Cranked Skyrme-Hartree-Fock calculation for superdeformed and hyperdeformed rotational bands in N=Z nuclei from 32S to 48Cr

With the use of the symmetry-unrestricted cranked Skyrme-Hartree-Fock method in the three-dimensional coordinate-mesh representation, we have carried out a systematic theoretical search for the superdeformed and hyperdeformed rotational bands in the mass A=30-50 region. Along the N=Z line, we have found superdeformed solutions in 32S, 36Ar, 40Ca, 44Ti, and hyperdeformed solutions in 36Ar, 40Ca, 44Ti, 48Cr. The superdeformed band in 40Ca is found to be extremely soft against both the axially symmetric (Y30) and asymmetric (Y31) octupole deformations. An interesting role of symmetry breaking in the mean field is pointed out