Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, ...including the transverse momenta ( ) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta ( ), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb super(-1). The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the distributions of the leading jets at high values, the distributions of the at high- and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.
A peaking structure in the J/ psi phi J/ psi phi mass spectrum near threshold is observed in B super( plus or minus ) arrow right J/ psi phi K super( plus or minus )B plus or minus arrow right J/ psi ...phi K plus or minus decays, produced in pp collisions at s=7 TeV collected with the CMS detector at the LHC. The data sample, selected on the basis of the dimuon decay mode of the J/ psi J/ psi , corresponds to an integrated luminosity of 5.2 fb super(-1). Fitting the structure to an S -wave relativistic Breit-Wigner lineshape above a three-body phase-space nonresonant component gives a signal statistical significance exceeding five standard deviations. The fitted mass and width values are m=4148.0 plus or minus 2.4(stat.) plus or minus 6.3(syst.)MeV and Gamma =28-11+15(stat.) plus or minus 19(syst.)MeV, respectively. Evidence for an additional peaking structure at higher J/ psi phi J/ psi phi mass is also reported.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).Dijet production has been measured in ... collisions at a nucleon-nucleon centre-of-mass energy of 5.02... A data sample ...corresponding to an integrated luminosity of 35 ... was collected using the Compact Muon Solenoid detector at the Large Hadron Collider. The dijet transverse momentum balance, azimuthal angle correlations, and pseudorapidity distributions are studied as a function of the transverse energy in the forward calorimeters (...). For ... collisions, the dijet transverse momentum ratio and the width of the distribution of dijet azimuthal angle difference are comparable to the same quantities obtained from a simulated ... reference and insensitive to ... In contrast, the mean value of the dijet pseudorapidity is found to change monotonically with increasing ..., indicating a correlation between the energy emitted at large pseudorapidity and the longitudinal motion of the dijet frame. The pseudorapidity distribution of the dijet system in minimum bias ... collisions is compared with next-to-leading-order perturbative QCD predictions obtained from both nucleon and nuclear parton distribution functions, and the data more closely match the latter.
Results are presented of a search for compositeness in electrons and muons using a data sample of pp collisions at a center-of-mass energy s = 7 TeV collected with the CMS detector at the LHC and ...corresponding to an integrated luminosity of 5.0 fb - 1 . Excited leptons (a a) are assumed to be produced via contact interactions in conjunction with a standard model lepton and to decay via a a a a gamma , yielding a final state with two energetic leptons and a photon. The number of events observed in data is consistent with that expected from the standard model. The 95% confidence upper limits for the cross section for the production and decay of excited electrons (muons), with masses ranging from 0.6 to 2 TeV, are 1.48 to 1.24 fb (1.31 to 1.11 fb). Excited leptons with masses below 1.9 TeV are excluded for the case where the contact interaction scale equals the excited lepton mass. The limits on the cross sections are the most stringent ones published to date.
A measurement of the t t A= production cross section in pp collisions at s = 7 TeV is presented. The results are based on data corresponding to an integrated luminosity of 2.3 fb-1 collected by the ...CMS detector at the LHC. Selected events are required to have one isolated, high transverse momentum electron or muon, large missing transverse energy, and hadronic jets, at least one of which must be consistent with having originated from a b quark. The measured cross section is 158.1 +/- 2.1 (stat .) +/- 10.2 (syst .) +/- 3.5 (lum .) pb , in agreement with standard model predictions.
An updated search for heavy narrow resonances decaying to muon or electron pairs using the CMS detector is presented. Data samples from pp collisions at s = 7 TeV and 8 TeV at the LHC, with ...integrated luminosities of up to 5.3 and 4.1 fb - 1 , respectively, are combined. No evidence for a heavy narrow resonance is observed. The analysis of the combined data sets excludes, at 95% confidence level, a Sequential Standard Model Z SSM a2 resonance lighter than 2590 GeV, a superstring-inspired Z I a2 lighter than 2260 GeV, and KaluzaaKlein gravitons lighter than 2390 (2030) GeV, assuming that the coupling parameter k / M A= Pl is 0.10 (0.05). These are the most stringent limits to date.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A measurement of W super(+)W super(-) production in pp collisions at ... is presented. The data were collected with the CMS ...detector at the LHC, and correspond to an integrated luminosity of 4.92 plus or minus 0.11 fb super(-1). The W super(+)W super(-) candidates consist of two oppositely charged leptons, electrons or muons, accompanied by large missing transverse energy. The W super(+)W super(-) production cross section is measured to be 52.4 plus or minus 2.0 (stat.) plus or minus 4.5 (syst.) plus or minus 1.2 (lum.) pb. This measurement is consistent with the standard model prediction of 47.0 plus or minus 2.0 pb at next-to-leading order. Stringent limits on the WW gamma and WWZ anomalous triple gauge-boson couplings are set.
Many models of new physics, including versions of supersymmetry (SUSY), predict production of events with low missing transverse energy, electroweak gauge bosons, and many energetic final-state ...particles. The stealth SUSY model yields this signature while conserving R-parity by means of a new hidden sector in which SUSY is approximately conserved. The results of a general search for new physics, with no requirement on missing transverse energy, in events with two photons and four or more hadronic jets are reported. The study is based on a sample of protonaproton collisions at s = 7 TeV corresponding to 4.96 fb - 1 of integrated luminosity collected with the CMS detector in 2011. Based on good agreement between the data and the standard model expectation, the data are used to determine model-independent cross-section limits and a limit on the squark mass in the framework of stealth SUSY. With this first study of its kind, squark masses less than 1430 GeV are excluded at the 95% confidence level.
An inclusive search for supersymmetric processes that produce final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of 8 TeV. The data sample ...corresponds to an integrated luminosity of 11.7 fb super(-1) collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, alpha sub(T), is used to discriminate between events with genuine and misreconstructed missing transverse energy. The search is based on an examination of the number of reconstructed jets per event, the scalar sum of transverse energies of these jets, and the number of these jets identified as originating from bottom quarks. No significant excess of events over the standard model expectation is found. Exclusion limits are set in the parameter space of simplified models, with a special emphasis on both compressed-spectrum scenarios and direct or gluino-induced production of third-generation squarks. For the case of gluino-mediated squark production, gluino masses up to 950-1125 GeV are excluded depending on the assumed model. For the direct pair-production of squarks, masses up to 450 GeV are excluded for a single light first- or second-generation squark, increasing to 600 GeV for bottom squarks.
Results from the first study of isolated-photon + jet correlations in relativistic heavy ion collisions are reported. The analysis uses data from PbPb collisions at a centre-of-mass energy of 2.76 ...TeV per nucleon pair corresponding to an integrated luminosity of 150 mu b - 1 recorded by the CMS experiment at the LHC. For events containing an isolated photon with transverse momentum p T gamma > 60 GeV / c and an associated jet with p T Jet > 30 GeV / c , the photon + jet p T imbalance is studied as a function of collision centrality and compared to pp data and pythia calculations at the same collision energy. Using the p T gamma of the isolated photon as an estimate of the momentum of the associated parton at production, this measurement allows an unbiased characterisation of the in-medium parton energy loss. For more central PbPb collisions, a significant decrease in the ratio p T Jet / p T gamma relative to that in the pythia reference is observed. Furthermore, significantly more p T gamma > 60 GeV / c photons in PbPb are observed not to have an associated p T Jet > 30 GeV / c jet, compared to the reference. However, no significant broadening of the photon + jet azimuthal correlation is observed.
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