209842972
Determination of alpha(s) using jet rates at LEP with the OPAL detector
Hadronic events produced in e(+)e(-) collisions by the LEP collider and recorded by the OPAL detector were used to form distributions based on the number of reconstructed jets. The data were collected between 1995 and 2000 and correspond to energies of 91 GeV, 130-136 GeV and 161-209 GeV. The jet rates were determined using four different jet-finding algorithms (Cone, JADE, Durham and Cambridge). The differential two-jet rate and the average jet rate with the Durham and Cambridge algorithms were used to measure alpha(S) in the LEP energy range by fitting an expression in which O(alpha(2)(S)) calculations were matched to a NLLA prediction and fitted to the data. Combining the measurements at different centre-of-mass energies, the value of alpha(s)(Mz) was determined to be as(Mz) = 0.1177 +/- 0.0006 (stat.) +/- 0.0012 (expt.) +/- 0.0010 (had.) +/- 0.0032 (theo.)
121279531
Results of the first integration test of the CMS drift tubes muon trigger
Two drift tubes (DTs) chambers of the CMS muon barrel system were exposed to a 40 MHz bunched muon beam at the CERN SPS, and for the first time the whole CMS Level-1 DTs-based trigger system chain was tested. Data at different energies and inclination angles of the incident muon beam were collected, as well as data with and without an iron absorber placed between the two chambers, to simulate the electromagnetic shower development in CMS. Special data-taking runs were dedicated to test for the first time the Track Finder system, which reconstructs track trigger candidates by performing a proper matching of the muon segments delivered by the two chambers. The present paper describes the results of these measurements.
209834941
Search for heavy long-lived charged particles in $pp$ collisions at $s=7$ TeV
The result of a search for heavy long-lived charged particles produced in pp collisions at sqrt(s) = 7 TeV at the LHC is described. The data sample has been collected using the CMS detector and corresponds to an integrated luminosity of 5.0 inverse femtobarns. The inner tracking detectors are used to define a sample of events containing tracks with high momentum and high ionization energy loss. A second sample of events with high-momentum and high-ionization tracks satisfying muon identification and long time-of-flight criteria is analyzed independently. In both cases, the results are consistent with the expected background estimated from data. The results are used to establish cross section limits as a function of mass within the context of models with long-lived gluinos, scalar top quarks and scalar taus. Cross section limits on hyper-meson particles, containing new elementary long-lived hyper-quarks predicted by a vector-like confinement model, are also presented. Lower limits at 95% confidence level on the mass of gluinos (scalar top quarks) are found to be 1098 (737) GeV. A limit of 928 (626) GeV is set for a gluino (scalar top quark) that hadronizes into a neutral bound state before reaching the muon detectors. The lower mass limit for a pair produced scalar tau is found to be 223 GeV. Mass limits for a hyper-kaon are placed at 484, 602, and 747 GeV for hyper-rho masses of 800, 1200, and 1600 GeV, respectively.
29757321
Search for physics beyond the standard model in events with a Z boson, jets, and missing transverse energy in pp collisions at √s=7 TeV
A search is presented for physics beyond the standard model (BSM) in events with a Z boson, jets, and missing transverse energy (MET). This signature is motivated by BSM physics scenarios, including supersymmetry. The study is performed using a sample of proton-proton collision data collected at sqrt(s) = 7 TeV with the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.98 inverse femtobarns. The contributions from the dominant standard model backgrounds are estimated from data using two complementary strategies, the jet-Z balance technique and a method based on modeling MET with data control samples. In the absence of evidence for BSM physics, we set limits on the non-standard-model contributions to event yields in the signal regions and interpret the results in the context of simplified model spectra. Additional information is provided to facilitate tests of other BSM physics models.
115986380
Study of hadronic final states at LEP
Recent analyses, performed using multihadronic Z 0 decays collected with the OPAL detector between 1991 and 2000 at the Large Electron Positron (LEP) collider, are presented. The first one is a study of correlations of particles with restricted momenta, indicating some difficulties with the Local Parton-Hadron Duality (LPHD) hypothesis when applied to many-particle inclusive observables of soft hadrons. In the second analysis, unbiased gluon jet properties are studied using a new technique called jet boost algorithm.
126243667
Further Tests of the CMS Drift Tubes Muon Trigger
121465283
Characterization of a potted 5-in. HPD with Rb2Te photocathode
Abstract We present the first Rb 2 Te 5 in. HPD test results in outside vacuum configuration. We are studying the properties of this new photodetector in normal working condition, in order to characterize its properties for Imaging Air Cherenkov Experiment.