Wolfenstein parameters fors1/2proton knockout (p,2p) reactions

A complete set of Wolfenstein parameters (${D}_{{i}^{'}j}$), induced polarizations ($P$), and analyzing powers (${A}_{y}$) have been measured for ($p,2p$) reactions on $^{6}\mathrm{Li}$, $^{12}\mathrm{C}$, and $^{40}\mathrm{Ca}$ targets in order to investigate possible nuclear medium effects on the nucleon-nucleon ($\mathit{NN}$) interaction. Most of these observables show significant reductions from the values for proton-proton scattering as monotonic functions of the nuclear density relevant to these reactions. The reductions of these ${D}_{{i}^{'}j}$ are reasonably reproduced by nonrelativistic plane-wave and distorted-wave calculations based on the impulse approximation, demonstrating that these suppressions are attributed to changes of the two body kinematics due to the finite separation energies of these reactions, while the reductions of ${A}_{y}$ and $P$ are much more prominent than the calculations. The relativistic calculations, which partly explain the ${A}_{y}$ and $P$ reductions, cannot reproduce the ${D}_{{i}^{'}j}$ data, but all the data are consistently reproduced when the parameters of the $\mathit{NN}$ interaction in a meson exchange model are renormalized, suggesting possible modifications of the $\mathit{NN}$ interaction by the surrounding nuclear medium.