Eur. Phys. J. A 9, 345-352
Double-beta decay matrix elements for

S. Stoica1 - H.V. Klapdor-Kleingrothaus2
1 National Institute of Physics and Nuclear Engineering,
P.O. Box MG-6, 76900-Bucharest, Romania
2 Max-Planck-Institut für Kernphysik, W-6900 Heidelberg, Germany
Received: 6 June 2000 / Revised version: 19 October 2000
Communicated by B. Povh
Abstract
Double-beta decay matrix elements (ME) for
are calculated
with different quasi-random phase approximation (QRPA)-based methods.
First, the ME for the two-neutrino mode are
computed using two choices for the single-particle (s.p.) basis:
i)
full shells and ii)
full shells.
When calculated with the renormalized QRPA (RQRPA) and
full-RQRPA their values are rather dependent on the size of the single-particle
basis used, while calculated with
proton-neutron QRPA (pnQRPA) and second-QRPA approaches such a dependence
was found to be small. The Ikeda sum rule was well fulfilled
within pnQRPA for both choices of the s.p. basis and
with a good approximation within second-QRPA, while
the RQRPA and full-RQRPA methods give deviations up to 21%.
Further, the ME for the neutrinoless mode are calculated
with the pnQRPA, RQRPA and full-RQRPA methods. They all give
close results for the calculation with the smaller basis (i),
while for the larger basis (ii), the results differ significantly
either from one method to another or within the same method.
Finally, using the most recent experimental limit for the
decay half-life of
a critical discussion
on the upper limits for the neutrino mass parameter
obtained with different theoretical approaches is given.
PACS
21.60.Jz Hartree-Fock and random-phase approximations
- 23.40.Hc Relation with nuclear matrix elements and nuclear structure
- 23.40.Bw Weak interaction and lepton (including neutrino) aspects
Copyright Società Italiana di Fisica, Springer-Verlag 2000