Search for CP Violation in Charged-Xi and Lambda Hyperon Decays

TL;DR

This study searched for CP violation in charged-Xi and Lambda hyperon decays by comparing proton and antiproton angular distributions, finding no evidence of CP violation within experimental uncertainties.

Contribution

The paper provides the most precise measurement to date of the CP-violating parameter in these hyperon decays, setting stringent limits on CP violation.

Findings

No evidence of CP violation was observed.

The CP-violating parameter $A_{\Xi\Lambda}$ measured as approximately 0 with uncertainties.

Results constrain theories predicting CP violation in hyperon decays.

Abstract

We have compared the proton and antiproton angular distributions in 117 million Xi-minus -> Lambda + pi-minus -> proton + pi-minus + pi-minus and 41 million anti-Xi-minus -> anti-Lamba + pi-plus -> antiproton + pi-plus + pi-plus decays using a subset of the data from the HyperCP experiment (E871) at Fermilab. We find no evidence of CP violation, with the direct-CP-violating parameter $A_{\Xi\Lambda} = \frac{\alpha_{\Xi}\alpha_{\Lambda} - \bar{\alpha}_{\Xi}\bar{\alpha}_{\Lambda}}{\alpha_{\Xi}\alpha_{\Lambda} + \bar{\alpha}_{\Xi}\bar{\alpha}_{\Lambda}} = [0.0+/-5.1(stat)+/-4.4(syst)]{\times}10^{-4}$.