Search for Physics Beyond the Standard Model in Opposite-Sign Dilepton Events in pp collisions at sqrt(s) = 7 TeV

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/2011-016 2011/03/08 CMS-SUS-10-007 Search for Physics Beyond the Standard Model in Opposite-sign Dilepton Events in pp Collisions at √s=7 TeV The CMS Collaboration∗ Abstract A search is presented for physics beyond the standard model (SM) in final states with opposite-sign isolated lepton pairs accompanied by hadronic jets and missing transverse energy. The search is performed using LHC data recorded with the CMS detector, corresponding to an integrated luminosity of 34 pb−1. No evidence for an event yield beyond SM expectations is found. An upper limit on the non-SM contribution to the signal region is deduced from the results. This limit is interpreted in the context of the constrained minimal supersymmetric model. Additional information is provided to allow testing the exclusion of specific models of physics beyond the SM. Submitted to the Journal of High Energy Physics ∗See Appendix A for the list of collaboration members arXiv:1103.1348v1 [hep-ex] 7 Mar 2011 1 1 Introduction In this paper we describe a search for physics beyond the standard model (BSM) in a sample of proton-proton collisions at a centre-of-mass energy of 7 TeV. The data sample was collected with the Compact Muon Solenoid (CMS) detector [1] at the Large Hadron Collider (LHC) between March and November of 2010 and corresponds to an integrated luminosity of 34 pb−1. The BSM signature in this search is motivated by three general considerations. First, new particles predicted by BSM physics scenarios are expected to be heavy, since they have so far eluded detection. Second, BSM physics signals with high enough cross sections to be observed in our current dataset are expected to be produced strongly, resulting in significant hadronic activity. Third, astrophysical evidence for dark matter suggests [2, 3] that the mass of weakly-interacting massive particles is of the order of the electroweak symmetry breaking scale. Such particles, if produced in pp collisions, could escape detection and give rise to an apparent imbalance in the event transverse energy. We therefore focus on the region of high missing transverse energy (Emiss T). An example of a specific BSM scenario is provided by R-parity conserving supersymmetric (SUSY) models in which new, heavy particles are pair-produced and subsequently undergo cascade decays, producing hadronic jets and leptons [4–10]. These cascade decays may terminate in the production of weakly-interacting massive particles, resulting in large Emiss T. The results reported in this paper are part of a broad program of BSM searches in events with jets and Emiss T, characterized by the number and type of leptons in the final state. Here we describe a search for events containing opposite-sign isolated lepton pairs (e+e−, e±µ∓,µ+µ−) in addition to the jets and Emiss T. Results from a complementary search with no electrons or muons in the final state have already been reported in Ref. [11]. Our analysis strategy is as follows. In order to select dilepton events, we use high-pTlepton triggers and a preselection based on that of the tt cross section measurement in the dilepton channel [12]. Good agreement is found between this data sample and predictions from SM Monte Carlo (MC) simulations in terms of the event yields and shapes of various kinematic distributions. Because BSM physics is expected to have large hadronic activity and Emiss Tas discussed above, we define a signal region with requirements on these quantities to select about 1% of dilepton tt events, as predicted by MC. The observed event yield in the signal region is compared with the predictions from two independent background estimation techniques based on data control samples, as well as with SM and BSM MC expectations. Finally, the robustness of the result is confirmed by an independent analysis based on hadronic activity triggers, different “physics object” reconstruction, and a complementary background estimation method. No specific BSM physics scenario, e.g. a particular SUSY model, has been used to optimize the search. In order to illustrate the sensitivity of the search, a simplified and practical model of SUSY breaking, the constrained minimal supersymmetric extension of the standard model (CMSSM) [13, 14], is used. The CMSSM is described by five parameters: the universal scalar and gaugino mass parameters (m0and m1/2, respectively), the universal trilinear soft SUSY breaking parameter A0, the ratio of the vacuum expectation values of the two Higgs doublets (tan β), and the sign of the Higgs mixing parameter µ. Throughout the paper, two CMSSM parameter sets, referred to as LM0 and LM1 [15], are used to illustrate possible CMSSM yields. The parameter values defining LM0 (LM1) are m0=200 (60)GeV/c2,m1/2 =160 (250)GeV/c2, A0=−400 (0)GeV; both LM0 and LM1 have tan β=10 and µ>0. These two scenarios are beyond the exclusion reach of previous searches performed at the Tevatron and LEP. They were recently excluded by a search performed at CMS in events with jets and Emiss T[11] based on the same data sample used for this search. In this analysis, the LM0 and LM1 scenarios serve as benchmarks which may be used to allow comparison of the sensitivity with other analyses. 23 Event Selection 2 CMS Detector The central feature of the CMS apparatus is a superconducting solenoid, 13 m in length and 6 m in diameter, which provides an axial magnetic field of 3.8 T. Within the field volume are several particle detection systems. Charged particle trajectories are measured by silicon pixel and silicon strip trackers, covering 0 ≤φ≤2πin azimuth and |η|<2.5 in pseudorapidity, defined as η=−log[tan θ/2], where θis the polar angle of the trajectory of the particle with respect to the counterclockwise proton beam direction. A crystal electromagnetic calorimeter and a brass/scintillator hadronic calorimeter surround the tracking volume, providing energy measurements of electrons and hadronic jets. Muons are identified and measured in gas-ionization detectors embedded in the steel return yoke outside the solenoid. The detector is nearly hermetic, allowing energy balance measurements in the plane transverse to the beam direction. A two-tier trigger system selects the most interesting pp collision events for use in physics analysis. A more detailed description of the CMS detector can be found elsewhere [1]. 3 Event Selection Samples of MC events are used to guide the design of the analysis. These events are generated using either the PYTHIA 6.4.22 [16] or MADGRAPH 4.4.12 [17] event generators. They are then simulated using a GEANT4-based model [18] of the CMS detector, and finally reconstructed and analyzed using the same software as is used to process collision data. We apply a preselection based on that of the tt cross section measurement in the dilepton channel [12]. Events with two opposite-sign, isolated leptons (e+e−, e±µ∓, or µ+µ−) are selected. At least one of the leptons must have pT>20 GeV/cand both must have pT>10 GeV/c, and the electrons (muons) must have |η|<2.5 (|η|<2.4). In events with more than two such leptons, the two leptons with the highest pTare selected. Events with an e+e−or µ+µ−pair with invariant mass between 76 GeV/c2and 106 GeV/c2or below 10 GeV/c2are removed, in order to suppress Drell–Yan (DY) Z/γ∗→`` events, as well as low mass dilepton resonances. Events are required to pass at least one of a set of single-lepton or double-lepton triggers. The efficiency for events containing two leptons passing the analysis selection to pass at least one of these triggers is very high, in excess of 99% for dilepton t¯ tevents. Because leptons produced in the decays of low-mass particles, such as hadrons containing b and c quarks, are nearly always inside jets, they can be suppressed by requiring the leptons to be isolated in space from other particles that carry a substantial amount of transverse momentum. The details of the lepton isolation measurement are given in Ref. [12]. In brief, a cone is constructed of size ∆R≡p(∆η)2+ (∆φ)2=0.3 around the lepton momentum direction. The lepton relative isolation is then quantified by summing the transverse energy (as measured in the calorimeters) and the transverse momentum (as measured in the silicon tracker) of all objects within this cone, excluding the lepton, and dividing by the lepton transverse momentum. The resulting quantity is required to be less than 0.15, rejecting the large background arising from QCD production of jets. We require the presence of at least two jets with pT>30 GeV/cand |η|<2.5, separated by ∆R>0.4 from leptons passing the analysis selection with pT>10 GeV/c. The anti-kTclustering algorithm [19] with ∆R=0.5 is used for jet clustering. Jets are reconstructed using calorimeter information and their energies are corrected using reconstructed tracks [20]. The event is required to satisfy HT>100 GeV, where HTis defined as the scalar sum of the transverse energies of the selected jets. In addition, the Emiss Tin the event is required to exceed 50 GeV. 3 Several techniques are used in CMS for calculating Emiss T[21]. Here, the raw Emiss T, calculated from calorimeter signals in the range |η|<5.0, is corrected by taking into account the contributions from minimally interacting muons. The Emiss Tis further corrected on a track-by-track basis for the expected response of the calorimeter derived from simulation, resulting in an improved Emiss Tresolution. The data yields and corresponding MC predictions after this event preselection are given in Table 1. The MC yields are normalized to 34 pb−1using next-to-leading order (NLO) cross sections. As expected, the MC predicts that the sample passing the preselection is dominated by dilepton tt. The data yield is in good agreement with the prediction. We also quote the yields for the LM0 and LM1 benchmark scenarios. Table 1: Data yields and MC predictions after preselection, using the quoted NLO production cross sections σ. The tt →`+`−corrresponds to dilepton tt, including t →W→τ→`; tt →other includes all other tt decay modes. The samples of MC tt, W±+ jets, and singletop events were generated with MADGRAPH. The Drell–Yan sample (which includes events with invariant masses as low as 10 GeV/c2) was generated using a mixture of MADGRAPH and PYTHIA. All other samples were generated with PYTHIA. The LM0 and LM1 benchmark scenarios are defined in the text. Uncertainties are statistical only. Sample σ(pb) ee µµ eµTotal tt →`+`−16.9 14.50 ±0.24 17.52 ±0.26 41.34 ±0.40 73.36 ±0.53 tt →other 140.6 0.49 ±0.04 0.21 ±0.03 1.02 ±0.06 1.72 ±0.08 Drell–Yan 18417 1.02 ±0.21 1.16 ±0.22 1.20 ±0.22 3.38 ±0.37 W±+ jets 28049 0.19 ±0.13 0.00 ±0.00 0.09 ±0.09 0.28 ±0.16 W+W−2.9 0.15 ±0.01 0.16 ±0.01 0.37 ±0.02 0.68 ±0.03 W±Z 0.3 0.02 ±0.00 0.02 ±0.00 0.04 ±0.00 0.09 ±0.00 ZZ 4.3 0.01 ±0.00 0.02 ±0.00 0.02 ±0.00 0.05 ±0.00 Single top 33.0 0.46 ±0.02 0.55 ±0.02 1.24 ±0.03 2.25 ±0.04 Total SM MC 16.85 ±0.34 19.63 ±0.34 45.33 ±0.47 81.81 ±0.67 Data 15 22 45 82 LM0 52.9 10.67 ±0.31 12.63 ±0.34 17.81 ±0.41 41.11 ±0.62 LM1 6.7 2.35 ±0.05 2.83 ±0.06 1.51 ±0.04 6.69 ±0.09 Figure 1 compares several kinematic distributions in data and SM MC for events passing the preselection. As an illustration, we also show the MC distributions for the LM1 benchmark point. We find that the SM MC reproduces the properties of the bulk of dilepton tt events. We therefore turn our attention to the tails of the Emiss Tand HTdistributions of the tt sample. To look for possible BSM contributions, we define a signal region that preserves about 1% of the dilepton tt events, by adding the following two requirements to the preselection described above: HT>300 GeV and y>8.5 GeV1/2, (1) where y≡Emiss T/√HT. The requirement is on yrather than Emiss Tbecause the variables HT and yare found to be almost uncorrelated in dilepton tt MC, with a correlation coefficient of ∼5%. This facilitates the use of a background estimation method based on data, as discussed in Section 4. 44 Background Estimates from Data (GeV) T H 0 50 100 150 200 250 300 350 400 450 500 Events 0 5 10 15 20 25 30 CMS = 7 TeVs at -1 34 pb µ/eµµEvents with ee/ ) 1/2 y (GeV 0 2 4 6 8 10 12 14 16 18 20 Events 0 5 10 15 20 25 30 35 CMS = 7 TeVs at -1 34 pb µ/eµµEvents with ee/ ) (GeV)llM( 0 50 100 150 200 250 300 Events 0 5 10 15 20 25 CMS = 7 TeVs at -1 34 pb µ/eµµEvents with ee/ ) (GeV/c)ll( T p 0 50 100 150 200 250 300 Events 0 5 10 15 20 25 30 CMS = 7 TeVs at -1 34 pb µ/eµµEvents with ee/ data - l + l →tt other→tt DY single top VV + jetsW LM1 Figure 1: Distributions of (top left) scalar sum of jet transverse energies (HT), (top right) y≡Emiss T/√HT, (bottom left) dilepton invariant mass M(``), and (bottom right) dilepton transverse momentum pT(``)for SM MC and data after preselection. The last bin contains the overflow. Here tt →`+`−corresponds to dilepton tt, including t →W→τ→`; tt →other includes all other tt decay modes, and VV indicates the sum of WW, WZ, and ZZ. The MC distributions for the LM1 benchmark points are also shown. The MC predicts 1.3 SM events, dominated by dilepton tt, in the signal region. The expectations for the LM0 and LM1 points are 8.6 and 3.6 events, respectively. 4 Background Estimates from Data We have developed two independent methods to estimate from data the background in the signal region. The first method exploits the fact that HTand yare nearly uncorrelated for the tt background. Four regions (A, B, C, and D) are defined in the yvs. HTplane, as indicated in Figure 2, where region D is the signal region defined in Eq. 1. In the absence of a signal, the yields in the regions A, B, and C can be used to estimate the yield in the signal region D as ND=NA×NC/NB; this method is referred to as the “ABCD method”. The expected event yields in the four regions for the SM MC, as well as the background prediction NA×NC/NB, are given in Table 2. We observe good agreement between the total SM MC predicted and observed yields. A 20% systematic uncertainty is assigned to the predicted yield of the ABCD method to take into account uncertainties from contributions of backgrounds other than dilepton tt (16%), finite MC statistics in the closure test (8%), and variation of the boundaries between the ABCD regions based on the uncertainty in the hadronic energy scale (8%). The second background estimate, henceforth referred to as the dilepton transverse momentum (pT(``)) method, is based on the idea [22] that in dilepton tt events the pTdistributions of the charged leptons and neutrinos from W decays are related, because of the common boosts 5 from the top and W decays. This relation is governed by the polarization of the W’s, which is well understood in top decays in the SM [23, 24] and can therefore be reliably accounted for. We then use the observed pT(``)distribution to model the pT(νν)distribution, which is identified with Emiss T. Thus, we use the number of observed events with HT>300 GeV and pT(``)/√HT>8.5 GeV1/2 to predict the number of background events with HT>300 GeV and y=Emiss T/√HT>8.5 GeV1/2. In practice, two corrections must be applied to this prediction, as described below. The first correction accounts for the Emiss T>50 GeV requirement in the preselection, which is needed to reduce the DY background. We rescale the prediction by a factor equal to the inverse of the fraction of events passing the preselection which also satisfy the requirement pT(``)> 50 GeV/c. This correction factor is determined from MC and is K50 =1.5. The second correction (KC) is associated with the known polarization of the W, which introduces a difference between the pT(``)and pT(νν)distributions. The correction KCalso takes into account detector effects such as the hadronic energy scale and resolution which affect the Emiss Tbut not pT(``). The total correction factor is K50 ×KC=2.1 ±0.6, where the uncertainty is dominated by the 5% uncertainty in the hadronic energy scale [25]. All background estimation methods based on data are in principle subject to signal contamination in the control regions, which tends to decrease the significance of a signal which may be present in the data by increasing the background prediction. In general, it is difficult to quantify these effects because we do not know what signal may be present in the data. Having two independent methods (in addition to expectations from MC) adds redundancy because signal contamination can have different effects in the different control regions for the two methods. For example, in the extreme case of a BSM signal with identical distributions of pT(``)and Emiss T, an excess of events might be seen in the ABCD method but not in the pT(``)method. Backgrounds in which one or both leptons do not originate from electroweak decays (non-W/Z leptons) are assessed using the method of Ref. [12]. A non-W/Z lepton is a lepton candidate originating from within a jet, such as a lepton from semileptonic b or c decays, a muon decayin-flight, a pion misidentified as an electron, or an unidentified photon conversion. Estimates of the contributions to the signal region from pure multijet QCD, with two non-W/Z leptons, and in W +jets, with one non-W/Z lepton in addition to the lepton from the decay of the W, are derived separately. We find 0.00+0.04 −0.00 and 0.0+0.4 −0.0 for the multijet QCD and W+jets contributions respectively, and thus consider these backgrounds to be negligible. Backgrounds from DY and from processes with two vector bosons and single top are negligible compared to dilepton tt. 5 Results We find one event in the signal region D. The event is in the eµchannel and contains 3 jets. The SM MC expectation is 1.3 events. Table 2 summarizes the event yields obtained for each of the four ABCD regions in the data and in the MC samples. The prediction of the ABCD method is given by NA×NC/NB= 1.3 ±0.8 (stat.)±0.3 (syst.)events. The data, together with SM expectations, are presented in Figure 2. The ABCD prediction is then compared with that of the pT(``)method. We find 1 event passing the requirements HT>300 GeV and pT(``)/√HT>8.5 GeV1/2. This leads to a predicted background of 2.1 ±2.1 (stat.)±0.6 (syst.)after applying the correction factor K50 ×KC= 66 Acceptance and Efficiency Systematic Uncertainties (GeV) T H 0 200 400 600 800 1000 1200 1400 ) 1/2 y (GeV 0 5 10 15 20 25 30 SM MC Data B A C D CMS = 7 TeVs at -1 34.0 pb µ/eµµEvents with ee/ Figure 2: Distributions of yvs. HTfor SM MC (2-dimensional histogram) and data (scatter plot). Here our choice of the ABCD regions is also shown. 2.1 ±0.6, as shown in Figure 3 (left). As a validation of the pT(``)method in a region with higher statistics, we also apply the pT(``) method in control region A by restricting HTto be in the range 125–300 GeV. Here the prediction is 9.0 ±6.0 (stat.)background events, in good agreement with the observed yield of 12 events, as shown in Figure 3 (right). In summary, for the signal region defined as HT>300 GeV and y>8.5 GeV1/2: we observe one event in the data, SM MC predicts 1.3 events, the ABCD method predicts 1.3 ±0.8 (stat.)± 0.3 (syst.)events, and the pT(``)method predicts 2.1 ±2.1 (stat.)±0.6 (syst.)events. All three background predictions are consistent within their uncertainties. We thus take as our best estimate of the SM yield in the signal region the error-weighted average of the two background estimates based on data and find a number of predicted background events NBG = 1.4 ±0.8, in good agreement with the observed signal yield. We therefore conclude that no evidence for a non-SM contribution to the signal region is observed. 6 Acceptance and Efficiency Systematic Uncertainties The acceptance and efficiency, as well as the systematic uncertainties in these quantities, depend on the signal model. For some of the individual uncertainties, it is reasonable to quote values based on SM control samples with kinematic properties similar to the SUSY benchmark models. For others that depend strongly on the kinematic properties of the event, the systematic uncertainties must be quoted model by model. The systematic uncertainty in the lepton acceptance consists of two parts: the trigger efficiency uncertainty and the identification and isolation uncertainty. The trigger efficiency for two leptons of pT>10 GeV/c, with one lepton of pT>20 GeV/cis close to 100%. We estimate the efficiency uncertainty to be a few percent, mostly in the low pTregion, using samples of Z →``. 7 Table 2: Data yields in the four regions of Figure 2, as well as the predicted yield in region D given by NA×NC/NB. The SM and BSM MC expectations are also shown. The quoted uncertainties are statistical only. Sample NANBNCNDNA×NC/NB tt →`+`−8.44 ±0.18 32.83 ±0.35 4.78 ±0.14 1.07 ±0.06 1.23 ±0.05 tt →other 0.12 ±0.02 0.78 ±0.05 0.16 ±0.02 0.02 ±0.01 0.02 ±0.01 Drell–Yan 0.17 ±0.08 1.18 ±0.22 0.04 ±0.04 0.12 ±0.07 0.01 ±0.01 W±+ jets 0.00 ±0.00 0.09 ±0.09 0.00 ±0.00 0.00 ±0.00 0.00 ±0.00 W+W−0.11 ±0.01 0.29 ±0.02 0.02 ±0.01 0.03 ±0.01 0.01 ±0.00 W±Z0.01 ±0.00 0.04 ±0.00 0.00 ±0.00 0.00 ±0.00 0.00 ±0.00 ZZ 0.01 ±0.00 0.02 ±0.00 0.00 ±0.00 0.00 ±0.00 0.00 ±0.00 Single top 0.29 ±0.01 1.04 ±0.03 0.04 ±0.01 0.01 ±0.00 0.01 ±0.00 Total SM MC 9.14 ±0.20 36.26 ±0.43 5.05 ±0.14 1.27 ±0.10 1.27 ±0.05 Data 12 37 4 1 1.30 ±0.78 LM0 4.04 ±0.19 4.45 ±0.20 13.92 ±0.36 8.63 ±0.27 12.63 ±0.88 LM1 0.52 ±0.02 0.26 ±0.02 1.64 ±0.04 3.56 ±0.06 3.33 ±0.27 ) 1/2 y (GeV 0 2 4 6 8 10 12 14 16 18 20 Events -3 10 -2 10 -1 10 1 10 2 10 3 10 MC predicted MC observed data predicted data observed µ/eµµEvents with ee/ > 300 GeV T H CMS = 7 TeVs, -1 = 34 pb int L ) 1/2 y (GeV 0 2 4 6 8 10 12 14 16 18 20 Events -3 10 -2 10 -1 10 1 10 2 10 3 10 MC predicted MC observed data predicted data observed µ/eµµEvents with ee/ < 300 GeV T 125 < H CMS = 7 TeVs, -1 = 34 pb int L Figure 3: Distributions of y(observed) and pT(``)/√HTscaled by the correction factor K50 (predicted) for (left) the signal region and (right) the control region A, for both MC and data. The vertical dashed line indicates the search region defined by y>8.5 GeV1/2. The deficit at low yis due to the Emiss T>50 GeV preselection requirement. For dilepton tt, LM0, and LM1, the trigger efficiency uncertainties are found to be less than 1%. We verify that the MC reproduces the lepton identification and isolation efficiencies in data using samples of Z →``; the data and MC efficiencies are found to be consistent within 2%. Another significant source of systematic uncertainty is associated with the jet and Emiss Tenergy scale. The impact of this uncertainty is final-state dependent. Final states characterized by very large hadronic activity and Emiss Tare less sensitive than final states where the Emiss Tand HTare typically close to the minimum requirements applied to these quantities. To be more quantitative, we have used the method of Ref. [12] to evaluate the systematic uncertainties in the acceptance for tt and for the two benchmark SUSY points using a 5% uncertainty in the hadronic energy scale [25]. For tt the uncertainty is 27%; for LM0 and LM1 the uncertainties are 14% and 6%, respectively. The uncertainty in the integrated luminosity is 11% [26]. 14 10 Summary [24] A. Czarnecki, J. G. Korner, and J. H. Piclum, “Helicity fractions of W bosons from top quark decays at NNLO in QCD”, Phys. Rev. D81 (2010) 111503. doi:10.1103/PhysRevD.81.111503. [25] CMS Collaboration, “Determination of the Jet Energy Scale in CMS with pp Collisions at √s=7 TeV”, CMS Physics Analysis Summary CMS-PAS-JME-10-010 (2010). [26] CMS Collaboration, “Measurement of CMS Luminosity”, CMS Physics Analysis Summary CMS-PAS-EWK-10-004 (2010). [27] CMS Collaboration, “Commissioning of the Particle-Flow Reconstruction in Minimum-Bias and Jet Events from pp Collisions at 7 TeV”, CMS Physics Analysis Summary CMS-PAS-PFT-10-002 (2010). [28] I. Bertram, G. Landsberg, J. Linnemann et al., “A Recipe for the construction of confidence limits”. FERMILAB-TM-2104, 2000. [29] B. Allanach, “SOFTSUSY: a program for calculating supersymmetric spectra”, Comput.Phys.Commun. 143 (2002) 305. doi:10.1016/S0010-4655(01)00460-X. [30] W. Beenakker et al., “Squark and Gluino Production at Hadron Colliders”, Nucl.Phys. B492 (1997) 51. doi:10.1016/S0550-3213(97)00084-9. [31] P. M. Nadolsky, H.-L. Lai, Q.-H. Cao et al., “Implications of CTEQ global analysis for collider observables”, Phys. Rev. D78 (2008) 013004. doi:10.1103/PhysRevD.78.013004. [32] CDF Collaboration, “Inclusive Search for Squark and Gluino Production in p¯ pCollisions at √s=1.96 TeV”, Phys. Rev. Lett. 102 (Mar, 2009) 121801. doi:10.1103/PhysRevLett.102.121801. [33] D0 Collaboration, “Search for squarks and gluinos in events with jets and missing transverse energy using 2.1 fb−1of collision data at √s=1.96 TeV”, Physics Letters B 660 (2008) 449. doi:10.1016/j.physletb.2008.01.042. [34] LEPSUSYWG, ALEPH, DELPHI, L3 and OPAL experiments, “LSP mass limit in Minimal SUGRA”. LEPSUSYWG/02-06.2. [35] D0 Collaboration, “Search for associated production of charginos and neutralinos in the trilepton final state using 2.3 fb−1of data”, Physics Letters B 680 (2009) 34. doi:10.1016/j.physletb.2009.08.011. 15 A The CMS Collaboration Yerevan Physics Institute, Yerevan, Armenia S. Chatrchyan, V. Khachatryan, A.M. Sirunyan, A. Tumasyan Institut f¨ur Hochenergiephysik der OeAW, Wien, Austria W. Adam, T. Bergauer, M. Dragicevic, J. Er¨ o, C. Fabjan, M. Friedl, R. Fr¨ uhwirth, V.M. Ghete, J. Hammer1, S. H¨ ansel, M. Hoch, N. H¨ ormann, J. Hrubec, M. Jeitler, G. Kasieczka, W. Kiesenhofer, M. Krammer, D. Liko, I. Mikulec, M. Pernicka, H. Rohringer, R. Sch¨ ofbeck, J. Strauss, F. Teischinger, P. Wagner, W. Waltenberger, G. Walzel, E. Widl, C.-E. Wulz National Centre for Particle and High Energy Physics, Minsk, Belarus V. Mossolov, N. Shumeiko, J. Suarez Gonzalez Universiteit 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 Vrije 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 Universit´e 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 Ghent 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 Universit´e Catholique de Louvain, Louvain-la-Neuve, Belgium S. Basegmez, G. Bruno, J. Caudron, L. Ceard, E. Cortina Gil, J. De Favereau De Jeneret, C. Delaere, D. Favart, A. Giammanco, G. Gr´ egoire, J. Hollar, V. Lemaitre, J. Liao, O. Militaru, S. Ovyn, D. Pagano, A. Pin, K. Piotrzkowski, N. Schul Universit´e de Mons, Mons, Belgium N. Beliy, T. Caebergs, E. Daubie Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil G.A. Alves, D. De Jesus Damiao, M.E. Pol, M.H.G. Souza Universidade 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 Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, Brazil F.A. Dias, T.R. Fernandez Perez Tomei, E. M. Gregores2, C. Lagana, F. Marinho, P.G. Mercadante2, S.F. Novaes, Sandra S. Padula Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria N. Darmenov1, L. Dimitrov, V. Genchev1, P. Iaydjiev1, S. Piperov, M. Rodozov, S. Stoykova, G. Sultanov, V. Tcholakov, R. Trayanov, I. Vankov 16 A The CMS Collaboration University of Sofia, Sofia, Bulgaria A. Dimitrov, M. Dyulendarova, R. Hadjiiska, A. Karadzhinova, V. Kozhuharov, L. Litov, E. Marinova, M. Mateev, B. Pavlov, P. Petkov Institute 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 State 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 Universidad de Los Andes, Bogota, Colombia A. Cabrera, B. Gomez Moreno, A.A. Ocampo Rios, A.F. Osorio Oliveros, J.C. Sanabria Technical University of Split, Split, Croatia N. Godinovic, D. Lelas, K. Lelas, R. Plestina3, D. Polic, I. Puljak University of Split, Split, Croatia Z. Antunovic, M. Dzelalija Institute Rudjer Boskovic, Zagreb, Croatia V. Brigljevic, S. Duric, K. Kadija, S. Morovic University of Cyprus, Nicosia, Cyprus A. Attikis, M. Galanti, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis Charles University, Prague, Czech Republic M. Finger, M. Finger Jr. Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt A. Awad, S. Khalil4, M.A. Mahmoud5 National Institute of Chemical Physics and Biophysics, Tallinn, Estonia A. Hektor, M. Kadastik, M. M¨ untel, M. Raidal, L. Rebane Department of Physics, University of Helsinki, Helsinki, Finland V. Azzolini, P. Eerola Helsinki Institute of Physics, Helsinki, Finland S. Czellar, J. H¨ ark¨ onen, V. Karim¨ aki, R. Kinnunen, M.J. Kortelainen, T. Lamp´ en, K. LassilaPerini, S. Lehti, T. Lind´ en, P. Luukka, T. M¨ aenp¨ a¨ a, E. Tuominen, J. Tuominiemi, E. Tuovinen, D. Ungaro, L. Wendland Lappeenranta University of Technology, Lappeenranta, Finland K. Banzuzi, A. Korpela, T. Tuuva Laboratoire d’Annecy-le-Vieux de Physique des Particules, IN2P3-CNRS, Annecy-le-Vieux, France D. Sillou DSM/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 17 Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France S. Baffioni, F. Beaudette, L. Benhabib, L. Bianchini, M. Bluj6, C. Broutin, P. Busson, C. Charlot, T. Dahms, L. Dobrzynski, S. Elgammal, R. Granier de Cassagnac, M. Haguenauer, P. Min´ e, C. Mironov, C. Ochando, P. Paganini, D. Sabes, R. Salerno, Y. Sirois, C. Thiebaux, B. Wyslouch7, A. Zabi Institut Pluridisciplinaire Hubert Curien, Universit´e de Strasbourg, Universit´e de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France J.-L. Agram8, J. Andrea, D. Bloch, D. Bodin, J.-M. Brom, M. Cardaci, E.C. Chabert, C. Collard, E. Conte8, F. Drouhin8, C. Ferro, J.-C. Fontaine8, D. Gel´ e, U. Goerlach, S. Greder, P. Juillot, M. Karim8, A.-C. Le Bihan, Y. Mikami, P. Van Hove Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules (IN2P3), Villeurbanne, France F. Fassi, D. Mercier Universit´e de Lyon, Universit´e Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucl´eaire 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 E. Andronikashvili Institute of Physics, Academy of Science, Tbilisi, Georgia L. Megrelidze Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia D. Lomidze RWTH 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 RWTH 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, M. Merschmeyer, A. Meyer, P. Papacz, H. Pieta, H. Reithler, S.A. Schmitz, L. Sonnenschein, J. Steggemann, D. Teyssier, M. Tonutti RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany M. Bontenackels, M. Davids, M. Duda, G. Fl¨ ugge, 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 Deutsches Elektronen-Synchrotron, Hamburg, Germany M. Aldaya Martin, W. Behrenhoff, U. Behrens, M. Bergholz9, K. Borras, A. Cakir, A. Campbell, E. Castro, D. Dammann, G. Eckerlin, D. Eckstein, A. Flossdorf, G. Flucke, A. Geiser, J. Hauk, H. Jung1, M. Kasemann, I. Katkov10, P. Katsas, C. Kleinwort, H. Kluge, A. Knutsson, M. Kr¨ amer, D. Kr¨ ucker, E. Kuznetsova, W. Lange, W. Lohmann9, R. Mankel, M. Marienfeld, I.-A. MelzerPellmann, A.B. Meyer, J. Mnich, A. Mussgiller, J. Olzem, D. Pitzl, A. Raspereza, A. Raval, M. Rosin, R. Schmidt9, T. Schoerner-Sadenius, N. Sen, A. Spiridonov, M. Stein, J. Tomaszewska, R. Walsh, C. Wissing 18 A The CMS Collaboration University of Hamburg, Hamburg, Germany C. Autermann, V. Blobel, S. Bobrovskyi, J. Draeger, H. Enderle, U. Gebbert, K. Kaschube, G. Kaussen, R. Klanner, J. Lange, B. Mura, S. Naumann-Emme, F. Nowak, N. Pietsch, C. Sander, H. Schettler, P. Schleper, M. Schr¨ oder, T. Schum, J. Schwandt, H. Stadie, G. Steinbr¨ uck, J. Thomsen Institut f¨ur 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, J.R. Komaragiri, T. Kuhr, D. Martschei, S. Mueller, Th. M¨ uller, 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. Zhukov10, E.B. Ziebarth Institute 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 University of Athens, Athens, Greece L. Gouskos, T.J. Mertzimekis, A. Panagiotou, E. Stiliaris University of Io´annina, Io´annina, Greece I. Evangelou, C. Foudas, P. Kokkas, N. Manthos, I. Papadopoulos, V. Patras, F.A. Triantis KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary A. Aranyi, G. Bencze, L. Boldizsar, C. Hajdu1, P. Hidas, D. Horvath11, A. Kapusi, K. Krajczar12, B. Radics, F. Sikler, G.I. Veres12, G. Vesztergombi12 Institute of Nuclear Research ATOMKI, Debrecen, Hungary N. Beni, J. Molnar, J. Palinkas, Z. Szillasi, V. Veszpremi University of Debrecen, Debrecen, Hungary P. Raics, Z.L. Trocsanyi, B. Ujvari Panjab 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 University of Delhi, Delhi, India S. Ahuja, S. Bhattacharya, B.C. Choudhary, P. Gupta, S. Jain, S. Jain, A. Kumar, K. Ranjan, R.K. Shivpuri Bhabha Atomic Research Centre, Mumbai, India R.K. Choudhury, D. Dutta, S. Kailas, V. Kumar, A.K. Mohanty1, L.M. Pant, P. Shukla Tata Institute of Fundamental Research - EHEP, Mumbai, India T. Aziz, M. Guchait13, A. Gurtu, M. Maity14, D. Majumder, G. Majumder, K. Mazumdar, G.B. Mohanty, A. Saha, K. Sudhakar, N. Wickramage Tata Institute of Fundamental Research - HECR, Mumbai, India S. Banerjee, S. Dugad, N.K. Mondal Institute 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 19 INFN Sezione di Bari a, Universit`a di Bari b, Politecnico di Bari c, Bari, Italy M. Abbresciaa,b, L. Barbonea,b, C. Calabriaa,b, A. Colaleoa, D. Creanzaa,c, N. De Filippisa,c,1, M. De Palmaa,b, L. Fiorea, G. Iasellia,c, L. Lusitoa,b, G. Maggia,c, M. Maggia, N. Mannaa,b, B. Marangellia,b, S. Mya,c, S. Nuzzoa,b, N. Pacificoa,b, G.A. Pierroa, A. Pompilia,b, G. Pugliesea,c, F. Romanoa,c, G. Rosellia,b, G. Selvaggia,b, L. Silvestrisa, R. Trentaduea, S. Tupputia,b, G. Zitoa INFN Sezione di Bologna a, Universit`a di Bologna b, Bologna, Italy G. Abbiendia, A.C. Benvenutia, D. Bonacorsia, S. Braibant-Giacomellia,b, L. Brigliadoria, P. Capiluppia,b, A. Castroa,b, F.R. Cavalloa, M. Cuffiania,b, G.M. Dallavallea, F. Fabbria, A. Fanfania,b, D. Fasanellaa, P. Giacomellia, M. Giuntaa, C. Grandia, S. Marcellinia, G. Masetti, M. Meneghellia,b, A. Montanaria, F.L. Navarriaa,b, F. Odoricia, A. Perrottaa, A.M. Rossia,b, T. Rovellia,b, G. Sirolia,b, R. Travaglinia,b INFN Sezione di Catania a, Universit`a di Catania b, Catania, Italy S. Albergoa,b, G. Cappelloa,b, M. Chiorbolia,b,1, S. Costaa,b, A. Tricomia,b, C. Tuvea INFN Sezione di Firenze a, Universit`a di Firenze b, Firenze, Italy G. Barbaglia, V. Ciullia,b, C. Civininia, R. D’Alessandroa,b, E. Focardia,b, S. Frosalia,b, E. Galloa, S. Gonzia,b, P. Lenzia,b, M. Meschinia, S. Paolettia, G. Sguazzonia, A. Tropianoa,1 INFN Laboratori Nazionali di Frascati, Frascati, Italy L. Benussi, S. Bianco, S. Colafranceschi15, F. Fabbri, D. Piccolo INFN Sezione di Genova, Genova, Italy P. Fabbricatore, R. Musenich INFN Sezione di Milano-Biccoca a, Universit`a di Milano-Bicocca b, Milano, Italy A. Benagliaa,b, F. De Guioa,b,1, L. Di Matteoa,b, A. Ghezzia,b, M. Malbertia,b, S. Malvezzia, A. Martellia,b, A. Massironia,b, D. Menascea, L. Moronia, M. Paganonia,b, D. Pedrinia, S. Ragazzia,b, N. Redaellia, S. Salaa, T. Tabarelli de Fatisa,b, V. Tancinia,b INFN Sezione di Napoli a, Universit`a di Napoli ”Federico II” b, Napoli, Italy S. Buontempoa, C.A. Carrillo Montoyaa,1, N. Cavalloa,16, A. Cimminoa,b, A. De Cosaa,b, F. Fabozzia,16, A.O.M. Iorioa, L. Listaa, M. Merolaa,b, P. Nolia,b, P. Paoluccia INFN Sezione di Padova a, Universit`a di Padova b, Universit`a di Trento (Trento) c, Padova, Italy P. Azzia, N. Bacchettaa, P. Bellana,b, D. Biselloa,b, A. Brancaa, R. Carlina,b, P. Checchiaa, M. De Mattiaa,b, T. Dorigoa, U. Dossellia, F. Fanzagoa, F. Gasparinia,b, U. Gasparinia,b, S. Lacapraraa,17, I. Lazzizzeraa,c, M. Margonia,b, M. Mazzucatoa, A.T. Meneguzzoa,b, M. Nespoloa,1, L. Perrozzia,1, N. Pozzobona,b, P. Ronchesea,b, F. Simonettoa,b, E. Torassaa, M. Tosia,b, S. Vaninia,b, P. Zottoa,b, G. Zumerlea,b INFN Sezione di Pavia a, Universit`a di Pavia b, Pavia, Italy U. Berzanoa, S.P. Rattia,b, C. Riccardia,b, P. Torrea,b, P. Vituloa,b INFN Sezione di Perugia a, Universit`a di Perugia b, Perugia, Italy M. Biasinia,b, G.M. Bileia, B. Caponeria,b, L. Fan` oa,b, P. Laricciaa,b, A. Lucaronia,b,1, G. Mantovania,b, M. Menichellia, A. Nappia,b, F. Romeoa,b, A. Santocchiaa,b, S. Taronia,b,1, M. Valdataa,b, R. Volpea,b INFN Sezione di Pisa a, Universit`a di Pisa b, Scuola Normale Superiore di Pisa c, Pisa, Italy P. Azzurria,c, G. Bagliesia, J. Bernardinia,b, T. Boccalia,1, G. Broccoloa,c, R. Castaldia, R.T. D’Agnoloa,c, R. Dell’Orsoa, F. Fioria,b, L. Fo` aa,c, A. Giassia, A. Kraana, F. Ligabuea,c, 20 A The CMS Collaboration T. Lomtadzea, L. Martinia,18, A. Messineoa,b, F. Pallaa, F. Palmonaria, G. Segneria, A.T. Serbana, P. Spagnoloa, R. Tenchinia, G. Tonellia,b,1, A. Venturia,1, P.G. Verdinia INFN Sezione di Roma a, Universit`a di Roma ”La Sapienza” b, Roma, Italy L. Baronea,b, F. Cavallaria, D. Del Rea,b, E. Di Marcoa,b, M. Diemoza, D. Francia,b, M. Grassia,1, E. Longoa,b, S. Nourbakhsha, G. Organtinia,b, A. Palmaa,b, F. Pandolfia,b,1, R. Paramattia, S. Rahatloua,b INFN Sezione di Torino a, Universit`a di Torino b, Universit`a del Piemonte Orientale (Novara) c, Torino, Italy N. Amapanea,b, R. Arcidiaconoa,c, S. Argiroa,b, M. Arneodoa,c, C. Biinoa, C. Bottaa,b,1, N. Cartigliaa, R. Castelloa,b, M. Costaa,b, N. Demariaa, A. Grazianoa,b,1, C. Mariottia, M. Maronea,b, S. Masellia, E. Migliorea,b, G. Milaa,b, V. Monacoa,b, M. Musicha,b, M.M. Obertinoa,c, N. Pastronea, M. Pelliccionia,b, A. Romeroa,b, M. Ruspaa,c, R. Sacchia,b, V. Solaa,b, A. Solanoa,b, A. Staianoa, D. Trocinoa,b, A. Vilela Pereiraa,b INFN Sezione di Trieste a, Universit`a di Trieste b, Trieste, Italy S. Belfortea, F. Cossuttia, G. Della Riccaa,b, B. Gobboa, D. Montaninoa,b, A. Penzoa Kangwon National University, Chunchon, Korea S.G. Heo, S.K. Nam Kyungpook 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 Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Korea Zero Kim, J.Y. Kim, S. Song Korea 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 University of Seoul, Seoul, Korea M. Choi, S. Kang, H. Kim, C. Park, I.C. Park, S. Park, G. Ryu Sungkyunkwan University, Suwon, Korea Y. Choi, Y.K. Choi, J. Goh, M.S. Kim, E. Kwon, J. Lee, S. Lee, H. Seo, I. Yu Vilnius University, Vilnius, Lithuania M.J. Bilinskas, I. Grigelionis, M. Janulis, D. Martisiute, P. Petrov, T. Sabonis Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico H. Castilla-Valdez, E. De La Cruz-Burelo, R. Lopez-Fernandez, A. S´ anchez-Hern´ andez, L.M. Villasenor-Cendejas Universidad Iberoamericana, Mexico City, Mexico S. Carrillo Moreno, F. Vazquez Valencia Benemerita Universidad Autonoma de Puebla, Puebla, Mexico H.A. Salazar Ibarguen Universidad Aut´onoma de San Luis Potos´ı, San Luis Potos´ı, Mexico E. Casimiro Linares, A. Morelos Pineda, M.A. Reyes-Santos University of Auckland, Auckland, New Zealand D. Krofcheck, J. Tam 21 University of Canterbury, Christchurch, New Zealand P.H. Butler, R. Doesburg, H. Silverwood National 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 Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland M. Cwiok, W. Dominik, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski Soltan Institute for Nuclear Studies, Warsaw, Poland T. Frueboes, R. Gokieli, M. G´ orski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, G. Wrochna, P. Zalewski Laborat´orio de Instrumenta¸c˜ao e F´ısica Experimental de Part´ıculas, Lisboa, Portugal N. Almeida, P. Bargassa, A. David, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, P. Musella, A. Nayak, J. Seixas, J. Varela Joint 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 Petersburg 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 Institute 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 Institute for Theoretical and Experimental Physics, Moscow, Russia V. Epshteyn, V. Gavrilov, V. Kaftanov†, M. Kossov1, A. Krokhotin, N. Lychkovskaya, V. Popov, G. Safronov, S. Semenov, V. Stolin, E. Vlasov, A. Zhokin Moscow State University, Moscow, Russia E. Boos, M. Dubinin19, L. Dudko, A. Gribushin, V. Klyukhin, O. Kodolova, A. Markina, S. Obraztsov, M. Perfilov, S. Petrushanko, L. Sarycheva, V. Savrin P.N. Lebedev Physical Institute, Moscow, Russia V. Andreev, M. Azarkin, I. Dremin, M. Kirakosyan, A. Leonidov, S.V. Rusakov, A. Vinogradov State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia I. Azhgirey, S. Bitioukov, V. Grishin1, 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 University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia P. Adzic20, M. Djordjevic, D. Krpic20, J. Milosevic Centro de Investigaciones Energ´eticas Medioambientales y Tecnol´ogicas (CIEMAT), Madrid, Spain M. Aguilar-Benitez, J. Alcaraz Maestre, P. Arce, C. Battilana, E. Calvo, M. Cepeda, M. Cerrada, M. Chamizo Llatas, N. Colino, B. De La Cruz, A. Delgado Peris, C. Diez Pardos, D. Dom´ ınguez V´ azquez, C. Fernandez Bedoya, J.P. Fern´ andez Ramos, A. Ferrando, J. Flix, M.C. Fouz, 22 A The CMS Collaboration 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, M.S. Soares, C. Willmott Universidad Aut´onoma de Madrid, Madrid, Spain C. Albajar, G. Codispoti, J.F. de Troc´ oniz Universidad de Oviedo, Oviedo, Spain J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, L. Lloret Iglesias, J.M. Vizan Garcia Instituto de F´ısica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain J.A. Brochero Cifuentes, I.J. Cabrillo, A. Calderon, S.H. Chuang, J. Duarte Campderros, M. Felcini21, 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 Gomez22, T. Rodrigo, A.Y. Rodr´ ıguez-Marrero, A. Ruiz-Jimeno, L. Scodellaro, M. Sobron Sanudo, I. Vila, R. Vilar Cortabitarte CERN, European Organization for Nuclear Research, Geneva, Switzerland D. Abbaneo, E. Auffray, G. Auzinger, P. Baillon, A.H. Ball, D. Barney, A.J. Bell23, D. Benedetti, C. Bernet3, 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. Cur´ e, 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, C. Hartl, J. Harvey, J. Hegeman, B. Hegner, H.F. Hoffmann, A. Honma, V. Innocente, P. Janot, K. Kaadze, E. Karavakis, P. Lecoq, C. Lourenc¸o, T. M¨ aki, L. Malgeri, M. Mannelli, L. Masetti, F. Meijers, S. Mersi, E. Meschi, R. Moser, M.U. Mozer, M. Mulders, E. Nesvold1, M. Nguyen, T. Orimoto, L. Orsini, E. Perez, A. Petrilli, A. Pfeiffer, M. Pierini, M. Pimi¨ a, G. Polese, A. Racz, J. Rodrigues Antunes, G. Rolandi24, T. Rommerskirchen, C. Rovelli25, M. Rovere, H. Sakulin, C. Sch¨ afer, C. Schwick, I. Segoni, A. Sharma, P. Siegrist, M. Simon, P. Sphicas26, M. Spiropulu19, F. St¨ ockli, M. Stoye, P. Tropea, A. Tsirou, P. Vichoudis, M. Voutilainen, W.D. Zeuner Paul Scherrer Institut, Villigen, Switzerland W. Bertl, K. Deiters, W. Erdmann, K. Gabathuler, R. Horisberger, Q. Ingram, H.C. Kaestli, S. K¨ onig, D. Kotlinski, U. Langenegger, F. Meier, D. Renker, T. Rohe, J. Sibille27, A. Starodumov28 Institute for Particle Physics, ETH Zurich, Zurich, Switzerland P. Bortignon, L. Caminada29, Z. Chen, S. Cittolin, G. Dissertori, M. Dittmar, J. Eugster, K. Freudenreich, C. Grab, A. Herv´ e, W. Hintz, P. Lecomte, W. Lustermann, C. Marchica29, P. Martinez Ruiz del Arbol, P. Meridiani, P. Milenovic30, 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 Universit¨at Z¨urich, Zurich, Switzerland E. Aguil´ o, C. Amsler, V. Chiochia, S. De Visscher, C. Favaro, M. Ivova Rikova, B. Millan Mejias, P. Otiougova, C. Regenfus, P. Robmann, A. Schmidt, H. Snoek National 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 23 National 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 Cukurova University, Adana, Turkey A. Adiguzel, M.N. Bakirci31, S. Cerci32, 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. Sogut33, D. Sunar Cerci32, B. Tali, H. Topakli31, D. Uzun, L.N. Vergili, M. Vergili, C. Zorbilmez Middle 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 Bogazici University, Istanbul, Turkey M. Deliomeroglu, D. Demir34, E. G¨ ulmez, B. Isildak, M. Kaya35, O. Kaya35, S. Ozkorucuklu36, N. Sonmez37 National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine L. Levchuk University 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. Newbold38, K. Nirunpong, A. Poll, S. Senkin, V.J. Smith, S. Ward Rutherford Appleton Laboratory, Didcot, United Kingdom L. Basso39, K.W. Bell, A. Belyaev39, 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 Imperial 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. Gilbert, A. Guneratne Bryer, G. Hall, Z. Hatherell, J. Hays, G. Iles, G. Karapostoli, L. Lyons, B.C. MacEvoy, A.-M. Magnan, J. Marrouche, R. Nandi, J. Nash, A. Nikitenko28, A. Papageorgiou, M. Pesaresi, K. Petridis, M. Pioppi40, D.M. Raymond, N. Rompotis, A. Rose, M.J. Ryan, C. Seez, P. Sharp, A. Sparrow, A. Tapper, S. Tourneur, M. Vazquez Acosta, T. Virdee, S. Wakefield, D. Wardrope, T. Whyntie Brunel 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 Baylor University, Waco, USA K. Hatakeyama Boston 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 Brown 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