An ab initio recipe for taming nuclear-structure dependence of V_ud: the ^10C→^10B superallowed transition

We report the first ab initio calculation of the nuclear-structure-dependent radiative correction δ_NS to the ^10C→^10B superallowed transition, computed with the no-core shell model and chiral effective field theory. We obtain δ_NS = - 0.400 (29)_nuc (12)_n,el with a 1.7-times reduction in the nuclear uncertainty when compared to the current literature estimate based on the shell model and Fermi gas picture. This work paves the way for a precise determination of V_ud from superallowed beta decays.