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Top-pair production and decay at NLO matched with parton showers

Campbell, John M.; Ellis, R. Keith; Nason, Paolo; Re, Emanuele

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Authors

John M. Campbell

Paolo Nason

Emanuele Re



Abstract

We present a next-to-leading order (NLO) calculation of tt¯ production in hadronic collisions interfaced to shower generators according to the POWHEG method. We start from an NLO result from previous work, obtained in the zero width limit, where radiative corrections to both production and decays are included. The POWHEG interface required an extension of the POWHEG BOX framework, in order to deal with radiation from the decay of resonances. This extension is fully general (i.e. it can be applied in principle to any process considered in the zero width limit), and is here applied for the first time. In order to perform a realistic simulation, we introduce finite width effects using different approximations, that we validated by comparing with published exact NLO results. We have interfaced our POWHEG code to the PYTHIA8 shower Monte Carlo generator. At this stage, we dealt with novel issues related to the treatment of resonances, especially with regard to the initial scale for the shower that needs to be set appropriately. This procedure affects, for example, the fragmentation function of the b quark, that we have studied with particular attention. We believe that the tool presented here improves over previous generators for all aspects that have to do with top decays, and especially for the study of issues related to top mass measurements that involve B hadrons or b jets. The work presented here also constitutes a first step towards a fully consistent matching of NLO calculations involving intermediate resonances decaying into coloured particles, with parton showers.

Citation

Campbell, J. M., Ellis, R. K., Nason, P., & Re, E. (2015). Top-pair production and decay at NLO matched with parton showers. Journal of High Energy Physics, 2015(04), Article 114. https://doi.org/10.1007/jhep04%282015%29114

Journal Article Type Article
Acceptance Date Mar 30, 2015
Online Publication Date Apr 21, 2015
Publication Date Apr 21, 2015
Deposit Date Jul 11, 2018
Publicly Available Date Mar 29, 2024
Journal Journal of High Energy Physics
Print ISSN 1126-6708
Publisher Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Peer Reviewed Peer Reviewed
Volume 2015
Issue 04
Article Number 114
DOI https://doi.org/10.1007/jhep04%282015%29114

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Published Journal Article (1.1 Mb)
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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
© The Author(s) 2015 Open Access This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.





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