Closepacking effects on strangeness and baryon production at the LHC

TL;DR

This paper explores how string closepacking during hadronization at the LHC enhances strangeness production, addressing discrepancies between data and standard models by introducing a background field that increases effective string tension.

Contribution

It introduces a string closepacking mechanism that increases effective string tension, improving the description of strangeness production in pp collisions at the LHC.

Findings

Model qualitatively reproduces many particle ratios.

Enhances strangeness production compared to default PYTHIA.

Challenges remain in describing XiC/D ratio and pT spectra shape.

Abstract

Data from the LHC show a rise in strange-hadron production with charged-particle multiplicity in pp collisions. The Monte-Carlo event generator PYTHIA, using its default Monash tune, instead predicts constant strangeness. We investigate a mechanism invoked during hadronization called string closepacking, where overlapping strings generate a background field, here assumed to be predominantly aligned with the beam axis. This increases the effective string tension, reducing strangeness suppression and thus enhancing strangeness production. We tune this model to LHC data and contrast it with several alternatives. We comment specifically on the challenge of simultaneously describing the non-strange p/pi ratio, and introduce a mechanism which may act to suppress it. Many of the salient particle-production ratios can be qualitatively described by this model, although the XiC/D ratio and the shape of pT spectra remain challenging to account for.