J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Published for SISSA by Springer Received: January 9, 2011 Accepted: February 16, 2011 Published: March 4, 2011 Search for heavy stable charged particles in pp collisions at √ s = 7TeV The CMS collaboration Abstract: The result of a search at the LHC for heavy stable charged particles pro- duced in pp collisions at √ s = 7 TeV is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb−1. Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no can- didate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398 GeV/c2, us- ing a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors. Keywords: Hadron-Hadron Scattering Open Access, Copyright CERN, for the benefit of the CMS Collaboration doi:10.1007/JHEP03(2011)024 http://dx.doi.org/10.1007/JHEP03(2011)024 J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Contents 1 Introduction 1 2 The CMS detector 2 3 Candidate selection and background estimation 2 4 Results 5 5 Conclusions 9 The CMS collaboration 13 1 Introduction Heavy stable (or quasi-stable) charged particles (HSCPs) appear in various extensions of the standard model (SM) [1–8]. If the lifetime of an HSCP produced at the Large Hadron Collider (LHC) is longer than a few nanoseconds, the particle will travel over distances that are comparable or larger than the size of a typical particle detector. In addition, if the HSCP mass is &100 GeV/c2, a significant fraction of these particles will have a velocity, β ≡ v/c, smaller than 0.9. These HSCPs will be directly observable through the distinctive signature of a high momentum (p) particle with an anomalously large rate of energy loss through ionization (dE/dx). Previous collider searches for HSCPs have often been performed under the assumption that these particles lose energy primarily through low-momentum-transfer interactions, even if they are strongly interacting, and are therefore likely to reach the outer muon systems of the detectors and be identified as muons [9–13]. The interactions with matter experienced by a strongly-interacting HSCP, which is expected to form a bound state (R- hadron) [14] in the process of hadronization, can lead to it flipping the sign of its electric charge or becoming neutral. A recent study [15] on the modeling of nuclear interactions of HSCPs traveling through matter, favours a scenario of charge suppression. In this model the majority of R-hadrons containing a gluino, g̃ (the supersymmetric partner of the gluon), or a supersymmetric bottom squark, are expected to emerge as neutral particles after traversing an amount of material typical of the detectors operating at LEP, the Tevatron, or LHC. If this model is correct, the majority of these HSCPs would not be observed in the muon system of a typical collider detector. Experimental strategies that do not rely on the muon-like behavior for the HSCPs are therefore of great importance. For instance, searches have been performed for very slow (β . 0.4) R-hadrons containing a gluino brought to rest in the detector [16, 17]. – 1 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 In this article we present a search for HSCPs produced in pp collisions at √ s = 7 TeV at the LHC with the Compact Muon Solenoid (CMS) detector [18]. The search is based on the data sample collected between April and August 2010 corresponding to an integrated luminosity of 3.1 pb−1. We use triggers requiring: a high-transverse-momentum muon (pT > 9 GeV/c); or a dimuon pair (pT > 3 GeV/c for each muon); or calorimeter- based missing transverse energy (Emiss T > 100 GeV), to search for HSCPs failing muon identification or emerging mainly as neutral particles after traversing the calorimeters; or a high-transverse-energy jet (ET > 100 GeV) to search for HSCPs accompanied by substantial hadronic activity. The analysis makes use of two approaches. In a first selection, referred to as “tracker-only”, the HSCP candidates are searched for as individual tracks reconstructed in the inner tracker detector with large dE/dx and pT. A second selection, referred to as “tracker-plus-muon”, additionally requires that the track is identified as a muon in the outer muon detector. For both selections, the mass of the candidate is calculated from the measured p and dE/dx. 2 The CMS detector The central feature of the CMS detector is a 3.8 T superconducting solenoid of 6 m internal diameter surrounding a silicon pixel and strip tracker, a crystal electromagnetic calorimeter, and a brass-scintillator hadronic calorimeter. Muons are measured in gaseous detectors embedded in the iron return yoke. Centrally produced charged particles are measured in the tracker by three layers of silicon pixel detectors, followed by ten microstrip layers. At pseudorapidities (η ≡ − ln tan(θ/2), where θ is the polar angle measured with respect to the beam direction) above ≈ 1.5, particles are tracked in two pixel and twelve strip layers arranged in disks perpendicular to the beam axis. In this analysis, the dE/dx measurement is based only on the information from the silicon strip detectors. The dE/dx measurement precision is limited by the silicon strip analogue-to-digital converter (ADC) modules that are characterized by a maximum number of counts per channel corresponding to about three times the average charge released by a minimum-ionizing particle (MIP) in 300 µm of silicon. This is the thickness of the modules mounted in the innermost silicon strip central layers. The pT resolution for tracks measured in the central (forward) region of the silicon tracker is 1% (2%) for pT values up to 50 GeV/c and degrades to 10% (20%) at pT values of 1 TeV/c. The trigger and reconstruction efficiencies for HSCPs in the muon detectors are limited by the requirements on the arrival time of the particles at the muon system. These requirements affect the efficiency for detecting slow HSCPs. The dependence of the muon trigger efficiency on the particle velocity is studied using data and Monte Carlo (MC) simulations and found to decrease, below β = 0.7. The muon trigger becomes completely inefficient at β = 0.5. A much more detailed description of the CMS apparatus can be found elsewhere [18]. 3 Candidate selection and background estimation Candidate HSCPs are pre-selected by requiring a track with |η| < 2.5, pT > 15 GeV/c, relative uncertainty on the pT less than 15%, and transverse (longitudinal) impact param- – 2 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 eter with respect to the reconstructed primary collision vertex less than 0.25 (2.0) cm. Candidate tracks are also required to have at least three measurements in the silicon-strip detector. For the tracker-plus-muon selection, we additionally require the track to be com- patible with track segments reconstructed in the muon system. As an estimator of the degree of compatibility of the observed charge measurements with the MIP hypothesis, a modified version of the Smirnov-Cramer-von Mises [19, 20] discriminant is used: Ias = 3 N × ( 1 12N + N∑ i=1 [ Pi × ( Pi − 2i− 1 2N )2 ]) , (3.1) where N is the number of charge measurements in the silicon-strip detectors, Pi is the probability for a MIP to produce a charge smaller or equal to the i-th charge measurement for the observed path length in the detector, and the sum is over the track measurements ordered in terms of increasing Pi. Non-relativistic HSCP candidates will have the value of the discriminant Ias approaching unity. The modification applied to the original form of the discriminant consists of multiplicating by Pi the term in round brackets. In this way the Ias value for tracks reconstructed with an anomalously low dE/dx, which may result from rare accidental associations of noise signals, is pushed toward low values. Thus the modification eliminates the sensitivity of the original discriminant to incompatibility with the MIP hypothesis due to low ionization. The charge probability density function used to calculate Pi is obtained using tracks with p > 5 GeV/c in events collected with a minimum bias trigger. Figure 1 shows normalized distributions of pT and Ias in data and two MC samples, for candidates passing the tracker-only pre-selection. The first MC sample contains events from QCD processes. The second MC sample contains signal events from pair-production of stable g̃ with a mass of 200 GeV/c2. Both samples are generated with the pythia v6.422 [21] MC package. More details on the simulation of the signal sample will be given below. The MC QCD simulations are found to reproduce the data, and the simulated signal is clearly separated. Because of the limited number of available simulated events with low transverse-momentum transfers, the MC QCD distributions display bin-to-bin variations in the size of the statistical errors. The most probable value of the particle dE/dx is determined using a harmonic esti- mator Ih of grade k = −2: Ih = ( 1 N ∑ i cki )1/k , (3.2) where ci is the charge per unit path length in the detector of the i-th measurement for a given track. In order to estimate the mass (m) of highly ionizing particles, the following relationship between Ih, p, and m is assumed: Ih = K m2 p2 + C. (3.3) Equation 3.3 reproduces the Bethe-Bloch formula [22] with an accuracy of better than 1% in the range 0.4 < β < 0.9, which corresponds to 1.1 < (dE/dx)/(dE/dx)MIP < 4.0. – 3 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 (GeV/c) T p 0 500 1000 fr ac tio n of tr ac ks /2 0 G eV /c -610 -510 -410 -310 -210 -110 Tracker - Only 200g~MC - MC - QCD Data -1 = 7 TeV 3.1 pb sCMS asI 0 0.2 0.4 0.6 0.8 1 fr ac tio n of tr ac ks /0 .0 2 -710 -610 -510 -410 -310 -210 -110 1 Tracker - Only 200g~MC - MC - QCD Data -1 = 7 TeV 3.1 pb sCMS Figure 1. Normalized distributions of pT (left) and Ias (right) in data and two MC samples, for candidates passing the tracker-only pre-selection. The two MC samples contain events from QCD processes and from pair-production of g̃ with a mass of 200 GeV/c2, respectively. The empirical parameters K and C are determined from data using a sample of low- momentum protons, for which the fitted values are K = 2.579 ± 0.001 MeV cm−1 c2 and C = 2.557 ± 0.001 MeV cm−1, and the mass resolution is 7%. The reconstructed mass distribution for kaons and protons is in very good agreement with the one obtained from MC following this procedure [23]. For masses above 100 GeV/c2, the mass resolution is expected to worsen because of the deterioration of the momentum resolution and because of the limit on the maximum charge that can be measured by the silicon strip tracker ADCs, which also affects the mass scale. These effects are taken into account by the MC: for a 300 GeV/c2 HSCP, the mass resolution and the reconstructed peak position are found to be 12% and 265 GeV/c2, respectively. The search is performed as a counting experiment. Signal candidates are required to have Ias and pT greater than threshold values and the mass to be in the range of 75 to 2000 GeV/c2, allowing sensitivity to HSCP masses as low as 100 GeV/c2. The Ias distribution for the pre-selected tracks, and in particular its tail, depends strongly on the number of charge measurements on the track. Thus, to increase the sensitivity of the search, pre-selected tracks are divided into subsamples according to the number of silicon strip measurements. Tracks with 18 measurements or more are merged into a single subsample. Tracks with a number of measurements in the range of 3 to 8 are also merged into a single subsample. In total 11 subsamples are formed whose populations do not differ by more than a factor of five. The Ias (pT ) threshold in each subsample is determined by requiring a constant efficiency on data for all subsamples, when the threshold is applied separately. A method that exploits the absence of correlation between the pT and dE/dx measurements in data is used to estimate the background from MIPs. In a given subsample j, the number of tracks that are expected to pass both the final pT and Ias thresholds set for the subsample is estimated as Dj = BjCj/Aj , where Aj is the number of tracks that – 4 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 fail both the Ias and pT selections and Bj (Cj) is the number of tracks that pass only the Ias (pT ) selection. The Bj and Cj tracks are then used to form a binned probability density function in Ih (p) for the Dj tracks. Finally, using the mass determination (eq. 3.3), the full mass spectrum of the background in the signal region D is predicted. By comparing the predicted and observed number of tracks for several very loose selec- tions in a control region of the mass spectrum, corresponding to masses below 75 GeV/c2, the prediction is found to underestimate systematically the observation by 12% (5%) for the tracker-only (tracker-plus-muon) selection. After correcting the predicted background by this amount, the remaining background systematic uncertainty is conservatively esti- mated as twice the r.m.s. of the prediction-to-observation ratio distribution The resulting uncertainty on the predicted background is 14% (17%). As significant background rejection can be obtained without a sizable effect on the sig- nal efficiency, the final selection is optimized by requiring the total expected background in the search region to be ∼ 0.05 events. This low-background choice optimizes the discovery potential even if just a handful of events are observed, and at the same time maintains significant exclusion sensitivity in the case that no events are observed. 4 Results In addition to the final “tight” selection, the result of a “loose” selection is reported in table 1. The loose selection retains a relatively large number of background candidates and allows us to compare the background prediction with the observed data. Figure 2 shows good agreement between the observed and predicted mass spectrum obtained using the loose selection for the tracker-plus-muon and tracker-only candidates. The results of the search with the final selection are also presented in table 1. No candidate HSCP track is observed in either the tracker-only or tracker-plus-muon analysis. Given the null result, cross section upper limits at the 95% C.L. are set on the HSCP production for two benchmark scenarios: direct production of g̃ pairs and supersymmetric top squark (t̃1) pairs. For a given mass, the cross section for g̃ production is expected to be much larger than that for t̃1 production at both the Tevatron and the LHC. Thus higher mass limits can be set for the former at both machines. However, as the mass of a produced particle increases, the ratio of the production cross section at the LHC to that at the Tevatron increases. For g̃ masses in the region of 350 GeV/c2, the increase in relative cross section outweighs the difference in integrated luminosity between the current Tevatron and LHC data sets, enabling the LHC to set the most sensitive limits on the search for g̃. Events with pair production of g̃ and t̃1, with mass values in the range 130-900 GeV/c2, are generated with pythia in order to compute the efficiency of our selection on these signals. The t̃1 and g̃ are treated as stable in all these samples and their hadronization is performed by pythia. A parameter relevant to the g̃ pair production, and not to the t̃1 pair production, is the fraction, f , of produced g̃ hadronizing into a g̃-gluon state (R-gluonball). This fraction is an unknown parameter of the hadronization model and affects the fraction of R-hadrons that are neutral at production, which in turn affects the detection efficiency. – 5 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 )2Mass (GeV/c 0 500 1000 2 T ra ck s / 5 0 G eV /c -110 1 10 210 310 Tracker + Muon Data-based prediction Data 400g~MC - -1 = 7 TeV 3.1 pb sCMS )2Mass (GeV/c 0 500 1000 2 T ra ck s / 5 0 G eV /c -110 1 10 210 Tracker - Only Data-based prediction Data 300g~MC - -1 = 7 TeV 3.1 pb sCMS Figure 2. Mass spectrum for the loose selection defined in table 1 for the tracker-plus-muon (left) and tracker-only (right) candidates. Shown are: observed spectrum (black dots with the error bars), data-based predicted background spectrum (red triangles) with its uncertainty (green band) and the spectrum predicted by MC for a signal of pair-produced stable g̃ with a mass of 400 (left) and 300 (right) GeV/c2 (blue histogram). LOOSE Mu Tk εI 3.2× 10−2 1.0× 10−2 Imin as 0.049 - 0.162 0.007 - 0.278 εpT 1.0× 10−1 3.2× 10−2 pmin T (GeV/c) 34 - 36 59 - 62 Expected 281± 2(stat.)± 49(syst.) 426± 1(stat.)± 62(syst.) Observed 307 452 TIGHT Mu Tk εI 1.0× 10−4 1.0× 10−4 Imin as 0.184 - 0.782 0.186 - 0.784 εpT 1.0× 10−3 3.2× 10−4 pmin T (GeV/c) 115 - 118 154 - 210 Expected 0.025± 0.002(stat.)± 0.004(syst.) 0.074± 0.002(stat.)± 0.011(syst.) Observed 0 0 Table 1. Selections used in the analysis and results of the search. The tracker-plus-muon and tracker-only selections are labeled as “Mu” and “Tk”, respectively. As explained in the text, the actual Ias (pT) thresholds are determined in the various subsamples by the requirement of a constant efficiency for candidate selection, εI (εpT ). These thresholds, indicated by Imin as (pmin T ), are therefore reported as a range of values. Expected and observed number of candidates in the signal region are reported in the “Expected” and “Observed” rows, respectively. Top: loose selection. Bottom: tight selection. – 6 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 In this study, results are obtained for two different values of f , 0.1 and 0.5, to show the effect of the hadronization model uncertainty on the sensitivity of the search. The interactions of the HSCPs with the CMS apparatus and the detector response are simulated in detail with the geant4 v9.2 [24, 25] toolkit. The R-hadron strong interactions with matter are modeled as in ref. [26, 27]. This model, like a number of others [15, 28–30], assumes that the probability of an interaction between the heavy parton and a quark in the target nucleon is low since the cross section varies with the inverse square of the parton mass according to perturbative QCD. The adopted model chooses a pragmatic approach based on analogy with observed low energy hadron scattering. However, given the very large uncertainties on the dynamics underlying R-hadron interactions, an extremely pessimistic scenario of complete charge suppression, where each nuclear interaction suffered by the R-hadron causes it to become neutral, is also considered. The tracker-only selection is expected to have sensitivity even in such a scenario. The total signal efficiency is reported in table 2 for some combinations of models and selections. Relatively small differences are found between the tracker-plus-muon and tracker-only selection except in the charge suppression scenario, where the tracker-plus- muon selection is completely inefficient. This analysis is found to be complementary to the search for long-lived stopped par- ticles presented in [17]. Indeed, for the case of g̃ with f = 0.1 and mass values below 500 GeV/c2, the fraction of HSCPs that have β < 0.4 and pass the final selection is less than 0.5%. Therefore the two analyses explore different ranges of produced particle veloc- ities with no overlap. The main sources of systematic uncertainty affecting the results presented in the fol- lowing are summarized in table 3. The uncertainty on the signal selection efficiency is estimated to be 15% for all considered combinations of models and selections. The main source of this uncertainty is an assumed 10% uncertainty on the jet energy scale [31], which affects both the jet and Emiss T trigger efficiency by about 10%. In a more recent study [32], the estimate of the uncertainty on the jet energy scale has been reduced by a factor of two. However, in this analysis we have conservatively chosen to retain the earlier estimate of 10%. The uncertainty on the muon trigger efficiency and the imperfect simulation of the synchronization of the muon trigger and readout electronics are studied with data and MC and are found to be the second most important source of systematic uncertainty. The total uncertainty on the trigger efficiency is 12%. The uncertainty on the offline muon track re- construction efficiency [33], offline track reconstruction efficiency in the inner tracker [34], track momentum scale [35] and ionization energy loss scale [23] is also found to yield no more than 5% uncertainty on the overall signal selection efficiency. The uncertainty on the absolute value of the integrated luminosity is estimated to be 11% [36]. The upper limit on the cross section is computed at 95% C.L. using a Bayesian method with a flat signal prior and a log-normal prior used for integration over the nuisance param- eters [19, 20, 22]. In order to obtain a conservative upper limit we set the expected back- ground to zero. The tracker-plus-muon selection provides better limits than the tracker- only for all scenarios but the one with complete charge suppression. For each considered scenario, the cross section upper limit obtained with the most sensitive selection is reported – 7 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 gluino mass (GeV/c2) 200 300 400 500 600 900 Theoretical cross section (pb) 606 57.2 8.98 1.87 0.470 0.0130 Mu; f=0.1 Total efficiency (%) 7.17 10.4 13.1 15.1 14.5 9.18 Expected 95% C.L. limit (pb) 15.1 10.4 8.25 7.16 7.47 11.8 Observed 95% C.L. limit (pb) 14.5 9.98 7.92 6.88 7.17 11.3 Mu; f=0.5; Total efficiency (%) 3.84 5.46 7.03 8.23 8.10 4.98 Expected 95% C.L. limit (pb) 28.2 19.8 15.4 13.1 13.3 21.7 Observed 95% C.L. limit (pb) 27.1 19.0 14.8 12.6 12.8 20.9 Tk; f=0.1; ch. suppr. Total efficiency (%) 0.59 2.44 4.16 6.39 8.60 7.66 Expected 95% C.L. limit (pb) 188 45.5 26.7 17.4 12.9 14.5 Observed 95% C.L. limit (pb) 176 42.6 25.0 16.2 12.1 13.6 stop mass (GeV/c2) 130 200 300 500 800 Theoretical cross section (pb) 120 13.0 1.31 0.0480 0.00110 Mu; Total efficiency (%) 2.99 9.50 14.7 19.6 14.0 Expected 95% C.L. limit (pb) 36.1 11.4 7.35 5.52 7.71 Observed 95% C.L. limit (pb) 34.7 10.9 7.06 5.30 7.39 Tk; ch. suppr. Total efficiency (%) 0.02 1.19 3.55 7.27 7.68 Expected 95% C.L. limit (pb) 5540 93.2 31.3 15.3 14.5 Observed 95% C.L. limit (pb) 5180 87.2 29.2 14.3 13.5 Table 2. Total signal selection efficiency and cross section upper limits for different combinations of models and selections: pair production of supersymmetric stop and gluinos; tracker-plus-muon (Mu) and tracker-only (Tk) selections; different fractions, f , of R-gluonball states produced after hadronization and charge suppression (ch. suppr.) scenario. Source of Systematic Error Relative Uncertainty (%) Theoretical cross section 10 - 25 Integrated luminosity 11 Trigger efficiency 12 Muon reconstruction efficiency 5 Track reconstruction efficiency < 5 Momentum scale < 5 Ionization energy loss scale < 3 Total uncertainty on signal acceptance 15 Table 3. Sources of systematic errors and corresponding relative uncertainties. – 8 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 in table 2 and figure 3, along with the theoretical predictions for g̃ and t̃1 pair produc- tion computed at next-to-leading order (NLO) + next-to-leading log (NLL) [37–40] using the prospino v2 program [41]. The g̃ theoretical predictions refer to the case where the squarks and gluino are degenerate in mass. In the heavy squark limit these cross sections are about 10% higher. For the case of t̃1, beyond LO, the cross section does not only depend on the t̃1 mass, but also, though to a much lesser extent [42], on the g̃ mass, the average mass of the first and second generation squarks and the stop mixing angle. For this reason, the t̃1 theoretical predictions reported in table 2 and figure 3 refer to the SPS1a’ benchmark scenario [43]. All systematic uncertainties discussed above are included in the cross section upper limits reported in table 2 and figure 3. From the intersection of the cross section limit curve and the lower edge of the theoretical cross section band we set a 95% C.L. lower limit of 398 (357) GeV/c2 on the mass of pair-produced g̃ with f = 0.1(0.5), using the tracker-plus-muon selection. The analogous limit on the t̃1 mass is 202 GeV/c2. In the charge suppression scenario we set, with the tracker-only selection, a 95% C.L. g̃ mass limit of 311 GeV/c2 for f = 0.1. 5 Conclusions In summary, the CMS detector has been used to identify highly ionizing, high-pT parti- cles and measure their masses. Two searches have been conducted: a very inclusive and model independent one that uses highly-ionizing tracks reconstructed in the inner tracker detector, and another requiring also that these tracks be identified in the CMS muon sys- tem. In each case, the observed distribution of the candidate masses is consistent with the expected background. We have set lower limits on masses of stable strongly interacting supersymmetric particles. For the case of g̃ with f = 0.1 and t̃1, a lower mass limit of 398 and 202 GeV/c2, respectively, is set at the 95% C.L. with the analysis that uses muon identification. In a pessimistic scenario of complete charge suppression the above g̃ mass limit is reduced to 311 GeV/c2 and is obtained with the tracker-only selection. The limits presented here on stable g̃ are the most restrictive to date. Acknowledgments We are grateful to Anna Kulesza and Michael Krämer for providing the theoretical produc- tion cross sections and associated uncertainties at next-to-leading order for pair production of g̃ and t̃1. We wish to congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and adminis- trative 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 – 9 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 )2Mass (GeV/c 200 400 600 800 1000 ( pb ) σ 10 210 )2Mass (GeV/c 200 400 600 800 1000 ( pb ) σ 10 210 -1 = 7 TeV 3.1 pb sCMS 95% C.L. Limits gg~gluino; 10% gg~gluino; 50% g; ch. suppr.g~gluino; 10% stop stop; ch. suppr. Theoretical Prediction gluino (NLO+NLL) stop (NLO+NLL) Figure 3. Predicted theoretical cross section and observed 95% C.L. upper limits on the cross sec- tion for the different combinations of models and scenarios considered: pair production of supersym- metric stop and gluinos; different fractions, f , of R-gluonball states produced after hadronization and charge suppression (“ch. suppr.”) scenarios. Only the results obtained with the most sensitive selection are reported: tracker-only for the charge suppression scenarios and tracker-plus-muon for all other cases. The bands represent the theoretical uncertainties on the cross section values. (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithua- nia); 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). Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. – 10 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 References [1] R. Barbieri, L.J. Hall and Y. Nomura, A constrained standard model from a compact extra dimension, Phys. Rev. D 63 (2001) 105007 [hep-ph/0011311] [SPIRES]. [2] T. Appelquist, H.-C. Cheng and B.A. Dobrescu, Bounds on universal extra dimensions, Phys. Rev. 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Khachatryan, A.M. Sirunyan, A. Tumasyan Institut für Hochenergiephysik der OeAW, Wien, Austria W. Adam, T. Bergauer, M. Dragicevic, J. Erö, C. Fabjan, M. Friedl, R. Frühwirth, V.M. Ghete, J. Hammer1, 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, A. Taurok, F. Teischinger, 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, L. Ceard, K. Cerny, 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 V. Adler, S. Beauceron, F. Blekman, S. Blyweert, J. D’Hondt, O. Devroede, R. Gonzalez Suarez, A. Kalogeropoulos, J. Maes, M. Maes, S. Tavernier, W. Van Doninck, P. Van Mul- ders, G.P. Van Onsem, I. Villella Université 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 Ghent University, Ghent, Belgium S. Costantini, M. Grunewald, B. Klein, A. Marinov, J. Mccartin, D. Ryckbosch, F. Thyssen, M. Tytgat, L. Vanelderen, P. Verwilligen, S. Walsh, N. Zaganidis Université Catholique de Louvain, Louvain-la-Neuve, Belgium S. Basegmez, G. Bruno, J. Caudron, J. De Favereau De Jeneret, C. Delaere, P. Demin, D. Favart, A. Giammanco, G. Grégoire, J. Hollar, V. Lemaitre, J. Liao, O. Militaru, S. Ovyn, D. Pagano, A. Pin, K. Piotrzkowski, L. Quertenmont, N. Schul Université 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 – 13 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, Brazil F.A. Dias, M.A.F. Dias, T.R. Fernandez Perez Tomei, E. M. Gregores2, F. Marinho, 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 University of Sofia, Sofia, Bulgaria M. Dyulendarova, R. Hadjiiska, 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, J. Wang, J. Wang, X. Wang, Z. Wang, M. Xu, M. Yang, J. Zang, Z. Zhang State Key Lab. of Nucl. Phys. and Tech., Peking University, Beijing, China Y. Ban, S. Guo, W. Li, Y. Mao, S.J. Qian, H. Teng, L. Zhang, B. Zhu 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, H. Rykaczewski Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt Y. Assran4, M.A. Mahmoud5 National Institute of Chemical Physics and Biophysics, Tallinn, Estonia A. Hektor, M. Kadastik, K. Kannike, M. Müntel, 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. Härkönen, A. Heikkinen, V. Karimäki, R. Kinnunen, J. Klem, M.J. Ko- rtelainen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, T. Mäenpää, E. Tuominen, J. Tuominiemi, E. Tuovinen, D. Ungaro, L. Wendland Lappeenranta University of Technology, Lappeenranta, Finland K. Banzuzi, A. Korpela, T. Tuuva – 14 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 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 Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France S. Baffioni, F. Beaudette, L. Bianchini, M. Bluj6, C. Broutin, P. Busson, C. Charlot, T. Dahms, L. Dobrzynski, R. Granier de Cassagnac, M. Haguenauer, P. Miné, C. Mironov, C. Ochando, P. Paganini, D. Sabes, R. Salerno, Y. Sirois, C. Thiebaux, B. Wyslouch7, A. Zabi Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Univer- sité de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France J.-L. Agram8, J. Andrea, A. Besson, D. Bloch, D. Bodin, J.-M. Brom, M. Cardaci, E.C. Chabert, C. Collard, E. Conte8, F. Drouhin8, C. Ferro, J.-C. Fontaine8, D. Gelé, 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 Université de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France C. Baty, 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, H. Xiao E. Andronikashvili Institute of Physics, Academy of Science, Tbilisi, Georgia V. Roinishvili 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, G. Masetti, M. Merschmeyer, A. Meyer, P. Papacz, H. Pieta, H. Reithler, S.A. Schmitz, L. Sonnenschein, J. Steggemann, D. Teyssier – 15 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 RWTH 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 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, I. Glushkov, J. Hauk, H. Jung, M. Kasemann, I. Katkov, P. Katsas, C. Kleinwort, H. Kluge, A. Knutsson, D. Krücker, E. Kuznetsova, W. Lange, W. Lohmann9, R. Mankel, M. Marienfeld, I.-A. Melzer-Pellmann, A.B. Meyer, J. Mnich, A. Mussgiller, J. Olzem, A. Parenti, A. Raspereza, A. Raval, R. Schmidt9, T. Schoerner-Sadenius, N. Sen, M. Stein, J. Tomaszewska, D. Volyanskyy, R. Walsh, C. Wissing University of Hamburg, Hamburg, Germany C. Autermann, 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. Schröder, T. Schum, J. Schwandt, A.K. Srivastava, H. Stadie, G. Steinbrück, J. Thomsen, R. Wolf Institut 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, M. Renz, C. Saout, A. Scheurer, P. Schieferdecker, F.-P. Schilling, G. Schott, H.J. Simonis, F.M. Stober, D. Troendle, J. Wagner-Kuhr, M. Zeise, V. Zhukov10, E.B. Ziebarth Institute of Nuclear Physics ”Demokritos”, Aghia Paraskevi, Greece G. Daskalakis, T. Geralis, S. Kesisoglou, A. Kyriakis, D. Loukas, I. Manolakos, A. Markou, C. Markou, C. Mavrommatis, E. Petrakou University of Athens, Athens, Greece L. Gouskos, T.J. Mertzimekis, A. Panagiotou1 University of Ioánnina, Ioánnina, 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, G. Debreczeni, C. Hajdu1, D. Horvath11, A. Kapusi, K. Krajczar12, A. Laszlo, F. Sikler, 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 – 16 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Panjab University, Chandigarh, India S. Bansal, S.B. Beri, V. Bhatnagar, N. Dhingra, 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, R.K. Shivpuri Bhabha Atomic Research Centre, Mumbai, India R.K. Choudhury, D. Dutta, S. Kailas, S.K. Kataria, 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 Studies in Theoretical Physics & Mathematics (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 INFN Sezione di Bari a, Università 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, M. De Palmaa,b, A. Dimitrova, L. Fiorea, G. Iasellia,c, L. Lusitoa,b,1, 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, Università 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, S. Marcellinia, M. Meneghellia,b, A. Montanaria, F.L. Navarriaa,b, F. Odoricia, A. Perrottaa, F. Primaveraa, A.M. Rossia,b, T. Rovellia,b, G. Sirolia,b, R. Travaglinia,b INFN Sezione di Catania a, Università 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, Università di Firenze b, Firenze, Italy G. Barbaglia, V. Ciullia,b, C. Civininia, R. D’Alessandroa,b, E. Focardia,b, S. Frosalia,b, E. Galloa, C. Gentaa, 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 – 17 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 INFN Sezione di Genova, Genova, Italy P. Fabbricatore, R. Musenich INFN Sezione di Milano-Biccoca a, Università di Milano-Bicocca b, Milano, Italy A. Benagliaa,b, F. De Guioa,b,1, L. Di Matteoa,b, A. Ghezzia,b,1, 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, Università di Napoli ”Federico II” b, Napoli, Italy S. Buontempoa, C.A. Carrillo Montoyaa, A. Cimminoa,b, A. De Cosaa,b, M. De Gruttolaa,b, F. Fabozzia,16, A.O.M. Iorioa, L. Listaa, M. Merolaa,b, P. Nolia,b, P. Paoluccia INFN Sezione di Padova a, Università di Padova b, Università di Trento (Trento) c, Padova, Italy P. Azzia, N. Bacchettaa, P. Bellana,b, D. Biselloa,b, A. Brancaa, R. Carlina,b, E. Contia, M. De Mattiaa,b, T. Dorigoa, F. Fanzagoa, F. Gasparinia,b, P. Giubilatoa,b, F. Gonellaa, A. Greselea,c, S. Lacapraraa,17, I. Lazzizzeraa,c, M. Margonia,b, M. Mazzucatoa, A.T. Meneguzzoa,b, M. Nespoloa, M. Pegoraroa, L. Perrozzia,1, N. Pozzobona,b, P. Ronchesea,b, E. Torassaa, M. Tosia,b, A. Triossia, S. Vaninia,b, S. Venturaa, G. Zumerlea,b INFN Sezione di Pavia a, Università di Pavia b, Pavia, Italy P. Baessoa,b, U. Berzanoa, C. Riccardia,b, P. Torrea,b, P. Vituloa,b, C. Viviania,b INFN Sezione di Perugia a, Università di Perugia b, Perugia, Italy M. Biasinia,b, G.M. Bileia, B. Caponeria,b, L. Fanòa,b, P. Laricciaa,b, A. Lucaronia,b,1, G. Mantovania,b, M. Menichellia, A. Nappia,b, A. Santocchiaa,b, L. Servolia, S. Taronia,b, M. Valdataa,b, R. Volpea,b,1 INFN Sezione di Pisa a, Università 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. Foàa,c, A. Giassia, A. Kraana, F. Ligabuea,c, T. Lomtadzea, L. Martinia, A. Messineoa,b, F. Pallaa, F. Palmonaria, S. Sarkara,c, G. Segneria, A.T. Serbana, P. Spagnoloa, R. Tenchinia, G. Tonellia,b,1, A. Venturia,1, P.G. Verdinia INFN Sezione di Roma a, Università 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, E. Longoa,b, G. Organtinia,b, A. Palmaa,b, F. Pandolfia,b,1, R. Paramattia, S. Rahatloua,b INFN Sezione di Torino a, Università di Torino b, Università 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, – 18 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 M.M. Obertinoa,c, N. Pastronea, M. Pelliccionia,b,1, A. Romeroa,b, M. Ruspaa,c, R. Sacchia,b, V. Solaa,b, A. Solanoa,b, A. Staianoa, D. Trocinoa,b, A. Vilela Pereiraa,b,1 INFN Sezione di Trieste a, Università di Trieste b, Trieste, Italy F. Ambroglinia,b, S. Belfortea, F. Cossuttia, G. Della Riccaa,b, B. Gobboa, D. Montaninoa,b, A. Penzoa Kangwon National University, Chunchon, Korea S.G. Heo Kyungpook National University, Daegu, Korea S. Chang, J. Chung, D.H. Kim, G.N. Kim, J.E. Kim, D.J. Kong, H. Park, 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. 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, 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. Sánchez Hernández, 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 Autónoma de San Luis Potośı, San Luis Potośı, Mexico E. Casimiro Linares, A. Morelos Pineda, M.A. Reyes-Santos University of Auckland, Auckland, New Zealand P. Allfrey, D. Krofcheck 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 – 19 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 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. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, G. Wrochna, P. Zalewski Laboratório de Instrumentação e F́ısica Experimental de Part́ıculas, Lisboa, Portugal N. Almeida, A. David, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, P. Martins, P. Musella, A. Nayak, P.Q. Ribeiro, J. Seixas, P. Silva, J. Varela1, H.K. Wöhri Joint Institute for Nuclear Research, Dubna, Russia I. Belotelov, P. Bunin, M. Finger, M. Finger Jr., 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 N. Bondar, V. Golovtsov, Y. Ivanov, V. Kim, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev Institute for Nuclear Research, Moscow, Russia Yu. Andreev, 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, G. Safronov, S. Semenov, V. Stolin, E. Vlasov, A. Zhokin Moscow State University, Moscow, Russia E. Boos, M. Dubinin18, L. Dudko, A. Ershov, A. Gribushin, O. Kodolova, I. Lokhtin, S. Obraztsov, S. Petrushanko, L. Sarycheva, V. Savrin, A. Snigirev P.N. Lebedev Physical Institute, Moscow, Russia V. Andreev, M. Azarkin, I. Dremin, M. Kirakosyan, 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. Adzic19, M. Djordjevic, D. Krpic19, J. Milosevic – 20 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Centro de Investigaciones Energéticas Medioambientales y Tec- nológicas (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, C. Diez Pardos, D. Domı́nguez Vázquez, C. Fer- nandez 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 Universidad Autónoma de Madrid, Madrid, Spain C. Albajar, G. Codispoti, J.F. de Trocóniz Universidad de Oviedo, Oviedo, Spain J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, L. Lloret Iglesias, J.M. Vizan Garcia Instituto de F́ısica 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. Felcini20, 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 Gomez21, T. Rodrigo, 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. Bell22, D. Benedetti, C. Bernet3, W. Bialas, P. Bloch, A. Bocci, S. Bolognesi, H. Breuker, G. Brona, K. Bunkowski, T. Camporesi, E. Cano, G. Cerminara, T. Christiansen, J.A. Coarasa Perez, B. Curé, D. D’Enterria, A. De Roeck, F. Duarte Ramos, 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, C. Henderson, G. Hesketh, H.F. Hoffmann, A. Honma, V. Innocente, P. Janot, E. Karavakis, P. Lecoq, C. Leonidopoulos, C. Lourenço, A. Macpherson, T. Mäki, 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. Pimiä, G. Polese, A. Racz, G. Rolandi23, T. Rommerskirchen, C. Rovelli24, M. Rovere, H. Sakulin, C. Schäfer, C. Schwick, I. Segoni, A. Sharma, P. Siegrist, M. Simon, P. Sphicas25, D. Spiga, M. Spiropulu18, F. Stöckli, M. Stoye, P. Tropea, A. Tsirou, A. Tsyganov, G.I. Veres12, 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. König, D. Kotlinski, U. Langenegger, F. Meier, D. Renker, T. Rohe, J. Sibille26, A. Starodumov27 – 21 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Institute for Particle Physics, ETH Zurich, Zurich, Switzerland P. Bortignon, L. Caminada28, Z. Chen, S. Cittolin, G. Dissertori, M. Dittmar, J. Eu- gster, K. Freudenreich, C. Grab, A. Hervé, W. Hintz, P. Lecomte, W. Lustermann, C. Marchica28, P. Martinez Ruiz del Arbol, P. Meridiani, P. Milenovic29, 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. Wallny20, M. Weber, L. Wehrli, J. Weng Universität 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, L. Wilke National Central University, Chung-Li, Taiwan Y.H. Chang, K.H. Chen, W.T. Chen, S. Dutta, A. Go, C.M. Kuo, S.W. Li, W. Lin, M.H. Liu, Z.K. Liu, Y.J. Lu, J.H. Wu, S.S. Yu 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. Bakirci30, S. Cerci31, 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. Sogut32, B. Tali, H. Topakli30, 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. Demir33, E. Gülmez, A. Halu, B. Isildak, M. Kaya34, O. Kaya34, S. Ozkorucuklu35, N. Sonmez36 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. Newbold37, K. Nirunpong, A. Poll, S. Senkin, V.J. Smith, S. Ward Rutherford Appleton Laboratory, Didcot, United Kingdom L. Basso, K.W. Bell, A. Belyaev, 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 – 22 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 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. Guneratne Bryer, G. Hall, Z. Hatherell, J. Hays, G. Iles, G. Karapostoli, L. Lyons, A.-M. Magnan, J. Marrouche, R. Nandi, J. Nash, A. Nikitenko27, A. Papageorgiou, M. Pesaresi, K. Petridis, M. Pioppi38, 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, A. Clough, 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 University of California, Davis, Davis, USA M.A. Borgia, R. Breedon, M. Calderon De La Barca Sanchez, D. Cebra, 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 University 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 University of California, Riverside, Riverside, USA J. Babb, R. Clare, J. Ellison, J.W. Gary, F. Giordano, G. Hanson, G.Y. Jeng, S.C. Kao, F. Liu, H. Liu, A. Luthra, H. Nguyen, G. Pasztor39, A. Satpathy, B.C. Shen†, R. Stringer, J. Sturdy, S. Sumowidagdo, R. Wilken, S. Wimpenny University 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, J. Muelmenstaedt, S. Padhi, C. Palmer, G. Petrucciani, H. Pi, M. Pieri, R. Ranieri, M. Sani, V. Sharma1, S. Simon, Y. Tu, A. Vartak, F. Würthwein, A. Yagil University 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, – 23 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 N. Mccoll, V. Pavlunin, F. Rebassoo, J. Ribnik, J. Richman, R. Rossin, D. Stuart, W. To, J.R. Vlimant California Institute of Technology, Pasadena, USA A. Bornheim, J. Bunn, Y. Chen, M. Gataullin, D. Kcira, V. Litvine, Y. Ma, A. Mott, H.B. Newman, C. Rogan, V. Timciuc, P. Traczyk, J. Veverka, R. Wilkinson, Y. Yang, R.Y. Zhu Carnegie 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, N. Terentyev, H. Vogel, I. Vorobiev University of Colorado at Boulder, Boulder, USA J.P. Cumalat, M.E. Dinardo, B.R. Drell, C.J. Edelmaier, W.T. Ford, B. Heyburn, E. Luiggi Lopez, U. Nauenberg, J.G. Smith, K. Stenson, K.A. Ulmer, S.R. Wagner, S.L. Zang Cornell University, Ithaca, USA L. Agostino, J. Alexander, A. Chatterjee, S. Das, N. Eggert, L.J. Fields, L.K. Gibbons, B. Heltsley, W. Hopkins, A. Khukhunaishvili, B. Kreis, V. Kuznetsov, G. Nicolas Kaufman, J.R. Patterson, D. Puigh, D. Riley, A. Ryd, X. Shi, W. Sun, W.D. Teo, J. Thom, J. Thompson, J. Vaughan, Y. Weng, L. Winstrom, P. Wittich Fairfield University, Fairfield, USA A. Biselli, G. Cirino, D. Winn Fermi 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. Bur- kett, J.N. Butler, V. Chetluru, H.W.K. Cheung, F. Chlebana, S. Cihangir, M. Demarteau, D.P. Eartly, V.D. Elvira, S. Esen, I. Fisk, J. Freeman, Y. Gao, E. Gottschalk, D. Green, K. Gunthoti, O. Gutsche, A. Hahn, J. Hanlon, R.M. Harris, J. Hirschauer, B. Hooberman, E. James, H. Jensen, M. Johnson, U. Joshi, R. Khatiwada, B. Kilminster, B. Klima, K. Kousouris, S. Kunori, S. Kwan, P. Limon, R. Lipton, J. Lykken, K. Maeshima, J.M. Marraffino, D. Mason, P. McBride, T. McCauley, T. Miao, K. Mishra, S. Mrenna, Y. Musienko40, C. Newman-Holmes, V. O’Dell, S. Popescu41, R. Pordes, O. Prokofyev, N. Saoulidou, E. Sexton-Kennedy, S. Sharma, A. Soha, 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 University 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, S. Klimenko, 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 – 24 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Florida International University, Miami, USA C. Ceron, V. Gaultney, L. Kramer, L.M. Lebolo, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez Florida State University, Tallahassee, USA T. Adams, A. Askew, D. Bandurin, J. Bochenek, J. Chen, B. Diamond, S.V. Gleyzer, J. Haas, S. Hagopian, V. Hagopian, M. Jenkins, K.F. Johnson, H. Prosper, S. Sekmen, V. Veeraraghavan Florida Institute of Technology, Melbourne, USA M.M. Baarmand, B. Dorney, S. Guragain, M. Hohlmann, H. Kalakhety, R. Ralich, I. Vodopiyanov University 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, E.J. Garcia-Solis, C.E. Gerber, D.J. Hofman, S. Khalatyan, F. Lacroix, C. O’Brien, C. Silvestre, A. Smoron, D. Strom, N. Varelas The University of Iowa, Iowa City, USA U. Akgun, E.A. Albayrak, B. Bilki, K. Cankocak42, 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 Johns Hopkins University, Baltimore, USA B.A. Barnett, B. Blumenfeld, A. Bonato, C. Eskew, D. Fehling, G. Giurgiu, A.V. Gritsan, Z.J. Guo, G. Hu, P. Maksimovic, S. Rappoccio, M. Swartz, N.V. Tran, A. Whitbeck The University of Kansas, Lawrence, USA P. Baringer, A. Bean, G. Benelli, O. Grachov, M. Murray, D. Noonan, V. Radicci, S. Sanders, J.S. Wood, V. Zhukova Kansas State University, Manhattan, USA T. Bolton, I. Chakaberia, A. Ivanov, M. Makouski, Y. Maravin, S. Shrestha, I. Svintradze, Z. Wan Lawrence Livermore National Laboratory, Livermore, USA J. Gronberg, D. Lange, D. Wright University 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 Massachusetts 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 – 25 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 University 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 University of Mississippi, University, USA L.M. Cremaldi, R. Godang, R. Kroeger, L. Perera, R. Rahmat, D.A. Sanders, D. Summers University 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, C. Lundstedt, H. Malbouisson, S. Malik, G.R. Snow State University of New York at Buffalo, Buffalo, USA U. Baur, A. Godshalk, I. Iashvili, A. Kharchilava, A. Kumar, S.P. Shipkowski, K. Smith Northeastern University, Boston, USA G. Alverson, E. Barberis, D. Baumgartel, O. Boeriu, M. Chasco, K. Kaadze, S. Reucroft, J. Swain, D. Wood, J. Zhang Northwestern University, Evanston, USA A. Anastassov, A. Kubik, N. Odell, R.A. Ofierzynski, B. Pollack, A. Pozdnyakov, M. Schmitt, S. Stoynev, M. Velasco, S. Won University 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, J. Warchol, M. Wayne, J. Ziegler The Ohio State University, Columbus, USA B. Bylsma, L.S. Durkin, J. Gu, C. Hill, P. Killewald, K. Kotov, T.Y. Ling, M. Rodenburg, G. Williams Princeton 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 University of Puerto Rico, Mayaguez, USA J.G. Acosta, X.T. Huang, A. Lopez, H. Mendez, S. Oliveros, J.E. Ramirez Vargas, A. Zatserklyaniy Purdue University, West Lafayette, USA E. Alagoz, V.E. Barnes, G. Bolla, L. Borrello, D. Bortoletto, A. Everett, A.F. Garfinkel, Z. Gecse, L. Gutay, Z. Hu, M. Jones, O. Koybasi, A.T. Laasanen, N. Leonardo, C. Liu, V. Maroussov, P. Merkel, D.H. Miller, N. Neumeister, K. Potamianos, I. Shipsey, D. Silvers, A. Svyatkovskiy, H.D. Yoo, J. Zablocki, Y. Zheng Purdue University Calumet, Hammond, USA P. Jindal, N. Parashar – 26 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 Rice University, Houston, USA C. Boulahouache, V. Cuplov, K.M. Ecklund, F.J.M. Geurts, J.H. Liu, J. Morales, B.P. Padley, R. Redjimi, J. Roberts, J. Zabel University 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 The Rockefeller University, New York, USA A. Bhatti, L. Demortier, K. Goulianos, G. Lungu, C. Mesropian, M. Yan Rutgers, 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 University of Tennessee, Knoxville, USA G. Cerizza, M. Hollingsworth, S. Spanier, Z.C. Yang, A. York Texas 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 Texas Tech University, Lubbock, USA N. Akchurin, C. Bardak, J. Damgov, C. Jeong, K. Kovitanggoon, S.W. Lee, P. Mane, Y. Roh, A. Sill, I. Volobouev, R. Wigmans, E. Yazgan Vanderbilt University, Nashville, USA E. Appelt, E. Brownson, D. Engh, C. Florez, W. Gabella, W. Johns, P. Kurt, C. Maguire, A. Melo, P. Sheldon, J. Velkovska University 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 Wayne State University, Detroit, USA S. Gollapinni, R. Harr, P.E. Karchin, P. Lamichhane, M. Mattson, C. Milstène, A. Sakharov University of Wisconsin, Madison, USA M. Anderson, M. Bachtis, J.N. Bellinger, D. Carlsmith, S. Dasu, J. Efron, L. Gray, K.S. Grogg, M. Grothe, R. Hall-Wilton1, M. Herndon, P. Klabbers, J. Klukas, A. Lanaro, C. Lazaridis, J. Leonard, D. Lomidze, R. Loveless, A. Mohapatra, D. Reeder, I. Ross, A. Savin, W.H. Smith, J. Swanson, M. Weinberg – 27 – J H E P 0 3 ( 2 0 1 1 ) 0 2 4 †: 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 Fayoum University, El-Fayoum, 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 California Institute of Technology, Pasadena, USA 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 The University of Kansas, Lawrence, USA 27: Also at Institute for Theoretical and Experimental Physics, Moscow, Russia 28: Also at Paul Scherrer Institut, Villigen, Switzerland 29: Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia 30: Also at Gaziosmanpasa University, Tokat, Turkey 31: Also at Adiyaman University, Adiyaman, Turkey 32: Also at Mersin University, Mersin, Turkey 33: Also at Izmir Institute of Technology, Izmir, Turkey 34: Also at Kafkas University, Kars, Turkey 35: Also at Suleyman Demirel University, Isparta, Turkey 36: Also at Ege University, Izmir, Turkey 37: Also at Rutherford Appleton Laboratory, Didcot, United Kingdom 38: Also at INFN Sezione di Perugia; Università di Perugia, Perugia, Italy 39: Also at KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary 40: Also at Institute for Nuclear Research, Moscow, Russia 41: Also at Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), Bucharest, Romania 42: Also at Istanbul Technical University, Istanbul, Turkey – 28 – Introduction The CMS detector Candidate selection and background estimation Results Conclusions The CMS collaboration