Abstract
The production cross-section of a top quark in association with a
W
boson is measured using proton–proton collisions at
s
=
8
TeV
. The dataset corresponds to an integrated luminosity of
20.2
fb
-
1
, and was collected in 2012 by the ATLAS detector at the Large Hadron Collider at CERN. The analysis is performed in the single-lepton channel. Events are selected by requiring one isolated lepton (electron or muon) and at least three jets. A neural network is trained to separate the
tW
signal from the dominant
t
t
¯
background. The cross-section is extracted from a binned profile maximum-likelihood fit to a two-dimensional discriminant built from the neural-network output and the invariant mass of the hadronically decaying
W
boson. The measured cross-section is
σ
tW
=
26
±
7
pb
, in good agreement with the Standard Model expectation.