Measurement of the W-boson mass in pp collisions at √s = 7 TeV with the ATLAS detector

Abstract

A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb⁻¹ of integrated luminosity. The selected data sample consists of 7.8×10⁶ candidates in the W→μν channel and 5.9×10⁶ candidates in the W→eν channel. The W-boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the W boson transverse mass in the electron and muon decay channels, yielding: mW = 80370 = ± 7 (stat.) ± 11 (exp. syst.) ±14 (mod. syst.) MeV = 80370 ±19MeV, where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty. A measurement of the mass difference between the W+ and W− bosons yields mW+ −mW−=−29 ± 28 MeV.