https://doi.org/10.1140/epja/i2007-10502-7
Regular Article - Theoretical Physics
Breaking of the SU(4) limit for the Gamow-Teller strength in N ∼ Z nuclei
1
Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstr. 9, D-64289, Darmstadt, Germany
2
Gesellschaft für Schwerionenforschung Darmstadt, Planckstr. 1, D-64259, Darmstadt, Germany
3
Institut de Recherches Subatomiques, Université Louis Pasteur, F-67037, Strasbourg, France
* e-mail: petermann@gsi.de
Received:
13
November
2007
Accepted:
15
November
2007
Published online:
3
December
2007
We have performed large-scale shell model calculations of the Gamow-Teller strength distributions in N ∼ Z pf -shell nuclei. These calculations were motivated by the experimental attempts to measure the low-lying GT strength for the even-even N = Z + 2 or N = Z - 2 nuclei 46Ti , 50Cr , 54Fe and 62Ge , where a sizable low-energy GT strength could be interpreted as reminiscence of SU(4) symmetry; in the limit of exact SU(4) symmetry the GT- strength would be concentrated in a single transition to the lowest T = 0, J = 1+ state in the daughter. We confirm that the SU(4) symmetry is strongly broken by the spin-orbit interaction and by increasing neutron excess.
PACS: 21.60.Cs Shell model – / 27.40.+z 39≤A≤58 – / 27.50.+e 59≤A≤89 – / 23.40.-s β decay; double β decay; electron and muon capture –
© Società Italiana di Fisica and Springer-Verlag, 2008
