Axial-vector weak coupling at medium momentum for astro neutrinos and double beta decays

Abstract

Neutrino nuclear responses associated with medium momentum transfer of q = 20–80 MeV/c for astro neutrinos and double beta decays (DBDs) were studied by using charge exchange (3He, t) reactions on 128Te and 130Te. Gamow–Teller and spin-dipole nuclear matrix elements (NMEs) are found to be reduced uniformly in the wide momentum region of q = 20–80 MeV/c with respect to pnQRPA NMEs by the coefficient of kNM ≈ 0.35, while the Fermi NME for the isobaric analog state is given by the sum rule limit in the momentum transfer region. The reduction is discussed in terms of the quenching of the axial vector coupling gAeff for astro-neutrinos and DBDs.