Neutrinoless doubleβdecay within the self-consistent renormalized quasiparticle random phase approximation and inclusion of induced nucleon currents

Abstract

The first, to our knowledge, calculation of neutrinoless double beta decay (0νββ-decay ) matrix elements within the self-consistent renormalized Quasiparticle Random Phase Approximation (SRQRPA) is presented. The contribution from the momentum-dependent induced nucleon currents to 0νββ-decay amplitude is taken into account. A detailed nuclear structure study includes the discussion of the sensitivity of the obtained SRQRPA results for 0νββ-decay of 76 Ge to the parameters of nuclear Hamiltonian, two-nucleon short-range correlations and the truncation of the model space. A comparison with the standard and renormalized QRPA results is presented. We have found a considerable reduction of the SRQRPA nuclear matrix elements, resulting in less stringent limits for the effective neutrino mass. PACS numbers:23.40. Hc, 21.60.Jz, 27.50.+e, 27.60.+j The neutrino mass and mixing of neutrinos are the main subject of the elementary 1

Double-beta decay

“…The shell-model truncation by Haxton and Stephenson (1984) was done in a way that minimized np pairing, and the upper limit in C mm from Engel et al (1989) was considered probably too large by the authors (though in their calculation they set g A = 1, which here would move the upper limit into the middle of the range). At the other end of the spectrum, the very small self-consistent RQRPA decay rates of reference Bobyk et al (2001) were obtained with a value of the np pairing strength that was not consistent with the measured ββ(2ν) rate; when the strength is adjusted to reproduce ββ(2ν) decay, the results for the ββ(0ν) rate are close to those of the plain QRPA in the same reference. Without any further culling, the remaining C's vary by about 1 order of magnitude, and the extracted m ββ 's vary by a factor of about three, from 0.022 to 0.068 eV for the lifetime we have chosen.…”

0νββnuclear matrix elements and the occupancy of individual orbits

“…[14] and to the evaluation of 0νββ matrix elements in Ref. [15]. Numerically, the double iteration procedure represents a challenging problem.…”

Neutrino beams as a probe of the nuclear isospin and spin–isospin excitations

“…[13]) and is well established for neutrinoless double-beta decay (see e.g. [19,20]). Using sumrules, one can relate the spin-dipole strength distribution to the neutron skin thickness defined as the difference between the root mean square radii of the proton and neutron distributions.…”