Study of W boson production in PbPb and pp collisions at √sNN = 2.76 TeV

Authors

Ekaterina Avdeeva, University of Nebraska-LincolnFollow
Kenneth A. Bloom, University of Nebraska-LincolnFollow
S. S. Bose, University of Nebraska-LincolnFollow
Jamila Butt, University of Nebraska-Lincoln
Daniel R. Claes, University of Nebraska-LincolnFollow
Aaron Dominguez, University of Nebraska-LincolnFollow
Michael Eads, University of Nebraska-LincolnFollow
P. Jindal, University of Nebraska-Lincoln
J. Keller, University of Nebraska-LincolnFollow
Ilya Kravchenko, University of Nebraska-LincolnFollow
J. Lazo-Flores, University of Nebraska-LincolnFollow
H. Malbouisson, University of Nebraska-Lincoln
Sudhir Malik, University of Nebraska-LincolnFollow
Gregory Snow, University of Nebraska-LincolnFollow

Date of this Version

2012

Citation

Physics Letters B 715 (2012) 66–87; http://dx.doi.org/10.1016/j.physletb.2012.07.025

Abstract

A measurement is presented of W-boson production in PbPb collisions carried out at a nucleon–nucleon (NN) centre-of-mass energy √s_NN of 2.76 TeV at the LHC using the CMS detector. In data corresponding to an integrated luminosity of 7.3 μb⁻¹, the number of W → μν_μ decays is extracted in the region of muon pseudorapidity |η^μ| < 2.1 and transverse momentum p^μ_T > 25 GeV/c. Yields of muons found per unit of pseudorapidity correspond to (159 ± 10(stat.) ± 12(syst.)) × 10⁻⁸ W⁺ and (154 ± 10(stat.) ± 12(syst.)) × 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 √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.