Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at √s = 7 TeV

Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at √s=7  TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36  pb^(-1). The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Λ^+=5.6  TeV (Λ^-=6.7  TeV) for destructive (constructive) interference is obtained at the 95% confidence level

Measurement of the B^+ Production Cross Section in pp Collisions at √s=7 TeV

Measurements of the total and differential cross sections dσ/dp_T^B and dσ/dy^B for B^+ mesons produced in pp collisions at √s=7  TeV are presented. The data correspond to an integrated luminosity of 5.8  pb^(-1) collected by the CMS experiment operating at the LHC. The exclusive decay B^+→J/ψK^+, with J/ψ→μ^+μ^-, is used to detect B^+ mesons and to measure the production cross section as a function of p_T^B and y^B. The total cross section for p_T^B>5  GeV and |y^B|<2.4 is measured to be 28.1±2.4±2.0±3.1  μb, where the first uncertainty is statistical, the second is systematic, and the last is from the luminosity measurement

Measurement of the Isolated Prompt Photon Production Cross Section in pp Collisions at √s = 7 TeV

The differential cross section for the inclusive production of isolated prompt photons has been measured as a function of the photon transverse energy E_T^y in pp collisions at √s = 7 TeV using data recorded by the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.9 pb^(-1). Photons are required to have a pseudorapidity │η^y│ 21 GeV, covering the kinematic region 0.006< X_T < 0.086. The measured cross section is found to be in agreement with next-to-leading-order perturbative QCD calculations

Measurement of Bose-Einstein correlations in pp collisions at √s = 0.9 and 7 TeV

Bose-Einstein correlations between identical particles are measured in samples of proton-proton collisions at 0.9 and 7TeV centre-of-mass energies, recorded by the CMS experiment at the LHC. The signal is observed in the form of an enhancement of number of pairs of same-sign charged particles with small relative momentum. The dependence of this enhancement on kinematic and topological features of the event is studied. Anticorrelations between same-sign charged particles are observed in the region of relative momenta higher than those in the signal region

Search for heavy stable charged particles in pp collisions at √s = 7 TeV

The result of a search at the LHC for heavy stable charged particles produced in pp collisions at √s = 7 TeV is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb^(-1). Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identication requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0:1 events. A lower limit at the 95% condence level on the mass of a stable gluino is set at 398 GeV/c^2, using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c^2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors