https://doi.org/10.1140/epjc/s10052-016-4538-2
Regular Article - Theoretical Physics
An NLO+PS generator for tt̅ and Wt production and decay including non-resonant and interference effects
1
Università di Milano-Bicocca and INFN, Sezione di Milano-Bicocca, Piazza della Scienza 3, 20126, Milan, Italy
2
INFN, Sezione di Milano-Bicocca, Piazza della Scienza 3, 20126, Milan, Italy
3
Physics Institute, Universität Zürich, Zurich, Switzerland
* e-mail: lindert@physik.uzh.ch
Received:
9
August
2016
Accepted:
28
November
2016
Published online:
18
December
2016
We present a Monte Carlo generator that implements significant theoretical improvements in the simulation of top-quark pair production and decay at the LHC. Spin correlations and off-shell effects in top-decay chains are described in terms of exact matrix elements for pp → ℓ+νℓl-ν̅lbb̅ at order α4αs2 plus full NLO QCD corrections, where the leptons ℓ and l belong to different families, and b quarks are massive. Thus, the contributions from tt̅ and Wt single-top production, plus contributions without top resonances and all relevant quantum interferences between different channels are fully included. Matrix elements are matched to the Pythia8 parton shower using a recently proposed method that allows for a consistent treatment of resonances in the POWHEG framework. These theoretical improvements are especially important for the interpretation of precision measurements of the top-quark mass, for single-top analyses in the Wt channel, and for tt̅ and Wt backgrounds in the presence of jet vetoes or cuts that enhance off-shell effects. The new generator is based on a process-independent interface of the OpenLoops amplitude generator with the POWHEG-BOX framework.
© The Author(s), 2016