New results on event-by-event ratio fluctuations in Pb+Pb collisions at CERN SPS energies

TL;DR

This paper reports on event-by-event hadron ratio fluctuations in Pb+Pb collisions at CERN SPS energies, revealing a universal scaling with multiplicities and potential signals of changes in baryon number-strangeness correlations.

Contribution

It presents new measurements of hadron ratio fluctuations across energies and centralities, identifying a universal scaling and possible indications of phase transition effects.

Findings

Universal scaling describes energy and centrality dependence of certain ratio fluctuations.

Scaling breaks for specific ratios, hinting at changes in baryon number-strangeness correlation.

Results suggest sensitivity of fluctuations to phase transition phenomena.

Abstract

Event-by-event fluctuations of produced particle multiplicities are believed to be sensitive to a deconfinement phase transition and the critical point of strongly interacting matter. The NA49 collaboration has conducted a systematic study of various fluctuation observables. In this contribution, recent results on hadron ratio fluctuations in central Pb+Pb collisions at sqrt(s_NN) = 6.3 to 17.3 GeV are reported. These results are complemented by the centrality dependence of hadron ratio fluctuations at sqrt(s_NN) = 17.3 GeV. A universal scaling was found, describing the energy and centrality dependence of the (K++ K-)/({\pi}++ {\pi}-) and (p + pbar)/({\pi}++ {\pi}-) ratio fluctuations purely by a change in the observed average hadron multiplicities. This scaling is broken for the fluctuations of the (K+ + K-)/(p + pbar) and K+/p ratios, possibly hinting at a change in the baryon number-strangeness correlation.