243 documents found, page 1 of 25
Measurements of the associated production of a Z boson and b jets in pp collisi...
CMS collaboration (2296 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, AgostinoMeasurements of the associated production of a Z boson with at least one jet originating from a b quark in proton-proton collisions at $\sqrt{s} =$ 8 TeV are presented. Differential cross sections are measured with data collected by the CMS experiment corresponding to an integrated luminosity of 19.8 inverse femtobarns. Z bosons are reconstructed through their decays to electrons and muons. Cross sections are m...
Search for top squark pair production in compressed-mass-spectrum scenarios in ...
CMS collaboration (2296 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, AgostinoAn inclusive search is performed for supersymmetry in final states containing jets and an apparent imbalance in transverse momentum, p→Tmiss , due to the production of unobserved weakly interacting particles in pp collisions at a centre-of-mass energy of 8 TeV. The data, recorded with the CMS detector at the CERN LHC, correspond to an integrated luminosity of 18.5 fb −1 . The dimensionless kinematic variable αT...
Search for Dark Matter and Supersymmetry with a Compressed Mass Spectrum in the...
CMS collaboration (2274 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, AgostinoA first search for pair production of dark matter candidates through vector boson fusion in proton-proton collisions at s=8 TeV is performed with the CMS detector. The vector boson fusion topology enhances missing transverse momentum, providing a way to probe supersymmetry, even in the case of a compressed mass spectrum. The data sample corresponds to an integrated luminosity of 18.5 fb−1, recorded by the CMS...
Measurements of the $\mathrm{t}\overline{\mathrm{t}}$ production cross section ...
CMS collaboration (2309 authors); Hollar, Jonathan; Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, CristóvãoA measurement of the top quark pair production ( $\mathrm{t}\overline{\mathrm{t}} $ ) cross section in proton–proton collisions at the centre-of-mass energy of 8 $\,\text {TeV}$ is presented using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.6 $\,\text {fb}^{-\text {1}}$ . This analysis is performed in the $\mathrm{t}\overline{\mathrm{t}} $ decay channels with...
Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV
CMS collaboration (2305 authors); Hollar, Jonathan; Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, CristóvãoImproved jet energy scale corrections, based on a data sample corresponding to an integrated luminosity of 19.7 fb(-1) collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 8 TeV, are presented. The corrections as a function of pseudorapidity η and transverse momentum p(T) are extracted from data and simulated events combining several channels and methods. They account succes...
Coherent $J/\psi$ photoproduction in ultra-peripheral PbPb collisions at $\sqrt...
CMS collaboration (2289 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, AgostinoThe cross section for coherent J/ψ photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, Xn0n , is measured with the CMS experiment in ultra-peripheral PbPb collisions at sNN=2.76 TeV . The analysis is based on a data sample corresponding to an integrated luminosity of 159 μb−1 , collected during the 2011 PbPb run. The J/ψ mesons are ...
The CMS trigger system
CMS collaboration (2308 authors); Hollar, Jonathan; Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, CristóvãoThis paper describes the CMS trigger system and its performance during Run 1 of the LHC. The trigger system consists of two levels designed to select events of potential physics interest from a GHz (MHz) interaction rate of proton-proton (heavy ion) collisions. The first level of the trigger is implemented in hardware, and selects events containing detector signals consistent with an electron, photon, muon, tau...
Measurement of the transverse momentum spectra of weak vector bosons produced i...
CMS collaboration (2300 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, AgostinoThe transverse momentum spectra of weak vector bosons are measured in the CMS experiment at the LHC. The measurement uses a sample of proton-proton collisions at $ \sqrt{s}=8 $ TeV, collected during a special low-luminosity running that corresponds to an integrated luminosity of 18.4 ± 0.5 pb$^{−1}$. The production of W bosons is studied in both electron and muon decay modes, while the production of Z bosons is...
Measurement of the mass difference between top quark and antiquark in pp collis...
CMS collaboration (2204 authors); Hollar, Jonathan; Nayak, Aruna; Calpas, Betty; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, PietroThe invariance of the standard model (SM) under the CPT transformation predicts equality of particle and antiparticle masses. This prediction is tested by measuring the mass difference between the top quark and antiquark ( Δmt=mt−mt‾ ) that are produced in pp collisions at a center-of-mass energy of 8 TeV, using events with a muon or an electron and at least four jets in the final state. The analysis is based o...
Multiplicity and rapidity dependence of strange hadron production in pp, pPb, a...
CMS collaboration (2296 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, AgostinoMeasurements of strange hadron (K0s, Lambda + anti-Lambda, and Xi+ + Xi-) transverse momentum spectra in pp, pPb, and PbPb collisions are presented over a wide range of rapidity and event charged-particle multiplicity. The data were collected with the CMS detector at the CERN LHC in pp collisions at sqrt(s) = 7 TeV, pPb collisions at sqrt(s[NN]) = 5.02 TeV, and PbPb collisions at sqrt(s[NN]) = 2.76 TeV. The ave...