Timescales in heavy ion collisions

TL;DR

This paper examines the timescales involved in heavy ion collisions, highlighting how femtoscopy measures long timescales and how energy-dependent measurements suggest possible phase transition effects.

Contribution

It provides a detailed analysis of timescales in heavy ion collisions, including new insights from shape analysis and relativistic measurements across different energies.

Findings

Femtoscopy measures very long timescales in low-energy collisions.

Relativistic measurements show timescale increase over energy range.

Possible indication of a first-order phase transition.

Abstract

The study of high energy collisions between heavy nuclei is a field unto itself, distinct from nuclear and particle physics. A defining aspect of heavy ion physics is the importance of a bulk, self-interacting system with a rich space-time substructure. I focus on the issue of timescales in heavy ion collisions, starting with proof from low-energy collisions that femtoscopy can, indeed, measure very long timescales. I then discuss the relativistic case, where detailed measurements over three orders of magnitude in energy reveal a timescale increase that might be due to a first-order phase transition. I discuss also consistency in evolution timescales as determined from traditional longitudinal sizes and a novel analysis using shape information.