Search for s channel single top quark production in pp collisions at \( \sqrt{s}=7 \) and 8 TeV

Journal of High Energy Physics, Sep 2016

A search is presented for single top quark production in the s channel in proton-proton collisions with the CMS detector at the CERN LHC in decay modes of the top quark containing a muon or an electron in the final state. The signal is extracted through a maximum-likelihood fit to the distribution of a multivariate discriminant defined using boosted decision trees to separate the expected signal contribution from background processes. The analysis uses data collected at centre-of-mass energies of 7 and 8 TeV and corresponding to integrated luminosities of 5.1 and 19.7 fb−1, respectively. The measured cross sections of 7.1 ± 8.1 pb (at 7 TeV) and 13.4 ± 7.3 pb (at 8 TeV) result in a best fit value of 2.0 ± 0.9 for the combined ratio of the measured and expected values. The signal significance is 2.5 standard deviations, and the upper limit on the rate relative to the standard model expectation is 4.7 at 95% confidence level.

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Search for s channel single top quark production in pp collisions at \( \sqrt{s}=7 \) and 8 TeV

Revised: June Search for s channel single top quark production in pp A search is presented for single top quark production in the s channel in proton-proton collisions with the CMS detector at the CERN LHC in decay modes of the top quark containing a muon or an electron in the nal state. The signal is extracted through a maximum-likelihood t to the distribution of a multivariate discriminant de ned using boosted decision trees to separate the expected signal contribution from background processes. The analysis uses data collected at centre-of-mass energies of 7 and 8 TeV and corresponding to integrated luminosities of 5.1 and 19.7 fb 1, respectively. The measured cross sections of 7:1 0:9 for the combined ratio of the measured and expected values. The signal signi cance is 2.5 standard deviations, and the upper limit on the rate relative to the standard model expectation is 4.7 at 95% con dence level. Hadron-Hadron scattering (experiments); Top physics - 7 and 8 TeV The CMS collaboration 1 Introduction 2 The CMS detector 3 Simulated samples 4 Selection and reconstruction 5 Implementation of the multivariate analysis 6 Multijet background 7 Systematic uncertainties 8 Cross section extraction 9 Results 10 Summary The CMS collaboration 1 Introduction the standard model (SM), which predicts three production channels: the s channel, the t channel, and the W-associated or tW production channel ( gure 1). The rst observations of single top quark production were announced by the D0 and CDF collaborations at the Fermilab Tevatron in 2009 [1, 2]. Evidence for s channel production was announced by the D0 collaboration in 2013 [3], while the process was de nitively observed when combining the searches from both the D0 and the CDF collaborations [4]. Evidence for s channel production was con rmed by the ATLAS Collaboration at the LHC [5], where the search is challenging because the process is suppressed in proton-proton (pp) collisions. For pp collisions at ps = 7 and 8 TeV, the SM predicted s channel cross sections are s(7 TeV) = 4:56 s(8 TeV) = 5:55 0:07 (scale) 0:17 (PDF) pb; and 0:08 (scale) 0:21 (PDF) pb; { 1 { whose production rate is studied in this paper, (middle) the dominant next-to-leading-order diagram in the t channel, and (right) the tW production channel. as calculated in quantum chromodynamics (QCD) at approximate next-to-next-to-leading order (NNLO), including resummation of soft-gluon emission within next-to-next-toleading logarithms (NNLL) [ 6 ]. The rst uncertainty corresponds to a doubling and halving of the renormalization and factorization scales. The second uncertainty is from the choice of parton distribution functions (PDFs) at the 90% con dence level (CL). All three single top quark production channels, shown in gure 1, are directly related to the Cabibbo-Kobayashi-Maskawa matrix element Vtb, providing a direct measurement of this SM parameter. The s channel production process is of special interest since a possible deviation from the SM prediction of its cross section may indicate the presence of mechanisms beyond the standard model (BSM), as predicted by models that involve the exchange of a non-SM mediator, such as a W0 boson or a charged Higgs boson [ 7 ]. A review of deviations from SM predictions for s and t channel modes in BSM scenarios can be found in ref. [8]. This paper presents a search performed at the CMS experiment for single top quark production in the s channel considering the leptonic decay channels of the W boson produced in top quark decay. Only the decays of the W boson into a muon or an electron (` = , e) and a corresponding neutrino are considered. Decays of the W boson into a tau lepton and a neutrino, where the tau lepton subsequently decays into a muon or an electron, are regarded as part of the signal. Events are selected considering the kinematic properties of physical objects reconstructed in the nal state. Three statistically independent analysis categories are therefore de ned, according to the number and avour of the reconstructed jets. Dedicated strategies are used in data to estimate and reject multijet backgrounds. The procedure for signal extraction consists of a simultaneous t to the distributions of multivariate discriminants trained separately in each analysis category on a set of kinematic variables that show separation between signal and background. This measurement is performed using LHC pp collision data collected by the CMS detector corresponding to the integrated luminosities of 5.1 and 19.7 fb 1 at centre-ofmass energies of 7 and 8 TeV, respectively. While at 7 TeV only the muon channel is considered, at 8 TeV both the muon and electron channels are included. 2 The CMS detector The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter providing an axial magnetic eld of 3.8 T. The inner region accommodates the { 2 { HJEP09(216)7 silicon pixel and strip tracker which records charged particle trajectories with high granularity and precision up to pseudorapidity j j = 2:5. An electromagnetic calorimeter (ECAL) made of lead tungstate crystals and a brass and scintillator sampling hadron calorimeter, both arranged in a barrel assembly and two endcaps, surround the tracking volume and extend up to the region j j < 3:0. Coverage up to j j = 5:0 is provided by a quartz- bre and steel absorber Cherenkov calorimeter. Muons are measured in gas-ionization detectors embedded in the steel ux-return yoke outside the solenoid. A more detailed description of the CMS detector, together with a de nition of the coordinate system and the relevant kinematic variables, can be found in ref. [9]. 3 Simulated samples The nominal s channel single top quark events in this study are generated using the nextto-leading order (NLO) powheg 1.0 [10] event generator. The CTEQ6.6M program [11] is used to model the proton PDF. The top quark mass is set to 172.5 GeV, and tau lepton decays are modelled with TAUOLA [12]. For the 7 TeV analysis, a large sample of signal events generated using the leading-order (LO) matrix-element CompHEP 4.4 [13] generator is employed for the training of the multivariate discriminant. The generators are interfaced to LO pythia 6.4 (Z2 tune) [14] for showering and hadronization. Monte Carlo (MC) simulated events with a single top quark are normalized to the approximate NNLO+NNLL cross section of 3.14 pb at 7 TeV and 3.79 pb at 8 TeV [ 6 ]. MC simulated events with a top antiquark are normalized to the approximate NNLO+NNLL cross section of 1.42 pb at 7 TeV and 1.76 pb at 8 TeV. The other single top quark processes, t channel, and tW production, are considered as backgrounds for this measurement and are simulated using the powheg 1.0 generator. The main background in this analysis is top quark pair production (tt) in nal states with one or two charged leptons. Single vector bosons in association with jets, W+jets, and Z+jets, are also included in the background. Both tt and single vector boson events are generated using LO matrix element MadGraph 5.1 [15] interfaced to pythia 6.4. The background from diboson (WW, ZZ, and WZ) events is small and is generated with pythia 6.4. Multijet background events from QCD processes are extracted directly from data or from a simulated sample generated with pythia 6.4 (see section 6). The cross sections for the background processes in the analysis are summarized in table 1. The cross sections are reported at approximate NNLO+NNLL accuracy for single top quark [ 6 ] and tt production [16], at NNLO accuracy for Z= +jets and W+n jets (with n = 1; 2; 3; and 4) events [17], and at the LO level for the remaining contributions. When stated, the cross section includes the branching ratio of the leptonic decay, including electrons, muons, and tau leptons. The multijet sample is de ned by the presence of at least one generator-level muon with pT > 15 GeV, and requiring the transverse momentum generated in the hard scattering parton process to be greater than 20 GeV. For all generated processes, the detector response is simulated using a detailed description of the CMS detector, based on Geant4 [18]. A reweighting procedure is applied to { 3 { HJEP09(216)7 Single top quark (t channel) Single antitop quark (t channel) Single top or antitop quark (tW) tt W(! ` )+1 jet W(! ` )+2 jets W(! ` )+3 jets W(! ` )+4 jets Z= (! `+` )+jets WW WZ ZZ -enriched multijet events per bunch crossing (pileup events) observed in data. 4 Selection and reconstruction The nal-state topology in the s channel is characterized by the presence of one isolated muon or electron, a neutrino that results in an imbalance in the transverse momentum of the event, and two b quarks, one originating from the top quark decay and one recoiling against the top quark. Events with at least one muon were selected by the online trigger [9], requiring pT > 17 GeV at 7 TeV, pT > 24 GeV at 8 TeV, j j < 2:1, and lepton isolation criteria. Similarly, for electrons at 8 TeV, the corresponding values are pT > 27 GeV and j j < 2:5. Because of the increase in instantaneous luminosity during the second part of the 7 TeV run, the single muon trigger had to be prescaled and was replaced by a hadronic trigger that required at least one muon as de ned above and at least one jet in the central region of the detector with pT > 30 GeV, satisfying an online b tagging criterion. Simulated leptonic trigger e ciencies are corrected to match those measured in data. Hadronic trigger e ciencies are not simulated but are measured in data and parametrized as a function of the jet pT in order to reweight the simulated events. At least one primary vertex is required to be reconstructed from at least four tracks and to satisfy jzPVj < 24 cm and PV < 2 cm, where jzPVj and PV are the respective longitudinal and transverse distances of the primary vertex relative to the center of the detector. When more than one interaction vertex is found, the one with largest sum in p2 T of associated tracks is de ned as the primary vertex. { 4 { The particle candidates are required to originate from the primary vertex, and are reconstructed using the CMS particle- ow (PF) algorithm [19]. Reconstructed muons with pT > 20 GeV at 7 TeV and pT > 26 GeV at 8 TeV within the trigger acceptance (j j < 2:1) are selected for analysis. At 8 TeV, reconstructed electrons [20] with pT > 30 GeV within j j < 2:5 are selected, excluding the transition region between ECAL barrel and endcaps (1:44 < j j < 1:57) where the reconstruction of electrons is not optimal. Lepton isolation is applied using the Irel variable, de ned as the ratio between the sum of the transverse energies (ET) of stable charged hadrons, photons, and neutral hadrons in a )2 + ( )2 around the lepton direction (where is the azimuth in radians), and the pT of the lepton. At 7 TeV, the muon isolation requirement is Irel < 0:15 neutral particles in pileup events. It is required Irel < 0:12 with R = 0:4 for muon isolation, and Irel < 0:1 with R = 0:3 for electron isolation. The presence of a single muon or electron satisfying the criteria described above is required to reduce the contribution from dilepton events, which can arise from tt or from qq ! `+` +jets Drell-Yan (DY) processes. Events containing additional muons or electrons, with looser requirements for muons of pT > 10 GeV within the full acceptance of j j < 2:5, and Irel < 0:2, and for electrons with pT > 20 GeV, j j < 2:5, and Irel < 0:15 are rejected. Jets are reconstructed using the anti-kT algorithm [ 21 ] with a distance parameter of 0.5, using as input the particles identi ed through the PF algorithm. To reduce contamination from pileup events, charged particle candidates not associated with the primary vertex are excluded from the jet reconstruction. The energies of jets are corrected by the estimated amount of energy deposited in the jet area [ 22 ] from pileup hadrons. Scale factors depending on the ET and of the jets [ 23 ] are further applied and re ect the detector response. The analysis considers jets within j j < 4:5 and pT > 40 GeV. We identify jets stemming from b quarks through b tagging algorithms [24]. The threshold on the discriminant value is set to provide a misidenti cation probability (mistag) for light-parton jets of about 0.1%. The corresponding b tagging e ciency ranges from 40 to 60%, depending on jet pT and and on the speci c algorithm. Simulated b tagging e ciencies are corrected to match those measured in data [24, 25]. The imbalance in transverse momentum (vector p=T) is de ned as the projection on the plane perpendicular to the beams of the negative of the vector sum of the momenta of all reconstructed particles in an event. Its magnitude is referred to as E=T. It is assumed that the x and y components of the missing momentum, (p=T)x and (p=T)y, are entirely due to the escaping neutrino. The longitudinal component pz; of the neutrino momentum is estimated from a quadratic equation obtained by imposing that the invariant mass of the lepton-neutrino system must be equal to the invariant mass of the W boson. In case of two real solutions, the smallest pz; is chosen, while when two complex solutions are found the imaginary part is eliminated by recalculating (p=T)x and (p=T)y independently, to provide a W boson with a transverse mass of 80.4 GeV. The W boson transverse mass is de ned as q mT = (pT;` + pT; ) 2 (px;` + px; ) 2 (py;` + py; ) ; 2 { 5 { where pT;` and pT; are the lepton and neutrino transverse momenta and px;`, py;`, px; and py; are the components of the lepton and neutrino transverse momenta along the x and y axes. Finally, four-momenta of top quark candidates are reconstructed from the lepton and the jet originating from the b quark produced in top quark decay, using also the quantities p=T and pz; . In events with more than 1 b jet, the one which results in a reconstructed top mass closer to the nominal one is chosen. The selected events are classi ed into statistically independent \N -jets M -tags" analysis categories, where N refers to the number of reconstructed jets above 40 GeV and M to the number of selected jets passing the b tagging requirement. Three event categories are used for this analysis: the 2-jets 2-tags category is s channel enriched, and employed in signal extraction, the 2-jets 1-tag category is useful to constrain the t channel and W+jets backgrounds, while the 3-jets 2-tags category is useful to constrain the dominant tt background. In each event category, further requirements are applied to reject the multijet background, which in the 8 TeV analysis is separated from the other components by means of a QCD BDT discriminator. The strategies to reject the multijet background and to estimate its contribution will be described in section 6. An additional selection is applied in the 8 TeV signal 2-jets 2-tags category that exploits the property of s channel events to have a lower number of additional jets with 20 < pT < 40 GeV (loose jets) than tt events. Only events with no more than 1 loose jet are selected. The requirement selects 60% of tt events and 90% of s channel events. Because of the presence of two b-tagged jets in the nal state, the 2-jets 2-tags and the 3-jets 2-tags categories are reconstructed with a top quark candidate for each of the two b jets. The candidate with invariant mass closest to the nominal top quark mass of 172.5 GeV is then selected for further study in the analysis. Using this method, the e ciency of association of the correct b jet to the top quark is measured to be 74% in s channel events and 70% in tt events. The dependence of the correct b jet association on top quark mass is evaluated in s channel events by changing the top quark mass by the conservative estimation of its uncertainty of 1.5 GeV, which yields changes in e ciency of less than 1%. 5 Implementation of the multivariate analysis Since the SM prediction for the signal yield is much smaller than the background processes, it is important to enhance the separation between signal and background events to measure the s channel with highest possible signi cance. A multivariate analysis was therefore developed, in which boosted decision tree (BDT) discriminants [ 26 ] are de ned for each event category, based on a set of input discriminants. In this section the BDTs for signal extraction are described, while in the next section the BDTs for the multijet background rejection will be presented. The BDT training and the choice of the input discriminants is performed separately for the muon channels at 7 and 8 TeV and for the electron channel at 8 TeV, taking into account the di erent selections and the di erent level of background, in particular for the multijet background. The samples employed for training and evaluation of performance { 6 { are taken from simulation, with the exception of the multijet background, which is taken from a data control sample, as described in section 6. Several discriminants are investigated for possible input to the BDTs, in particular kinematic and angular variables exploiting the properties of s channel events [ 27 ]. For each channel, the set of input variables are de ned according to the following criteria. A variable must be well modelled in simulation, and must signi cantly increase the discrimination power of a BDT (after comparing performance of the BDTs trained without it). The most important variables chosen as input to the BDTs in the 2-jets 2-tags category are: mT, the angular separation between the two jets ( Rbb), the invariant mass of the system composed of the lepton and subleading jet (m`b2), the transverse momentum of the two-jet system (pbTb), and the di erence in azimuthal angle between the top quark and the leading jet ( t;b1). The leading and subleading jets refer to the two jets with largest pT. The other variables used as input to the BDTs are the invariant mass of the top quark candidate in the event (m` b), the scalar sum of the pT of all jets (HT), the cosine of the angle between lepton and the beam axis in the top quark rest frame (cos `), E=T, the lepton pT, and the di erence in azimuthal angle between the top quark and the next-to-leading b jet ( t;b2). b-tagged jet (pqT). 6 Multijet background variables, where the simulation is normalized to the number of events selected in data. The most important variables chosen as input to the BDTs in the 2-jets 1-tags category are: the angular separation between the two jets ( Rbq), the cosine of the angle between the lepton and the jet recoiling against the top quark in the top quark rest frame (cos ), m` b, the invariant mass of the two-jet system (mbq), and HT. The other variables are the invariant mass of the system composed of the lepton and subleading jet (m`;j2), the lepton pseudorapidity ( `), and the di erence in azimuthal angle between the p=T and the lepton ( p=T;`). The most important variables chosen as input to the BDTs in the 3-jets 2-tags category are: pbTb, m`b2, the cosine of the angle between the lepton and the non b-tagged jet in the top quark rest frame (cos q), and mT. The other variables are m` b, HT, the transverse momentum of the next-to-leading b jet (pbT2), and the transverse momentum of the non In the 7 TeV analysis, the W boson mT distribution is employed to discriminate against the multijet background. Multijet events populate the lower part of the mT spectrum and the requirement mT > 50 GeV is applied to suppress their contribution to a negligible level in the 2-jets 1-tag event category. The number of multijet events that pass the selection is estimated from simulation. In the other categories, the level of multijet production is already small compared to other backgrounds, and its contribution is estimated through a maximum-likelihood t to the mT distribution. In the 8 TeV analysis, BDT discriminants, referred to as QCD BDTs, are used to reject multijet events following the same procedure as in section 5. For each event category a { 7 { CMS 50 100 150 200 250 1 2 3 4 5 the 2-jets 2-tags category: (upper left) mT and (upper right) Rbb for the muon channel at 7 TeV, (middle left) m`b2 and (middle right) mT for the muon channel at 8 TeV, and (bottom left) mT and (bottom right) pbb for the electron channel at 8 TeV. The simulation is normalized to the data and the multijet background is normalized through the maximum-likelihood t discussed in section 6, prior to rejecting the multijet background. The smaller error bands represent only the systematic uncertainties on the background normalizations, while the larger ones include the total systematic uncertainty obtained from the sum in quadrature of the individual contributions listed in section 7. { 8 { Lepton Event category Acceptance (%) QCD BDT is trained using multijet events as signal against non-multijet processes, and the distribution of the QCD BDT discriminant in data is employed to de ne a multijetenriched interval. Events with the discriminant value in this interval are rejected from the analysis. The number of rejected multijet events is estimated through a maximumlikelihood t to the QCD BDT distribution in the multijet-enriched interval in data. This number, multiplied by a scale factor obtained from the selection acceptance, provides the yield of remaining multijet events for each category. The most important variables chosen as input to the QCD BDTs in the 2-jets 2-tags category are: lepton pT, lepton , m` b, mT, cos , and the transverse momentum of the leading b jet (pbT). The distributions for the multijet background are extracted from a data sample enriched with such events. In the muon channel, the sample is de ned by an anti-isolation requirement on the muon (0:2 < Irel < 0:5 at 7 TeV and Irel > 0:2 at 8 TeV). In the electron channel, it is de ned by requiring the failure either of the isolation criteria or the tight identi cation criteria on the electron. Since the number of events in the multijet-enriched data sample at 7 TeV is lower than at 8 TeV due to smaller integrated luminosity, no QCD BDT is de ned in the 7 TeV analysis. lection. Di erent acceptances are observed in the di erent event categories since the QCD BDT selection is optimized to minimize the loss of signal events. and simulation in the 2-jets 2-tags category for muon and electron channels at 8 TeV, where the simulation is normalized to events in data. Both in 7 and 8 TeV analyses (except for 2-jets 1-tag category at 7 TeV) a maximumlikelihood t is performed to determine the yield in multijet events. We de ne the parametrized function F (x) = a V (x) + b M (x), where x represents the discriminant variable and V (x) and M (x) are the respective distributions (templates) in the sum of all processes including a W or Z boson in the nal state, or multijet events. The V (x) distribution is taken from simulation, while M (x) is the template based on the multijet-enriched data sample. The total uncertainty on the multijet background is obtained by considering the statistical uncertainty from the t and possible systematic contributions, which are evaluated by repeating the t after changing the sum of non-multijet components by 20% and employing { 9 { CMS CMS Data the 2-jets 2-tags event category, in (left) the muon and (right) electron channel at 8 TeV. The simulation is normalized to the data. While the smaller error bands include the systematic uncertainties on the background normalizations only, the larger ones include the total systematic uncertainty obtained summing in quadrature the individual contributions discussed in section 7. a multijet template model taken from an independent sample in data, where neither of the two jets pass the b tagging requirement. 7 Systematic uncertainties Several sources of systematic uncertainties have been investigated and determined as follows. Uncertainties on the normalization are summarized in table 3. Uncertainties on tt and W+jets are based on the CMS measurements [28] and [29], respectively. We refer to a 7 TeV measurement of relative uncertainty in W+jets, since it represents the most recent result within CMS of the W boson production cross section in association with two b jets. Uncertainties on Z+jets and dibosons come from refs. [30] and [31], respectively, while the uncertainties on single top quark tW production and t channel are taken from refs. [ 6, 32, 33 ]. Uncertainties on the multijet background normalization reported in the The uncertainties on jet energy scale (JES) and jet energy resolution (JER) are taken into account in line with ref. [34]. The \unclustered energy" in the event, which is computed by subtracting from the p=T the negative vector sum of the uncorrected transverse momenta of jets and leptons not clustered in jets, is changed by 10%. For each of these changes the E=T is recalculated accordingly. The uncertainties in lepton-reconstruction and triggere ciency scale factors are measured using DY events. The parametrizations describing the hadronic trigger e ciencies are varied and new weights are applied to simulated events in order to estimate the hadronic trigger uncertainty. The scale factors used to correct simulation to reproduce the b tagging e ciency and the mistag fraction measured in data are changed by their measured uncertainties [25]. The uncertainty in the total number of interactions per bunch crossing (5%) is propagated to the modelling of pileup in the simulated samples. The integrated luminosity is known to an uncertainty of 2.2% for the 7 TeV data [35] and 2.6% for the 8 TeV data [36]. tt W+jets Z+jets Diboson on the multijet background refer to the 2-jets 2-tags, 2-jets 1-tag, and 3-jets 2-tags categories, respectively. The uncertainty from the choice of factorization and renormalization scales F and R in the QCD calculation is based on dedicated simulated samples of tt, single top quark production in s channel and t channel, and W+jets events, with F and R varied from half to twice their nominal values. The uncertainty from matching matrix element and parton shower thresholds is determined from simulated samples of tt and W+jets with parton matching threshold doubled and halved relative to their nominal values. The uncertainty on the chosen set of PDF is estimated by reweighting the simulated events with each of the 52 eigenvectors of the CT10 PDF parametrization [37]. Di erential measurements have shown that the pT spectrum of the top quarks in tt events is signi cantly softer than the one generated using MC simulation programs [38]. Scale factors for event reweighting are derived from these measurements. The s channel cross section is remeasured based on samples without any reweighting and samples that have been reweighted with doubled weights, as an indication of the corresponding uncertainty. The e ect of the limited number of events in the simulated samples has been taken into account using the \Barlow-Beeston light" method [39]. 8 Cross section extraction A binned maximum-likelihood t is performed to the BDT data distributions in the 2-jets 2-tags, 2-jets 1-tag, and 3-jets 2-tags categories simultaneously. In particular, the inclusion in the t of the 2-jets 1-tag and 3-jets 2-tags regions largely constrains the W+jets and the tt backgrounds respectively while taking into account all possible correlations in the systematic uncertainties for the three samples. The expected total yield i in each bin i of the BDT distribution is given by the sum of all the background contributions Bp;i and the signal yields Si scaled by the signal-strength modi er signal, which is de ned as the ratio between the measured signal cross section and the SM prediction, as i( signal; u) = signal Si + X cp( u)Bp;i: p HJEP09(216)7 S, and Bp, are scaled to the integrated luminosity of the data according to the SM cross sections. The uncertainty in each background normalization, except for multijet events, is included in the likelihood model through a \nuisance" parameter with a log-normal prior (cp( u)). The multijet component is instead xed to the value estimated with the method described in section 6. The measured s channel cross section is given by the value of signal at which the logarithm of the likelihood function reaches its maximum. The 68% CL interval for the cross section is evaluated by pro ling the logarithm of the likelihood as a function of signal, and taking the parameter values for which the pro le likelihood is 0.5 units below The impact from the systematic uncertainty in the background normalizations on the s channel cross section is evaluated by removing one nuisance at a time from the likelihood model and measuring the corresponding change in the total uncertainty. The impact of the uncertainties that are not included in the t are evaluated using the following procedure. For each systematic e ect two pseudo-experiments are generated by changing the corresponding quantity by +1 and 1 standard deviation. Maximum-likelihood ts are then performed for each of the pseudo-experiments, and the di erences between the tted signal and the nominal one are taken as the corresponding uncertainties. The uncertainties arising from di erent systematic sources are combined according to ref. [40]. A breakdown of contributions to the overall uncertainty in the measurement is reported in table 4. the event categories in the muon channel at 7 TeV and muon and electron channels at 8 TeV, after the t to the combined channels. Tables 5, 6 and 7 summarize the number of events selected according to the requirements described in section 4, including the requirement mT > 50 GeV at 7 TeV in the 2-jets 1-tag category, and after the t to the combined channels. The SM expectation for the s channel in the 2-jets 2-tags category is 64 events selected in the muon channel at 7 TeV, 223 in the muon channel at 8 TeV, and 171 in the The sensitivity to the s channel single top quark signal is estimated using the derivative electron channel at 8 TeV. of the likelihood test statistic, de ned as q0 = ; and evaluated at the maximum-likelihood estimate in the background-only hypothesis. Pseudo-data are generated to construct the distribution of the test statistic for the background-only and the signal + background hypotheses. All the nuisance parameters are allowed to vary according to their prior distributions in the pseudo-experiments, while in the evaluation of q0, the likelihood is maximized only with respect to the background normalizations nuisance parameters. Source Statistical tt, single top quark normalization W/Z+jets, diboson normalization Multijet normalization Lepton e ciency Hadronic trigger Luminosity JER & JES b tagging & mistag Pileup Unclustered E=T R; F scales Matching thresholds PDF Top quark pT reweighting Total uncertainty cross section measurement. Di erent prior uncertainties have been assigned to tt, single top quark t channel and tW production, W+jets, Z+jets and diboson normalizations, see section 7. , 7 TeV , 8 TeV e, 8 TeV + e, 8 TeV 7+8 TeV 10 12 12 | 34 14 30 2 1 4 9 6 7 7 6 55 11 14 12 2 3 1 6 7 5 9 6 18 16 28 17 47 15 15 11 3 1 5 | 39 15 11 8 34 11 8 5 64 340 110 40 16 40 19 50 16 14 14 13 | 29 14 31 12 5 2 6 7 2 7 7 54 4290 620 90 46 290 130 420 347 300 110 30 13 60 16 40 12 Process tt W+jets Z+jets Diboson Multijet tW t channel s channel 1380 150 22 3 70 37 135 129 80 30 7 3 20 6 16 5 4960 580 160 59 130 149 570 452 , 7 TeV , 8 TeV e, 8 TeV Total MC 1920 110 7060 370 6240 320 Data 1883 7023 6301 of the simulated samples are quoted after the likelihood-maximization procedure for the combined t. The uncertainties include the statistical uncertainty on the simulation, the background normalizations uncertainties and the b tagging uncertainty. tt W+jets 6390 4850 240 26 78 750 2260 281 310 310 50 10 78 60 140 5 480 38900 32900 2640 650 4640 5380 12730 1412 99240 1800 1500 580 140 460 460 760 9 33200 20090 1820 330 6080 3820 7680 870 910 940 390 70 300 330 460 5 3260 94 13 0 40 78 210 38 220 20 5 0 40 13 30 2 , 7 TeV , 8 TeV of the simulated samples are quoted after the likelihood-maximization procedure for the combined 7+8 TeV t. The uncertainties include the statistical uncertainty on the simulation, the background normalizations uncertainties and the b tagging uncertainty. of the simulated samples are quoted after the likelihood-maximization procedure for the combined t. The uncertainties include the statistical uncertainty on the simulation, the background normalizations uncertainties and the b tagging uncertainty. 9 Results The single top quark production cross section in the s channel has been measured to be: s = 7:1 s = 11:7 s = 16:8 s = 13:4 8:1 (stat + syst) pb, muon channel, 7 TeV; 7:5 (stat + syst) pb, muon channel, 8 TeV; 9:1 (stat + syst) pb, electron channel, 8 TeV; 7:3 (stat + syst) pb, combined, 8 TeV. CMS .031000 0 / v E -00.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0 CMS Data (upper left) 2-jets 2-tags, (upper right) 2-jets 1-tag, and (bottom) 3-jets 2-tags event category, for the muon channel at 7 TeV. The simulation is normalized to the combined (7+8 TeV) t results. The inner uncertainty bands include the post- t background normalizations uncertainties only, the outer ones include the total systematic uncertainty obtained summing in quadrature the individual The observed (expected) signi cance of the measurement is 0.9 (0.5) standard deviations at 7 TeV and 2.3 (0.8) for the combined muon and electron t at 8 TeV. The 68% CL interval for the expected signi cance is 0.0{1.5 at 7 TeV and 0.0{1.8 at 8 TeV. The combined t to the 7 and 8 TeV data determines the signal cross section relative to the SM predictions with a best t value of signal = 2:0 0:9. The observed signi cance of the measurement is 2.5 standard deviations with 1.1 standard deviations expected. The observed upper limit on the s channel cross section at 95% CL is 31.4 pb at 7 TeV and 28.8 pb for the combined muon and electron channel at 8 TeV. Combining the 7 and 8 TeV data, the observed upper limit on the signal strength is 4.7. In table 8, we report a summary of the observed and expected upper limits at 7 and 8 TeV and for the combination of the channels. 10 Summary A search is presented for single top quark production in the s channel in pp collisions at centre-of-mass energies of 7 and 8 TeV with the CMS detector at the LHC. A multivariate approach based on boosted decision trees is adopted to discriminate the signal from 3 .01800 0 Muon, 19.7 fb-1 (8 TeV), 2-jets 1-tag CMS CMS Data the (upper left) 2-jets 2-tags, (upper right) 2-jets 1-tag, and (bottom) 3-jets 2-tags event category, for the muon channel at 8 TeV. The simulation is normalized to the combined (7+8 TeV) t results. The inner uncertainty bands include the post- t background normalizations uncertainties only, the outer ones include the total systematic uncertainty, obtained summing in quadrature the individual data. Both the expected limits assuming the presence of a SM signal or in the absence of a signal are reported. In the hypothesis of a SM signal, the 68% CL interval for the expected limit is also reported within square brackets. In the last row the upper limits are given in terms of the rate relative to the SM expectation. 1 ./01400 s ten1200 v Electron, 19.7 fb-1 (8 TeV), 2-jets 1-tag CMS CMS Data 3000 2000 1000 the (upper left) 2-jets 2-tags, (upper right) 2-jets 1-tag, and (bottom) 3-jets 2-tags event category, for the electron channel at 8 TeV. The simulation is normalized to the combined (7+8 TeV) t results. The inner uncertainty bands include the post- t background normalizations uncertainties only, the outer ones include the total systematic uncertainty, obtained summing in quadrature the individual contributions. background contributions. The cross section is measured to be 7:1 8:1 (stat + syst) pb at 7 TeV and 13:4 7:3 (stat + syst) pb at 8 TeV, corresponding to a combined signal rate relative to SM expectations of 2:0 0:9 (stat + syst). The observed signi cance of the combined measurement is 2.5 standard deviations with 1.1 standard deviations expected. The observed and expected upper limits on the combined signal strength are found to be 4.7 and 3.1 at 95% CL, respectively. The measurements are in agreement with the prediction of the standard model. Acknowledgments We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative sta s at CERN and at other CMS institutes for their contributions to the success of the CMS e ort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so e ectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER, ERC IUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy O ce; the Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS programme of the Foundation for Polish Science, co nanced from European Union, Regional Development Fund; the OPUS programme of the National Science Center (Poland); the Compagnia di San Paolo (Torino); the Consorzio per la Fisica (Trieste); MIUR project 20108T4XTM (Italy); the Thalis and Aristeia programmes co nanced by EU-ESF and the Greek NSRF; the National Priorities Research Program by Qatar National Research Fund; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand); and the Welch Foundation, contract C-1845. Open Access. 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Ribeiro Cipriano University of Split, Faculty of Science, Split, Croatia Z. Antunovic, M. Kovac Institute Rudjer Boskovic, Zagreb, Croatia V. Brigljevic, K. Kadija, J. Luetic, S. Micanovic, L. Sudic University of Cyprus, Nicosia, Cyprus H. Rykaczewski Charles University, Prague, Czech Republic M. Bodlak, M. Finger10, M. Finger Jr.10 A. Attikis, G. Mavromanolakis, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis, Academy of Scienti c Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt E. El-khateeb11;11, T. Elkafrawy11, A. Mohamed12, E. Salama13;11 National Institute of Chemical Physics and Biophysics, Tallinn, Estonia B. Calpas, M. Kadastik, M. Murumaa, M. Raidal, A. Tiko, C. Veelken Department of Physics, University of Helsinki, Helsinki, Finland P. Eerola, J. Pekkanen, M. Voutilainen Helsinki Institute of Physics, Helsinki, Finland J. Harkonen, V. Karimaki, R. Kinnunen, T. Lampen, K. Lassila-Perini, S. Lehti, T. Linden, P. Luukka, T. Peltola, J. Tuominiemi, E. Tuovinen, L. Wendland Lappeenranta University of Technology, Lappeenranta, Finland J. Talvitie, T. Tuuva DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France M. Besancon, F. Couderc, M. Dejardin, D. Denegri, B. Fabbro, J.L. Faure, C. Favaro, F. Ferri, S. Ganjour, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, E. Locci, M. Machet, J. Malcles, J. Rander, A. Rosowsky, M. Titov, A. Zghiche Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France A. Abdulsalam, I. Antropov, S. Ba oni, F. Beaudette, P. Busson, L. Cadamuro, E. Chapon, C. Charlot, O. Davignon, N. Filipovic, R. Granier de Cassagnac, M. Jo, S. Lisniak, L. Mastrolorenzo, P. Mine, I.N. Naranjo, M. Nguyen, C. Ochando, G. Ortona, P. Paganini, P. Pigard, S. Regnard, R. Salerno, J.B. Sauvan, Y. Sirois, T. Strebler, Y. Yilmaz, A. Zabi Institut Pluridisciplinaire Hubert Curien, Universite de Strasbourg, Universite de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France J.-L. Agram14, J. Andrea, A. Aubin, D. Bloch, J.-M. Brom, M. Buttignol, E.C. Chabert, N. Chanon, C. Collard, E. Conte14, X. Coubez, J.-C. Fontaine14, D. Gele, U. Goerlach, C. Goetzmann, A.-C. Le Bihan, J.A. Merlin2, K. Skovpen, P. Van Hove Centre de Calcul de l'Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France S. Gadrat Universite de Lyon, Universite Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucleaire de Lyon, Villeurbanne, France S. Beauceron, C. Bernet, G. Boudoul, E. Bouvier, C.A. Carrillo Montoya, R. Chierici, D. Contardo, B. Courbon, P. Depasse, H. El Mamouni, J. Fan, J. Fay, S. Gascon, M. Gouzevitch, B. Ille, F. Lagarde, I.B. Laktineh, M. Lethuillier, L. Mirabito, A.L. Pequegnot, S. Perries, J.D. Ruiz Alvarez, D. Sabes, L. Sgandurra, V. Sordini, M. Vander Donckt, P. Verdier, S. Viret HJEP09(216)7 Georgian Technical University, Tbilisi, Georgia T. Toriashvili15 Z. Tsamalaidze10 Tbilisi State University, Tbilisi, Georgia RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany C. Autermann, S. Beranek, L. Feld, A. Heister, M.K. Kiesel, K. Klein, M. Lipinski, A. Ostapchuk, M. Preuten, F. Raupach, S. Schael, J.F. Schulte, T. Verlage, H. Weber, V. Zhukov6 RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany M. Ata, M. Brodski, E. Dietz-Laursonn, D. Duchardt, M. Endres, M. Erdmann, S. Erdweg, T. Esch, R. Fischer, A. Guth, T. Hebbeker, C. Heidemann, K. Hoepfner, S. Knutzen, P. Kreuzer, M. Merschmeyer, A. Meyer, P. Millet, S. Mukherjee, M. Olschewski, K. Padeken, P. Papacz, T. Pook, M. Radziej, H. Reithler, M. Rieger, F. Scheuch, L. Sonnenschein, D. Teyssier, S. Thuer RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany V. Cherepanov, Y. Erdogan, G. Flugge, H. Geenen, M. Geisler, F. Hoehle, B. Kargoll, T. Kress, A. Kunsken, J. Lingemann, A. Nehrkorn, A. Nowack, I.M. Nugent, C. Pistone, O. Pooth, A. Stahl Deutsches Elektronen-Synchrotron, Hamburg, Germany M. Aldaya Martin, I. Asin, N. Bartosik, O. Behnke, U. Behrens, K. Borras16, A. Burgmeier, A. Campbell, C. Contreras-Campana, F. Costanza, C. Diez Pardos, G. Dolinska, S. Dooling, T. Dorland, G. Eckerlin, D. Eckstein, T. Eichhorn, G. Flucke, E. Gallo17, J. Garay Garcia, A. Geiser, A. Gizhko, P. Gunnellini, J. Hauk, M. Hempel18, H. Jung, A. Kalogeropoulos, O. Karacheban18, M. Kasemann, P. Katsas, J. Kieseler, C. Kleinwort, I. Korol, W. Lange, J. Leonard, K. Lipka, A. Lobanov, W. Lohmann18, R. Mankel, I.-A. MelzerPellmann, A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, S. Naumann-Emme, A. Nayak, E. Ntomari, H. Perrey, D. Pitzl, R. Placakyte, A. Raspereza, B. Roland, M.O . Sahin, P. Saxena, T. Schoerner-Sadenius, C. Seitz, S. Spannagel, N. Stefaniuk, K.D. Trippkewitz, R. Walsh, C. Wissing University of Hamburg, Hamburg, Germany V. Blobel, M. Centis Vignali, A.R. Draeger, J. Er e, E. Garutti, K. Goebel, D. Gonzalez, M. Gorner, J. Haller, M. Ho mann, R.S. Hoing, A. Junkes, R. Klanner, R. Kogler, N. Kovalchuk, T. Lapsien, T. Lenz, I. Marchesini, D. Marconi, M. Meyer, D. Nowatschin, J. Ott, F. Pantaleo2, T. Pei er, A. Perieanu, N. Pietsch, J. Poehlsen, D. Rathjens, C. Sander, C. Scharf, P. Schleper, E. Schlieckau, A. Schmidt, S. Schumann, J. Schwandt, V. Sola, H. Stadie, G. Steinbruck, F.M. Stober, H. Tholen, D. Troendle, E. Usai, L. Vanelderen, A. Vanhoefer, B. Vormwald Institut fur Experimentelle Kernphysik, Karlsruhe, Germany C. Barth, C. Baus, J. Berger, C. Boser, E. Butz, T. Chwalek, F. Colombo, W. De Boer, A. Descroix, A. Dierlamm, S. Fink, F. Frensch, R. Friese, M. Gi els, A. Gilbert, Pardo, B. Maier, H. Mildner, M.U. Mozer, T. Muller, Th. Muller, M. Plagge, G. Quast, K. Rabbertz, S. Rocker, F. Roscher, M. Schroder, G. Sieber, H.J. Simonis, R. Ulrich, J. Wagner-Kuhr, S. Wayand, M. Weber, T. Weiler, S. Williamson, C. Wohrmann, R. Wolf Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece A. Psallidas, I. Topsis-Giotis G. Anagnostou, G. Daskalakis, T. Geralis, V.A. Giakoumopoulou, A. Kyriakis, D. Loukas, National and Kapodistrian University of Athens, Athens, Greece A. Agapitos, S. Kesisoglou, A. Panagiotou, N. Saoulidou, E. Tziaferi University of Ioannina, Ioannina, Greece I. Evangelou, G. Flouris, C. Foudas, P. Kokkas, N. Loukas, N. Manthos, I. Papadopoulos, E. Paradas, J. Strologas Wigner Research Centre for Physics, Budapest, Hungary G. Bencze, C. Hajdu, A. Hazi, P. Hidas, D. Horvath19, F. Sikler, V. Veszpremi, G. Vesztergombi20, A.J. Zsigmond Institute of Nuclear Research ATOMKI, Debrecen, Hungary N. Beni, S. Czellar, J. Karancsi21, J. Molnar, Z. Szillasi2 University of Debrecen, Debrecen, Hungary M. Bartok22, A. Makovec, P. Raics, Z.L. Trocsanyi, B. Ujvari National Institute of Science Education and Research, Bhubaneswar, India S. Choudhury23, P. Mal, K. Mandal, D.K. Sahoo, N. Sahoo, S.K. Swain Panjab University, Chandigarh, India S. Bansal, S.B. Beri, V. Bhatnagar, R. Chawla, R. Gupta, U.Bhawandeep, A.K. Kalsi, A. Kaur, M. Kaur, R. Kumar, A. Mehta, M. Mittal, J.B. Singh, G. Walia University of Delhi, Delhi, India Ashok Kumar, A. Bhardwaj, B.C. Choudhary, R.B. Garg, S. Malhotra, M. Naimuddin, N. Nishu, K. Ranjan, R. Sharma, V. Sharma Saha Institute of Nuclear Physics, Kolkata, India S. Bhattacharya, K. Chatterjee, S. Dey, S. Dutta, N. Majumdar, A. Modak, K. Mondal, S. Mukhopadhyay, A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar, M. Sharan Bhabha Atomic Research Centre, Mumbai, India R. Chudasama, D. Dutta, V. Jha, V. Kumar, A.K. Mohanty2, L.M. Pant, P. Shukla, A. Topkar Tata Institute of Fundamental Research, Mumbai, India T. Aziz, S. Banerjee, S. Bhowmik24, R.M. Chatterjee, R.K. Dewanjee, S. Dugad, S. Ganguly, S. Ghosh, M. Guchait, A. Gurtu25, Sa. Jain, G. Kole, S. Kumar, B. Mahakud, HJEP09(216)7 N. Sur, B. Sutar, N. Wickramage26 Indian Institute of Science Education and Research (IISER), Pune, India S. Chauhan, S. Dube, A. Kapoor, K. Kothekar, S. Sharma Institute for Research in Fundamental Sciences (IPM), Tehran, Iran H. Bakhshiansohi, H. Behnamian, S.M. Etesami27, A. Fahim28, M. Khakzad, M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi, F. Rezaei Hosseinabadi, B. Safarzadeh29, M. Zeinali University College Dublin, Dublin, Ireland M. Felcini, M. Grunewald INFN Sezione di Bari a, Universita di Bari b, Politecnico di Bari c, Bari, Italy M. Abbresciaa;b, C. Calabriaa;b, C. Caputoa;b, A. Colaleoa, D. Creanzaa;c, L. Cristellaa;b, N. De Filippisa;c, M. De Palmaa;b, L. Fiorea, G. Iasellia;c, G. Maggia;c, M. Maggia, G. Minielloa;b, S. Mya;c, S. Nuzzoa;b, A. Pompilia;b, G. Pugliesea;c, R. Radognaa;b, A. Ranieria, G. Selvaggia;b, L. Silvestrisa;2, R. Vendittia;b INFN Sezione di Bologna a, Universita di Bologna b, Bologna, Italy G. Abbiendia, C. Battilana2, D. Bonacorsia;b, S. Braibant-Giacomellia;b, L. Brigliadoria;b, R. Campaninia;b, P. Capiluppia;b, A. Castroa;b, F.R. Cavalloa, S.S. Chhibraa;b, G. Codispotia;b, M. Cu ania;b, G.M. Dallavallea, F. Fabbria, A. Fanfania;b, D. Fasanellaa;b, P. Giacomellia, C. Grandia, L. Guiduccia;b, S. Marcellinia, G. Masettia, A. Montanaria, F.L. Navarriaa;b, A. Perrottaa, A.M. Rossia;b, T. Rovellia;b, G.P. Sirolia;b, N. Tosia;b;2 INFN Sezione di Catania a, Universita di Catania b, Catania, Italy G. Cappellob, M. Chiorbolia;b, S. Costaa;b, A. Di Mattiaa, F. Giordanoa;b, R. Potenzaa;b, A. Tricomia;b, C. Tuvea;b INFN Sezione di Firenze a, Universita di Firenze b, Firenze, Italy G. Barbaglia, V. Ciullia;b, C. Civininia, R. D'Alessandroa;b, E. Focardia;b, V. Goria;b, P. Lenzia;b, M. Meschinia, S. Paolettia, G. Sguazzonia, L. Viliania;b;2 INFN Laboratori Nazionali di Frascati, Frascati, Italy L. Benussi, S. Bianco, F. Fabbri, D. Piccolo, F. Primavera2 INFN Sezione di Genova a, Universita di Genova b, Genova, Italy V. Calvellia;b, F. Ferroa, M. Lo Veterea;b, M.R. Mongea;b, E. Robuttia, S. Tosia;b INFN Sezione di Milano-Bicocca a, Universita di Milano-Bicocca b, Milano, Italy L. Brianza, M.E. Dinardoa;b, S. Fiorendia;b, S. Gennaia, R. Gerosaa;b, A. Ghezzia;b, P. Govonia;b, S. Malvezzia, R.A. Manzonia;b;2, B. Marzocchia;b, D. Menascea, L. Moronia, M. Paganonia;b, D. Pedrinia, S. Ragazzia;b, N. Redaellia, T. Tabarelli de Fatisa;b INFN Sezione di Napoli a, Universita di Napoli 'Federico II' b, Napoli, Italy, Universita della Basilicata c, Potenza, Italy, Universita G. Marconi d, Roma, S. Buontempoa, N. Cavalloa;c, S. Di Guidaa;d;2, M. Espositoa;b, F. Fabozzia;c, A.O.M. Iorioa;b, G. Lanzaa, L. Listaa, S. Meolaa;d;2, M. Merolaa, P. Paoluccia;2, C. Sciaccaa;b, F. Thyssen, F. Tramontanoa;b INFN Sezione di Padova a, Universita di Padova b, Padova, Italy, Universita di Trento c, Trento, Italy P. Azzia;2, N. Bacchettaa, L. Benatoa;b, D. Biselloa;b, A. Bolettia;b, A. Brancaa;b, R. Carlina;b, P. Checchiaa, M. Dall'Ossoa;b;2, T. Dorigoa, U. Dossellia, F. Gasparinia;b, U. Gasparinia;b, A. Gozzelinoa, K. Kanishcheva;c, S. Lacapraraa, M. Margonia;b, A.T. Meneguzzoa;b, M. Passaseoa, J. Pazzinia;b;2, N. Pozzobona;b, P. Ronchesea;b, F. Simonettoa;b, E. Torassaa, M. Tosia;b, M. Zanetti, P. Zottoa;b, A. Zucchettaa;b;2, G. Zumerlea;b INFN Sezione di Pavia a, Universita di Pavia b, Pavia, Italy A. Braghieria, A. Magnania;b, P. Montagnaa;b, S.P. Rattia;b, V. Rea, C. Riccardia;b, P. Salvinia, I. Vaia;b, P. Vituloa;b INFN Sezione di Perugia a, Universita di Perugia b, Perugia, Italy L. Alunni Solestizia;b, G.M. Bileia, D. Ciangottinia;b;2, L. Fanoa;b, P. Laricciaa;b, G. Mantovania;b, M. Menichellia, A. Sahaa, A. Santocchiaa;b INFN Sezione di Pisa a, Universita di Pisa b, Scuola Normale Superiore di Pisa c, Pisa, Italy K. Androsova;30, P. Azzurria;2, G. Bagliesia, J. Bernardinia, T. Boccalia, R. Castaldia, M.A. Cioccia;30, R. Dell'Orsoa, S. Donatoa;c;2, G. Fedi, L. Foaa;cy, A. Giassia, M.T. Grippoa;30, F. Ligabuea;c, T. Lomtadzea, L. Martinia;b, A. Messineoa;b, F. Pallaa, A. Rizzia;b, A. Savoy-Navarroa;31, A.T. Serbana, P. Spagnoloa, R. Tenchinia, G. Tonellia;b, A. Venturia, P.G. Verdinia INFN Sezione di Roma a, Universita di Roma b, Roma, Italy L. Baronea;b, F. Cavallaria, G. D'imperioa;b;2, D. Del Rea;b;2, M. Diemoza, S. Gellia;b, C. Jordaa, E. Longoa;b, F. Margarolia;b, P. Meridiania, G. Organtinia;b, R. Paramattia, F. Preiatoa;b, S. Rahatloua;b, C. Rovellia, F. Santanastasioa;b, P. Traczyka;b;2 INFN Sezione di Torino a, Universita di Torino b, Torino, Italy, Universita del Piemonte Orientale c, Novara, Italy N. Amapanea;b, R. Arcidiaconoa;c;2, S. Argiroa;b, M. Arneodoa;c, R. Bellana;b, C. Biinoa, N. Cartigliaa, M. Costaa;b, R. Covarellia;b, A. Deganoa;b, N. Demariaa, L. Fincoa;b;2, B. Kiania;b, C. Mariottia, S. Masellia, E. Migliorea;b, V. Monacoa;b, E. Monteila;b, M.M. Obertinoa;b, L. Pachera;b, N. Pastronea, M. Pelliccionia, G.L. Pinna Angionia;b, F. Raveraa;b, A. Romeroa;b, M. Ruspaa;c, R. Sacchia;b, A. Solanoa;b, A. Staianoa HJEP09(216)7 S. Belfortea, V. Candelisea;b, M. Casarsaa, F. Cossuttia, G. Della Riccaa;b, B. Gobboa, C. La Licataa;b, M. Maronea;b, A. Schizzia;b, A. Zanettia Kangwon National University, Chunchon, Korea A. Kropivnitskaya, S.K. Nam Kyungpook National University, Daegu, Korea D.H. Kim, G.N. Kim, M.S. Kim, D.J. Kong, S. Lee, Y.D. Oh, A. Sakharov, D.C. Son Chonbuk National University, Jeonju, Korea J.A. Brochero Cifuentes, H. Kim, T.J. Kim32 Chonnam National University, Institute for Universe and Elementary Particles, S. Cho, S. Choi, Y. Go, D. Gyun, B. Hong, H. Kim, Y. Kim, B. Lee, K. Lee, K.S. Lee, Kwangju, Korea S. Song Korea University, Seoul, Korea S. Lee, J. Lim, S.K. Park, Y. Roh Seoul National University, Seoul, Korea H.D. Yoo University of Seoul, Seoul, Korea Sungkyunkwan University, Suwon, Korea Y. Choi, J. Goh, D. Kim, E. Kwon, J. Lee, I. Yu Vilnius University, Vilnius, Lithuania V. Dudenas, A. Juodagalvis, J. Vaitkus M. Choi, H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park, G. Ryu, M.S. Ryu National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia I. Ahmed, Z.A. Ibrahim, J.R. Komaragiri, M.A.B. Md Ali33, F. Mohamad Idris34, W.A.T. Wan Abdullah, M.N. Yusli, Z. Zolkapli Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico E. Casimiro Linares, H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-De La Cruz35, A. Hernandez-Almada, R. Lopez-Fernandez, J. Mejia Guisao, A. Sanchez-Hernandez Universidad Iberoamericana, Mexico City, Mexico S. Carrillo Moreno, F. Vazquez Valencia Benemerita Universidad Autonoma de Puebla, Puebla, Mexico I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada Universidad Autonoma de San Luis Potos , San Luis Potos , Mexico A. Morelos Pineda D. Krofcheck P.H. Butler M. Waqas University of Auckland, Auckland, New Zealand University of Canterbury, Christchurch, New Zealand National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan A. Ahmad, M. Ahmad, Q. Hassan, H.R. Hoorani, W.A. Khan, T. Khurshid, M. Shoaib, National Centre for Nuclear Research, Swierk, Poland H. Bialkowska, M. Bluj, B. Boimska, T. Frueboes, M. Gorski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, P. Zalewski Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland G. Brona, K. Bunkowski, A. Byszuk36, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski, M. Misiura, M. Olszewski, M. Walczak Laboratorio de Instrumentac~ao e F sica Experimental de Part culas, Lisboa, Portugal P. Bargassa, C. Beir~ao Da Cruz E Silva, A. Di Francesco, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, J. Hollar, N. Leonardo, L. Lloret Iglesias, F. Nguyen, J. Rodrigues Antunes, J. Seixas, O. Toldaiev, D. Vadruccio, J. Varela, P. Vischia Joint Institute for Nuclear Research, Dubna, Russia M. Gavrilenko, I. Golutvin, A. Kamenev, V. Karjavin, V. Korenkov, A. Lanev, A. Malakhov, V. Matveev37;38, V.V. Mitsyn, P. Moisenz, V. Palichik, V. Perelygin, S. Shmatov, S. Shulha, N. Skatchkov, V. Smirnov, E. Tikhonenko, A. Zarubin Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia V. Golovtsov, Y. Ivanov, V. Kim39, E. Kuznetsova, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev Institute for Nuclear Research, Moscow, Russia Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, A. Karneyeu, M. Kirsanov, N. Krasnikov, A. Pashenkov, D. Tlisov, A. Toropin Institute for Theoretical and Experimental Physics, Moscow, Russia V. Epshteyn, V. Gavrilov, N. Lychkovskaya, V. Popov, I. Pozdnyakov, G. Safronov, A. Spiridonov, E. Vlasov, A. Zhokin National Research Nuclear University 'Moscow Engineering Physics Institute' (MEPhI), Moscow, Russia M. Chadeeva, R. Chistov, M. Danilov, V. Rusinov, E. Tarkovskii P.N. Lebedev Physical Institute, Moscow, Russia V. Andreev, M. Azarkin38, I. Dremin38, M. Kirakosyan, A. Leonidov38, G. Mesyats, S.V. Rusakov Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, A. Baskakov, A. Belyaev, E. Boos, V. Bunichev, M. Dubinin40, L. Dudko, V. Klyukhin, O. Kodolova, N. Korneeva, I. Lokhtin, I. Miagkov, S. Obraztsov, M. Per lov, S. Petrushanko, V. Savrin Physics, Protvino, Russia A. Uzunian, A. Volkov State Research Center of Russian Federation, Institute for High Energy I. Azhgirey, I. Bayshev, S. Bitioukov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine, V. Petrov, R. Ryutin, A. Sobol, L. Tourtchanovitch, S. Troshin, N. Tyurin, University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia P. Adzic41, P. Cirkovic, D. Devetak, J. Milosevic, V. Rekovic Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid, Spain J. Alcaraz Maestre, E. Calvo, M. Cerrada, M. Chamizo Llatas, N. Colino, B. De La Cruz, A. Delgado Peris, A. Escalante Del Valle, C. Fernandez Bedoya, J.P. Fernandez Ramos, J. Flix, M.C. Fouz, P. Garcia-Abia, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, E. Navarro De Martino, A. Perez-Calero Yzquierdo, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, J. Santaolalla, M.S. Soares Universidad Autonoma de Madrid, Madrid, Spain C. Albajar, J.F. de Troconiz, M. Missiroli, D. Moran Universidad de Oviedo, Oviedo, Spain J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, E. Palencia Cortezon, J.M. Vizan Garcia Santander, Spain Instituto de F sica de Cantabria (IFCA), CSIC-Universidad de Cantabria, I.J. Cabrillo, A. Calderon, J.R. Castin~eiras De Saa, E. Curras, P. De Castro Manzano, M. Fernandez, J. Garcia-Ferrero, G. Gomez, A. Lopez Virto, J. Marco, R. Marco, C. Martinez Rivero, F. Matorras, J. Piedra Gomez, T. Rodrigo, A.Y. Rodr guez-Marrero, A. Ruiz-Jimeno, L. Scodellaro, N. Trevisani, I. Vila, R. Vilar Cortabitarte CERN, European Organization for Nuclear Research, Geneva, Switzerland D. Abbaneo, E. Au ray, G. Auzinger, M. Bachtis, P. Baillon, A.H. Ball, D. Barney, A. Benaglia, J. Bendavid, L. Benhabib, G.M. Berruti, P. Bloch, A. Bocci, A. Bonato, C. Botta, H. Breuker, T. Camporesi, R. Castello, G. Cerminara, M. D'Alfonso, D. d'Enterria, A. Dabrowski, V. Daponte, A. David, M. De Gruttola, F. De Guio, A. De Roeck, S. De Visscher, E. Di Marco42, M. Dobson, M. Dordevic, B. Dorney, T. du Pree, D. Duggan, M. Dunser, N. Dupont, A. Elliott-Peisert, G. Franzoni, J. Fulcher, W. Funk, D. Gigi, K. Gill, D. Giordano, M. Girone, F. Glege, R. Guida, S. Gundacker, M. Gutho , J. Hammer, P. Harris, J. Hegeman, V. Innocente, P. Janot, H. Kirschenmann, M.J. Kortelainen, K. Kousouris, K. Krajczar, P. Lecoq, C. Lourenco, M.T. Lucchini, N. Magini, L. Malgeri, M. Mannelli, A. Martelli, L. Masetti, F. Meijers, S. Mersi, E. Meschi, F. Moortgat, S. Morovic, M. Mulders, M.V. Nemallapudi, H. Neugebauer, S. Orfanelli43, L. Orsini, L. Pape, E. Perez, M. Peruzzi, A. Petrilli, G. Petrucciani, A. Pfei er, M. Pierini, D. Piparo, A. Racz, T. Reis, G. Rolandi44, M. Rovere, M. Ruan, H. Sakulin, C. Schafer, C. Schwick, M. Seidel, A. Sharma, P. Silva, M. Simon, P. Sphicas45, J. Steggemann, B. Stieger, M. Stoye, Y. Takahashi, D. Treille, A. Triossi, A. Tsirou, G.I. Veres20, N. Wardle, H.K. Wohri, A. Zagozdzinska36, W.D. Zeuner Paul Scherrer Institut, Villigen, Switzerland W. Bertl, K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, D. Kotlinski, U. Langenegger, T. Rohe Institute for Particle Physics, ETH Zurich, Zurich, Switzerland F. Bachmair, L. Bani, L. Bianchini, B. Casal, G. Dissertori, M. Dittmar, M. Donega, P. Eller, C. Grab, C. Heidegger, D. Hits, J. Hoss, G. Kasieczka, P. Lecomtey, W. Lustermann, B. Mangano, M. Marionneau, P. Martinez Ruiz del Arbol, M. Masciovecchio, M.T. Meinhard, D. Meister, F. Micheli, P. Musella, F. Nessi-Tedaldi, F. Pandol , J. Pata, F. Pauss, L. Perrozzi, M. Quittnat, M. Rossini, M. Schonenberger, A. Starodumov46, M. Takahashi, V.R. Tavolaro, K. Theo latos, R. Wallny Universitat Zurich, Zurich, Switzerland T.K. Aarrestad, C. Amsler47, L. Caminada, M.F. Canelli, V. Chiochia, A. De Cosa, C. Galloni, A. Hinzmann, T. Hreus, B. Kilminster, C. Lange, J. Ngadiuba, D. Pinna, G. Rauco, P. Robmann, D. Salerno, Y. Yang National Central University, Chung-Li, Taiwan M. Cardaci, K.H. Chen, T.H. Doan, Sh. Jain, R. Khurana, M. Konyushikhin, C.M. Kuo, W. Lin, Y.J. Lu, A. Pozdnyakov, S.S. Yu National Taiwan University (NTU), Taipei, Taiwan Arun Kumar, P. Chang, Y.H. Chang, Y.W. Chang, Y. Chao, K.F. Chen, P.H. Chen, C. Dietz, F. Fiori, U. Grundler, W.-S. Hou, Y. Hsiung, Y.F. Liu, R.-S. Lu, M. Min~ano Moya, E. Petrakou, J.f. Tsai, Y.M. Tzeng Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand B. Asavapibhop, K. Kovitanggoon, G. Singh, N. Srimanobhas, N. Suwonjandee Cukurova University, Adana, Turkey A. Adiguzel, M.N. Bakirci48, S. Damarseckin, Z.S. Demiroglu, C. Dozen, E. Eskut, S. Girgis, G. Gokbulut, Y. Guler, E. Gurpinar, I. Hos, E.E. Kangal49, G. Onengut50, K. Ozdemir51, A. Polatoz, D. Sunar Cerci52, B. Tali52, H. Topakli48, C. Zorbilmez Middle East Technical University, Physics Department, Ankara, Turkey B. Bilin, S. Bilmis, B. Isildak53, G. Karapinar54, M. Yalvac, M. Zeyrek Bogazici University, Istanbul, Turkey E. Gulmez, M. Kaya55, O. Kaya56, E.A. Yetkin57, T. Yetkin58 Istanbul Technical University, Istanbul, Turkey A. Cakir, K. Cankocak, S. Sen59, F.I. Vardarl Institute for Scintillation Materials of National Academy of Science of Ukraine, Kharkov, Ukraine B. Grynyov Kharkov, Ukraine L. Levchuk, P. Sorokin National Scienti c Center, Kharkov Institute of Physics and Technology, HJEP09(216)7 University of Bristol, Bristol, United Kingdom R. Aggleton, F. Ball, L. Beck, J.J. Brooke, E. Clement, D. Cussans, H. Flacher, J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath, J. Jacob, L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold60, S. Paramesvaran, A. Poll, T. Sakuma, S. Seif El Nasr-storey, S. Senkin, D. Smith, V.J. Smith Rutherford Appleton Laboratory, Didcot, United Kingdom K.W. Bell, A. Belyaev61, C. Brew, R.M. Brown, L. Calligaris, D. Cieri, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, E. Olaiya, D. Petyt, C.H. Shepherd-Themistocleous, A. Thea, I.R. Tomalin, T. Williams, S.D. Worm Imperial College, London, United Kingdom M. Baber, R. Bainbridge, O. Buchmuller, A. Bundock, D. Burton, S. Casasso, M. Citron, D. Colling, L. Corpe, P. Dauncey, G. Davies, A. De Wit, M. Della Negra, P. Dunne, A. Elwood, D. Futyan, G. Hall, G. Iles, R. Lane, R. Lucas60, L. Lyons, A.-M. Magnan, S. Malik, J. Nash, A. Nikitenko46, J. Pela, M. Pesaresi, D.M. Raymond, A. Richards, A. Rose, C. Seez, A. Tapper, K. Uchida, M. Vazquez Acosta62, T. Virdee, S.C. Zenz Brunel University, Uxbridge, United Kingdom J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, D. Leslie, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner Baylor University, Waco, USA A. Borzou, K. Call, J. Dittmann, K. Hatakeyama, H. Liu, N. Pastika The University of Alabama, Tuscaloosa, USA O. Charaf, S.I. Cooper, C. Henderson, P. Rumerio Boston University, Boston, USA D. Arcaro, A. Avetisyan, T. Bose, D. Gastler, D. Rankin, C. Richardson, J. Rohlf, L. Sulak, D. Zou Brown University, Providence, USA J. Alimena, G. Benelli, E. Berry, D. Cutts, A. Ferapontov, A. Garabedian, J. Hakala, U. Heintz, O. Jesus, E. Laird, G. Landsberg, Z. Mao, M. Narain, S. Piperov, S. Sagir, R. Syarif University of California, Davis, Davis, USA R. Breedon, G. Breto, M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher, G. Funk, M. Gardner, W. Ko, R. Lander, C. Mclean, M. Mulhearn, D. Pellett, J. Pilot, F. Ricci-Tam, S. Shalhout, J. Smith, M. Squires, D. Stolp, M. Tripathi, S. Wilbur, R. Yohay University of California, Los Angeles, USA R. Cousins, P. Everaerts, A. Florent, J. Hauser, M. Ignatenko, D. Saltzberg, E. Takasugi, V. Valuev, M. Weber University of California, Riverside, Riverside, USA K. Burt, R. Clare, J. Ellison, J.W. Gary, G. Hanson, J. Heilman, M. Ivova PANEVA, P. Jandir, E. Kennedy, F. Lacroix, O.R. Long, M. Malberti, M. Olmedo Negrete, A. Shrinivas, H. Wei, S. Wimpenny, B. R. Yates University of California, San Diego, La Jolla, USA J.G. Branson, G.B. Cerati, S. Cittolin, R.T. D'Agnolo, M. Derdzinski, A. Holzner, R. Kelley, D. Klein, J. Letts, I. Macneill, D. Olivito, S. Padhi, M. Pieri, M. Sani, V. Sharma, S. Simon, M. Tadel, A. Vartak, S. Wasserbaech63, C. Welke, F. Wurthwein, A. Yagil, G. Zevi Della Porta University of California, Santa Barbara, Santa Barbara, USA J. Bradmiller-Feld, C. Campagnari, A. Dishaw, V. Dutta, K. Flowers, M. Franco Sevilla, P. Ge ert, C. George, F. Golf, L. Gouskos, J. Gran, J. Incandela, N. Mccoll, S.D. Mullin, J. Richman, D. Stuart, I. Suarez, C. West, J. Yoo California Institute of Technology, Pasadena, USA D. Anderson, A. Apresyan, A. Bornheim, J. Bunn, Y. Chen, J. Duarte, A. Mott, H.B. Newman, C. Pena, M. Spiropulu, J.R. Vlimant, S. Xie, R.Y. Zhu Carnegie Mellon University, Pittsburgh, USA M.B. Andrews, V. Azzolini, A. Calamba, B. Carlson, T. Ferguson, M. Paulini, J. Russ, M. Sun, H. Vogel, I. Vorobiev University of Colorado Boulder, Boulder, USA J.P. Cumalat, W.T. Ford, A. Gaz, F. Jensen, A. Johnson, M. Krohn, T. Mulholland, U. Nauenberg, K. Stenson, S.R. Wagner Cornell University, Ithaca, USA J. Alexander, A. Chatterjee, J. Chaves, J. Chu, S. Dittmer, N. Eggert, N. Mirman, G. Nicolas Kaufman, J.R. Patterson, A. Rinkevicius, A. Ryd, L. Skinnari, L. So , W. Sun, S.M. Tan, W.D. Teo, J. Thom, J. Thompson, J. Tucker, Y. Weng, P. Wittich Fermi National Accelerator Laboratory, Batavia, USA S. Abdullin, M. Albrow, G. Apollinari, S. Banerjee, L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, G. Bolla, K. Burkett, J.N. Butler, H.W.K. Cheung, F. Chlebana, S. Cihangir, V.D. Elvira, I. Fisk, J. Freeman, E. Gottschalk, L. Gray, D. Green, S. Grunendahl, O. Gutsche, J. Hanlon, D. Hare, R.M. Harris, S. Hasegawa, J. Hirschauer, Z. Hu, B. Jayatilaka, S. Jindariani, M. Johnson, U. Joshi, B. Klima, B. Kreis, S. Lammel, J. Lewis, J. Linacre, D. Lincoln, R. Lipton, T. Liu, R. Lopes De Sa, J. Lykken, K. Maeshima, J.M. Marra no, S. Maruyama, D. Mason, P. McBride, P. Merkel, S. Mrenna, S. Nahn, C. Newman-Holmesy, V. O'Dell, K. Pedro, O. Prokofyev, G. Rakness, E. SextonKennedy, A. Soha, W.J. Spalding, L. Spiegel, S. Stoynev, N. Strobbe, L. Taylor, S. Tkaczyk, HJEP09(216)7 N.V. Tran, L. Uplegger, E.W. Vaandering, C. Vernieri, M. Verzocchi, R. Vidal, M. Wang, H.A. Weber, A. Whitbeck University of Florida, Gainesville, USA D. Acosta, P. Avery, P. Bortignon, D. Bourilkov, A. Brinkerho , A. Carnes, M. Carver, D. Curry, S. Das, R.D. Field, I.K. Furic, J. Konigsberg, A. Korytov, K. Kotov, P. Ma, K. Matchev, H. Mei, P. Milenovic64, G. Mitselmakher, D. Rank, R. Rossin, L. Shchutska, M. Snowball, D. Sperka, N. Terentyev, L. Thomas, J. Wang, S. Wang, J. Yelton Florida International University, Miami, USA S. Hewamanage, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez Florida State University, Tallahassee, USA A. Ackert, J.R. Adams, T. Adams, A. Askew, S. Bein, J. Bochenek, B. Diamond, J. Haas, S. Hagopian, V. Hagopian, K.F. Johnson, A. Khatiwada, H. Prosper, M. Weinberg Florida Institute of Technology, Melbourne, USA M.M. Baarmand, V. Bhopatkar, S. Colafranceschi65, M. Hohlmann, H. Kalakhety, D. Noonan, T. Roy, F. Yumiceva University of Illinois at Chicago (UIC), Chicago, USA M.R. Adams, L. Apanasevich, D. Berry, R.R. Betts, I. Bucinskaite, R. Cavanaugh, O. Evdokimov, L. Gauthier, C.E. Gerber, D.J. Hofman, P. Kurt, C. O'Brien, I.D. Sandoval Gonzalez, P. Turner, N. Varelas, Z. Wu, M. Zakaria, J. Zhang The University of Iowa, Iowa City, USA B. Bilki66, W. Clarida, K. Dilsiz, S. Durgut, R.P. Gandrajula, M. Haytmyradov, V. Khristenko, J.-P. Merlo, H. Mermerkaya67, A. Mestvirishvili, A. Moeller, J. Nachtman, H. Ogul, Y. Onel, F. Ozok68, A. Penzo, C. Snyder, E. Tiras, J. Wetzel, K. Yi Johns Hopkins University, Baltimore, USA I. Anderson, B.A. Barnett, B. Blumenfeld, A. Cocoros, N. Eminizer, D. Fehling, L. Feng, A.V. Gritsan, P. Maksimovic, M. Osherson, J. Roskes, U. Sarica, M. Swartz, M. Xiao, Y. Xin, C. You The University of Kansas, Lawrence, USA P. Baringer, A. Bean, C. Bruner, R.P. Kenny III, D. Majumder, M. Malek, W. Mcbrayer, M. Murray, S. Sanders, R. Stringer, Q. Wang Kansas State University, Manhattan, USA A. Ivanov, K. Kaadze, S. Khalil, M. Makouski, Y. Maravin, A. Mohammadi, L.K. Saini, N. Skhirtladze, S. Toda Lawrence Livermore National Laboratory, Livermore, USA D. Lange, F. Rebassoo, D. Wright University of Maryland, College Park, USA C. Anelli, A. Baden, O. Baron, A. Belloni, B. Calvert, S.C. Eno, C. Ferraioli, J.A. Gomez, N.J. Hadley, S. Jabeen, R.G. Kellogg, T. Kolberg, J. Kunkle, Y. Lu, A.C. Mignerey, Y.H. Shin, A. Skuja, M.B. Tonjes, S.C. Tonwar Massachusetts Institute of Technology, Cambridge, USA A. Apyan, R. Barbieri, A. Baty, R. Bi, K. Bierwagen, S. Brandt, W. Busza, I.A. Cali, Z. Demiragli, L. Di Matteo, G. Gomez Ceballos, M. Goncharov, D. Gulhan, Y. Iiyama, G.M. Innocenti, M. Klute, D. Kovalskyi, Y.S. Lai, Y.-J. Lee, A. Levin, P.D. Luckey, A.C. Marini, C. Mcginn, C. Mironov, S. Narayanan, X. Niu, C. Paus, C. Roland, G. Roland, J. Salfeld-Nebgen, G.S.F. Stephans, K. Sumorok, K. Tatar, M. Varma, D. Velicanu, J. Veverka, J. Wang, T.W. Wang, B. Wyslouch, M. Yang, V. Zhukova University of Minnesota, Minneapolis, USA A.C. Benvenuti, B. Dahmes, A. Evans, A. Finkel, A. Gude, P. Hansen, S. Kalafut, S.C. Kao, K. Klapoetke, Y. Kubota, Z. Lesko, J. Mans, S. Nourbakhsh, N. Ruckstuhl, R. Rusack, N. Tambe, J. Turkewitz University of Mississippi, Oxford, USA J.G. Acosta, S. Oliveros University of Nebraska-Lincoln, Lincoln, USA E. Avdeeva, R. Bartek, K. Bloom, S. Bose, D.R. Claes, A. Dominguez, C. Fangmeier, R. Gonzalez Suarez, R. Kamalieddin, D. Knowlton, I. Kravchenko, F. Meier, J. Monroy, F. Ratnikov, J.E. Siado, G.R. Snow State University of New York at Bu alo, Bu alo, USA M. Alyari, J. Dolen, J. George, A. Godshalk, C. Harrington, I. Iashvili, J. Kaisen, A. Kharchilava, A. Kumar, S. Rappoccio, B. Roozbahani Northeastern University, Boston, USA G. Alverson, E. Barberis, D. Baumgartel, M. Chasco, A. Hortiangtham, A. Massironi, D.M. Morse, D. Nash, T. Orimoto, R. Teixeira De Lima, D. Trocino, R.-J. Wang, D. Wood, J. Zhang Northwestern University, Evanston, USA S. Bhattacharya, K.A. Hahn, A. Kubik, J.F. Low, N. Mucia, N. Odell, B. Pollack, M. Schmitt, K. Sung, M. Trovato, M. Velasco University of Notre Dame, Notre Dame, USA N. Dev, M. Hildreth, C. Jessop, D.J. Karmgard, N. Kellams, K. Lannon, N. Marinelli, F. Meng, C. Mueller, Y. Musienko37, M. Planer, A. Reinsvold, R. Ruchti, G. Smith, S. Taroni, N. Valls, M. Wayne, M. Wolf, A. Woodard The Ohio State University, Columbus, USA L. Antonelli, J. Brinson, B. Bylsma, L.S. Durkin, S. Flowers, A. Hart, C. Hill, R. Hughes, W. Ji, T.Y. Ling, B. Liu, W. Luo, D. Puigh, M. Rodenburg, B.L. Winer, H.W. Wulsin Princeton University, Princeton, USA O. Driga, P. Elmer, J. Hardenbrook, P. Hebda, S.A. Koay, P. Lujan, D. Marlow, T. Medvedeva, M. Mooney, J. Olsen, C. Palmer, P. Piroue, D. Stickland, C. Tully, A. Zuranski S. Malik University of Puerto Rico, Mayaguez, USA Purdue University, West Lafayette, USA A. Barker, V.E. Barnes, D. Benedetti, D. Bortoletto, L. Gutay, M.K. Jha, M. Jones, A.W. Jung, K. Jung, A. Kumar, D.H. Miller, N. Neumeister, B.C. Radburn-Smith, X. Shi, I. Shipsey, D. Silvers, J. Sun, A. Svyatkovskiy, F. Wang, W. Xie, L. Xu Purdue University Calumet, Hammond, USA N. Parashar, J. Stupak Rice University, Houston, USA A. Adair, B. Akgun, Z. Chen, K.M. Ecklund, F.J.M. Geurts, M. Guilbaud, W. Li, B. Michlin, M. Northup, B.P. Padley, R. Redjimi, J. Roberts, J. Rorie, Z. Tu, J. Zabel University of Rochester, Rochester, USA B. Betchart, A. Bodek, P. de Barbaro, R. Demina, Y. Eshaq, T. Ferbel, M. Galanti, A. Garcia-Bellido, J. Han, O. Hindrichs, A. Khukhunaishvili, K.H. Lo, P. Tan, M. Verzetti Rutgers, The State University of New Jersey, Piscataway, USA J.P. Chou, E. Contreras-Campana, D. Ferencek, Y. Gershtein, E. Halkiadakis, M. Heindl, D. Hidas, E. Hughes, S. Kaplan, R. Kunnawalkam Elayavalli, A. Lath, K. Nash, H. Saka, S. Salur, S. Schnetzer, D. She eld, S. Somalwar, R. Stone, S. Thomas, P. Thomassen, M. Walker University of Tennessee, Knoxville, USA M. Foerster, G. Riley, K. Rose, S. Spanier, K. Thapa Texas A&M University, College Station, USA O. Bouhali69, A. Castaneda Hernandez69, A. Celik, M. Dalchenko, M. De Mattia, A. Delgado, S. Dildick, R. Eusebi, J. Gilmore, T. Huang, T. Kamon70, V. Krutelyov, R. Mueller, I. Osipenkov, Y. Pakhotin, R. Patel, A. Perlo , A. Rose, A. Safonov, A. Tatarinov, K.A. Ulmer2 Texas Tech University, Lubbock, USA N. Akchurin, C. Cowden, J. Damgov, C. Dragoiu, P.R. Dudero, J. Faulkner, S. Kunori, K. Lamichhane, S.W. Lee, T. Libeiro, S. Undleeb, I. Volobouev Vanderbilt University, Nashville, USA E. Appelt, A.G. Delannoy, S. Greene, A. Gurrola, R. Janjam, W. Johns, C. Maguire, Y. Mao, A. Melo, H. Ni, P. Sheldon, S. Tuo, J. Velkovska, Q. Xu University of Virginia, Charlottesville, USA M.W. Arenton, B. Cox, B. Francis, J. Goodell, R. Hirosky, A. Ledovskoy, H. Li, C. Lin, C. Neu, T. Sinthuprasith, X. Sun, Y. Wang, E. Wolfe, J. Wood, F. Xia Wayne State University, Detroit, USA C. Clarke, R. Harr, P.E. Karchin, C. Kottachchi Kankanamge Don, P. Lamichhane, J. Sturdy University of Wisconsin - Madison, Madison, WI, USA D.A. Belknap, D. Carlsmith, M. Cepeda, S. Dasu, L. Dodd, S. Duric, B. Gomber, M. Grothe, M. Herndon, A. Herve, P. Klabbers, A. Lanaro, A. Levine, K. Long, R. Loveless, A. Mohapatra, I. Ojalvo, T. Perry, G.A. Pierro, G. Polese, T. Ruggles, T. Sarangi, A. Savin, A. Sharma, N. Smith, W.H. Smith, D. Taylor, P. Verwilligen, N. Woods y: Deceased China 1: Also at Vienna University of Technology, Vienna, Austria 2: Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland 3: Also at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, Moscow, Russia 4: Also at Institut Pluridisciplinaire Hubert Curien, Universite de Strasbourg, Universite de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France 5: Also at National Institute of Chemical Physics and Biophysics, Tallinn, Estonia 6: Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 7: Also at Universidade Estadual de Campinas, Campinas, Brazil 8: Also at Centre National de la Recherche Scienti que (CNRS) - IN2P3, Paris, France 9: Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France 10: Also at Joint Institute for Nuclear Research, Dubna, Russia 11: Also at Ain Shams University, Cairo, Egypt 12: Also at Zewail City of Science and Technology, Zewail, Egypt 13: Also at British University in Egypt, Cairo, Egypt 14: Also at Universite de Haute Alsace, Mulhouse, France 15: Also at Tbilisi State University, Tbilisi, Georgia 16: Also at RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany 17: Also at University of Hamburg, Hamburg, Germany 18: Also at Brandenburg University of Technology, Cottbus, Germany 19: Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary 20: Also at Eotvos Lorand University, Budapest, Hungary 21: Also at University of Debrecen, Debrecen, Hungary 23: Also at Indian Institute of Science Education and Research, Bhopal, India 24: Also at University of Visva-Bharati, Santiniketan, India 25: Now at King Abdulaziz University, Jeddah, Saudi Arabia 26: Also at University of Ruhuna, Matara, Sri Lanka 27: Also at Isfahan University of Technology, Isfahan, Iran 28: Also at University of Tehran, Department of Engineering Science, Tehran, Iran 29: Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran 30: Also at Universita degli Studi di Siena, Siena, Italy 31: Also at Purdue University, West Lafayette, USA 32: Now at Hanyang University, Seoul, Korea 33: Also at International Islamic University of Malaysia, Kuala Lumpur, Malaysia 34: Also at Malaysian Nuclear Agency, MOSTI, Kajang, Malaysia 35: Also at Consejo Nacional de Ciencia y Tecnolog a, Mexico city, Mexico 36: Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland 37: Also at Institute for Nuclear Research, Moscow, Russia 38: Now at National Research Nuclear University 'Moscow tute' (MEPhI), Moscow, Russia 39: Also at St. Petersburg State Polytechnical University, St. Petersburg, Russia 40: Also at California Institute of Technology, Pasadena, USA 41: Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia 42: Also at INFN Sezione di Roma; Universita di Roma, Roma, Italy 43: Also at National Technical University of Athens, Athens, Greece 44: Also at Scuola Normale e Sezione dell'INFN, Pisa, Italy 45: Also at National and Kapodistrian University of Athens, Athens, Greece 46: Also at Institute for Theoretical and Experimental Physics, Moscow, Russia 47: Also at Albert Einstein Center for Fundamental Physics, Bern, Switzerland 48: Also at Gaziosmanpasa University, Tokat, Turkey 49: Also at Mersin University, Mersin, Turkey 50: Also at Cag University, Mersin, Turkey 51: Also at Piri Reis University, Istanbul, Turkey 52: Also at Adiyaman University, Adiyaman, Turkey 53: Also at Ozyegin University, Istanbul, Turkey 54: Also at Izmir Institute of Technology, Izmir, Turkey 55: Also at Marmara University, Istanbul, Turkey 56: Also at Kafkas University, Kars, Turkey 57: Also at Istanbul Bilgi University, Istanbul, Turkey 58: Also at Yildiz Technical University, Istanbul, Turkey 59: Also at Hacettepe University, Ankara, Turkey Kingdom Belgrade, Serbia 60: Also at Rutherford Appleton Laboratory, Didcot, United Kingdom 61: Also at School of Physics and Astronomy, University of Southampton, Southampton, United 62: Also at Instituto de Astrof sica de Canarias, La Laguna, Spain 63: Also at Utah Valley University, Orem, USA 64: Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, 65: Also at Facolta Ingegneria, Universita di Roma, Roma, Italy 67: Also at Erzincan University, Erzincan, Turkey 68: Also at Mimar Sinan University, Istanbul, Istanbul, Turkey 69: Also at Texas A&M University at Qatar, Doha, Qatar 70: Also at Kyungpook National University, Daegu, Korea [6] N. Kidonakis , NNLL threshold resummation for top-pair and single-top production , Phys. Part. Nucl . 45 ( 2014 ) 714 [arXiv: 1210 .7813] [INSPIRE]. [7] M. Hashemi , Observability of Heavy Charged Higgs through s-channel Single Top Events at [21] M. Cacciari , G.P. Salam and G. Soyez, The anti-kt jet clustering algorithm , JHEP 04 ( 2008 ) [22] M. Cacciari , G.P. Salam and G. Soyez , The Catchment Area of Jets, JHEP 04 ( 2008 ) 005 [23] CMS collaboration, Jet Performance in pp Collisions at 7 TeV, CMS- PAS-JME- 10-003 [26] L. Breiman , J. Friedman , C.J. Stone and R.A. Olshen , Classi cation and regression trees, [27] S. Heim , Q.-H. Cao , R. Schwienhorst and C.P. Yuan , Next-to-leading order QCD corrections


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V. Khachatryan, A. M. Sirunyan, A. Tumasyan, W. Adam. Search for s channel single top quark production in pp collisions at \( \sqrt{s}=7 \) and 8 TeV, Journal of High Energy Physics, 2016, 27, DOI: 10.1007/JHEP09(2016)027