Potential and limitations of the HBT method

TL;DR

The paper reviews the capabilities and limitations of the HBT method in analyzing the size, shape, and evolution of homogeneity regions in hadroproduction, highlighting what parameters can be inferred and what requires additional assumptions.

Contribution

It provides a theoretical discussion and a theorem clarifying which parameters of the Wigner function can be obtained with the HBT method and what additional assumptions are necessary for full reconstruction.

Findings

The HBT method reveals certain parameters of the Wigner function.

Complete reconstruction of the emission function requires additional assumptions.

A theorem specifies which Wigner function parameters are accessible via HBT.

Abstract

The HBT method is used to get information about the sizes, shapes and sometimes also about the time evolution of the homogeneity regions in hadroproduction processes. Homogeneity region K is the region where the hadrons with momentum K are produced. The size and shape of he homogeneity region is described by the Wigner function W(K,X) evaluated in the interaction picture after all the hadrons had been produced. Additional information about the interaction region is contained in the emission functio S(K,X). A theorem is presented and discussed which specifies which of the parameters characterizing the Wigner functin can and which cannot be obtained using the HBT method. In order to obtain the complete Wigner fuction additional assumptions are needed. For instance, it is enough to know the distribution of the centers of the homogeneity regions <X>_K. In order to find the emission function further assumptions are required. No systematic analysis is available, but some instructive examples are discussed.