Forward-backward multiplicity fluctuations in ultra-relativistic nuclear collisions with wounded quarks and fluctuating strings

TL;DR

This paper presents a semi-analytical model of particle fluctuations in ultra-relativistic nuclear collisions, incorporating wounded quarks and fluctuating strings, and compares model predictions with experimental data.

Contribution

It introduces a semi-analytical approach to analyze string fluctuations and their impact on particle correlations in high-energy nuclear collisions.

Findings

String fluctuations are constrained by experimental emission functions.

Common fluctuation measures have limited range and similar values across models.

Different end-point distributions yield similar correlation results.

Abstract

We analyze a generic model where wounded quarks are amended with strings in which both end-point positions fluctuate in spatial rapidity. With the assumption that the strings emit particles independently of one another and with a uniform distribution in rapidity, we are able to analyze the model semi-analytically, which allows for its detailed understanding. Using as a constraint the one-body string emission functions obtained from the experimental data for collisions at $\sqrt{s_{NN}}=200$ GeV, we explore the two-body correlations for various scenarios of string fluctuations. We find that the popular measures used to quantify the longitudinal fluctuations are limited with upper and lower bounds and assume close values for the most likely models of the end-point distributions, which may explain why various approaches yield here very similar results.