Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependence

Abstract In the context of Monte Carlo (MC) generators with parton showers that have next-to-leading-logarithmic (NLL) precision, the cutoff Q 0 terminating the shower evolution should be viewed as an infrared factorization scale so that parameters or non-perturbative effects of the MC generator may...

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Main Authors: André H. Hoang, Oliver L. Jin, Simon Plätzer, Daniel Samitz
Format: Article
Language:English
Published: SpringerOpen 2025-07-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP07(2025)005
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author André H. Hoang
Oliver L. Jin
Simon Plätzer
Daniel Samitz
author_facet André H. Hoang
Oliver L. Jin
Simon Plätzer
Daniel Samitz
author_sort André H. Hoang
collection DOAJ
description Abstract In the context of Monte Carlo (MC) generators with parton showers that have next-to-leading-logarithmic (NLL) precision, the cutoff Q 0 terminating the shower evolution should be viewed as an infrared factorization scale so that parameters or non-perturbative effects of the MC generator may have a field theoretic interpretation with a controllable scheme dependence. This implies that the generator’s parton level should be carefully defined within QCD perturbation theory with subleading order precision. Furthermore, it entails that the shower cut Q 0 is not treated as one of the generator’s tuning parameters, but that the tuning can be carried out reliably for a range of Q 0 values and that the hadron level description is Q 0-invariant. This in turn imposes non-trival constraints on the behavior of the generator’s hadronization model, so that its parameters can adapt accordingly when the Q 0 value is changed. We investigate these features using the angular ordered parton shower and the cluster hadronization model implemented in the Herwig 7.2 MC generator focusing in particular on the e + e − 2-jettiness distribution, where the shower is known to be NLL precise and where QCD factorization imposes stringent constraints on the hadronization corrections. We show that the Herwig default cluster hadronization model does not exhibit these features or consistency with QCD factorization with a satisfying precision. We design a modification of the cluster hadronization model, where some dynamical parton shower aspects are added that are missing in the default model. For this novel dynamical cluster hadronization model these features and consistency with QCD factorization are realized much more accurately.
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spelling doaj-art-782c8b9603b945d0b0d526af7adac8d22025-08-20T04:01:42ZengSpringerOpenJournal of High Energy Physics1029-84792025-07-012025715410.1007/JHEP07(2025)005Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependenceAndré H. Hoang0Oliver L. Jin1Simon Plätzer2Daniel Samitz3Faculty of Physics, University of ViennaFaculty of Physics, University of ViennaInstitute of Physics, NAWI Graz, University of GrazStefan Meyer Institute for Subatomic PhysicsAbstract In the context of Monte Carlo (MC) generators with parton showers that have next-to-leading-logarithmic (NLL) precision, the cutoff Q 0 terminating the shower evolution should be viewed as an infrared factorization scale so that parameters or non-perturbative effects of the MC generator may have a field theoretic interpretation with a controllable scheme dependence. This implies that the generator’s parton level should be carefully defined within QCD perturbation theory with subleading order precision. Furthermore, it entails that the shower cut Q 0 is not treated as one of the generator’s tuning parameters, but that the tuning can be carried out reliably for a range of Q 0 values and that the hadron level description is Q 0-invariant. This in turn imposes non-trival constraints on the behavior of the generator’s hadronization model, so that its parameters can adapt accordingly when the Q 0 value is changed. We investigate these features using the angular ordered parton shower and the cluster hadronization model implemented in the Herwig 7.2 MC generator focusing in particular on the e + e − 2-jettiness distribution, where the shower is known to be NLL precise and where QCD factorization imposes stringent constraints on the hadronization corrections. We show that the Herwig default cluster hadronization model does not exhibit these features or consistency with QCD factorization with a satisfying precision. We design a modification of the cluster hadronization model, where some dynamical parton shower aspects are added that are missing in the default model. For this novel dynamical cluster hadronization model these features and consistency with QCD factorization are realized much more accurately.https://doi.org/10.1007/JHEP07(2025)005FactorizationRenormalization GroupParton Shower
spellingShingle André H. Hoang
Oliver L. Jin
Simon Plätzer
Daniel Samitz
Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependence
Journal of High Energy Physics
Factorization
Renormalization Group
Parton Shower
title Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependence
title_full Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependence
title_fullStr Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependence
title_full_unstemmed Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependence
title_short Matching hadronization and perturbative evolution: the cluster model in light of infrared shower cutoff dependence
title_sort matching hadronization and perturbative evolution the cluster model in light of infrared shower cutoff dependence
topic Factorization
Renormalization Group
Parton Shower
url https://doi.org/10.1007/JHEP07(2025)005
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AT simonplatzer matchinghadronizationandperturbativeevolutiontheclustermodelinlightofinfraredshowercutoffdependence
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