Measurement of the W-boson mass in pp collisions at root 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 ×

10 6

candidates in the

W → μ ν

channel and

5.9 ×

10 6

candidates in the

W → e ν

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

m W

= 80370

± 7

( stat. ) ± 11 ( exp. syst. )

± 14

( mod. syst. )

MeV

= 80370

± 19

MeV ,

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

m

W +

-

m

W -

= -

29 ± 28

MeV.