Measurement of the Xi0 -> Lambda gamma Decay Asymmetry and Branching Fraction

TL;DR

This paper reports the first measurement of decay asymmetry and branching fraction for Xi0 -> Lambda gamma using data from the NA48 experiment, providing new insights into hyperon radiative decays.

Contribution

It presents the first evidence of decay asymmetry in Xi0 -> Lambda gamma and precise measurements of its branching fraction based on experimental data.

Findings

Decay asymmetry alpha = -0.78 +- 0.18 (stat) +- 0.06 (syst)

Branching fraction Br = (1.16 +- 0.05 (stat) +- 0.06 (syst)) x 10^-3

First evidence of asymmetry in this decay mode

Abstract

In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Xi0 -> Lambda gamma have been found with an estimated background of 58+-8 events. From these events the Xi0 -> Lambda gamma decay asymmetry has been determined to alpha(Xi0 -> Lambda gamma) = -0.78 +- 0.18_stat +- 0.06_syst, which is the first evidence of a decay asymmetry in Xi0 -> Lambda gamma. The branching fraction of the decay has been measured to be Br(Xi0 -> Lambda gamma) = (1.16 +- 0.05_stat +- 0.06_syst) x 10^-3.