Measurement of the forward W boson cross-section in pp collisions at √s = 7 TeV

Abstract: A measurement of the inclusive W → μν production cross-section using data from pp collisions at a centre-of-mass energy of √s = 7TeV is presented. The analysis is based on an integrated luminosity of about 1.0 fb ^-1 recorded with the LHCb detector. Results are reported for muons with a transverse momentum greater than 20 GeV/c and pseudorapidity between 2.0 and 4.5. The W ⁺ and W ^- production cross-sections are measured to be (formula presented.). where the first uncertainty is statistical, the second is systematic and the third is due to the luminosity determination. Cross-section ratios and differential distributions as functions of the muon pseudorapidity are also presented. The ratio of W ⁺ to W ^- cross-sections in the same fiducial kinematic region is determined to be (formula presented.). where the uncertainties are statistical and systematic, respectively. Results are in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics.