https://doi.org/10.1140/epjc/s10052-023-12154-x
Regular Article - Theoretical Physics
Matrix element corrections in the Pythia8 parton shower in the context of matched simulations at next-to-leading order
1
INFN, Sezione di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
2
Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
3
Scientific Computing Division, Fermi National Accelerator Laboratory, 60510, Batavia, IL, USA
Received:
4
September
2023
Accepted:
15
October
2023
Published online:
27
October
2023
We discuss the role of matrix element corrections (MEC) to parton showers in the context of MC@NLO-type matchings for processes that feature unstable resonances, where MEC are liable to result in double-counting issues, and are thus generally not employed. By working with Pythia8, we show that disabling all MEC is actually unnecessary in computations based on the narrow-width approximation, and we propose alternative MEC settings which, while still avoiding double counting, allow one to include hard-recoil effects in the simulations of resonance decays. We illustrate our findings by considering 
production at the LHC, and by comparing MadGraph5-aMC@NLO predictions with those of POWHEG-BOX and standalone Pythia8.
© The Author(s) 2023
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3. SCOAP3 supports the goals of the International Year of Basic Sciences for Sustainable Development.
