A New Limit on Time-Reversal Violation in Beta Decay

TL;DR

This paper presents the most sensitive measurement to date of time-reversal violation in neutron beta decay, constraining new physics beyond the Standard Model through a precise determination of the D coefficient.

Contribution

The study provides an improved experimental limit on the D coefficient, refining constraints on time-reversal symmetry violation in beta decay.

Findings

Measured D coefficient: (-0.96 ± 1.89 (stat) ± 1.01 (sys))×10^{-4}

Phase between g_A and g_V: 180.013° ± 0.028°

Sets new upper bounds on time-reversal violation in beta decay.

Abstract

We report the results of an improved determination of the triple correlation $D P \cdot(p_{e}\times p_{\nu})$ that can be used to limit possible time-reversal invariance in the beta decay of polarized neutrons and constrain extensions to the Standard Model. Our result is $D=(-0.96\pm 1.89 (stat)\pm 1.01 (sys))\times 10^{-4}$. The corresponding phase between g_A and g_V is $\phi_{AV} = 180.013^\circ\pm0.028^\circ$ (68 % confidence level). This result represents the most sensitive measurement of D in beta decay.