Chiral Effective Field Theory Calculations of Weak Transitions in Light Nuclei

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We report Quantum Monte Carlo calculations of weak transitions in $A\leq 10$ nuclei, based on the Norfolk two- and three-nucleon chiral interactions, and associated one- and two-body axial currents.

• We find that the contribution from two-body currents is at the $2$ - $3\%$ level, with the exception of matrix elements entering the rates of $^8$Li, $^8$B, and $^8$He beta decays.
• These matrix elements are suppressed in impulse approximation based on the (leading order) Gamow Teller transition operator alone; two-body currents provide a $20$ - $30\%$ correction, which is, however, insufficient to bring theory in agreement with experimental data.
• For the other transitions, the agreement with the data is satisfactory, and the results exhibit a negligible to mild model dependence when different combinations of Norfolk interactions are utilized to construct the nuclear wave functions.