Recent results on Bose-Einstein correlations by the PHENIX Experiment

TL;DR

This paper presents recent results from the PHENIX experiment on Bose-Einstein correlations, revealing how HBT radii depend on various parameters and their implications for understanding the quark-gluon plasma phase transition and the critical point in high-energy collisions.

Contribution

It provides new measurements of azimuthal-angle dependence and particle type differences in HBT radii, and explores their connection to the QCD critical point and phase transition signals.

Findings

Strong azimuthal-angle dependence of HBT radii observed

Differences between kaon and pion HBT radii analyzed

Non-monotonic collision energy dependence suggests critical phenomena

Abstract

Bose-Einstein momentum correlation functions of identical bosons reveal the shape and size of the (soft) particle emitting source of the given particle. The widths of these correlation functions are called HBT radii, named after Brown and Twiss who studied the angular diameter of stars via intensity correlations in their radio telescopes. Today, high energy physics experiments measure the HBT radii as a function of many parameters: particle type, transverse momentum, azimuthal angle, collision energy, collision geometry. In this paper we present results from the RHIC PHENIX experiment. These include the observation of strong azimuthal-angle dependence of the extracted Gaussian HBT radii, the similarities and differences between kaon and pion HBT radii. The key point of this paper is the application of Bose-Einstein correlations to the search for the critical point: how HBT radii would show the appearance of a first order phase transition, and what the non-monotonic collision energy dependence of the pion source tells us about the critical point; and how the non-Gaussian shape of correlation functions is related to one of the critical exponents.