Physics from HBT radii

TL;DR

This paper derives an approximate formula linking true and HBT homogeneity regions in multiparticle production, emphasizing the importance of using the center of mass system for accurate HBT radius calculations and discussing the method's limitations.

Contribution

It introduces a new approximate formula for relating true and HBT homogeneity regions and highlights the necessity of using the center of mass system over LCMS for HBT radius calculations.

Findings

Using the center of mass system improves HBT radius accuracy.

HBT radii do not constrain the relative positions of homogeneity regions.

HBT radii are limited in describing interparticle interactions in coordinate space.

Abstract

An approximate formula connecting the true and the HBT homogeneity regions in multiparticle production processes is derived. It implies that when calculating the HBT radii one should use the ceter of mass systems of the pairs rather than the now popular LCMS system. A discussion of several examples clarifies the potential and limitations of the HBT method. The even cumulants of the X-distribution, inculding the HBT radii, can be determined for each homogeneity region, but the relative positions of the homogeneity regions are unconstrained. This makes the HBT radii of little use for calculating quantities dependent on the interparticle interactions in coordinate space.