Baryon anticorrelations and the Pauli principle in PYTHIA

TL;DR

This paper investigates baryon anticorrelations in hadron collisions using PYTHIA, identifying that modifications at the string-fragmentation level can improve agreement with experimental data, and suggests Pauli principle effects may be missing in current models.

Contribution

It introduces simple modifications to PYTHIA's fragmentation process that qualitatively reproduce baryon anticorrelation data and highlights the potential role of Pauli principle effects at the quark level.

Findings

Modified PYTHIA policies reproduce anticorrelation behavior

Baryon anticorrelations originate at string fragmentation level

Pauli principle effects may be missing in current models

Abstract

We present a computational investigation of a problem of hadron collisions from recent years, that of baryon anticorrelations. This is an experimental dearth of baryons near other baryons in phase space, not seen upon examining numerical Monte Carlo simulations. We have addressed one of the best known Monte Carlo codes, PYTHIA, to see what baryon (anti)correlations it produces, where they are originated at the string-fragmentation level in the underlying Lund model, and what simple modifications could lead to better agreement with data. We propose two ad-hoc alterations of the fragmentation code, a "one-baryon" and an "always-baryon" policies that qualitatively reproduce the data behaviour, i.e anticorrelation, and suggest that lacking Pauli-principle induced corrections at the quark level could be the culprit behind the current disagreement between computations and experiment.