Measurement of associated W + charm production in pp collisions at √s = 7 TeV

Authors

S. Chatrchyan, Yerevan Physics Institute
Ekaterina Avdeeva, University of Nebraska-LincolnFollow
Kenneth A. Bloom, University of Nebraska - LincolnFollow
S. Bose, University of Nebraska-LincolnFollow
Daniel R. Claes, University of Nebraska-LincolnFollow
Aaron Dominguez, University of Nebraska-LincolnFollow
M. Eads, University of Nebraska-LincolnFollow
Rebeca Gonzalez Suarez, University of Nebraska-LincolnFollow
J. Keller, University of Nebraska-LincolnFollow
Ilya Kravchenko, University of Nebraska-LincolnFollow
J. Lazo-Flores, University of Nebraska-LincolnFollow
S. Malik, University of Nebraska-LincolnFollow
F. Meier, University of Nebraska-LincolnFollow
Gregory R. Snow, University of Nebraska-LincolnFollow
CMS collaboration, CMS collaboration

Date of this Version

2-4-2014

Citation

JHEP02(2014)013; doi:10.1007/JHEP02(2014)013

Comments

Copyright © 2014 CERN, issued under cc license; published by Springer.

Abstract

Measurements are presented of the associated production of a W boson and a charm-quark jet (W + c) in pp collisions at a center-of-mass energy of 7TeV. The analysis is conducted with a data sample corresponding to a total integrated luminosity of 5 fb−1, collected by the CMS detector at the LHC. W boson candidates are identified by their decay into a charged lepton (muon or electron) and a neutrino. The W + c measurements are performed for charm-quark jets in the kinematic region p^jet_T > 25 GeV, |ɳ^jet| < 2.5, for two different thresholds for the transverse momentum of the lepton from the W-boson decay, and in the pseudorapidity range |ɳ^ℓ| < 2.1. Hadronic and inclusive semileptonic decays of charm hadrons are used to measure the following total cross sections: σ(pp → W+ c + X) × B(W → ℓν) = 107.7 ± 3.3 (stat.) ± 6.9 (syst.) pb (p^ℓ_T > 25 GeV) and σ (pp→ W+ c + X)×B(W→ ℓν) = 84.1 ± 2.0 (stat.) ± 4.9 (syst.) pb (p^ℓ_T > 35 GeV), and the cross section ratios σ (pp → W⁺ +¯c + X)/ σ (pp → W⁻ + c + X) = 0.954 ± 0.025 (stat.) ± 0.004 (syst.) (p^ℓ_T > 25 GeV) and σ (pp → W⁺ + c + X)/ σ (pp → W⁻ + c + X) = 0.938 ± 0.019 (stat.) ± 0.006 (syst.) (p^ℓ_T > 35 GeV). Cross sections and cross section ratios are also measured differentially with respect to the absolute value of the pseudorapidity of the lepton from the W-boson decay. These are the first measurements from the LHC directly sensitive to the strange quark and antiquark content of the proton. Results are compared with theoretical predictions and are consistent with the predictions based on global fits of parton distribution functions.