Limits on tensor type weak currents from nuclear and neutron $\beta$~decays

TL;DR

This paper evaluates the current experimental limits on tensor-type weak currents from nuclear and neutron beta decays, showing they are more restrictive than previous pion decay measurements and exploring future measurement sensitivities.

Contribution

It provides updated bounds on tensor weak currents using recent data and compares their stringency to other experimental results, also analyzing future measurement prospects.

Findings

Limits on tensor currents are tighter than previous pion decay bounds.

Current bounds: |(C_T + C'_T)/C_A| < 0.0037.

Future experiments could reach sensitivities of 10^{-3}.

Abstract

The limits on time-reversal invariant tensor-type weak currents from nuclear and neutron $\beta$ decays are evaluated including most recent experimental data. We find that $ -0.14 \times 10^{-2} < (C_T + C^\prime_T)/C_A < 1.4 \times 10^{-2} $ and $ -0.16 < (C_T - C^\prime_T)/C_A < 0.16$ (90% C.L.), while for the case $C_T = C^\prime_T$ the limits are $ | C_T/C_A | < 3.7 \times 10^{-3} $. These limits are shown to be more stringent than those from recent measurements of the radiative pion decay. In addition, the sensitivity of future $10^{-3}$-level correlation measurements is investigated.