6He beta-decay rate and the suppression of the axial constant in nuclear matter

TL;DR

This paper presents a microscopic calculation of 6He beta-decay using chiral perturbation theory and JISP potentials, achieving close agreement with experimental decay rates and suggesting that axial constant suppression is inherently included.

Contribution

The study introduces a novel combination of chiral perturbation theory and JISP potentials for accurate beta-decay rate calculations, highlighting the role of mesonic currents.

Findings

Calculated decay rate within 3% of experimental value

Chiral-perturbation-theory-based mesonic currents improve agreement

Suppression of the axial constant is inherently included in the model

Abstract

We present a microscopic calculation of the 6He beta-decay into the ground state of 6Li. To this end, we use chiral perturbation theory at next-to-next-to-next-to-leading order to describe the nuclear weak-currents. The nuclear wave functions are derived from the J-matrix inverse scattering nucleon-nucleon potential (JISP), and the Schroedinger equation is solved using the hyperspherical-harmonics expansion. Our calculation brings the theoretical decay-rate within 3% of the measured one. This success is attributed to the use of chiral-perturbation-theory based mesonic currents, whose contribution is qualitatively different compared to standard nuclear physics approach, where the use of meson exchange currents worsens the comparison to experiment. The inherent inconsistency in the use of the JISP potential together with chiral-perturbation-theory based is argued not to affect this conclusion, though a more detailed investigation is called for. We conclude that any suppression of the axial constant in nuclear matter is included in this description of the weak interaction in the nucleus.