Speaker
Ms
Lotta Jokiniemi
(University of Jyväskylä)
Description
Ground-state-to-ground-state neutrinoless double beta ($0\nu\beta\beta$) decays
in nuclei of current experimental interest are revisited. In order to improve
the reliability of the nuclear matrix elements (NMEs) for the light
Majorana-neutrino mode, the NMEs are calculated by exploiting
the newly available data on isovector spin-dipole (IVSD) $J^{\pi}=2^-$ giant resonances obtained at RCNP, Osaka.
In order to correctly describe the IVSD up to and beyond the giant-resonance
region, the present computations are performed in extended no-core
single-particle model spaces using the proton-neutron quasiparticle
random-phase approximation (pnQRPA) with two-nucleon interactions based on
the Bonn one-boson-exchange G matrix. The appropriate short-range correlations,
nucleon form factors, higher-order
nucleonic weak currents, and partial restoration of the isospin symmetry are
included in the calculations. The results are compared with earlier calculations
of Hyvärinen and Suhonen [Phys. Rev. C **91**, 024613 (2015)]
performed in much smaller single-particle bases without access to the
IVSD $J^{\pi}=2^-$ giant-resonance data reported here.
The study offers a new way of fitting the $g_{ph}$ parameter of pnQRPA to the measured IVSD giant resonance
instead of fitting it to the Gamow-Teller giant resonance in the traditional way. In fact, we study
three different combinations to fit this parameter to available data and study the associated errors in the
$0\nu\beta\beta$ NMEs.
Primary author
Ms
Lotta Jokiniemi
(University of Jyväskylä)
Co-authors
Prof.
Dieter Frekers
(Westfälische Wilhelms-Universität, Münster, Germany)
Prof.
Hiroyasu Ejiri
(Research Center for Nuclear Physics, Osaka University)
Prof.
Jouni Suhonen
(University of Jyväskylä)
