Quantum canonical ensemble and correlation femtoscopy at fixed multiplicities

TL;DR

This paper explores quantum canonical ensemble methods to analyze particle correlations at fixed multiplicities, providing analytical tools for femtoscopy in high-energy collisions.

Contribution

It introduces a recurrence relation for the partition function to calculate correlation functions in finite systems, assessing the validity of thermal Wick's theorem.

Findings

Derived analytical formulas for correlation function suppression effects.

Analyzed the dependence of Bose-Einstein correlations on pair momentum.

Provided tools for femtoscopy analysis in A+A and p+p collisions.

Abstract

Identical particle correlations at fixed multiplicity are considered by means of quantum canonical ensemble of finite systems. We calculate one-particle momentum spectra and two-particle Bose-Einstein correlation functions in the ideal gas by using a recurrence relation for the partition function. Within such a model we investigate the validity of the thermal Wick's theorem and its applicability for decomposition of the two-particle distribution function. The dependence of the Bose-Einstein correlation parameters on the average momentum of the particle pair is also investigated. Specifically, we present the analytical formulas that allow one to estimate the effect of suppressing the correlation functions in a finite canonical system. The results can be used for the femtoscopy analysis of the A+A and p+p collisions with selected (fixed) multiplicity.