Speaker
Summary
The large centre-of-mass energy available at the proton-proton collider LHC
allows for the copious production of top quark pairs in association with
other final state particles at high transverse momentum. The ATLAS experiment
has measured several final state observables that are sensitive to additional
parton radiation in top anti-top quark final states. Examples are the
multiplicity of jets for various transverse momentum thresholds or the
probability to emit jets above a given threshold in a fixed rapidity region.
These measurements are compared to modern Monte Carlo generators based on
NLO QCD matrix element or LO multi-leg matrix elements. The data are able to
constrain the uncertainty on the modelling of the top pair production
mechanism. We also discuss top production in association with photons
and Z bosons. In addition, we the discuss production of top quark pairs in
association with heavy quarks (beauty and charm).
