Description of the two-neutrino ββ decay of ¹⁰⁰Mo by pnMAVA

Authors: Kotila, J.; Suhonen, J.; Delion, D.S.

Source: Journal of Physics G: Nuclear and Particle Physics, Volume 37, Number 1, January 2010 , pp. 15101-15112(12)

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Abstract:

The microscopic anharmonic vibrator approach (MAVA) is a scheme where the one- and two-phonon states of an even-even nucleus are treated consistently by using a realistic microscopic nuclear Hamiltonian. This model has recently been extended to describe odd-odd nuclei by adding proton-neutron phonons in a scheme called the proton-neutron MAVA (pnMAVA). In this paper, we apply pnMAVA to compute the nuclear matrix elements corresponding to the two-neutrino double beta (2νββ) decay of ¹⁰⁰Mo to the ground state and the first excited 0⁺ state of ¹⁰⁰Ru in a realistic single-particle space. We also compute the GT− and GT+ Gamow-Teller strength functions and compare them with the plain pnQRPA (proton-neutron QRPA) and available data. The redistribution of strength to four-quasiparticle degrees of freedom can be clearly seen in the GT+ function. The more striking effect is seen in the 2νββ matrix element corresponding to the ground-state transition where the incoherence of individual contributions is stronger for the pnMAVA than for the pnQRPA, and a 15% reduction in the magnitude of the matrix element is obtained for the pnMAVA. The 2νββ transition rate to the excited 0⁺ state is zero in a pnQRPA calculation, whereas the pnMAVA result is not far from the measured decay rate.

Document Type: Research article

DOI: http://dx.doi.org/10.1088/0954-3899/37/1/015101

Publication date: 2010-01-01