Strangeness enhancement in pp collisions from string closepacking in Pythia 8.3

Fuente: arXiv
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Main Authors: Altmann, Javira, Bernardinis, Lorenzo, Skands, Peter, Zaccolo, Valentina
Format: Preprint
Published: 2026
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author Altmann, Javira
Bernardinis, Lorenzo
Skands, Peter
Zaccolo, Valentina
author_facet Altmann, Javira
Bernardinis, Lorenzo
Skands, Peter
Zaccolo, Valentina
contents Measurements at LHC show an increased production of strange hadrons with charged multiplicity in pp collisions, which is not described by the Lund String Model (with the Monash tune) implemented in PYTHIA. This work investigates string closepacking, a mechanism invoked during hadronization where overlapping strings create a background field that increases the effective string tension. This reduces strangeness suppression, effectively enhancing production. The model also incorporates an option for "popcorn destructive interference", which suppresses baryon production, to address the non-strange $p/π$ ratio, utilizing color algebra arguments; and an option for "strange junctions", which enhances strangeness specifically within the baryon sector. The Trieste tunes of this model to LHC data are presented. The closepacking model is in qualitative agreement with many of the salient particle ratios, although the $Ξ_c/D$ ratio and the shape of $p_\perp$ spectra remain challenging to account for. Overall, the closepacking model with the Trieste tunes provides a competitive description of enhanced strangeness production in pp collisions, improving upon existing PYTHIA models while avoiding excessive proton yields.
format Preprint
id arxiv_https___arxiv_org_abs_2604_27752
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Strangeness enhancement in pp collisions from string closepacking in Pythia 8.3
Altmann, Javira
Bernardinis, Lorenzo
Skands, Peter
Zaccolo, Valentina
High Energy Physics - Phenomenology
Measurements at LHC show an increased production of strange hadrons with charged multiplicity in pp collisions, which is not described by the Lund String Model (with the Monash tune) implemented in PYTHIA. This work investigates string closepacking, a mechanism invoked during hadronization where overlapping strings create a background field that increases the effective string tension. This reduces strangeness suppression, effectively enhancing production. The model also incorporates an option for "popcorn destructive interference", which suppresses baryon production, to address the non-strange $p/π$ ratio, utilizing color algebra arguments; and an option for "strange junctions", which enhances strangeness specifically within the baryon sector. The Trieste tunes of this model to LHC data are presented. The closepacking model is in qualitative agreement with many of the salient particle ratios, although the $Ξ_c/D$ ratio and the shape of $p_\perp$ spectra remain challenging to account for. Overall, the closepacking model with the Trieste tunes provides a competitive description of enhanced strangeness production in pp collisions, improving upon existing PYTHIA models while avoiding excessive proton yields.
title Strangeness enhancement in pp collisions from string closepacking in Pythia 8.3
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2604.27752