714 research outputs found

    The Underlying Event at the LHC

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    We discuss a study of "minimum-bias'' collisions and the "Underlying Event" at CMS (under nominal conditions) by measuring charged particles and muons. The Underlying Event is studied by examining charged particles in the "transverse" region in charged particle jet production and in the central region of Drell-Yan muon-pair production (after removing the muon-pair)

    Potential to Discover Supersymmetry in Events with Muons, Jets and Missing Energy in pp Collisions at s\sqrt{s} = 14 TeV with the CMS Detector

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    Generic signatures of supersymmetry with R-Parity conservation include those of single isolated muons or like-sign isolated dimuon pairs, accompanied with energetic jets and missing transverse energy. The ability of CMS to discover supersymmetry with these signals is estimated for 10 fb^-1 of collected data with the inclusive single- and di-muon High Level Trigger paths. The selection criteria are optimized and the systematic effects are studied for a single low-mass benchmark point of the constrained MSSM with m_0 = 60 GeV/c^2, m_1/2 = 250 GeV/c^2, tan beta = 10, A_0 = 0, and mu > 0. Discovery contours in the (m_0, m_1/2) plane are presented for integrated luminosities ranging from 1 to 100 fb^-1

    Efficiency of Finding Muon Track Trigger Primitives in CMS Cathode Strip Chambers

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    In the CMS Experiment, muon detection in the forward direction is accomplished by cathode strip chambers~(CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using~36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge~(MTCC) exercise conducted by the~CMS experiment in~2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area (<‚ÄČ‚Ā£0.01< \! 0.01~m2^2), results presented in this paper were obtained by many installed CSCs operating {\em in situ} over an area of ‚Čą‚ÄČ‚Ā£23\approx \! 23~m2^2 as a part of the~CMS experiment. The efficiency of finding 2-dimensional trigger primitives within 6-layer chambers was found to be~99.93¬Ī0.03%99.93 \pm 0.03\%. These segments, found by the CSC electronics within 800800~ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System

    Differential cross section measurements for the production of a W boson in association with jets in proton‚Äďproton collisions at ‚ąös = 7 TeV

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    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 (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), 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[superscript ‚ąí1]. 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 pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

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