Bose-Einstein Correlations of pi0 Pairs from Hadronic Z0 Decays

TL;DR

This study reports the observation of Bose-Einstein correlations in neutral pion pairs from Z0 decays, providing measurements of source size and chaoticity, and analyzing their origin using Monte Carlo models.

Contribution

First measurement of Bose-Einstein correlations in pi0 pairs from Z0 decays with detailed source parameter extraction.

Findings

Measured chaoticity parameter lambda = 0.55 +- 0.10 +- 0.10

Determined source radius R = (0.59 +- 0.08 +- 0.05) fm

Correlations mainly from pions from different hadron decays

Abstract

We observed Bose-Einstein correlation in pi0 pairs produced in Z0 decays using the data sample collected by the OPAL detector at LEP 1 from 1991 to 1995. Using a static Gaussian picture for the pion emitter source, we obtain the chaoticity parameter lambda = 0.55 +- 0.10 +- 0.10 and the source radius R = (0.59 +- 0.08 +- 0.05) fm. according to the JETSET and HERWIG Monte Carlo models, the Bose-Einstein correlations in our data sample largely connect pi0s originating from the decays of different hadrons. Prompt pions formed at string break-up of cluster decays only form a small fraction of the sample.