Isospin-symmetry breaking in kaon production: the role of charge-symmetry

TL;DR

This paper investigates the observed excess of charged over neutral kaons in heavy ion collisions, highlighting the role of charge-symmetry and isospin transformations in explaining the phenomenon.

Contribution

It demonstrates that charge-symmetry in initial nuclei can lead to equal charged and neutral kaon production in the isospin-symmetry limit, addressing discrepancies in models.

Findings

Charge-symmetry in initial nuclei influences kaon charge ratios.

Models underestimate the charge-to-neutral kaon ratio.

Charge-symmetry considerations can explain kaon production asymmetries.

Abstract

An excess of charged versus neutral kaons has been recently reported by the NA61/SHINE collaboration. Similar excesses were also present in previous experiments, even if with larger errors. Models for hadron productions in heavy ion collisions systematically underestimate the measured charge-to-neutral kaon ratio. In this report, we comment on the role of charge-symmetry as a specific isospin transformation. In particular, we show that the ensemble of the initial colliding nuclei being charge-symmetric is sufficient for producing an equal number of charged and neutral kaons in the isospin-symmetry exact limit.