Double β Decay and the Axial Strength

Quenching of the weak axial strength g A is discussed and relations of this quenching to the nuclear matrix elements of double beta decays are highlighted. An analysis of Gamow-Teller transitions in the mass range A = 62 -142 is presented and its results are compared with those of many previous works. The enhancement of the axial charge is discussed for first-forbidden pseudoscalar transitions. Higher-forbidden transitions are introduced and their role in determining the effective value of g A is examined, in particular from the point of view of the -decay half-lives and the shapes of electron spectra of forbidden non-unique transitions.