A. Poves

Disassembling the nuclear matrix elements of the neutrinoless ββ decay

Abstract In this article we analyze the nuclear matrix elements (NME) of the neutrinoless double beta decays ( 0 ν β β ) of the nuclei 48 Ca, 76 Ge, 82 Se, 124 Sn, 128 Te, 130 Te and 136 Xe in the framework of the interacting shell model (ISM). We study the relative value of the different contributions to the NMEs, such as higher order terms in the nuclear current, finite nuclear size effects and short range correlations, as well as their evolution with the maximum seniority permitted in the wave functions. We discuss also the build-up of the NMEs as a function of the distance between the decaying neutrons. We calculate the decays to 0 1 + final states and find that these decays are at least 25 times more suppressed with respect to the ground state to ground state transition.

Shell Model Studies of the Double Beta Decays of 76Ge, 82Se, and 136Xe.

The lifetimes for the double beta decays of

Full pf shell model study of A =48 nuclei

~{76}

Influence of pairing on the nuclear matrix elements of the neutrinoless betabeta decays.

Ge,

Collapse of the N=28 shell closure in (42)Si.

~{82}

Shell Model Studies of the Double Beta Decays of {sup 76}Ge, {sup 82}Se, and {sup 136}Xe

Se and

Shell model study of the neutron-rich nuclei around N=28

~{136}

The onset of deformation at the N = 20 neutron shell closure far from stability

Xe are calculated using very large shell model spaces. The two neutrino matrix elements obtained are in good agreement with the present experimental data. For

Intrinsic vs laboratory frame description of the deformed nucleus 48Cr.

1.85\,10~{25} yr.

Full pf shell study of A=47 and A=49 nuclei

,