Comparison of the 12C(e,e'p) cross section at low momentum transfer with a relativistic calculation

The (e,e(')p(0)) cross section of C-12 has been measured at an energy transfer of 60 MeV and a momentum transfer of 104.4 MeV/c using a 197.5 MeV continuous electron beam. The cross section at missing momenta between 181.5 and 304.8 MeV/c obtained from the experiment is compared with theoretical calculations based on the relativistic distorted-wave impulse approximation with and without meson-exchange currents (MEC). The contribution of MEC due to the seagull current is large in the high-missing-momentum region, in particular for the longitudinal component. The cross sections calculated using three different current-conserving operators (cc1, cc2, and cc3) are similar, in contrast to the (gamma,p) reaction, where the operators give very different results. The shape of the measured cross section is well described by the calculations, whereas its magnitude is slightly smaller than that described by the calculations.