolton, I. Chakaberia, A. Ivanov, M. Makouski, Y. Maravin, S. Shrestha, I. Svintradze, Z. Wan \cmsinstskipLawrence Livermore National Laboratory, Livermore, USA
J. Gronberg, D. Lange, D. Wright \cmsinstskipUniversity of Maryland, College Park, USA
A. Baden, M. Boutemeur, S.C. Eno, D. Ferencek, J.A. Gomez, N.J. Hadley, R.G. Kellogg, M. Kirn, Y. Lu, A.C. Mignerey, K. Rossato, P. Rumerio, F. Santanastasio, A. Skuja, J. Temple, M.B. Tonjes, S.C. Tonwar, E. Twedt \cmsinstskipMassachusetts Institute of Technology, Cambridge, USA
B. Alver, G. Bauer, J. Bendavid, W. Busza, E. Butz, I.A. Cali, M. Chan, V. Dutta, P. Everaerts, G. Gomez Ceballos, M. Goncharov, K.A. Hahn, P. Harris, Y. Kim, M. Klute, Y.-J. Lee, W. Li, C. Loizides, P.D. Luckey, T. Ma, S. Nahn, C. Paus, D. Ralph, C. Roland, G. Roland, M. Rudolph, G.S.F. Stephans, K. Sumorok, K. Sung, E.A. Wenger, S. Xie, M. Yang, Y. Yilmaz, A.S. Yoon, M. Zanetti \cmsinstskipUniversity of Minnesota, Minneapolis, USA
P. Cole, S.I. Cooper, P. Cushman, B. Dahmes, A. De Benedetti, P.R. Dudero, G. Franzoni, J. Haupt, K. Klapoetke, Y. Kubota, J. Mans, V. Rekovic, R. Rusack, M. Sasseville, A. Singovsky \cmsinstskipUniversity of Mississippi, University, USA
L.M. Cremaldi, R. Godang, R. Kroeger, L. Perera, R. Rahmat, D.A. Sanders, D. Summers \cmsinstskipUniversity of Nebraska-Lincoln, Lincoln, USA
K. Bloom, S. Bose, J. Butt, D.R. Claes, A. Dominguez, M. Eads, J. Keller, T. Kelly, I. Kravchenko, J. Lazo-Flores, H. Malbouisson, S. Malik, G.R. Snow \cmsinstskipState University of New York at Buffalo, Buffalo, USA
U. Baur, A. Godshalk, I. Iashvili, S. Jain, A. Kharchilava, A. Kumar, S.P. Shipkowski, K. Smith \cmsinstskipNortheastern University, Boston, USA
G. Alverson, E. Barberis, D. Baumgartel, O. Boeriu, M. Chasco, S. Reucroft, J. Swain, D. Wood, J. Zhang \cmsinstskipNorthwestern University, Evanston, USA
A. Anastassov, A. Kubik, N. Odell, R.A. Ofierzynski, B. Pollack, A. Pozdnyakov, M. Schmitt, S. Stoynev, M. Velasco, S. Won \cmsinstskipUniversity of Notre Dame, Notre Dame, USA
L. Antonelli, D. Berry, M. Hildreth, C. Jessop, D.J. Karmgard, J. Kolb, T. Kolberg, K. Lannon, W. Luo, S. Lynch, N. Marinelli, D.M. Morse, T. Pearson, R. Ruchti, J. Slaunwhite, N. Valls, M. Wayne, J. Ziegler \cmsinstskipThe Ohio State University, Columbus, USA
B. Bylsma, L.S. Durkin, J. Gu, C. Hill, P. Killewald, K. Kotov, M. Rodenburg, G. Williams \cmsinstskipPrinceton University, Princeton, USA
N. Adam, E. Berry, P. Elmer, D. Gerbaudo, V. Halyo, P. Hebda, A. Hunt, J. Jones, E. Laird, D. Lopes Pegna, D. Marlow, T. Medvedeva, M. Mooney, J. Olsen, P. Piroué, X. Quan, H. Saka, D. Stickland, C. Tully, J.S. Werner, A. Zuranski \cmsinstskipUniversity of Puerto Rico, Mayaguez, USA
J.G. Acosta, X.T. Huang, A. Lopez, H. Mendez, S. Oliveros, J.E. Ramirez Vargas, A. Zatserklyaniy \cmsinstskipPurdue University, West Lafayette, USA
E. Alagoz, V.E. Barnes, G. Bolla, L. Borrello, D. Bortoletto, A. Everett, A.F. Garfinkel, L. Gutay, Z. Hu, M. Jones, O. Koybasi, M. Kress, A.T. Laasanen, N. Leonardo, C. Liu, V. Maroussov, P. Merkel, D.H. Miller, N. Neumeister, I. Shipsey, D. Silvers, A. Svyatkovskiy, H.D. Yoo, J. Zablocki, Y. Zheng \cmsinstskipPurdue University Calumet, Hammond, USA
P. Jindal, N. Parashar \cmsinstskipRice University, Houston, USA
C. Boulahouache, V. Cuplov, K.M. Ecklund, F.J.M. Geurts, B.P. Padley, R. Redjimi, J. Roberts, J. Zabel \cmsinstskipUniversity of Rochester, Rochester, USA
B. Betchart, A. Bodek, Y.S. Chung, R. Covarelli, P. de Barbaro, R. Demina, Y. Eshaq, H. Flacher, A. Garcia-Bellido, P. Goldenzweig, Y. Gotra, J. Han, A. Harel, D.C. Miner, D. Orbaker, G. Petrillo, D. Vishnevskiy, M. Zielinski \cmsinstskipThe Rockefeller University, New York, USA
A. Bhatti, R. Ciesielski, L. Demortier, K. Goulianos, G. Lungu, C. Mesropian, M. Yan \cmsinstskipRutgers, the State University of New Jersey, Piscataway, USA
O. Atramentov, A. Barker, D. Duggan, Y. Gershtein, R. Gray, E. Halkiadakis, D. Hidas, D. Hits, A. Lath, S. Panwalkar, R. Patel, A. Richards, K. Rose, S. Schnetzer, S. Somalwar, R. Stone, S. Thomas \cmsinstskipUniversity of Tennessee, Knoxville, USA
G. Cerizza, M. Hollingsworth, S. Spanier, Z.C. Yang, A. York \cmsinstskipTexas A&M University, College Station, USA
J. Asaadi, R. Eusebi, J. Gilmore, A. Gurrola, T. Kamon, V. Khotilovich, R. Montalvo, C.N. Nguyen, I. Osipenkov, J. Pivarski, A. Safonov, S. Sengupta, A. Tatarinov, D. Toback, M. Weinberger \cmsinstskipTexas Tech University, Lubbock, USA
N. Akchurin, J. Damgov, C. Jeong, K. Kovitanggoon, S.W. Lee, Y. Roh, A. Sill, I. Volobouev, R. Wigmans, E. Yazgan \cmsinstskipVanderbilt University, Nashville, USA
E. Appelt, E. Brownson, D. Engh, C. Florez, W. Gabella, M. Issah, W. Johns, P. Kurt, C. Maguire, A. Melo, P. Sheldon, S. Tuo, J. Velkovska \cmsinstskipUniversity of Virginia, Charlottesville, USA
M.W. Arenton, M. Balazs, S. Boutle, M. Buehler, S. Conetti, B. Cox, B. Francis, R. Hirosky, A. Ledovskoy, C. Lin, C. Neu, R. Yohay \cmsinstskipWayne State University, Detroit, USA
S. Gollapinni, R. Harr, P.E. Karchin, P. Lamichhane, M. Mattson, C. Milstène, A. Sakharov \cmsinstskipUniversity of Wisconsin, Madison, USA
M. Anderson, M. Bachtis, J.N. Bellinger, D. Carlsmith, S. Dasu, J. Efron, K. Flood, L. Gray, K.S. Grogg, M. Grothe, R. Hall-Wilton\cmsAuthorMark1, M. Herndon, P. Klabbers, J. Klukas, A. Lanaro, C. Lazaridis, J. Leonard, R. Loveless, A. Mohapatra, D. Reeder, I. Ross, A. Savin, W.H. Smith, J. Swanson, M. Weinberg \cmsinstskip†: Deceased
1:  Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland
2:  Also at Universidade Federal do ABC, Santo Andre, Brazil
3:  Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France
4:  Also at Suez Canal University, Suez, Egypt
5:  Also at British University, Cairo, Egypt
6:  Also at Soltan Institute for Nuclear Studies, Warsaw, Poland
7:  Also at Massachusetts Institute of Technology, Cambridge, USA
8:  Also at Université de Haute-Alsace, Mulhouse, France
9:  Also at Brandenburg University of Technology, Cottbus, Germany
10: Also at Moscow State University, Moscow, Russia
11: Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary
12: Also at Eötvös Loránd University, Budapest, Hungary
13: Also at Tata Institute of Fundamental Research - HECR, Mumbai, India
14: Also at University of Visva-Bharati, Santiniketan, India
15: Also at Facoltà Ingegneria Università di Roma ”La Sapienza”, Roma, Italy
16: Also at Università della Basilicata, Potenza, Italy
17: Also at Laboratori Nazionali di Legnaro dell’ INFN, Legnaro, Italy
18: Also at Università degli studi di Siena, Siena, Italy
19: Also at Faculty of Physics of University of Belgrade, Belgrade, Serbia
20: Also at University of California, Los Angeles, Los Angeles, USA
21: Also at University of Florida, Gainesville, USA
22: Also at Université de Genève, Geneva, Switzerland
23: Also at Scuola Normale e Sezione dell’ INFN, Pisa, Italy
24: Also at INFN Sezione di Roma; Università di Roma ”La Sapienza”, Roma, Italy
25: Also at University of Athens, Athens, Greece
26: Also at California Institute of Technology, Pasadena, USA
27: Also at The University of Kansas, Lawrence, USA
28: Also at Institute for Theoretical and Experimental Physics, Moscow, Russia
29: Also at Paul Scherrer Institut, Villigen, Switzerland
30: Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia
31: Also at Gaziosmanpasa University, Tokat, Turkey
32: Also at Adiyaman University, Adiyaman, Turkey
33: Also at Mersin University, Mersin, Turkey
34: Also at Izmir Institute of Technology, Izmir, Turkey
35: Also at Kafkas University, Kars, Turkey
36: Also at Suleyman Demirel University, Isparta, Turkey
37: Also at Ege University, Izmir, Turkey
38: Also at Rutherford Appleton Laboratory, Didcot, United Kingdom
39: Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom
40: Also at INFN Sezione di Perugia; Università di Perugia, Perugia, Italy
41: Also at Institute for Nuclear Research, Moscow, Russia
42: Also at Los Alamos National Laboratory, Los Alamos, USA


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