Beam-Energy and System-Size Dependence of Dynamical Net Charge Fluctuations

TL;DR

This paper measures net charge fluctuations in various heavy-ion and proton collisions across different energies, revealing their dependence on system size, energy, and angular acceptance, and examining their scaling behaviors.

Contribution

It provides new measurements of net charge fluctuations across multiple collision systems and energies, analyzing their scaling and angular dependence.

Findings

Dynamical fluctuations are non-zero at all energies.

Fluctuations show approximate 1/N_{part} scaling.

Strong dependence on azimuthal and pseudorapidity ranges.

Abstract

We present measurements of net charge fluctuations in $Au + Au$ collisions at $\sqrt{s_{NN}} = $ 19.6, 62.4, 130, and 200 GeV, $Cu + Cu$ collisions at $\sqrt{s_{NN}} = $ 62.4, 200 GeV, and $p + p$ collisions at $\sqrt{s} = $ 200 GeV using the net charge dynamical fluctuations measure $\nu_{+-,dyn}$. The dynamical fluctuations are non-zero at all energies and exhibit a rather modest dependence on beam energy. We find that at a given energy and collision system, net charge dynamical fluctuations violate $1/N_{ch}$ scaling, but display approximate $1/N_{part}$ scaling. We observe strong dependence of dynamical fluctuations on the azimuthal angular range and pseudorapidity widths.