Abstract
Abstract
Applications of the proxy-SU(3) model of Bonatsos and collaborators to nuclei in A = 60–90 region introduces proxy-SU(4) symmetry. Shell model spaces with single particle orbits 1
p
3/2, 1
p
1/2, 0
f
5/2 and 0
g
9/2 are essential for these nuclei and also protons and neutrons in this region occupy the same single particle orbits. With this and applying the ‘proxy scheme’, the 0
g
9/2 changes to 0
f
7/2 giving the spectrum generating algebra U(40) ⊃ [U(10) ⊃ G ⊃ SO(3)] ⨂ [SU
ST
(4) ⊃ SU
S
(2) ⨂ SU
T
(2)]. With G = SU(3), we have the proxy-SU(3) model. It is easy to see that proxy-SU(3) symmetry implies goodness of the SU(4) symmetry appearing above, i.e. proxy-SU(4) symmetry. Shell model calculations pointing out the need for 0
g
9/2 orbit, ground state masses, shape changes and shape co-existence in A = 60–90 region and GT distributions clearly show the importance of proxy-SU(4) in this mass region. Besides presenting this evidence, new proxy schemes with G = SU(5), SO(6) and SO(10) that are generated by good proxy-SU(4) symmetry are described in some detail. An important feature is that the four proxy symmetries SU(3), SO(6), SU(5) and SO(10) appear twice.
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