Energy Dependence of $K\pi$, $p\pi$, and $Kp$ Fluctuations in Au+Au Collisions from $\rm \sqrt{s_{NN}}$ = 7.7 to 200 GeV

TL;DR

This study investigates how fluctuations in particle pairs like $K o ext{pi}$, $p o ext{pi}$, and $Kp$ vary with collision energy in heavy-ion collisions, aiming to find signs of the QCD critical point.

Contribution

It provides the first comprehensive measurement of dynamical particle pair fluctuations across a wide energy range in Au+Au collisions, using the $ u_{dyn}$ observable.

Findings

Fluctuations show a smooth energy dependence without abrupt changes.

No evidence of critical point signatures within the studied energy range.

Results help constrain the location of the QCD critical point.

Abstract

A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy-ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical $K\pi$, $p\pi$, and $Kp$ fluctuations as measured by the STAR experiment in central 0-5\% Au+Au collisions from center-of-mass collision energies $\rm \sqrt{s_{NN}}$ = 7.7 to 200 GeV are presented. The observable $\rm \nu_{dyn}$ was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the $K\pi$, $p\pi$, and $Kp$ pairs. The energy dependences of these fluctuations from central 0-5\% Au+Au collisions all demonstrate a smooth evolution with collision energy.