K/pi Fluctuations at Relativistic Energies

TL;DR

This study measures $K/\pi$ fluctuations in gold-gold collisions across various energies, finding that fluctuations are energy-independent and scale with multiplicity density, providing insights into the dynamics of heavy-ion collisions.

Contribution

It presents new measurements of $K/\pi$ fluctuations at multiple energies and centralities, highlighting their scaling with multiplicity density and extending previous results to higher energies.

Findings

$K/\pi$ fluctuations are energy-independent in central collisions.

Fluctuations scale with multiplicity density, not participant number.

Results are consistent with previous measurements at lower energies.

Abstract

We report results for $K/\pi$ fluctuations from Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6, 62.4, 130, and 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. Our results for $K/\pi$ fluctuations in central collisions show little dependence on the incident energies studied and are on the same order as results observed by NA49 at the Super Proton Synchrotron in central Pb+Pb collisions at $\sqrt{s_{NN}}$ = 12.3 and 17.3 GeV. We also report results for the collision centrality dependence of $K/\pi$ fluctuations as well as results for $K^{+}/\pi^{+}$, $K^{-}/\pi^{-}$, $K^{+}/\pi^{-}$, and $K^{-}/\pi^{+}$ fluctuations. We observe that the $K/\pi$ fluctuations scale with the multiplicity density, $dN/d\eta$, rather than the number of participating nucleons.