1,020 research outputs found
SDN next generation integrated architecture for HEP and global science
I describe a software-defined global system under development by Caltech and partner network teams in support of the LHC and other major science programs that coordinates workflows among hundreds of multi-petabyte data stores and petascale computing facilities interlinked by 100 Gbps networks, and the Exascale systems needed by the next decade
First measurement of hadronic event shapes in pp collisions at √s = 7 TeV
Hadronic event shapes have been measured in proton–proton collisions at √s = 7 TeV source, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 pb^(−1). Event-shape distributions, corrected for detector response, are compared with five models of QCD multijet production
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
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
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Probing color coherence effects in pp collisions at [Formula: see text].
A study of color coherence effects in pp collisions at a center-of-mass energy of 7[Formula: see text] is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36 pb[Formula: see text]. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily
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
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