Bose-Einstein Correlations in e+e- to W+W- at 172 and 183 GeV

TL;DR

This study investigates Bose-Einstein correlations among pions produced in electron-positron collisions at 172 and 183 GeV, aiming to understand their origin in W boson decays and inter-W interactions.

Contribution

It provides the first evidence of Bose-Einstein correlations in W decays and attempts to distinguish correlations from pions originating from the same or different W bosons.

Findings

Bose-Einstein correlations are observed in W decays.

No definitive evidence for correlations between pions from different W bosons.

Measured source radius R is approximately 0.92 fm.

Abstract

Bose-Einstein correlations between like-charge pions are studied in hadronic final states produced by e+e- annihilations at center-of-mass energies of 172 and 183 GeV. Three event samples are studied, each dominated by one of the processes W+W- to qqlnu, W+W- to qqqq, or (Z/g)* to qq. After demonstrating the existence of Bose-Einstein correlations in W decays, an attempt is made to determine Bose-Einstein correlations for pions originating from the same W boson and from different W bosons, as well as for pions from (Z/g)* to qq events. The following results are obtained for the individual chaoticity parameters lambda assuming a common source radius R: lambda_same = 0.63 +- 0.19 +- 0.14, lambda_diff = 0.22 +- 0.53 +- 0.14, lambda_Z = 0.47 +- 0.11 +- 0.08, R = 0.92 +- 0.09 +- 0.09. In each case, the first error is statistical and the second is systematic. At the current level of statistical precision it is not established whether Bose-Einstein correlations, between pions from different W bosons exist or not.