EFT* for electroweak processes of light nuclei

Recently we succeeded to make a reliable EFT prediction in a totally parameter-free manner for the S factors for the solar pp and hep processes, p + p → d + e + νe and He+ p → He+ e+ νe[1]. The strategy used in there is to embed a highly sophisticated standard nuclear physics approach (SNPA) exploiting realistic potentials[2,3] into an EFT framework, that we refer to as EFT∗. Up to next-next-to-leading order in chiral expansion, it turnes out that there is effectively only one counter-term relevant to this process, the coefficient of which – (d̂) – has been renormalized to reproduce the experimental value of the tritium-beta decay. Our study has also led to very accurate EFT calculations on two-body weak processes that also receive contributions from the d̂ term, μ− d capture rate[4], and ν − d scattering cross section[5].