4,819 research outputs found
Search for a Standard Model Higgs Boson in CMS via Vector Boson Fusion in the H->WW->l\nu l\nu Channel
We present the potential for discovering the Standard Model Higgs boson
produced by the vector-boson fusion mechanism. We considered the decay of Higgs
bosons into the W+W- final state, with both W-bosons subsequently decaying
leptonically. The main background is ttbar with one or more jets produced. This
study is based on a full simulation of the CMS detector, and up-to-date
reconstruction codes. The result is that a signal of 5 sigma significance can
be obtained with an integrated luminosity of 12-72 1/fb for Higgs boson masses
between 130-200 GeV. In addition, the major background can be measured directly
to 7% from the data with an integrated luminosity of 30 1/fb. In this study, we
also suggested a method to obtain information in Higgs mass using the
transverse mass distributions.Comment: 26 pages, 22 figure
Simulation of the CMS Resistive Plate Chambers
The Resistive Plate Chamber (RPC) muon subsystem contributes significantly to
the formation of the trigger decision and reconstruction of the muon trajectory
parameters. Simulation of the RPC response is a crucial part of the entire CMS
Monte Carlo software and directly influences the final physical results. An
algorithm based on the parametrization of RPC efficiency, noise, cluster size
and timing for every strip has been developed. Experimental data obtained from
cosmic and proton-proton collisions at TeV have been used for
determination of the parameters. A dedicated validation procedure has been
developed. A good agreement between the simulated and experimental data has
been achieved.Comment: to be published in JINS
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Measurement of masses in the [Formula: see text] system by kinematic endpoints in pp collisions at [Formula: see text].
A simultaneous measurement of the top-quark, W-boson, and neutrino masses is reported for [Formula: see text] events selected in the dilepton final state from a data sample corresponding to an integrated luminosity of 5.0 fb-1 collected by the CMS experiment in pp collisions at [Formula: see text]. The analysis is based on endpoint determinations in kinematic distributions. When the neutrino and W-boson masses are constrained to their world-average values, a top-quark mass value of [Formula: see text] is obtained. When such constraints are not used, the three particle masses are obtained in a simultaneous fit. In this unconstrained mode the study serves as a test of mass determination methods that may be used in beyond standard model physics scenarios where several masses in a decay chain may be unknown and undetected particles lead to underconstrained kinematics
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Search for supersymmetry in hadronic final states with missing transverse energy using the variables αT and b-quark multiplicity in pp collisions at [Formula: see text].
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-1 collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, αT, 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
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Search for physics beyond the standard model in events with τ leptons, jets, and large transverse momentum imbalance in pp collisions at [Formula: see text].
A search for physics beyond the standard model is performed with events having one or more hadronically decaying τ leptons, highly energetic jets, and large transverse momentum imbalance. The data sample corresponds to an integrated luminosity of 4.98 fb-1 of proton-proton collisions at [Formula: see text] collected with the CMS detector at the LHC in 2011. The number of observed events is consistent with predictions for standard model processes. Lower limits on the mass of the gluino in supersymmetric models are determined
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Search for decays of stopped long-lived particles produced in proton-proton collisions at [Formula: see text].
A search has been performed for long-lived particles that could have come to rest within the CMS detector, using the time intervals between LHC beam crossings. The existence of such particles could be deduced from observation of their decays via energy deposits in the CMS calorimeter appearing at times that are well separated from any proton-proton collisions. Using a data set corresponding to an integrated luminosity of 18.6[Formula: see text] of 8[Formula: see text] proton-proton collisions, and a search interval corresponding to 281 h of trigger livetime, 10 events are observed, with a background prediction of [Formula: see text] events. Limits are presented at 95 % confidence level on gluino and top squark production, for over 13 orders of magnitude in the mean proper lifetime of the stopped particle. Assuming a cloud model of R-hadron interactions, a gluino with mass [Formula: see text]1000[Formula: see text] and a top squark with mass [Formula: see text]525[Formula: see text] are excluded, for lifetimes between 1 [Formula: see text]s and 1000[Formula: see text]. These results are the most stringent constraints on stopped particles to date
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