Polarization transfer and spin response functions in quasielastic ((p)over-right-arrow,(n)over-right-arrow) reactions at 346 MeV

A complete see of polarization transfer coefficients has been measured for quasielastic ((p) over right arrow,(n) over right arrow) reactions on H-2, Li-6, C-12, Ca-40, and Pb-208 at a bombarding energy of 346 MeV and a laboratory scattering angle of 22 degrees (q(lab) approximate to 1.7 fm(-1)). The spin-longitudinal R-L and spin-transverse R-T response functions are extracted within a framework of a plane-wave impulse approximation with eikonal and optimal factorization approximations. The theoretically expected enhancement of R-L/R-T is not observed. The observed R-L is consistent with the pionic enhanced R-L expected by random-phase approximation (RPA) calculations. On the contrary, a large excess of the observed R-T is found in comparison with R-T Of the quasielastic electron scattering as well as of RPA calculations. This excess masks the effect of pionic correlations in R-L/R-T. The theoretical calculations are performed in a distorted-wave impulse approximation with RPA correlations, which indicates that the nuclear absorption effect depends on the spin direction. This spin-direction dependence is responsible in part for the excess of R-T. [S0556-2813(99)02306-7].