Pion Number Fluctuations and Correlations in the Statistical System with Fixed Isospin

TL;DR

This paper investigates how isospin conservation affects pion number fluctuations and correlations in finite systems, revealing suppression or enhancement effects and their dependence on system size and quantum statistics.

Contribution

It provides a detailed analysis of pion number fluctuations and correlations under fixed isospin constraints, including finite-size effects and Bose statistics enhancements.

Findings

Neutral pions show fluctuation enhancement due to isospin conservation.

Charged pions exhibit suppressed fluctuations from isospin conservation.

Total pion fluctuations peak in small systems and approach thermodynamic limits.

Abstract

The statistical system of pions with zero total isospin is studied. The suppression effects for the average yields due to isospin conservation are the same for $\pi^0$, $\pi^+$ and $\pi^-$. However, a behavior of the corresponding particle number fluctuations are different. For neutral pions there is the enhancement of the fluctuations, whereas for charged pions the isospin conservation suppresses fluctuations. The correlations between the numbers of charged and neutral pions are observed for finite systems. This causes a maximum of the total pion number fluctuations for small systems. The thermodynamic limit values for the scaled variances of neutral and charged pions are calculated. The enhancements of the fluctuations due to Bose statistics are found and discussed.