HBT interferometry with quantum transport of the interfering pair

TL;DR

This paper investigates the quantum transport of interfering pion pairs during heavy-ion collisions using a path-integral approach, revealing how multiple scattering and particle decays influence HBT radii and the interpretation of freeze-out conditions.

Contribution

It introduces a quantum transport model for interfering pion pairs in heavy-ion collisions, combining hydrodynamics and path-integral methods to analyze HBT interferometry.

Findings

Quantum transport yields HBT radii close to chemical freeze-out values.

Particle decays increase HBT radii beyond chemical freeze-out.

Combined effects produce HBT radii between chemical and thermal freeze-out.

Abstract

In the late stage of the evolution of a pion system in high-energy heavy-ion collisions when pions undergo multiple scatterings, the quantum transport of the interfering pair of identical pions plays an important role in determining the characteristics of the Hanbury-Brown-Twiss (HBT) interference. We study the quantum transport of the interfering pair using the path-integral method, in which the evolution of the bulk matter is described by relativistic hydrodynamics while the paths of the two interfering pions by test particles following the fluid positions and velocity fields. We investigate in addition the effects of secondary pion sources from particle decays, for nuclear collisions at AGS and RHIC energies. We find that quantum transport of the interfering pair leads to HBT radii close to those for the chemical freeze-out configuration. Particle decays however lead to HBT radii greater than those for the chemical freeze-out configuration. As a consequence, the combined effects give rise to HBT radii between those extracted from the chemical freeze-out configuration and the thermal freeze-out configuration. Proper quantum treatments of the interfering pairs in HBT calculations at the pion multiple scattering stage are important for our understanding of the characteristics of HBT interferometry in heavy-ion collisions.