Unmasking short-range correlations via initial-state fluctuations in relativistic heavy-ion collisions

TL;DR

This paper shows that initial-state fluctuations in relativistic heavy-ion collisions are highly sensitive to nucleon-nucleon short-range correlations, providing a new way to probe nuclear structure.

Contribution

It introduces the incorporation of NN-SRCs into initial conditions, revealing their impact on fluctuation observables and establishing a link to nuclear structure studies.

Findings

Higher-order fluctuations differ by over 10% with and without NN correlations.

Universal scaling of fluctuation measures with nuclear size and density.

Heavy-ion collisions can probe two-body and many-body nuclear interactions.

Abstract

Although relativistic heavy-ion collisions have emerged as a powerful probe for studying nuclear structure, the potential influence of nucleon-nucleon short-range correlations (NN-SRCs) on the initial state has remained an open question. By incorporating NN-SRCs into the initial conditions, we demonstrate that higher-order fluctuations of the initial transverse size, $n$-particle $c_{E/S}\{n\}$, which can be directly mapped to final-state mean transverse momentum fluctuations, exhibit remarkable sensitivity to NN-SRCs. Quantitatively, $c_{E/S}\{3\}$ and $c_{E/S}\{4\}$ differ by more than 10\% between systems with and without NN correlations. Moreover, we report a universal scaling of these quantities with $A^{-1/3}$ and the average nuclear density, mirroring the connection between the SRC effect and the EMC effect in electron scatterings. This work establishes relativistic heavy-ion collisions as a new tool for probing nuclear structure and constraining two-body or many-body NN interactions across different energy scales and system sizes.