Description of the two neutrino double β decay in deformed nuclei with projected spherical single particle basis

Abstract

Using an angular-momentum-projected single-particle basis, a proton-neutron quasiparticle random-phase approximation approach is used to study the 2νββ properties of 10 isotopes, exhibiting various quadrupole deformations. The parent and daughter nuclei exhibit different quadrupole deformations. Since the projected basis enables a unified description of deformed and spherical nuclei, situations where the nuclei involved in the double β decay process are both spherical, both deformed, or one spherical and the other deformed can be treated through a single formalism. Dependence of single β − and β + strength distribution on atomic mass number and nuclear deformation is analyzed. For the double β decay process, the Gamow-Teller transition amplitudes and half-lives are calculated. Results are compared with experimental data as well as with predictions of other theoretical approaches. The agreement between the present results and experimental data is fairly good.

Neutrino–nuclear responses for astro-neutrinos, single beta decays and double beta decays

“…These spherical QRPA models have been extended to deformed QRPA approaches, e.g. in [593,607,608,609,610,611,612,613].…”

FRpnQRPA approach with the gauge symmetry restored. Application for the 2νββdecay

“…The proton and neutron pairing strengths are different slightly from those from the quoted reference since the dimension of the single particle basis used in the present paper is different from that from Ref. [11]. The strength χ was taken to be…”

“…The parameters defining the single particle energies are those of the spherical shell model, the deformation parameter d and the parameter k are fixed as described in Ref. [11]. The proton and neutron pairing strengths are different slightly from those from the quoted reference since the dimension of the single particle basis used in the present paper is different from that from Ref.…”

Unified description of 21+states within the deformed quasiparticle random-phase approximation

“…The resulting equations of motion have formally a similar form as the ones corresponding to a spherical system. Later on, this method was used to describe various collective excitations in deformed nuclei, like two-neutrino double beta decay [23][24][25], magnetic collective states [26], and collective excitations in atomic clusters [27].…”