Relativistic predictions of quasielastic proton-nucleus spin observables based on a complete Lorentz invariant representation of the NN scattering matrix

摘要

Within the framework of the relativistic plane wave impulse approximation(RPWIA), complete sets of quasielastic $(\vec{p}, \vec{p}^{'})$ and $(\vec{p},\vec{n})$ spin observables are calculated employing a general Lorentz invariantrepresentation of the NN scattering matrix (referred to as the IA2representation). The use of a complete representation eliminates thearbitrariness of a previously-used five-term parameterization (commonly calledthe IA1 representation) and allows for the correct incorporation ofeffective-mass-type medium effects within the RPWIA framework and within thecontext of the Walecka model. For quasielastic scattering from a $^{40}$Catarget at incident proton energies between 200 and 500 MeV, we investigate thesensitivity of complete sets of spin observables to effective nucleon massesfor both IA1 and IA2 representations. In general it is seen that the IA1representation may overestimate the importance of nuclear medium effects,whereas the IA2-based predictions nearly correspond to values for freenucleon-nucleon scattering.