Additional nucleon current contributions to neutrinoless doubleβdecay

Abstract

We have examined the importance of momentum dependent induced nucleon currents such as weak-magnetism and pseudoscalar couplings to the amplitude of neutrinoless double beta decay (0νββ-decay) in the mechanisms of light and heavy Majorana neutrino as well as in that of Majoron emission.Such effects are expected to occur in all nuclear models in the direction of reducing the light neutrino matrix elements by about 30%. To test this we have performed a calculation of the nuclear matrix elements of the experimentally interesting nuclei A = 76, 82, 96, 100, 116, 128, 130, 136 and 150 within the proton-neutron renormalized Quasiparticle Random Phase Approximation (pn-RQRPA). We have found that indeed such corrections vary * Permanent address:

Nuclear matrix elements for double-βdecay

“…The theory of 0νββ decay was first formulated by Furry [18] and further developed by Primakoff and Rosen [19], Molina and Pascual [20], Doi et al [1], Haxton and Stephenson [21], and, more recently, by Tomoda [2] and Šimkovic et al [3]. All these formulations often differ by factors of 2, by the number of terms retained in the nonrelativistic expansion of the current and by their contribution.…”

“…All these formulations often differ by factors of 2, by the number of terms retained in the nonrelativistic expansion of the current and by their contribution. In order to have a standard set of calculations to be compared with the QRPA and the ISM, we adopt in this article the formulation of Šimkovic et al [3]. The transition operator in momentum space, p = | q|, is written as…”

“…[11] and [12]. In 1999 a new formulation of 0νββ was introduced [3] and calculations within the QRPA [13] and the ISM [14] were performed, as well as within other models, as discussed in the following Sec. II C. In 2009, we developed [15] a new method to evaluate nuclear matrix elements for double-β decay within the framework of the microscopic interacting boson model (IBM-2).…”

Overlap of quasiparticle random-phase approximation states based on ground states of different nuclei: Mathematical properties and test calculations

“…Because F 1 mm [Eq. (57)] has sixfold summations with respect to (μν), it is truncated separately, as mentioned before. We show the convergence of the overlap matrix elements with respect to N F + N I in Fig.…”

Overlap of quasiparticle random-phase approximation states for nuclear matrix elements of the neutrino-less double-βdecay

“…After the closure approximation is applied to the nuclear matrix elements of the 0νββ decay (e.g., Refs. [2,10,25]), one of those matrix elements, the Gamow-Teller type as an example, is written as…”