Experimental Aspects of Nuclear Matrix Elements for Double Beta Decays and Astro Neutrinos

Abstract

Abstract We report briefly recent experimental studies of nuclear responses (square of nuclear matrix element NME) for astro-neutrinos and double beta decays (DBDs) by single EC/β decays, charge exchange reactions (CERs) and ordinary muou captures (OMCs). The NMEs are shown to be uniformly reduced with respect to quasi-particle and pnQRPA NMEs in wide multipole and momentum regions. The reduction is expressed by the quenching coefficient g A e f f / g A . Impact of the reduction on astro-neutrino and DBD studies is discussed.