Bose-Einstein correlations and color reconnection in hadronic W

TL;DR

This study investigates Bose-Einstein correlations and color reconnection effects in hadronic W pair decays at LEP, providing constraints on their impact on W mass measurements.

Contribution

It presents the first combined LEP results on Bose-Einstein correlations and color reconnection, constraining their effects on W mass systematic uncertainties.

Findings

Bose-Einstein correlations between different W decay particles are consistent with zero.

Measurements exclude extreme color reconnection models.

Results limit the systematic uncertainty in W mass measurements.

Abstract

We report on studies of Bose-Einstein correlations and color reconnection in hadronic W pair production at LEP. Bose-Einstein correlations between identical particles from the decay of different W's are studied by comparing the particle correlation in hadronic W pair decays to those in events which are constructed from the combination of the hadronic parts of two events where one of the Ws decays leptonicaly. The LEP combined result of the strength of the effect is consistent with zero and can be used to limit the systematic uncertainty due to Bose-Einstein correlations on the W mass measurements. Color reconnection is expected to affect the production of particles in hadronic decays of W pairs. Measurements of inclusive charged particle multiplicities, and of their angular distribution with respect to the four jet axes of the events, are used to test models of color reconnection. The results are both consistent with models without color reconnection and models with moderate color reconnection. They can be used to exclude more extreme models of color reconnection and thereby limit the uncertainty due to color reconnection on the W mass measurement.