16 research outputs found
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