Pseudorapidity dependence of long-range two-particle correlations in pPb collisions at root sNN=5.02 TeV

Peer reviewe

The structural and dynamics neutron study of proton conductors: Difficulties and improvement procedures in protonated perovskite

With the expected development of Hydrogen as energy vector, there is a great impetus on the study of thermally stable proton conductors, the core of fuel cells, electrolysers and potential CO2 converters. Prior to a successful industrial application one should first well determine their extremely complex physical and chemical behaviour related to the unique character of the proton. The difficulties in comprehension of the nature of mobile protonic species, their location (especially the differentiation between bulk and surface species) as well as local and long range dynamics are different as a function of the hydration level: i) in hydrates the number of protons not really involved in the conduction is much larger than that of protonic conducting species, ii) in non-hydrated materials, the total amount of conducting protons can be very small, as dopants in semiconductors, and similar to that arising from surface water and physisorbed protonic moieties. The attempts and difficulties to locate and identify the protonic species and their dynamics using the neutron techniques are discussed in the light of representative examples, with emphasis on proton conducting perovskites

Study of W boson production in PbPb and pp collisions at root s(NN)=2.76 TeV

A measurement is presented of W-boson production in PbPb collisions carried out at a nucleon-nucleon (NN) centre-of-mass energy root S-NN of 2.76 TeV at the LHC using the CMS detector. In data corresponding to an integrated luminosity of 7.3 mu b(-1), the number of W -> mu v(mu) decays is extracted in the region of muon pseudorapidity vertical bar eta mu vertical bar 25 GeV/c. Yields of muons found per unit of pseudorapidity correspond to (159 +/- 10(stat.) +/- 12(syst.)) x 10(-8) W and (154 +/- 10(stat.) +/- 12(syst.)) x 10(-8) W- bosons per minimum-bias PbPb collision. The dependence of W production on the centrality of PbPb collisions is consistent with a scaling of the yield by the number of incoherent NN collisions. The yield of W bosons is also studied in a sample of pp interactions at root S = 2.76 TeV corresponding to an integrated luminosity of 231 nb(-1). The individual W+ and W- yields in PbPb and pp collisions are found to agree, once the neutron and proton content in Pb nuclei is taken into account. Likewise, the difference observed in the dependence of the positive and negative muon production on pseudorapidity is consistent with next-to-leading-order perturbative QCD calculations. (c) 2012 CERN. Published by Elsevier B.V. All rights reserved

Measurement of the charge asymmetry in top-quark pair production in proton-proton collisions at root s=7 TeV

The difference in angular distributions between top quarks and antiquarks, commonly referred to as the charge asymmetry, is measured in pp collisions at the LHC with the CMS experiment. The. data sample corresponds to an integrated luminosity of 1.09 fb(-1) at a centre-of-mass energy of 7 TeV. Top-quark pairs are selected in the final state with an electron or muon and four or more jets. At least one jet is identified as originating from b-quark hadronization. The charge asymmetry is measured in two variables, one based on the pseudorapidities (eta) of the top quarks and the other on their rapidities (y). The results A(C)(eta) = -0.017 +/- 0.032 (stat.)(-0.036)(+0.025) (syst.) and A(C)(y) = -0.013 +/- 0.028 (stat.)(-0.031)(+0.029) (syst.) are consistent within uncertainties with the standard-model predictions. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved

Measurement of the ttˉt\bar{t} production cross section in pp collisions at s =\sqrt{s}\ = 7 TeV using the kinematic properties of events with leptons and jets

This is the Pre-Print version of the Article. The official published version can be accessed from the link below - Copyright @ 2011 Springer VerlagA measurement of the top-antitop production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 inverse picobarns and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three or more hadronic jets. The kinematic properties of the events are used to separate the top-antitop signal from W+jets and QCD multijet background events. The measured cross section is 173 + 39 - 32 (stat. + syst.) pb, consistent with standard model expectations