Relativistic distorted-wave impulse approximation analysis of ¹²C(e,e^'p) for Q²<2 (GeV/c)²

We analyze data for ¹²C(e,e^'p) with Q²<2 (GeV/c)² using the relativistic distorted-wave impulse approximation (RDWIA) based upon Dirac-Hartree wave functions. The 1p normalization extracted from data for Q²>0.6 (GeV/c)² is approximately 0.87, independent of Q², which is consistent with the predicted depletion of the 1p_3/2 orbital by short-range correlations. The total 1p and 1s strength for E_m<80 MeV approaches 100% of IPSM (independent particle shell model), consistent with a continuum contribution for 30<E_m<80 MeV of about 12% of IPSM. Similarly, a scale factor of 1.12 brings RDWIA calculations into good agreement with ¹²C(e,e^'p) data for transparency. We also analyzed low Q² data from which a recent nonrelativistic RDWIA analysis suggested that spectroscopic factors might depend strongly upon the resolution of the probe. We find that the momentum distributions for their empirical Woods-Saxon wave functions fit to low Q² data for parallel kinematics are too narrow to reproduce data for quasiperpendicular kinematics, especially for larger Q², and are partly responsible for reducing fitted normalization factors. Although the RDWIA normalization factors for Q²<0.2 (GeV/c)² are also smaller than obtained for Q²>0.6 (GeV/c)², the effect is smaller, and we argue that it should be attributed to the effective single-nucleon current operator instead of to spectroscopic factors, which are probe-independent properties of nuclear structure. However, remediation of the failure of RDWIA calculations to reproduce low Q² data for parallel kinematics will require a more sophisticated modification of the current method than a simple multiplicative factor.