The heavy ions are "preheated" prior to hight energy collisions

TL;DR

This paper proposes a novel connection between low-energy nuclear structure and high-energy collision effects by introducing the concept of preheated nuclei with thermal density matrices, using semiclassical methods to explain observed differences.

Contribution

It introduces the idea of preheating nuclei with an effective temperature to account for shape differences affecting high-energy collision observables.

Findings

Nuclear shape differences are linked to low-energy properties.

Thermal density matrices can model excited state contributions.

Semiclassical flucton method is suitable for finite-temperature calculations.

Abstract

The so called "isobar run" or RHIC was designed to compare a number of observables for collisions of $^{96}_{40}Zr$ with those of $^{96}_{44}Ru$, aimed at identification of $Z$-dependent effects. However, as the STAR data have shown with unprecedented accuracy, these two nuclides differ stronger than expected, producing effects larger than those depending on charge. So far, multiple studies tried to quantify their shape differences, in relation to various observables. General consensus is that these differences somehow should be related to nuclear structure, in particularly properties of the lowest excited states. Yet the precise connection between these fields -- low and high energy nuclear physics -- is still missing. In this paper I propose such a connection, via a concept of thermal density matrices of a "preheated" nuclei. The effective temperature should parameterize which set of excited states should be included in the calculations. I also suggest semiclassical "flucton" method at finite temperatures to be used to calculate thermal density matrices.