Nuclear ab initio calculations of 6He β-decay for beyond the Standard Model studies

Abstract

Precision measurements of β-decay observables offer the possibility to search for deviations from the Standard Model. A possible discovery of such deviations requires accompanying first-principles calculations. Here we compute the nuclear structure corrections for the β-decay of 6He which is of central interest in several experimental efforts. We employ the impulse approximation together with wave functions calculated using the ab initio no-core shell model with potentials based on chiral effective field theory. We use these state-of-the-art calculations to give a novel and comprehensive analysis of theoretical uncertainties. We find that nuclear corrections, which we compute within the sensitivity of future experiments, create significant deviation from the naive Gamow-Teller predictions, making their accurate assessment essential in searches for physics beyond the Standard Model.