T violation in radiative $\beta$ decay and electric dipole moments

TL;DR

This paper investigates how beyond the standard model sources of time-reversal violation affect radiative beta decay and electric dipole moments, showing current EDM bounds strongly limit observable T-violation in decay.

Contribution

It establishes a connection between T-violation effects in radiative beta decay and electric dipole moments, constraining new physics models using existing EDM bounds.

Findings

Current EDM bounds strongly constrain T-odd correlations in radiative beta decay.

BSM sources of T-violation above the electroweak scale induce correlated effects in decay and EDMs.

The study links observable decay asymmetries to fundamental CP-violating parameters.

Abstract

In radiative $\beta$ decay, $T$ violation can be studied through a spin-independent $T$-odd correlation. We consider contributions to this correlation by beyond the standard model (BSM) sources of $T$-violation, arising above the electroweak scale. At the same time such sources, parametrized by dimension-6 operators, can induce electric dipole moments (EDMs). As a consequence, the manifestations of the $T$-odd BSM physics in radiative $\beta$ decay and EDMs are not independent. Here we exploit this connection to show that current EDM bounds already strongly constrain the spin-independent $T$-odd correlation in radiative $\beta$ decay.