Polarization Transfer in the ^4He(\vec e,e'\vec p)^3H Reaction up to Q^2 = 2.6 (GeV/c)^2

We have measured the proton recoil polarization in the ^4He(\vec e,e'\vec p)^3H reaction at Q^2 = 0.5, 1.0, 1.6, and 2.6 (GeV/c)^2. The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a predicted medium modification of the proton form factors based on a quark-meson coupling model. In contrast, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.Comment: 5 pages, 3 figures, uses revtex.sty, submitted to Physical Review Letter

Measurement of the He-3(e,e ' p)pn reaction at high missing energies and momenta

Results of the Jefferson Lab Hall A quasielastic He-3(e,e'p)pn measurements are presented. These measurements were performed at fixed transferred momentum and energy, q=1502 MeV/c and omega=840 MeV, respectively, for missing momenta p(m) up to 1 GeV/c and missing energies in the continuum region, up to pion threshold; this kinematic coverage is much more extensive than that of any previous experiment. The cross section data are presented along with the effective momentum density distribution and compared to theoretical models

Recoil polarization for Delta excitation in pion electroproduction - art. no. 102002

We measured angular distributions of recoil-polarization response functions for neutral pion electroproduction for W=1.23 GeV at Q(2)=1.0 (GeV/c)(2), obtaining 14 separated response functions plus 2 Rosenbluth combinations; of these, 12 have been observed for the first time. Dynamical models do not describe quantities governed by imaginary parts of interference products well, indicating the need for adjusting magnitudes and phases for nonresonant amplitudes. We performed a nearly model-independent multipole analysis and obtained values for Re (S1+/M1+)= -(6.84 +/- 0.15)% and Re (E1+/M1+)= -(2.91 +/- 0.19)% that are distinctly different from those from the traditional Legendre analysis based upon M1+ dominance and l(pi)<= 1 truncation