J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Published for SISSA by Springer Received: April 28, 2013 Accepted: June 14, 2013 Published: July 26, 2013 Measurement of the Λ0 b lifetime in pp collisions at√ s = 7TeV The CMS collaboration E-mail: cms-publication-committee-chair@cern.ch Abstract: A measurement of the Λ0 b lifetime using the decay Λ0 b → J/ψΛ in proton- proton collisions at √ s = 7 TeV is presented. The data set, corresponding to an integrated luminosity of about 5 fb−1, was recorded with the CMS experiment at the Large Hadron Collider using triggers that selected dimuon events in the J/ψ mass region. The Λ0 b lifetime is measured to be 1.503± 0.052 (stat.)± 0.031 (syst.) ps. Keywords: Hadron-Hadron Scattering ArXiv ePrint: 1304.7495 Open Access, Copyright CERN, for the benefit of the CMS collaboration doi:10.1007/JHEP07(2013)163 mailto:cms-publication-committee-chair@cern.ch http://arxiv.org/abs/1304.7495 http://dx.doi.org/10.1007/JHEP07(2013)163 J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Contents 1 Introduction 1 2 CMS detector 2 3 Event selection and efficiency modelling 2 4 Proper decay time fit 4 5 Results 6 6 Summary 10 The CMS collaboration 14 1 Introduction The study of b baryons is a necessary ingredient to understand b-hadron phenomenology. The heavy-quark expansion model of nonperturbative quantum chromodynamics provides a framework for predicting properties of heavy-flavour hadrons, including their lifetimes. Here, a simple description is used where the heavy b quark is surrounded by a light quark or diquark system. Estimates can be made of the lifetime and of the ratio of lifetimes be- tween particles sharing the same heavy-quark flavour [1–8]. The early calculation predicted a spread of the lifetimes of order 5% among all b hadrons [1] and the ratio of the Λ0 b and B0 lifetimes, τΛ0 b /τB0 , to be greater than 0.90 [9] (see also table 12 in the autumn 2012 on- line update at http://www.slac.stanford.edu/xorg/hfag/). The initial measurements of the b-baryon lifetime were generally lower than predicted [9], which motivated more refined calculations. This resulted in predictions as low as τΛ0 b /τB0 = 0.86 ± 0.05 [10]. An overview of the current state of the predictions and measurements can be found in ref. [9]. Measurements of the Λ0 b lifetime prior to 2011 can be found in refs. [11–27]. More recent measurements of the Λ0 b lifetime include: 1.537 ± 0.045 ± 0.014 ps from CDF [28], 1.303±0.075±0.035 ps from D0 [29], and 1.449±0.036±0.017 ps from ATLAS [30], where the first uncertainties are statistical and the second are systematic. In this paper, a measurement of τΛ0 b is presented, using the decay Λ0 b → J/ψΛ, with Λ → pπ− and J/ψ → µ+µ−. The kinematically analogous channel B0 → J/ψK0 S, with K0 S → π+π−, is used as a cross-check, with selection criteria similar to those for the Λ0 b analysis. Charge-conjugate states are assumed throughout this paper. The measurement is made using proton-proton collision data at √ s = 7 TeV recorded by the Compact Muon Solenoid (CMS) experiment operating at the Large Hadron Collider (LHC). The data set for this measurement was collected in 2011 using J/ψ-enriched dimuon triggers, and corresponds to an integrated luminosity of about 5 fb−1 [31]. – 1 – http://www.slac.stanford.edu/xorg/hfag/ J H E P 0 7 ( 2 0 1 3 ) 1 6 3 2 CMS detector The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter. The main subdetectors used for the analysis are the silicon tracker, consisting of silicon pixel and silicon strip layers, and the muon system. The tracker is immersed in a 3.8 T axial magnetic field of the superconducting solenoid. The pixel tracker consists of three barrel layers and two endcap disks at each barrel end. The strip tracker has 10 barrel layers and 12 endcap disks at each barrel end. The tracker provides an impact parameter resolution of∼15µm and a transverse momentum (pT) resolution of about 1.5% for 100 GeV particles. Charged hadrons, including pions and protons, are not explicitly identified by their type. Muons are measured in gas-ionisation detectors that are embedded in the steel return yoke outside the solenoid. In the barrel, there is a drift tube system interspersed with resistive plate chambers, and in the endcaps there is a cathode strip chamber system, also interspersed with resistive plate chambers. The first-level trigger used in this analysis is based on the muon system alone, while the high-level trigger uses additional information from the tracker. A detailed description of the CMS detector can be found in ref. [32]. The CMS experiment uses a right-handed coordinate system, with the origin at the nominal interaction point, the x axis pointing towards the centre of the LHC ring, the y axis pointing up (perpendicular to the plane of the LHC ring), and the z axis along the anticlockwise-beam direction. The polar angle θ is measured from the positive z axis and the pseudorapidity is defined by η = − ln[tan(θ/2)]. The azimuthal angle is measured from the positive x axis in the plane perpendicular to the beam. 3 Event selection and efficiency modelling Dimuon triggers optimised for selecting events with J/ψ candidates are used. The trigger requires two oppositely charged muons with an invariant mass compatible with the J/ψ- meson mass. The dimuon candidate must also be found in the central region (dimuon rapidity |yµ+µ− | < 1.25), which is the region with the best impact parameter and dimuon invariant-mass resolution. With increasing instantaneous luminosity, the trigger require- ments were adjusted several times during the data-taking period. In the course of data taking, the dimuon mass window was changed from 2.5-4.0 GeV to 2.30-3.35 GeV, while the minimum transverse momentum of the dimuon candidate was increased from 6.5 GeV to 13 GeV. Additional requirements were also added during this period: the distance of closest approach between the two muons was required to be less than 0.5 cm, the vertex-fit χ2 probability of the two muons was required to be greater than 0.5%, and the two muons were required to bend away from each other in the tracker. The four charged particles (µ+µ−pπ−) in the decay channel Λ0 b → J/ψΛ allow for a full reconstruction of the Λ0 b baryon. The selection requirements are chosen to maximise the ratio of signal yield to the square root of the signal-plus-background yield. Events with two oppositely charged muons are selected. The muons are reconstructed using information from the tracker and the muon system. The muon candidates must be within the kinematic acceptance of the detector by demanding the muon transverse momentum pµT satisfies pµT > – 2 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 3.5 GeV for muon pseudorapidity |ηµ| < 1.2, and pµT > 3.0-3.5 GeV for 1.2 < |ηµ| < 1.6, where the pµT threshold decreases linearly as a function of |ηµ|. The muon candidates are also required to have a track χ2 per degree of freedom less than 1.8, at least 11 tracker hits, at least two hits in the pixel system, a match to at least one track segment in the muon system, and a transverse (longitudinal) impact parameter less than 3 cm (30 cm) with respect to the primary event vertex. The preliminary choice for the primary vertex is the one with the highest sum of the squares of pT of the tracks associated with it. The two muons are then used to form a J/ψ candidate. A Λ candidate is formed using oppositely charged tracks with the proton candidate required to have pT>1.8 GeV and the pion candidate pT>0.46 GeV. The higher-momentum track is taken as the proton. Kinematic vertex fits are used to identify the Λ0 b candidates [33]. An initial uncon- strained fit is used to measure three selection parameters. First, the proton-pion invariant mass (mpπ−) is found from the Λ candidate tracks and is required to be within 6 MeV of the world-average Λ mass [34]. The Λ candidates are rejected if the dipion invariant mass mπ+π− is within 10 MeV of the K0 S mass [34], when the proton candidate is assigned a pion mass. Then, the dimuon invariant mass (mµ+µ−) is determined from an unconstrained fit to the J/ψ candidate tracks and is required to be within 300 MeV of its world-average value [34]. Finally, a pointing angle is measured for the Λ candidate, which is defined as the angle between the momentum of the reconstructed Λ particle and the vector between its production and decay vertices. The pointing angle is required to be less than 0.015 rad. To determine the proper decay time t of a Λ0 b candidate, another kinematic vertex fit is performed where the two muon tracks and the Λ candidate are constrained to come from a common vertex, with the Λ and J/ψ candidate masses constrained to their respective nominal values [34]. The Λ vertex-fit χ2 probability must be greater than 10%. The separation between the Λ vertex and the eventual primary vertex (as defined below) must be larger than 10σ, where σ is the calculated uncertainty in the relative position. In addition, the Λ vertex must be at least 3 cm away from the mean pp collision position in the transverse plane. Multiple pp interactions per bunch crossing are present in the data. The reconstructed event vertex with the smallest impact parameter in the z direction to the Λ0 b candidate trajectory is selected as the primary production vertex. The position of the primary vertex is recalculated excluding the tracks from the Λ0 b decay if they were used for the initial primary-vertex reconstruction. The proper decay time t is found for each Λ0 b candidate by calculating the ratio of the decay length and the momentum of the Λ0 b, divided by the world-average Λ0 b mass [34]. As a cross-check, the B0 lifetime, τB0 , is determined using the B0 → J/ψK0 S channel. A completely analogous procedure is followed to find the B0 candidates, replacing the proton-track hypothesis with a pion-track hypothesis and fitting for a K0 S candidate instead of a Λ candidate. The K0 S candidates are formed assuming both tracks are pions (the higher-momentum one is required to have pT>1.8 GeV, the lower-momentum one to have pT>0.5 GeV), with mπ+π− within 12 MeV of the world-average value [34]. A candidate is vetoed if replacing the pion-mass hypothesis by the proton mass yields an invariant – 3 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 mass mpπ− within 10 MeV of the Λ mass [34]. The pointing angle and other kinematic requirements are the same as those for the Λ0 b selection. Simulated event samples are used to model the signal and background distributions. The pythia 6.422 [35] event generator is used, with the Λ0 b lifetime fixed to 1.425 ps [34] and the b-hadron decays described by the evtgen 9.1 simulation package [36]. The particle propagation and detector simulation is performed using Geant4 9.4 [37], and the events are fully reconstructed with the same software as the data. The differences between the reconstructed and generated values for the proper decay time, the flight length, and the candidate Λ0 b momentum are found to be compatible with zero in the simulated sample. The sideband-subtracted data distributions in each of the selection variables are compared to those in simulated data and found to be consistent within their uncertainties. The overall reconstruction and selection efficiency as a function of the proper decay time t is determined from the simulated signal samples by calculating the ratio of the numbers of reconstructed and generated Λ0 b (B0) candidates in bins of proper decay time. Figure 1 displays the ratio of the reconstruction and selection efficiencies measured from simulation to the overall average efficiency, as a function of the proper decay time for the B0 (top) and Λ0 b (bottom). The efficiencies are consistent with being independent of the proper decay time, as shown by the solid horizontal line in each plot. The Λ0 b efficiency depends on various kinematic variables such as the Λ0 b transverse momentum. Therefore, a comprehensive comparison of the distributions of these variables between the data and the Monte Carlo simulation was performed, and in all cases the distributions were found to be consistent. 4 Proper decay time fit Unbinned extended maximum-likelihood fits are performed to determine the Λ0 b and B0 lifetimes. The input variables are the invariant mass m, proper decay time t, and its uncertainty σt, calculated per candidate from the kinematic vertex fit using full error propagation. The likelihood fit is implemented using the RooFit 3.53 package [38]. The likelihood function (ignoring the normalisation terms for simplicity) is L = ∏ i [ Nsig ·G2(mi;msig, σm1 , σm2 , f) · e−t/τsig ⊗G(ti;µ, S · σt,i) +Nprompt · P (mi; a) ·G(ti;µ, S · σt,i) +Nnonprompt · P (mi; a) · e−t/τnonprompt ⊗G(ti;µ, S · σt,i) ] , (4.1) where the index i goes over the events, Nsig is the number of signal events, Nprompt is the number of prompt background events not coming from b-hadron decays, and Nnonprompt is the corresponding number of nonprompt background events coming from b-hadron decays. The prompt background is dominated by J/ψ mesons directly produced in the pp collision, while the nonprompt background is dominated by J/ψ mesons from decays of b hadrons. In both cases, the J/ψ mesons are combined with real or misidentified Λ candidates from the event. The parameters τsig and τnonprompt denote the lifetime of the signal and of nonprompt background, respectively. In eq. (4.1), the G2 function is the sum of two Gaussians with – 4 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 ) [ps]0t(B 0 2 4 6 8 10 av er ag e ef fic ie nc y ef fic ie nc y 0.8 1 1.2 Simulated efficiency Average efficiency Line with slope + turn-on curve CMS simulation = 7 TeVs t < 10 ps ) [ps]0t(B 0 0.2 0.4 0.6 0.8 1 av er ag e ef fic ie nc y ef fic ie nc y 0.9 1 1.1 1.2 t < 1 ps Simulated efficiency Average efficiency Line with slope + turn-on curve CMS simulation = 7 TeVs ) [ps]bΛt( 0 2 4 6 8 10 av er ag e ef fic ie nc y ef fic ie nc y 0.6 0.8 1 1.2 1.4 Simulated efficiency Average efficiency Line with slope + turn-on curve CMS simulation = 7 TeVs t < 10 ps ) [ps]bΛt( 0 0.2 0.4 0.6 0.8 1 av er ag e ef fic ie nc y ef fic ie nc y 0.6 0.8 1 1.2 1.4 t < 1 ps Simulated efficiency Average efficiency Line with slope + turn-on curve CMS simulation = 7 TeVs Figure 1. The ratio of the reconstruction and selection efficiencies to the overall average efficiency as a function of proper decay time for B0 (upper two plots) and Λ0 b (lower two plots). The second and fourth plots show the B0 and Λ0 b efficiency ratios, respectively, for smaller proper decay times t < 1 ps. The horizontal solid lines show a ratio of 1, while the dashed lines display the results from fitting the efficiencies to the function given by eq. (5.1). a common mean msig and widths σm1 and σm2 , and the parameter f denotes the relative fraction of the area of the two Gaussians. The function G refers to a single Gaussian – 5 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Hadron Nsig m (MeV) τ (ps) Λ0 b 1013± 40 5619.7± 0.5 1.503± 0.052 B0 6772± 87 5278.9± 0.2 1.526± 0.019 Table 1. Summary of the fit results for Λ0 b and B0 with their statistical uncertainties. describing the detector lifetime resolution, with a mean µ and a width S · σt,i, where S is a scale factor determined from the fit. This resolution function is common to all three likelihood components since the σt distributions do not differ significantly. The effect of using this simplifying assumption on σt is evaluated as a systematic uncertainty and found to be negligible. For the background components, the invariant-mass m distribution is parameterised by a normalised first-degree polynomial of slope a, P (m; a). The prompt and nonprompt backgrounds share the same slope. The maximum-likelihood fit to the data is performed allowing all parameters to vary. 5 Results Projections of the invariant-mass and proper decay time distributions and the results of the fits for the B0 and Λ0 b are shown in the upper panels of figures 2 and 3, respectively. The lower panels in each figure give the proper decay time projections and fit results for low-mass sideband (left), signal (center), and high-mass sideband (right) regions of the invariant-mass distribution. The signal region is defined to be within 2σ of the mass peak, where σ is the mass resolution obtained by integrating the double-Gaussian signal function with its parameter values determined from the fit. The low-mass sideband region goes from 5.15 (5.4) GeV to within 3σ below the peak, and the high-mass sideband region runs from 3σ above the peak to 5.75 (6.0) GeV for the B0 (Λ0 b). The lower plot in each panel of figures 2 and 3 displays the pull distribution for the corresponding data and fit results shown in the upper plot. The results from the fits are summarised in table 1, where the uncertainties are statisti- cal only. The measured B0 lifetime shown in the table is consistent with the world-average value of 1.519 ± 0.007 ps [34]. The mass values for both Λ0 b and B0 given in the table compare well with the world-average values [34]. The fitting procedure is validated by studying simulated pseudo-experiments in which the proper decay time distributions are generated using different lifetime values. The resulting lifetime measurements found from the fit are compatible with being unbiased, and the width of the pull distribution, (measured value−input value)/uncertainty, is consistent with 1.0. Sources of systematic uncertainty are detector alignment, efficiency as a function of proper decay time, event selection, and fit model. To estimate possible effects due to uncertainties in the alignment, nine different simulated samples with distorted geometries are produced and analysed [39]. The lifetime difference between the nominal result and the sample that produces the largest deviation (scaled to the estimated residual misalignment present in the detector) is taken as the systematic uncertainty from this source. – 6 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 [GeV]sKψInvariant mass J/ 5.2 5.3 5.4 5.5 5.6 5.7 Ev en ts / ( 0 .0 06 G eV ) 200 400 600 800 1000 1200 1400 0B CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background [GeV] s KψInvariant mass J/ 5.2 5.3 5.4 5.5 5.6 5.7 σ)/ fit -n ob s (n -2 -1 0 1 2 3 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 Ev en ts / ( 0 .1 6 ps ) 1 10 210 310 0B CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ)/ fit -n ob s (n -4 -3 -2 -1 0 1 2 3 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 E ve nt s / ( 0 .1 6 ps ) 1 10 210 310 LSB0B CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ )/ fit -n ob s (n -4 -2 0 2 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 E ve nt s / ( 0 .1 6 ps ) 1 10 210 310 SR0B CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ )/ fit -n ob s (n -2 0 2 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 E ve nt s / ( 0 .1 6 ps ) 1 10 210 310 HSB0B CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ )/ fit -n ob s (n -6 -4 -2 0 2 4 Figure 2. Projections of the invariant-mass and proper decay time distributions and the results of the fit are shown for the B0 decay in the upper panels. The dark solid lines give the results of the overall fit to the data. The lighter solid lines are the signal contributions, and the dashed and dotted lines show the prompt and nonprompt background contributions, respectively. The lower panels display the proper decay time projections for the low-mass sideband (LSB, left), the signal (SR), and the high-mass sideband (HSB, right) regions defined in the text. The lower plots in each panel give the corresponding pull distributions for the data and fit results shown. All plots are from the same fit. Since the overall efficiency, determined through simulation, is consistent with being independent of the proper decay time, as shown in figure 1, no efficiency correction is used – 7 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 [GeV]ΛψInvariant mass J/ 5.4 5.5 5.6 5.7 5.8 5.9 6 Ev en ts / ( 0 .0 06 G eV ) 50 100 150 200 250 bΛ CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background [GeV]ΛψInvariant mass J/ 5.4 5.5 5.6 5.7 5.8 5.9 6 σ)/ fit -n ob s (n -2 -1 0 1 2 3 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 Ev en ts / ( 0 .1 6 ps ) 1 10 210 310 bΛ CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ)/ fit -n ob s (n -3 -2 -1 0 1 2 3 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 E ve nt s / ( 0 .1 6 ps ) 1 10 210 310 LSBbΛ CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ )/ fit -n ob s (n -2 0 2 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 E ve nt s / ( 0 .1 6 ps ) 1 10 210 310 SRbΛ CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ )/ fit -n ob s (n -2 0 2 4 Proper decay time [ps] 0 2 4 6 8 10 12 14 E ve nt s / ( 0 .1 6 ps ) 1 10 210 310 HSBbΛ CMS -1 = 7 TeV L = 5 fbs Fit function Signal Prompt background Nonprompt background Proper decay time [ps] 0 2 4 6 8 10 12 14 σ )/ fit -n ob s (n -2 0 2 Figure 3. Projections of the invariant-mass and proper decay time distributions and the results of the fit are shown for the Λ0 b decay in the upper panels. The dark solid lines give the results of the overall fit to the data. The lighter solid lines are the signal contributions, and the dashed and dotted lines show the prompt and nonprompt background contributions, respectively. The lower panels display the proper decay time projections for the low-mass sideband (LSB, left), the signal (SR), and the high-mass sideband (HSB, right) regions defined in the text. The lower plots in each panel give the corresponding pull distributions for the data and fit results shown. All plots are from the same fit. in the lifetime result. Nevertheless, the effect of a possible proper-decay-time-dependent efficiency is included as a systematic uncertainty. To this end, the efficiency is included – 8 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Source Systematic uncertainty (ps) Alignment 0.005 Efficiency 0.030 Event selection 0.005 Fit model 0.004 Total 0.031 Table 2. Summary of the systematic uncertainties in the Λ0 b lifetime measurement. in the likelihood function in eq. (4.1) as a function of the measured proper decay time. The difference between the lifetime found using a constant efficiency (i.e. no efficiency in the likelihood) and that found using the fitted efficiency function is taken as a systematic uncertainty. The efficiency is fit to the function ε(t) = p0 · ( 1 + p1t+ p2 1 + e−t/p3 ) , (5.1) where the free parameters pi are determined from the fit. This parameterisation has the useful feature that as the parameter p2 goes to 0, the function becomes a straight line, which is consistent with the behaviour of the B0 efficiencies shown in figure 1. The results of fitting this function to the B0 and Λ0 b efficiencies are shown by the dashed lines in figure 1. To account for possible biases from the event selection criteria, a systematic uncertainty is calculated from the difference between the observed and expected values in simulated events using the full analysis chain. Simulated pseudo-experiments produced with different input parameter values and different modelling of the fit functions are used to estimate the corresponding systematic uncertainties on the lifetime measurement. Variations include: using two different lifetimes to describe the nonprompt background to control the possible presence of a second non- prompt background component, varying the prompt and nonprompt background, varying the lifetime of the nonprompt background to control possible correlation to the lifetime of the background, and using larger per-event uncertainties for the background components to control a possible mismodelling of the resolution. Extending the likelihood function in eq. (4.1) from a single detector lifetime resolution σt for all three components to individual resolutions per component showed a negligible effect. Table 2 gives the systematic uncer- tainties from the four sources and their sum in quadrature, which is taken as the overall systematic uncertainty on the Λ0 b lifetime measurement. Checks are also performed to see if any detector effect leads to a systematic deviation not covered by the ones previously discussed. This is done by dividing the data sample into parts, where each of the partitions is expected to give the same results. The checks are performed with azimuthal angle, pseudorapidity, transverse momentum, run era, muons bending away or towards each other, and number of primary interaction vertices. No statistically significant effects are seen. For the Λ0 b channel, we also remove the K0 S-mass- veto requirement on the Λ candidate and find a negligible effect on the lifetime result. – 9 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Year of publication 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 [p s] b Λτ 0.6 0.8 1.0 1.2 1.4 1.6 ,P D G 20 12 0 Bτ/ b Λτ 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 PDG 2012 average Not used in PDG 2012 average Used in PDG 2012 average CMS - this measurement Figure 4. Evolution over time of the Λ0 b lifetime measurements (left scale) [11–30] and the ratio of the measurements to the 2012 world-average B0 lifetime τB0 [34] (right scale). The values shown as open circles were not included in the Particle Data Group (PDG) 2012 average [34], displayed as the band, while those shown as filled circles were included. The result of this analysis is shown by the open square. The inner error bars represent the statistical uncertainties, and the outer error bars show the combined statistical and systematic uncertainties added in quadrature. Where needed, points have been shifted slightly along the time axis to enhance clarity. 6 Summary A measurement of the Λ0 b lifetime has been presented using the decay Λ0 b→J/ψΛ in pp collisions at √ s = 7 TeV with the CMS detector. From a data set corresponding to an inte- grated luminosity of about 5 fb−1, the Λ0 b lifetime is found to be τΛ0 b = 1.503±0.052 (stat.)± 0.031 (syst.) ps. The kinematically similar decay B0→J/ψK0 S was used as a cross-check, con- firming that no efficiency correction was needed. The Λ0 b lifetime result is in agreement with the world-average value of 1.425 ± 0.032 ps [34] and has a precision comparable to that of other recent measurements [28–30]. As illustrated in figure 4, this new result con- firms the tendency of the more recent measurements that give larger lifetimes, in better agreement with the early theoretical predictions [1, 9]. Acknowledgments We congratulate our colleagues in the CERN accelerator departments for the excellent per- formance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively 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: BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS – 10 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Ko- rea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Ar- menia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEPCenter, IPST and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (U.S.A.). Individuals have received support from the Marie-Curie programme and the Euro- pean Research Council and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Tech- nologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS programme of Foundation for Polish Science, co- financed by EU, Regional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF. Open Access. 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Chatrchyan, V. Khachatryan, A.M. Sirunyan, A. Tumasyan Institut für Hochenergiephysik der OeAW, Wien, Austria W. Adam, T. Bergauer, M. Dragicevic, J. Erö, C. Fabjan1, M. Friedl, R. Frühwirth1, V.M. Ghete, N. Hörmann, J. Hrubec, M. Jeitler1, W. Kiesenhofer, V. Knünz, M. Krammer1, I. Krätschmer, D. Liko, I. Mikulec, D. Rabady2, B. Rahbaran, C. Rohringer, H. Rohringer, R. Schöfbeck, J. Strauss, A. Taurok, W. Treberer-Treberspurg, W. Waltenberger, C.-E. Wulz1 National Centre for Particle and High Energy Physics, Minsk, Belarus V. Mossolov, N. Shumeiko, J. Suarez Gonzalez Universiteit Antwerpen, Antwerpen, Belgium S. Alderweireldt, M. Bansal, S. Bansal, T. Cornelis, E.A. De Wolf, X. Janssen, A. Knutsson, S. Luyckx, L. Mucibello, S. Ochesanu, B. Roland, R. Rougny, H. Van Haevermaet, P. Van Mechelen, N. Van Remortel, A. Van Spilbeeck Vrije Universiteit Brussel, Brussel, Belgium F. Blekman, S. Blyweert, J. D’Hondt, A. Kalogeropoulos, J. Keaveney, M. Maes, A. Olbrechts, S. Tavernier, W. Van Doninck, P. Van Mulders, G.P. Van Onsem, I. Villella Université Libre de Bruxelles, Bruxelles, Belgium B. Clerbaux, G. De Lentdecker, L. Favart, A.P.R. Gay, T. Hreus, A. Léonard, P.E. Marage, A. Mohammadi, T. Reis, T. Seva, L. Thomas, C. Vander Velde, P. Vanlaer, J. Wang Ghent University, Ghent, Belgium V. Adler, K. Beernaert, L. Benucci, A. Cimmino, S. Costantini, S. Dildick, G. Garcia, B. Klein, J. Lellouch, A. Marinov, J. Mccartin, A.A. Ocampo Rios, D. Ryckbosch, M. Sigamani, N. Strobbe, F. Thyssen, M. Tytgat, S. Walsh, E. Yazgan, N. Zaganidis Université Catholique de Louvain, Louvain-la-Neuve, Belgium S. Basegmez, C. Beluffi3, G. Bruno, R. Castello, A. Caudron, L. Ceard, C. Delaere, T. du Pree, D. Favart, L. Forthomme, A. Giammanco4, J. Hollar, V. Lemaitre, J. Liao, O. Militaru, C. Nuttens, D. Pagano, A. Pin, K. Piotrzkowski, A. Popov5, M. Selvaggi, J.M. Vizan Garcia Université de Mons, Mons, Belgium N. Beliy, T. Caebergs, E. Daubie, G.H. Hammad Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil G.A. Alves, M. Correa Martins Junior, T. Martins, M.E. Pol, M.H.G. Souza Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil W.L. Aldá Júnior, W. Carvalho, J. Chinellato6, A. Custódio, E.M. Da Costa, D. De Jesus Damiao, C. De Oliveira Martins, S. Fonseca De Souza, H. Malbouisson, – 14 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 M. Malek, D. Matos Figueiredo, L. Mundim, H. Nogima, W.L. Prado Da Silva, A. Santoro, L. Soares Jorge, A. Sznajder, E.J. Tonelli Manganote6, A. Vilela Pereira Universidade Estadual Paulista a, Universidade Federal do ABC b, São Paulo, Brazil T.S. Anjosb, C.A. Bernardesb, F.A. Diasa,7, T.R. Fernandez Perez Tomeia, E.M. Gregoresb, C. Laganaa, F. Marinhoa, P.G. Mercadanteb, S.F. Novaesa, Sandra S. Padulaa Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria V. Genchev2, P. Iaydjiev2, S. Piperov, M. Rodozov, G. Sultanov, M. Vutova University of Sofia, Sofia, Bulgaria A. Dimitrov, R. Hadjiiska, V. Kozhuharov, L. Litov, B. Pavlov, P. Petkov Institute of High Energy Physics, Beijing, China J.G. Bian, G.M. Chen, H.S. Chen, C.H. Jiang, D. Liang, S. Liang, X. Meng, J. Tao, J. Wang, X. Wang, Z. Wang, H. Xiao, M. Xu State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China C. Asawatangtrakuldee, Y. Ban, Y. Guo, W. Li, S. Liu, Y. Mao, S.J. Qian, H. Teng, D. Wang, L. Zhang, W. Zou Universidad de Los Andes, Bogota, Colombia C. Avila, C.A. Carrillo Montoya, J.P. Gomez, B. Gomez Moreno, J.C. Sanabria Technical University of Split, Split, Croatia N. Godinovic, D. Lelas, R. Plestina8, D. Polic, I. Puljak University of Split, Split, Croatia Z. Antunovic, M. Kovac Institute Rudjer Boskovic, Zagreb, Croatia V. Brigljevic, S. Duric, K. Kadija, J. Luetic, D. Mekterovic, S. Morovic, L. Tikvica University of Cyprus, Nicosia, Cyprus A. Attikis, G. Mavromanolakis, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis Charles University, Prague, Czech Republic M. Finger, M. Finger Jr. Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt Y. Assran9, A. Ellithi Kamel10, M.A. Mahmoud11, A. Mahrous12, A. Radi13,14 National Institute of Chemical Physics and Biophysics, Tallinn, Estonia M. Kadastik, M. Müntel, M. Murumaa, M. Raidal, L. Rebane, A. Tiko Department of Physics, University of Helsinki, Helsinki, Finland P. Eerola, G. Fedi, M. Voutilainen – 15 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Helsinki Institute of Physics, Helsinki, Finland J. Härkönen, V. Karimäki, R. Kinnunen, M.J. Kortelainen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, T. Mäenpää, T. Peltola, E. Tuominen, J. Tuominiemi, E. Tuovinen, L. Wendland Lappeenranta University of Technology, Lappeenranta, Finland A. Korpela, T. Tuuva DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France M. Besancon, S. Choudhury, F. Couderc, M. Dejardin, D. Denegri, B. 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Van Hove Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France S. Gadrat Université de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France S. Beauceron, N. Beaupere, G. Boudoul, S. Brochet, J. Chasserat, R. Chierici, D. Contardo, P. Depasse, H. El Mamouni, J. Fay, S. Gascon, M. Gouzevitch, B. Ille, T. Kurca, M. Lethuillier, L. Mirabito, S. Perries, L. Sgandurra, V. Sordini, Y. Tschudi, M. Vander Donckt, P. Verdier, S. Viret Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia Z. Tsamalaidze17 RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany C. Autermann, S. Beranek, B. Calpas, M. Edelhoff, L. Feld, N. Heracleous, O. Hindrichs, K. Klein, J. Merz, A. Ostapchuk, A. Perieanu, F. Raupach, J. Sammet, S. Schael, D. Sprenger, H. Weber, B. Wittmer, V. Zhukov5 – 16 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany M. Ata, J. Caudron, E. Dietz-Laursonn, D. Duchardt, M. Erdmann, R. Fischer, A. Güth, T. Hebbeker, C. Heidemann, K. Hoepfner, D. Klingebiel, P. Kreuzer, M. Merschmeyer, A. Meyer, M. Olschewski, K. Padeken, P. Papacz, H. Pieta, H. Reithler, S.A. Schmitz, L. Sonnenschein, J. Steggemann, D. Teyssier, S. Thüer, M. Weber RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany V. Cherepanov, Y. Erdogan, G. Flügge, H. Geenen, M. Geisler, W. Haj Ahmad, F. Hoehle, B. Kargoll, T. Kress, Y. Kuessel, J. Lingemann2, A. Nowack, I.M. Nugent, L. Perchalla, O. Pooth, A. Stahl Deutsches Elektronen-Synchrotron, Hamburg, Germany M. Aldaya Martin, I. Asin, N. Bartosik, J. Behr, W. Behrenhoff, U. Behrens, M. Bergholz18, A. Bethani, K. Borras, A. Burgmeier, A. Cakir, L. Calligaris, A. Campbell, F. Costanza, C. Diez Pardos, T. Dorland, G. Eckerlin, D. Eckstein, G. Flucke, A. Geiser, I. Glushkov, P. Gunnellini, S. Habib, J. Hauk, G. Hellwig, H. Jung, M. Kasemann, P. Katsas, C. Kleinwort, H. Kluge, M. Krämer, D. Krücker, E. Kuznetsova, W. Lange, J. Leonard, K. Lipka, W. Lohmann18, B. Lutz, R. Mankel, I. Marfin, I.-A. Melzer-Pellmann, A.B. Meyer, J. Mnich, A. Mussgiller, S. Naumann-Emme, O. Novgorodova, F. Nowak, J. Olzem, H. Perrey, A. Petrukhin, D. Pitzl, R. Placakyte, A. Raspereza, P.M. Ribeiro Cipriano, C. Riedl, E. Ron, J. Salfeld-Nebgen, R. Schmidt18, T. Schoerner-Sadenius, N. Sen, M. Stein, R. Walsh, C. Wissing University of Hamburg, Hamburg, Germany V. Blobel, H. Enderle, J. Erfle, U. Gebbert, M. Görner, M. Gosselink, J. Haller, K. Heine, R.S. Höing, G. Kaussen, H. Kirschenmann, R. Klanner, J. Lange, T. Peiffer, N. Pietsch, D. Rathjens, C. Sander, H. Schettler, P. Schleper, E. Schlieckau, A. Schmidt, M. Schröder, T. Schum, M. Seidel, J. Sibille19, V. Sola, H. Stadie, G. Steinbrück, J. Thomsen, D. Troendle, L. Vanelderen Institut für Experimentelle Kernphysik, Karlsruhe, Germany C. Barth, C. Baus, J. Berger, C. Böser, T. Chwalek, W. De Boer, A. Descroix, A. Dierlamm, M. Feindt, M. Guthoff2, C. Hackstein, F. Hartmann2, T. Hauth2, M. Heinrich, H. Held, K.H. Hoffmann, U. Husemann, I. Katkov5, J.R. Komaragiri, A. Kornmayer2, P. Lobelle Pardo, D. Martschei, S. Mueller, Th. Müller, M. Niegel, A. Nürnberg, O. Oberst, J. Ott, G. Quast, K. Rabbertz, F. Ratnikov, N. Ratnikova, S. Röcker, F.-P. Schilling, G. Schott, H.J. Simonis, F.M. Stober, R. Ulrich, J. Wagner-Kuhr, S. Wayand, T. Weiler, M. Zeise Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece G. Anagnostou, G. Daskalakis, T. Geralis, S. Kesisoglou, A. Kyriakis, D. Loukas, A. Markou, C. Markou, E. Ntomari University of Athens, Athens, Greece L. Gouskos, T.J. Mertzimekis, A. Panagiotou, N. Saoulidou, E. Stiliaris – 17 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 University of Ioánnina, Ioánnina, Greece X. Aslanoglou, I. Evangelou, G. Flouris, C. Foudas, P. Kokkas, N. Manthos, I. Papadopoulos, E. Paradas KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary G. Bencze, C. Hajdu, P. Hidas, D. Horvath20, B. Radics, F. Sikler, V. Veszpremi, G. Vesztergombi21, A.J. Zsigmond Institute of Nuclear Research ATOMKI, Debrecen, Hungary N. Beni, S. Czellar, J. Molnar, J. Palinkas, Z. Szillasi University of Debrecen, Debrecen, Hungary J. Karancsi, P. Raics, Z.L. Trocsanyi, B. Ujvari Panjab University, Chandigarh, India S.B. Beri, V. Bhatnagar, N. Dhingra, R. Gupta, M. Kaur, M.Z. Mehta, M. Mittal, N. Nishu, L.K. Saini, A. Sharma, J.B. Singh University of Delhi, Delhi, India Ashok Kumar, Arun Kumar, S. Ahuja, A. Bhardwaj, B.C. Choudhary, S. Malhotra, M. Naimuddin, K. Ranjan, P. Saxena, V. Sharma, R.K. Shivpuri Saha Institute of Nuclear Physics, Kolkata, India S. Banerjee, S. Bhattacharya, K. Chatterjee, S. Dutta, B. Gomber, Sa. Jain, Sh. Jain, R. Khurana, A. Modak, S. Mukherjee, D. Roy, S. Sarkar, M. Sharan Bhabha Atomic Research Centre, Mumbai, India A. Abdulsalam, D. Dutta, S. Kailas, V. Kumar, A.K. Mohanty2, L.M. Pant, P. Shukla, A. Topkar Tata Institute of Fundamental Research - EHEP, Mumbai, India T. Aziz, R.M. Chatterjee, S. Ganguly, S. Ghosh, M. Guchait22, A. Gurtu23, G. Kole, S. Kumar, M. Maity24, G. Majumder, K. Mazumdar, G.B. Mohanty, B. Parida, K. Sudhakar, N. Wickramage Tata Institute of Fundamental Research - HECR, Mumbai, India S. Banerjee, S. Dugad Institute for Research in Fundamental Sciences (IPM), Tehran, Iran H. Arfaei25, H. Bakhshiansohi, S.M. Etesami26, A. Fahim25, H. Hesari, A. Jafari, M. Khakzad, M. Mohammadi Najafabadi, S. Paktinat Mehdiabadi, B. Safarzadeh27, M. Zeinali University College Dublin, Dublin, Ireland M. Grunewald INFN Sezione di Bari a, Università di Bari b, Politecnico di Bari c, Bari, Italy M. Abbresciaa,b, L. Barbonea,b, C. Calabriaa,b, S.S. Chhibraa,b, A. Colaleoa, D. Creanzaa,c, N. De Filippisa,c,2, M. De Palmaa,b, L. Fiorea, G. Iasellia,c, G. Maggia,c, M. Maggia, – 18 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 B. Marangellia,b, S. Mya,c, S. Nuzzoa,b, N. Pacificoa, A. Pompilia,b, G. Pugliesea,c, G. Selvaggia,b, L. Silvestrisa, G. Singha,b, R. Vendittia,b, P. Verwilligena, G. Zitoa INFN Sezione di Bologna a, Università di Bologna b, Bologna, Italy G. Abbiendia, A.C. Benvenutia, D. Bonacorsia,b, S. Braibant-Giacomellia,b, L. Brigliadoria,b, R. Campaninia,b, P. Capiluppia,b, A. Castroa,b, F.R. Cavalloa, M. Cuffiania,b, G.M. Dallavallea, F. Fabbria, A. Fanfania,b, D. Fasanellaa,b, P. Giacomellia, C. Grandia, L. Guiduccia,b, S. Marcellinia, G. Masettia,2, M. Meneghellia,b, A. Montanaria, F.L. Navarriaa,b, F. Odoricia, A. Perrottaa, F. Primaveraa,b, A.M. Rossia,b, T. Rovellia,b, G.P. Sirolia,b, N. Tosia,b, R. Travaglinia,b INFN Sezione di Catania a, Università di Catania b, Catania, Italy S. Albergoa,b, M. Chiorbolia,b, S. Costaa,b, R. Potenzaa,b, A. Tricomia,b, C. Tuvea,b 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, S. Gonzia,b, V. Goria,b, P. Lenzia,b, M. Meschinia, S. Paolettia, G. Sguazzonia, A. Tropianoa,b INFN Laboratori Nazionali di Frascati, Frascati, Italy L. Benussi, S. Bianco, F. Fabbri, D. Piccolo INFN Sezione di Genova a, Università di Genova b, Genova, Italy P. Fabbricatorea, R. Musenicha, S. Tosia,b INFN Sezione di Milano-Bicocca a, Università di Milano-Bicocca b, Milano, Italy A. Benagliaa, F. De Guioa,b, L. Di Matteoa,b, S. Fiorendia,b, S. Gennaia, A. Ghezzia,b, P. Govoni, M.T. Lucchini2, S. Malvezzia, R.A. Manzonia,b,2, A. Martellia,b,2, A. Massironia,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, Università di Napoli ’Federico II’ b, Università della Basilicata (Potenza) c, Università G. Marconi (Roma) d, Napoli, Italy S. Buontempoa, N. Cavalloa,c, A. De Cosaa,b, F. Fabozzia,c, A.O.M. Iorioa,b, L. Listaa, S. Meolaa,d,2, M. Merolaa, P. Paoluccia,2 INFN Sezione di Padova a, Università di Padova b, Università di Trento (Trento) c, Padova, Italy P. Azzia, N. Bacchettaa, P. Bellana,b, M. Biasottoa,28, D. Biselloa,b, A. Brancaa,b, R. Carlina,b, P. Checchiaa, T. Dorigoa, M. Galantia,b,2, F. Gasparinia,b, U. Gasparinia,b, P. Giubilatoa,b, A. Gozzelinoa, M. Gulminia,28, K. Kanishcheva,c, S. Lacapraraa, I. Lazzizzeraa,c, M. Margonia,b, A.T. Meneguzzoa,b, J. Pazzinia,b, N. Pozzobona,b, P. Ronchesea,b, F. Simonettoa,b, E. Torassaa, M. Tosia,b, S. Vaninia,b, P. Zottoa,b, A. Zucchettaa,b, G. Zumerlea,b INFN Sezione di Pavia a, Università di Pavia b, Pavia, Italy M. Gabusia,b, S.P. Rattia,b, C. Riccardia,b, P. Vituloa,b – 19 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 INFN Sezione di Perugia a, Università di Perugia b, Perugia, Italy M. Biasinia,b, G.M. Bileia, L. Fanòa,b, P. Laricciaa,b, G. Mantovania,b, M. Menichellia, A. Nappia,b†, F. Romeoa,b, A. Sahaa, A. Santocchiaa,b, A. Spieziaa,b INFN Sezione di Pisa a, Università di Pisa b, Scuola Normale Superiore di Pisa c, Pisa, Italy K. Androsova,29, P. Azzurria, G. Bagliesia, T. Boccalia, G. Broccoloa,c, R. Castaldia, R.T. D’Agnoloa,c,2, R. Dell’Orsoa, F. Fioria,c, L. Foàa,c, A. Giassia, A. Kraana, F. Ligabuea,c, T. Lomtadzea, L. Martinia,29, A. Messineoa,b, F. Pallaa, A. Rizzia,b, A.T. Serbana, P. Spagnoloa, P. Squillaciotia, R. Tenchinia, G. Tonellia,b, A. Venturia, P.G. Verdinia, C. Vernieria,c INFN Sezione di Roma a, Università di Roma b, Roma, Italy L. Baronea,b, F. Cavallaria, D. Del Rea,b, M. Diemoza, C. Fanellia,b, M. Grassia,b,2, E. Longoa,b, F. Margarolia,b, P. Meridiania, F. Michelia,b, S. Nourbakhsha,b, G. Organtinia,b, R. Paramattia, S. Rahatloua,b, L. Soffia,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, N. Cartigliaa, S. Casassoa,b, M. Costaa,b, D. Dattolaa, N. Demariaa, C. Mariottia, S. Masellia, E. Migliorea,b, V. Monacoa,b, M. Musicha, M.M. Obertinoa,c, N. Pastronea, M. Pelliccionia,2, A. Potenzaa,b, A. Romeroa,b, M. Ruspaa,c, R. Sacchia,b, A. Solanoa,b, A. Staianoa, U. Tamponia INFN Sezione di Trieste a, Università di Trieste b, Trieste, Italy S. Belfortea, V. Candelisea,b, M. Casarsaa, F. Cossuttia,2, G. Della Riccaa,b, B. Gobboa, C. La Licataa,b, M. Maronea,b, D. Montaninoa,b, A. Penzoa, A. Schizzia,b, A. Zanettia Kangwon National University, Chunchon, Korea T.Y. Kim, S.K. Nam Kyungpook National University, Daegu, Korea S. Chang, D.H. Kim, G.N. Kim, J.E. Kim, D.J. Kong, Y.D. Oh, H. Park, D.C. Son Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Korea J.Y. Kim, Zero J. Kim, S. Song Korea University, Seoul, Korea S. Choi, D. Gyun, B. Hong, M. Jo, H. Kim, T.J. Kim, K.S. Lee, S.K. Park, Y. Roh University of Seoul, Seoul, Korea M. Choi, J.H. Kim, C. Park, I.C. Park, S. Park, G. Ryu Sungkyunkwan University, Suwon, Korea Y. Choi, Y.K. Choi, J. Goh, M.S. Kim, E. Kwon, B. Lee, J. Lee, S. Lee, H. Seo, I. Yu – 20 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Vilnius University, Vilnius, Lithuania I. Grigelionis, A. Juodagalvis Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-de La Cruz30, R. Lopez-Fernandez, J. Mart́ınez-Ortega, A. Sanchez-Hernandez, 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 D. Krofcheck University of Canterbury, Christchurch, New Zealand A.J. Bell, P.H. Butler, R. Doesburg, S. Reucroft, H. Silverwood National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan M. Ahmad, M.I. Asghar, J. Butt, H.R. Hoorani, S. Khalid, W.A. Khan, T. Khurshid, S. Qazi, M.A. Shah, M. Shoaib National Centre for Nuclear Research, Swierk, Poland H. Bialkowska, B. Boimska, T. Frueboes, M. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, G. Wrochna, P. Zalewski Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland G. Brona, K. Bunkowski, M. Cwiok, W. Dominik, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski, M. Misiura, W. Wolszczak Laboratório de Instrumentação e F́ısica Experimental de Part́ıculas, Lisboa, Portugal N. Almeida, P. Bargassa, A. David, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, J. Rodrigues Antunes, J. Seixas2, J. Varela, P. Vischia Joint Institute for Nuclear Research, Dubna, Russia S. Afanasiev, P. Bunin, M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin, V. Konoplyanikov, A. Lanev, A. Malakhov, V. Matveev, P. Moisenz, V. Palichik, V. Perelygin, S. Shmatov, N. Skatchkov, V. Smirnov, A. Zarubin Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia S. Evstyukhin, V. Golovtsov, Y. Ivanov, V. Kim, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev, An. Vorobyev – 21 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Institute for Nuclear Research, Moscow, Russia Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, M. Kirsanov, N. Krasnikov, A. Pashenkov, D. Tlisov, A. Toropin Institute for Theoretical and Experimental Physics, Moscow, Russia V. Epshteyn, M. Erofeeva, V. Gavrilov, N. Lychkovskaya, V. Popov, G. Safronov, S. Semenov, A. Spiridonov, V. Stolin, E. Vlasov, A. Zhokin P.N. Lebedev Physical Institute, Moscow, Russia V. Andreev, M. Azarkin, I. Dremin, M. Kirakosyan, A. Leonidov, G. Mesyats, S.V. Rusakov, A. Vinogradov Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia A. Belyaev, E. Boos, M. Dubinin7, L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova, I. Lokhtin, A. Markina, S. Obraztsov, S. Petrushanko, V. Savrin, A. Snigirev State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia 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, A. Uzunian, A. Volkov University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia P. Adzic31, M. Ekmedzic, D. Krpic31, J. Milosevic Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain M. Aguilar-Benitez, J. Alcaraz Maestre, C. Battilana, E. Calvo, M. Cerrada, M. Chamizo Llatas2, N. Colino, B. De La Cruz, A. Delgado Peris, D. Domı́nguez Vázquez, C. Fernandez Bedoya, J.P. Fernández Ramos, A. Ferrando, J. Flix, M.C. Fouz, P. Garcia-Abia, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, G. Merino, E. Navarro De Martino, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, J. Santaolalla, M.S. Soares, C. Willmott Universidad Autónoma de Madrid, Madrid, Spain C. Albajar, J.F. de Trocóniz Universidad de Oviedo, Oviedo, Spain H. Brun, J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, L. Lloret Iglesias, J. Piedra Gomez Instituto de F́ısica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain J.A. Brochero Cifuentes, I.J. Cabrillo, A. Calderon, S.H. Chuang, J. Duarte Campderros, M. Fernandez, G. Gomez, J. Gonzalez Sanchez, A. Graziano, C. Jorda, A. Lopez Virto, – 22 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 J. Marco, R. Marco, C. Martinez Rivero, F. Matorras, F.J. Munoz Sanchez, T. Rodrigo, A.Y. Rodŕıguez-Marrero, A. Ruiz-Jimeno, L. Scodellaro, I. Vila, R. Vilar Cortabitarte CERN, European Organization for Nuclear Research, Geneva, Switzerland D. Abbaneo, E. Auffray, G. Auzinger, M. Bachtis, P. Baillon, A.H. Ball, D. Barney, J. Bendavid, J.F. Benitez, C. Bernet8, G. Bianchi, P. Bloch, A. Bocci, A. Bonato, O. Bondu, C. Botta, H. Breuker, T. Camporesi, G. Cerminara, T. Christiansen, J.A. Coarasa Perez, S. Colafranceschi32, D. d’Enterria, A. Dabrowski, A. De Roeck, S. De Visscher, S. Di Guida, M. Dobson, N. Dupont-Sagorin, A. Elliott-Peisert, J. Eugster, W. Funk, G. Georgiou, M. Giffels, D. Gigi, K. Gill, D. Giordano, M. Girone, M. Giunta, F. Glege, R. Gomez-Reino Garrido, S. Gowdy, R. Guida, J. Hammer, M. Hansen, P. Harris, C. Hartl, B. Hegner, A. Hinzmann, V. Innocente, P. Janot, E. Karavakis, K. Kousouris, K. Krajczar, P. Lecoq, Y.-J. Lee, C. Lourenço, N. Magini, M. Malberti, L. Malgeri, M. Mannelli, L. Masetti, F. Meijers, S. Mersi, E. Meschi, R. Moser, M. Mulders, P. Musella, E. Nesvold, L. Orsini, E. Palencia Cortezon, E. Perez, L. Perrozzi, A. Petrilli, A. Pfeiffer, M. Pierini, M. Pimiä, D. Piparo, G. Polese, L. Quertenmont, A. Racz, W. Reece, G. Rolandi33, C. Rovelli34, M. Rovere, H. Sakulin, F. Santanastasio, C. Schäfer, C. Schwick, I. Segoni, S. Sekmen, A. Sharma, P. Siegrist, P. Silva, M. Simon, P. Sphicas35, D. Spiga, M. Stoye, A. Tsirou, G.I. Veres21, J.R. Vlimant, H.K. Wöhri, S.D. Worm36, 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 Institute for Particle Physics, ETH Zurich, Zurich, Switzerland F. Bachmair, L. Bäni, P. Bortignon, M.A. Buchmann, B. Casal, N. Chanon, A. Deisher, G. Dissertori, M. Dittmar, M. Donegà, M. Dünser, P. Eller, K. Freudenreich, C. Grab, D. Hits, P. Lecomte, W. Lustermann, A.C. Marini, P. Martinez Ruiz del Arbol, N. Mohr, F. Moortgat, C. Nägeli37, P. Nef, F. Nessi-Tedaldi, F. Pandolfi, L. Pape, F. Pauss, M. Peruzzi, F.J. Ronga, M. Rossini, L. Sala, A.K. Sanchez, A. Starodumov38, B. Stieger, M. Takahashi, L. Tauscher†, A. Thea, K. Theofilatos, D. Treille, C. Urscheler, R. Wallny, H.A. Weber Universität Zürich, Zurich, Switzerland C. Amsler39, V. Chiochia, C. Favaro, M. Ivova Rikova, B. Kilminster, B. Millan Mejias, P. Otiougova, P. Robmann, H. Snoek, S. Taroni, S. Tupputi, M. Verzetti National Central University, Chung-Li, Taiwan M. Cardaci, K.H. Chen, C. Ferro, C.M. Kuo, S.W. Li, W. Lin, Y.J. Lu, R. Volpe, S.S. Yu National Taiwan University (NTU), Taipei, Taiwan P. Bartalini, P. Chang, Y.H. Chang, Y.W. Chang, Y. Chao, K.F. Chen, C. Dietz, U. Grundler, W.-S. Hou, Y. Hsiung, K.Y. Kao, Y.J. Lei, R.-S. Lu, D. Majumder, E. Petrakou, X. Shi, J.G. Shiu, Y.M. Tzeng, M. Wang Chulalongkorn University, Bangkok, Thailand B. Asavapibhop, N. Suwonjandee – 23 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Cukurova University, Adana, Turkey A. Adiguzel, M.N. Bakirci40, S. Cerci41, C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut, E. Gurpinar, I. Hos, E.E. Kangal, A. Kayis Topaksu, G. Onengut, K. Ozdemir, S. Ozturk42, A. Polatoz, K. Sogut43, D. Sunar Cerci41, B. Tali41, H. Topakli40, M. Vergili Middle East Technical University, Physics Department, Ankara, Turkey I.V. Akin, T. Aliev, B. Bilin, S. Bilmis, M. Deniz, H. Gamsizkan, A.M. Guler, G. Karapinar44, K. Ocalan, A. Ozpineci, M. Serin, R. Sever, U.E. Surat, M. Yalvac, M. Zeyrek Bogazici University, Istanbul, Turkey E. Gülmez, B. Isildak45, M. Kaya46, O. Kaya46, S. Ozkorucuklu47, N. Sonmez48 Istanbul Technical University, Istanbul, Turkey H. Bahtiyar49, E. Barlas, K. Cankocak, Y.O. Günaydin50, F.I. Vardarlı, M. Yücel National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine L. Levchuk, P. Sorokin University of Bristol, Bristol, United Kingdom J.J. Brooke, E. Clement, D. Cussans, H. Flacher, R. Frazier, J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath, L. Kreczko, S. Metson, D.M. Newbold36, K. Nirunpong, A. Poll, S. Senkin, V.J. Smith, T. Williams Rutherford Appleton Laboratory, Didcot, United Kingdom L. Basso51, K.W. Bell, A. Belyaev51, C. Brew, R.M. Brown, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, J. Jackson, E. Olaiya, D. Petyt, B.C. Radburn-Smith, C.H. Shepherd-Themistocleous, I.R. Tomalin, W.J. Womersley Imperial College, London, United Kingdom R. Bainbridge, O. Buchmuller, D. Burton, D. Colling, N. Cripps, M. Cutajar, P. Dauncey, G. Davies, M. Della Negra, W. Ferguson, J. Fulcher, D. Futyan, A. Gilbert, A. Guneratne Bryer, G. Hall, Z. Hatherell, J. Hays, G. Iles, M. Jarvis, G. Karapostoli, M. Kenzie, R. Lane, R. Lucas36, L. Lyons, A.-M. Magnan, J. Marrouche, B. Mathias, R. Nandi, J. Nash, A. Nikitenko38, J. Pela, M. Pesaresi, K. Petridis, M. Pioppi52, D.M. Raymond, S. Rogerson, A. Rose, C. Seez, P. Sharp†, A. Sparrow, A. Tapper, M. Vazquez Acosta, T. Virdee, S. Wakefield, N. Wardle, T. Whyntie Brunel University, Uxbridge, United Kingdom M. Chadwick, J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, D. Leggat, D. Leslie, W. Martin, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner Baylor University, Waco, U.S.A. J. Dittmann, K. Hatakeyama, A. Kasmi, H. Liu, T. Scarborough The University of Alabama, Tuscaloosa, U.S.A. O. Charaf, S.I. Cooper, C. Henderson, P. Rumerio – 24 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Boston University, Boston, U.S.A. A. Avetisyan, T. Bose, C. Fantasia, A. Heister, P. Lawson, D. Lazic, J. Rohlf, D. Sperka, J. St. John, L. Sulak Brown University, Providence, U.S.A. J. Alimena, S. Bhattacharya, G. Christopher, D. Cutts, Z. Demiragli, A. Ferapontov, A. Garabedian, U. Heintz, G. Kukartsev, E. Laird, G. Landsberg, M. Luk, M. Narain, M. Segala, T. Sinthuprasith, T. Speer University of California, Davis, Davis, U.S.A. R. Breedon, G. Breto, M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher, M. Gardner, R. Houtz, W. Ko, A. Kopecky, R. Lander, O. Mall, T. Miceli, R. Nelson, D. Pellett, F. Ricci-Tam, B. Rutherford, M. Searle, J. Smith, M. Squires, M. Tripathi, S. Wilbur, R. Yohay University of California, Los Angeles, U.S.A. V. Andreev, D. Cline, R. Cousins, S. Erhan, P. Everaerts, C. Farrell, M. Felcini, J. Hauser, M. Ignatenko, C. Jarvis, G. Rakness, P. Schlein†, E. Takasugi, P. Traczyk, V. Valuev, M. Weber University of California, Riverside, Riverside, U.S.A. J. Babb, R. Clare, M.E. Dinardo, J. Ellison, J.W. Gary, F. Giordano2, G. Hanson, H. Liu, O.R. Long, A. Luthra, H. Nguyen, S. Paramesvaran, J. Sturdy, S. Sumowidagdo, R. Wilken, S. Wimpenny University of California, San Diego, La Jolla, U.S.A. W. Andrews, J.G. Branson, G.B. Cerati, S. Cittolin, D. Evans, A. Holzner, R. Kelley, M. Lebourgeois, J. Letts, I. Macneill, B. Mangano, S. Padhi, C. Palmer, G. Petrucciani, M. Pieri, M. Sani, V. Sharma, S. Simon, E. Sudano, M. Tadel, Y. Tu, A. Vartak, S. Wasserbaech53, F. Würthwein, A. Yagil, J. Yoo University of California, Santa Barbara, Santa Barbara, U.S.A. D. Barge, R. Bellan, C. Campagnari, M. D’Alfonso, T. Danielson, K. Flowers, P. Geffert, C. George, F. Golf, J. Incandela, C. Justus, P. Kalavase, D. Kovalskyi, V. Krutelyov, S. Lowette, R. Magaña Villalba, N. Mccoll, V. Pavlunin, J. Ribnik, J. Richman, R. Rossin, D. Stuart, W. To, C. West California Institute of Technology, Pasadena, U.S.A. A. Apresyan, A. Bornheim, J. Bunn, Y. Chen, E. Di Marco, J. Duarte, D. Kcira, Y. Ma, A. Mott, H.B. Newman, C. Rogan, M. Spiropulu, V. Timciuc, J. Veverka, R. Wilkinson, S. Xie, Y. Yang, R.Y. Zhu Carnegie Mellon University, Pittsburgh, U.S.A. V. Azzolini, A. Calamba, R. Carroll, T. Ferguson, Y. Iiyama, D.W. Jang, Y.F. Liu, M. Paulini, J. Russ, H. Vogel, I. Vorobiev – 25 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 University of Colorado at Boulder, Boulder, U.S.A. J.P. Cumalat, B.R. Drell, W.T. Ford, A. Gaz, E. Luiggi Lopez, U. Nauenberg, J.G. Smith, K. Stenson, K.A. Ulmer, S.R. Wagner Cornell University, Ithaca, U.S.A. J. Alexander, A. Chatterjee, N. Eggert, L.K. Gibbons, W. Hopkins, A. Khukhunaishvili, B. Kreis, N. Mirman, G. Nicolas Kaufman, J.R. Patterson, A. Ryd, E. Salvati, W. Sun, W.D. Teo, J. Thom, J. Thompson, J. Tucker, Y. Weng, L. Winstrom, P. Wittich Fairfield University, Fairfield, U.S.A. D. Winn Fermi National Accelerator Laboratory, Batavia, U.S.A. S. Abdullin, M. Albrow, J. Anderson, G. Apollinari, L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, K. Burkett, J.N. Butler, V. Chetluru, H.W.K. Cheung, F. Chlebana, S. Cihangir, V.D. Elvira, I. Fisk, J. Freeman, Y. Gao, E. Gottschalk, L. Gray, D. Green, O. Gutsche, R.M. Harris, J. Hirschauer, B. Hooberman, S. Jindariani, M. Johnson, U. Joshi, B. Klima, S. Kunori, S. Kwan, J. Linacre, D. Lincoln, R. Lipton, J. Lykken, K. Maeshima, J.M. Marraffino, V.I. Martinez Outschoorn, S. Maruyama, D. Mason, P. McBride, K. Mishra, S. Mrenna, Y. Musienko54, C. Newman-Holmes, V. O’Dell, O. Prokofyev, E. Sexton-Kennedy, S. Sharma, W.J. Spalding, L. Spiegel, L. Taylor, S. Tkaczyk, N.V. Tran, L. Uplegger, E.W. Vaandering, R. Vidal, J. Whitmore, W. Wu, F. Yang, J.C. Yun University of Florida, Gainesville, U.S.A. D. Acosta, P. Avery, D. Bourilkov, M. Chen, T. Cheng, S. Das, M. De Gruttola, G.P. Di Giovanni, D. Dobur, A. Drozdetskiy, R.D. Field, M. Fisher, Y. Fu, I.K. Furic, J. Hugon, B. Kim, J. Konigsberg, A. Korytov, A. Kropivnitskaya, T. Kypreos, J.F. Low, K. Matchev, P. Milenovic55, G. Mitselmakher, L. Muniz, R. Remington, A. Rinkevicius, N. Skhirtladze, M. Snowball, J. Yelton, M. Zakaria Florida International University, Miami, U.S.A. V. Gaultney, S. Hewamanage, L.M. Lebolo, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez Florida State University, Tallahassee, U.S.A. T. Adams, A. Askew, J. Bochenek, J. Chen, B. Diamond, S.V. Gleyzer, J. Haas, S. Hagopian, V. Hagopian, K.F. Johnson, H. Prosper, V. Veeraraghavan, M. Weinberg Florida Institute of Technology, Melbourne, U.S.A. M.M. Baarmand, B. Dorney, M. Hohlmann, H. Kalakhety, F. Yumiceva University of Illinois at Chicago (UIC), Chicago, U.S.A. M.R. Adams, L. Apanasevich, V.E. Bazterra, R.R. Betts, I. Bucinskaite, J. Callner, R. Cavanaugh, O. Evdokimov, L. Gauthier, C.E. Gerber, D.J. Hofman, S. Khalatyan, P. Kurt, F. Lacroix, D.H. Moon, C. O’Brien, C. Silkworth, D. Strom, P. Turner, N. Varelas – 26 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 The University of Iowa, Iowa City, U.S.A. U. Akgun, E.A. Albayrak, B. Bilki56, W. Clarida, K. Dilsiz, F. Duru, S. Griffiths, J.-P. Merlo, H. Mermerkaya57, A. Mestvirishvili, A. Moeller, J. Nachtman, C.R. Newsom, H. Ogul, Y. Onel, F. Ozok49, S. Sen, P. Tan, E. Tiras, J. Wetzel, T. Yetkin58, K. Yi Johns Hopkins University, Baltimore, U.S.A. B.A. Barnett, B. Blumenfeld, S. Bolognesi, D. Fehling, G. Giurgiu, A.V. Gritsan, G. Hu, P. Maksimovic, M. Swartz, A. Whitbeck The University of Kansas, Lawrence, U.S.A. P. Baringer, A. Bean, G. Benelli, R.P. Kenny III, M. Murray, D. Noonan, S. Sanders, R. Stringer, J.S. Wood Kansas State University, Manhattan, U.S.A. A.F. Barfuss, I. Chakaberia, A. Ivanov, S. Khalil, M. Makouski, Y. Maravin, S. Shrestha, I. Svintradze Lawrence Livermore National Laboratory, Livermore, U.S.A. J. Gronberg, D. Lange, F. Rebassoo, D. Wright University of Maryland, College Park, U.S.A. A. Baden, B. Calvert, S.C. Eno, J.A. Gomez, N.J. Hadley, R.G. Kellogg, T. Kolberg, Y. Lu, M. Marionneau, A.C. Mignerey, K. Pedro, A. Peterman, A. Skuja, J. Temple, M.B. Tonjes, S.C. Tonwar Massachusetts Institute of Technology, Cambridge, U.S.A. A. Apyan, G. Bauer, W. Busza, E. Butz, I.A. Cali, M. Chan, V. Dutta, G. Gomez Ceballos, M. Goncharov, Y. Kim, M. Klute, Y.S. Lai, A. Levin, P.D. Luckey, T. Ma, S. Nahn, C. Paus, D. Ralph, C. Roland, G. Roland, G.S.F. Stephans, F. Stöckli, K. Sumorok, K. Sung, D. Velicanu, R. Wolf, B. Wyslouch, M. Yang, Y. Yilmaz, A.S. Yoon, M. Zanetti, V. Zhukova University of Minnesota, Minneapolis, U.S.A. B. Dahmes, A. De Benedetti, G. Franzoni, A. Gude, J. Haupt, S.C. Kao, K. Klapoetke, Y. Kubota, J. Mans, N. Pastika, R. Rusack, M. Sasseville, A. Singovsky, N. Tambe, J. Turkewitz University of Mississippi, Oxford, U.S.A. L.M. Cremaldi, R. Kroeger, L. Perera, R. Rahmat, D.A. Sanders, D. Summers University of Nebraska-Lincoln, Lincoln, U.S.A. E. Avdeeva, K. Bloom, S. Bose, D.R. Claes, A. Dominguez, M. Eads, R. Gonzalez Suarez, J. Keller, I. Kravchenko, J. Lazo-Flores, S. Malik, G.R. Snow State University of New York at Buffalo, Buffalo, U.S.A. J. Dolen, A. Godshalk, I. Iashvili, S. Jain, A. Kharchilava, A. Kumar, S. Rappoccio, Z. Wan – 27 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 Northeastern University, Boston, U.S.A. G. Alverson, E. Barberis, D. Baumgartel, M. Chasco, J. Haley, D. Nash, T. Orimoto, D. Trocino, D. Wood, J. Zhang Northwestern University, Evanston, U.S.A. A. Anastassov, K.A. Hahn, A. Kubik, L. Lusito, N. Mucia, N. Odell, B. Pollack, A. Pozdnyakov, M. Schmitt, S. Stoynev, M. Velasco, S. Won University of Notre Dame, Notre Dame, U.S.A. D. Berry, A. Brinkerhoff, K.M. Chan, M. Hildreth, C. Jessop, D.J. Karmgard, J. Kolb, K. Lannon, W. Luo, S. Lynch, N. Marinelli, D.M. Morse, T. Pearson, M. Planer, R. Ruchti, J. Slaunwhite, N. Valls, M. Wayne, M. Wolf The Ohio State University, Columbus, U.S.A. L. Antonelli, B. Bylsma, L.S. Durkin, C. Hill, R. Hughes, K. Kotov, T.Y. Ling, D. Puigh, M. Rodenburg, G. Smith, C. Vuosalo, G. Williams, B.L. Winer, H. Wolfe Princeton University, Princeton, U.S.A. E. Berry, P. Elmer, V. Halyo, P. Hebda, J. Hegeman, A. Hunt, P. Jindal, S.A. Koay, D. Lopes Pegna, P. Lujan, D. Marlow, T. Medvedeva, M. Mooney, J. Olsen, P. Piroué, X. Quan, A. Raval, H. Saka, D. Stickland, C. Tully, J.S. Werner, S.C. Zenz, A. Zuranski University of Puerto Rico, Mayaguez, U.S.A. E. Brownson, A. Lopez, H. Mendez, J.E. Ramirez Vargas Purdue University, West Lafayette, U.S.A. E. Alagoz, D. Benedetti, G. Bolla, D. Bortoletto, M. De Mattia, A. Everett, Z. Hu, M. Jones, K. Jung, O. Koybasi, M. Kress, N. Leonardo, V. Maroussov, P. Merkel, D.H. Miller, N. Neumeister, I. Shipsey, D. Silvers, A. Svyatkovskiy, M. Vidal Marono, F. Wang, L. Xu, H.D. Yoo, J. Zablocki, Y. Zheng Purdue University Calumet, Hammond, U.S.A. S. Guragain, N. Parashar Rice University, Houston, U.S.A. A. Adair, B. Akgun, K.M. Ecklund, F.J.M. Geurts, W. Li, B.P. Padley, R. Redjimi, J. Roberts, J. Zabel University of Rochester, Rochester, U.S.A. B. Betchart, A. Bodek, R. Covarelli, P. de Barbaro, R. Demina, Y. Eshaq, T. Ferbel, A. Garcia-Bellido, P. Goldenzweig, J. Han, A. Harel, D.C. Miner, G. Petrillo, D. Vishnevskiy, M. Zielinski The Rockefeller University, New York, U.S.A. A. Bhatti, R. Ciesielski, L. Demortier, K. Goulianos, G. Lungu, S. Malik, C. Mesropian Rutgers, The State University of New Jersey, Piscataway, U.S.A. S. Arora, A. Barker, J.P. Chou, C. Contreras-Campana, E. Contreras-Campana, D. Duggan, D. Ferencek, Y. Gershtein, R. Gray, E. Halkiadakis, D. Hidas, A. Lath, – 28 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 S. Panwalkar, M. Park, R. Patel, V. Rekovic, J. Robles, K. Rose, S. Salur, S. Schnetzer, C. Seitz, S. Somalwar, R. Stone, S. Thomas, M. Walker University of Tennessee, Knoxville, U.S.A. G. Cerizza, M. Hollingsworth, S. Spanier, Z.C. Yang, A. York Texas A&M University, College Station, U.S.A. R. Eusebi, W. Flanagan, J. Gilmore, T. Kamon59, V. Khotilovich, R. Montalvo, I. Osipenkov, Y. Pakhotin, A. Perloff, J. Roe, A. Safonov, T. Sakuma, I. Suarez, A. Tatarinov, D. Toback Texas Tech University, Lubbock, U.S.A. N. Akchurin, J. Damgov, C. Dragoiu, P.R. Dudero, C. Jeong, K. Kovitanggoon, S.W. Lee, T. Libeiro, I. Volobouev Vanderbilt University, Nashville, U.S.A. E. Appelt, A.G. Delannoy, S. Greene, A. Gurrola, W. Johns, C. Maguire, Y. Mao, A. Melo, M. Sharma, P. Sheldon, B. Snook, S. Tuo, J. Velkovska University of Virginia, Charlottesville, U.S.A. M.W. Arenton, S. Boutle, B. Cox, B. Francis, J. Goodell, R. Hirosky, A. Ledovskoy, C. Lin, C. Neu, J. Wood Wayne State University, Detroit, U.S.A. S. Gollapinni, R. Harr, P.E. Karchin, C. Kottachchi Kankanamge Don, P. Lamichhane, A. Sakharov University of Wisconsin, Madison, U.S.A. M. Anderson, D.A. Belknap, L. Borrello, D. Carlsmith, M. Cepeda, S. Dasu, E. Friis, K.S. Grogg, M. Grothe, R. Hall-Wilton, M. Herndon, A. Hervé, K. Kaadze, P. Klabbers, J. Klukas, A. Lanaro, C. Lazaridis, R. Loveless, A. Mohapatra, M.U. Mozer, I. Ojalvo, G.A. Pierro, I. Ross, A. Savin, W.H. Smith, J. Swanson ... †: Deceased 1 : Also at Vienna University of Technology, Vienna, Austria 2 : Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland 3 : Also at Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France 4 : Also at National Institute of Chemical Physics and Biophysics, Tallinn, Estonia 5 : Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia 6 : Also at Universidade Estadual de Campinas, Campinas, Brazil 7 : Also at California Institute of Technology, Pasadena, U.S.A. 8 : Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France – 29 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 9 : Also at Suez Canal University, Suez, Egypt 10 : Also at Cairo University, Cairo, Egypt 11 : Also at Fayoum University, El-Fayoum, Egypt 12 : Also at Helwan University, Cairo, Egypt 13 : Also at British University in Egypt, Cairo, Egypt 14 : Now at Ain Shams University, Cairo, Egypt 15 : Also at National Centre for Nuclear Research, Swierk, Poland 16 : Also at Université de Haute Alsace, Mulhouse, France 17 : Also at Joint Institute for Nuclear Research, Dubna, Russia 18 : Also at Brandenburg University of Technology, Cottbus, Germany 19 : Also at The University of Kansas, Lawrence, U.S.A. 20 : Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary 21 : Also at Eötvös Loránd University, Budapest, Hungary 22 : Also at Tata Institute of Fundamental Research - HECR, Mumbai, India 23 : Now at King Abdulaziz University, Jeddah, Saudi Arabia 24 : Also at University of Visva-Bharati, Santiniketan, India 25 : Also at Sharif University of Technology, Tehran, Iran 26 : Also at Isfahan University of Technology, Isfahan, Iran 27 : Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran 28 : Also at Laboratori Nazionali di Legnaro dell’ INFN, Legnaro, Italy 29 : Also at Università degli Studi di Siena, Siena, Italy 30 : Also at Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Mexico 31 : Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia 32 : Also at Facoltà Ingegneria, Università di Roma, Roma, Italy 33 : Also at Scuola Normale e Sezione dell’INFN, Pisa, Italy 34 : Also at INFN Sezione di Roma, Roma, Italy 35 : Also at University of Athens, Athens, Greece 36 : Also at Rutherford Appleton Laboratory, Didcot, United Kingdom 37 : Also at Paul Scherrer Institut, Villigen, Switzerland 38 : Also at Institute for Theoretical and Experimental Physics, Moscow, Russia 39 : Also at Albert Einstein Center for Fundamental Physics, Bern, Switzerland 40 : Also at Gaziosmanpasa University, Tokat, Turkey 41 : Also at Adiyaman University, Adiyaman, Turkey 42 : Also at The University of Iowa, Iowa City, U.S.A. 43 : Also at Mersin University, Mersin, Turkey 44 : Also at Izmir Institute of Technology, Izmir, Turkey 45 : Also at Ozyegin University, Istanbul, Turkey 46 : Also at Kafkas University, Kars, Turkey 47 : Also at Suleyman Demirel University, Isparta, Turkey 48 : Also at Ege University, Izmir, Turkey 49 : Also at Mimar Sinan University, Istanbul, Istanbul, Turkey 50 : Also at Kahramanmaras Sütcü Imam University, Kahramanmaras, Turkey 51 : Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom 52 : Also at INFN Sezione di Perugia; Università di Perugia, Perugia, Italy 53 : Also at Utah Valley University, Orem, U.S.A. 54 : Also at Institute for Nuclear Research, Moscow, Russia – 30 – J H E P 0 7 ( 2 0 1 3 ) 1 6 3 55 : Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia 56 : Also at Argonne National Laboratory, Argonne, U.S.A. 57 : Also at Erzincan University, Erzincan, Turkey 58 : Also at Yildiz Technical University, Istanbul, Turkey 59 : Also at Kyungpook National University, Daegu, Korea – 31 – Introduction CMS detector Event selection and efficiency modelling Proper decay time fit Results Summary The CMS collaboration