Abstract:
Proton recoil polarization was measured in the quasielastic He-4((e) over right arrow, e '(p) over right arrow)H-3 reaction at Q(2) = 0.8 and 1.3 (GeV/c)(2) with unprecedented precision. The polarization-transfer coefficients are found to differ from those of the H-1((e) over right arrow, e '(p) over right arrow) reaction, contradicting a relativistic distorted-wave approximation and favoring either the inclusion of medium-modified proton form factors predicted by the quark-meson coupling model or a spin-dependent charge-exchange final-state interaction. For the first time, the polarization-transfer ratio is studied as a function of the virtuality of the proton.
