Abstract
This Letter presents evidence for single top-quark production in the
$s$-channel using proton-proton collisions at a centre-of-mass energy of 8 TeV
with the ATLAS detector at the CERN Large Hadron Collider. The analysis is
performed on events containing one isolated electron or muon, large missing
transverse momentum and exactly two $b$-tagged jets in the final state. The
analysed data set corresponds to an integrated luminosity of 20.3 fb$^-1$.
The signal is extracted using a maximum-likelihood fit of a discriminant which
is based on the matrix element method and optimized in order to separate
single-top-quark $s$-channel events from the main background contributions,
which are top-quark pair production and $W$ boson production in association
with heavy-flavour jets. The measurement leads to an observed signal
significance of 3.2 standard deviations and a measured cross-section of
$\sigma_s=4.8\pm0.8$(stat.)$^+1.6_-1.3$(syst.) pb, which is consistent with
the Standard Model expectation. The expected significance for the analysis is
3.9 standard deviations.
Users
Please
log in to take part in the discussion (add own reviews or comments).