A Measurement of the Branching Ratio and Asymmetry of the Decay Cascade^0-->Sigma^0/gamma

TL;DR

This study measures the branching ratio and emission asymmetry of the rare decay Cascade0-->Sigma0/gamma, providing precise experimental data and analysis of decay distributions in hyperon decay.

Contribution

First measurement of the branching ratio and asymmetry parameter for the Cascade0-->Sigma0/gamma decay in a high-statistics experiment.

Findings

Branching ratio BR = (3.34 +/- 0.05 +/- 0.09) x 10^(-3)

Sigma0 emission asymmetry alpha = -0.63 +/- 0.09

4045 signal events identified with low background

Abstract

We have studied the rare weak radiative hyperon decay Cascade0-->Sigma0/gamma in the KTeV experiment at Fermilab. We have identified 4045 signal events over a background of 804 events. The dominant Cascade0-->Lambda/pi0 decay, which was used for normalization, is the only important background source. An analysis of the acceptance of both modes yields a branching ratio of BR(Cascade0-->Sigma0/gamma)=(3.34 +/- 0.05 +/- 0.09) x 10^(-3). By analyzing the final state decay distributions, we have also determined that the Sigma0 emission asymmetry parameter for this decay is alpha = -0.63 +/- 0.09.