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Reis, T.

Publications and source records attributed to Reis, T..

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Measurement of the differential cross section for top quark pair production in pp collisions at $\sqrt{s} = 8\,\text {TeV} $

The normalized differential cross section for top quark pair (tt¯) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb –1 . The measurements are performed in the lepton+jets (e/μ +jets) and in the dilepton (e + e – , μ + μ – , and e ± μ ∓ ) decay channels. The tt¯ cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt¯ system. The data are compared with several predictions from perturbative quantum chromodynamic up to approximate next-to-next-to-leading-order precision. Furthermore, no significant deviations are observed relative to the standard model predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Evidence for collective multiparticle correlations in p – Pb collisions

The second-order azimuthal anisotropy Fourier harmonics, v₂, are obtained in p−Pb and PbPb collisions over a wide pseudorapidity (η) range based on correlations among six or more charged particles. The p-Pb data, corresponding to an integrated luminosity of 35 nb⁻¹, were collected during the 2013 LHC p-Pb run at a nucleon-nucleon center-of-mass energy of 5.02 TeV by the CMS experiment. A sample of semiperipheral PbPb collision data at √s = 2.76 TeV, corresponding to an integrated luminosity of 2.5 μb⁻¹ and covering a similar range of particle multiplicities as the p−Pb data, is also analyzed for comparison. The six- and eight-particle cumulant and the Lee-Yang zeros methods are used to extract the v₂ coefficients, extending previous studies of two- and four-particle correlations. For both the p−Pb and PbPb systems, the v₂ values obtained with correlations among more than four particles are consistent with previously published four-particle results. These data support the interpretation of a collective origin for the previously observed long-range (large Δη) correlations in both systems. The ratios of v2 values corresponding to correlations including different numbers of particles are compared to theoretical predictions that assume a hydrodynamic behavior of a p−Pb system dominated by fluctuations in the positions of participant nucleons. These results provide new insights into the multiparticle dynamics of collision systems with a very small overlapping region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗