Neutrinoless double beta decay of76Ge,82Se,

Abstract

The neutrinoless double beta decay (0νββ-decay) transition to the first excited 0 + collective final state is examined for A=76, 82, 100 and 136 nuclei by assuming light and heavy Majorana neutrino exchange mechanisms as well as the trilinear R-parity violating contributions. Realistic calculations of nuclear matrix elements have been performed within the renormalized Quasiparticle Random Phase Approximation. Transitions to the first excited twoquadrupole phonon 0 + state are described within a boson expansion formalism and alternatively by using the operator recoupling method. We present the sensitivity parameters to different lepton number violating signals, which can be used in planning the 0νββ-decay experiments. The half-life of 0νββ-decay to the first excited state 0 + 1 is by a factor of 10 to 100 larger than that of the transition to the ground state, 0 + g.s. .

Nuclear matrix elements for double-βdecay

“…In this case, there appears to be no correlation between IBM-2 and other calculations. It should be noted, however, that the QRPA-Tü results shown in Table V were done before an error was discovered in the treatment of short-range correlations [34] and with two different methods for treating the excited 0 + 2 state, the recoupling method (RCM) and the boson expansion method (BEM) [32]. These results are therefore inconsistent by a factor of approximately 2 with those in Table IV and Ref.…”

Neutrinoless double-beta decay and physics beyond the standard model

“…More directly, it is also possible to infer the dominant mechanism purely within the context of neutrinoless double beta decay and closely related processes. Relevant techniques discussed in the literature include (i) the comparison of 0νββ decay rates in different isotopes [104][105][106] (this possibility is discussed in detail in the contribution by Fogli et al), (ii) the comparison of 0νβ − β − with 0νβ + β + [107], (iii) the comparison of 0νββ with electron capture [107], (iv) the comparison of of 0νββ decay to the ground state and an excited state [108] and (v) the experimental determination of the angular and energy distribution of the outgoing electrons in 0νββ [4,[109][110][111][112][113][114].…”

Double Beta Decays and Neutrino Masses

“…Thus the ratio may be used to identify the process, 22,24,68) provided that both the theoretical calculation and the experimental measurement are made accurately.…”

“…Nuclear matrix elements for excited states have been discussed in terms of QRPA. 23,68) The matrix elements are quite sensitive to the nuclear structures and processes. Although the transition rates for excited states are much smaller than the rate for the ground state, the experiment is nearly free of BG's.…”