News on strangeness production from the NA61/SHINE experiment

TL;DR

This paper presents new experimental results on strangeness production in medium-sized nuclear collisions at CERN SPS, revealing energy and system size dependencies and unexpected meson production excesses, with comparisons to theoretical models.

Contribution

It provides the first comprehensive analysis of Lambda hyperons and K mesons in Ar+Sc collisions at SPS energies, highlighting novel excess phenomena and model comparisons.

Findings

Lambda-to-pion and strangeness-to-pion ratios depend on energy and system size

An unexpected excess of charged over neutral K mesons in Ar+Sc and π−+C collisions

Results are consistent with some particle production models and extend existing data

Abstract

Strangeness production in high-energy hadronic and nuclear collisions continues to be one of the central topics in the study of strongly interacting matter. The data collected by the NA61/SHINE experiment at the CERN SPS North Area allow for a comprehensive scan of the strangeness production across various collision energies and system sizes. This article focuses on the new results of the strangeness production in central collisions of medium-sized nuclei, such as Ar+Sc, at the SPS energy range. In particular, the results for Lambda hyperons and charged and neutral $K$ mesons are shown. The energy and system size dependencies of Lambda-to-pion and strangeness-to-pion ratios are also explored. Moreover, an unexpected excess of charged over neutral $K$ meson production in Ar+Sc and $\pi^-$+C interactions is presented. The obtained results are compared with predictions from selected particle production models, as well as with existing world data from proton-proton and nucleus-nucleus collisions.