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Double-β decay within a consistent deformed approach

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Double-β decay within a consistent deformed approach

In this paper we present a timely application of the proton-neutron deformed quasiparticle random-phase approximation (pn-dQRPA), designed to describe in a consistent way the 1+ Gamow-Teller states in oddodd deformed nuclei. For this purpose we apply a projection before variation procedure by using a singleparticle basis with projected angular momentum, provided by the diagonalization of a spherical mean field plus quadrupole-quadrupole interaction. The residual Hamiltonian contains pairing plus proton-neutron dipole terms in particle-hole and particle-particle channels, with constant strengths. As an example we describe the two-neutrino double-beta (2νββ) decay of 150Nd to the ground state of 150Sm. The experimental (p,n) type of strength in 150Nd and the (n,p) type of strength in 150Sm are reasonably reproduced and the 2νββ decay matrix element depicts a strong dependence upon the particle-particle strength gpp. The experimental half-life is reproduced for gpp = 0.05. It turns out that the measured half-lives for 2νββ transitions between other deformed superfluid partners with mass numbers A = 82,96,100,128,130,238 are reproduced with fairly good accuracy by using this value of gpp.

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