Dynamics of the quasielastic 16O(e,e′p) reaction at Q2≈0.8 (GeV/c)2 -: art. no. 034606

The physics program in Hall A at Jefferson Lab commenced in the summer of 1997 with a detailed investigation of the O-16(e,e(')p) reaction in quasielastic, constant (q,omega) kinematics at Q(2)approximate to0.8 (GeV/c)(2), qapproximate to1 GeV/c, and omegaapproximate to445 MeV. Use of a self-calibrating, self-normalizing, thin-film waterfall target enabled a systematically rigorous measurement. Five-fold differential cross-section data for the removal of protons from the 1p-shell have been obtained for 0<p(miss)<350 MeV/c. Six-fold differential cross-section data for 0<E-miss<120 MeV were obtained for 0<p(miss)<340 MeV/c. These results have been used to extract the A(LT) asymmetry and the R-L, R-T, R-LT, and RL+TT effective response functions over a large range of E-miss and p(miss). Detailed comparisons of the 1p-shell data with Relativistic Distorted-Wave Impulse Approximation (RDWIA), Relativistic Optical-Model Eikonal Approximation (ROMEA), and Relativistic Multiple-Scattering Glauber Approximation (RMSGA) calculations indicate that two-body currents stemming from meson-exchange currents (MEC) and isobar currents (IC) are not needed to explain the data at this Q(2). Further, dynamical relativistic effects are strongly indicated by the observed structure in A(LT) at p(miss)approximate to300 MeV/c. For 25<E-miss<50 MeV and p(miss)approximate to50 MeV/c, proton knockout from the 1s(1/2)-state dominates, and ROMEA calculations do an excellent job of explaining the data. However, as p(miss) increases, the single-particle behavior of the reaction is increasingly hidden by more complicated processes, and for 280<p(miss)<340 MeV/c, ROMEA calculations together with two-body currents stemming from MEC and IC account for the shape and transverse nature of the data, but only about half the magnitude of the measured cross section. For 50<E-miss<120 MeV and 145<p(miss)<340 MeV/c, (e,e(')pN) calculations which include the contributions of central and tensor correlations (two-nucleon correlations) together with MEC and IC (two-nucleon currents) account for only about half of the measured cross section. The kinematic consistency of the 1p-shell normalization factors extracted from these data with respect to all available O-16(e,e(')p) data is also examined in detail. Finally, the Q(2)-dependence of the normalization factors is discussed.