AN ALTERNATIVE APPROACH IN NUCLEAR DOUBLE BETA DECAY THEORY

A new formula as a series of commutators of two axial vector currents and the nuclear Hamiltonian H_S derived for estimating the 2β-decay nuclear matrix element without using explicitly the closure approximation. With a simple assumption of the nuclear wave function and the Hamiltonian H_S, it is shown that the leading term in 2υ-2β decay matrix element vanishes and thus the smallness of 2υ-2β decay probability seems to be understood.