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HK: Physik der Hadronen und Kerne

HK 16: Kernphysik/Spektroskopie II

HK 16.8: Talk

Tuesday, March 18, 2003, 17:45–18:00, A

Is Pseudospin-Symmetry also seen in Proton-Nucleus Scattering? — •Helmut Leeb¹ and S.A. Sofianos² — ¹Atominstitut d.Österr. Univ., TU Wien,1040 Wien, Austria — ²Department of Physics, UNISA, Pretoria, South Africa

Originally, pseudospin-symmetry has been introduced to explain the quasidegeneracy of spherical shell orbitals (n,l,j=l+0.5) and (n-1,l+2,j+1.5), where n, l and j are the radial, orbital angular momentum and total angular momentum quantum numbers, respectively. This symmetry approximately persists also in deformend nuclei and is, as outlined by Ginocchio in the ninties, a consequence of the invariance of the Dirac Hamiltonian with V=-W under specific SU(2) transformations. Here V and W are the 4th component of a vector potential and W is a scalar potential, respectively. The extension of the concept of pseudospin-symmetry to the scattering regime has been controversely discussed. While Bowlin et al. do not find any indication in low energy proton-nucleus scattering data, recent studies of proton-lead data at E=800 MeV show only a weak pseudospin-dependent scattering amplitude. In this contribution we derive exact expressions and inequalities for the pseudospin-dependent scattering ampitude in terms of observables. Applying these relations, a systematic study of proton-nucleus scattering.data over an extended mass and energy range is performed. Explanations of the previous findings are given.