Two-body currents in the reaction 12C(e, e′p)11B at high missing momenta

The reaction 12C(e, e′p)11B has been studied in the dip region at an energy transfer ω = 212 MeV, a three-momentum transfer |q| = 270 MeV/c, and missing momenta in the range from 360 MeV/c to 600 MeV/c. Data have been obtained for the ground-state transtition and a multiplet of states centered at an excitation energy of about 7 MeV in 11B. Distorted-wave impulse approximation calculations under-estimate the data for the ground-state transition and those for the multiplet of states by one and two orders of magnitude, respectively. Long-range correlations in the initial state bring the results of the calculations closer to the data, while two-step processes are shown to increase the calculated strength for the excitation of the multiplet of states by an order ot magnitude relative to the one-step calculations. Calculations that include two-body currents are able to give a proper account of both data sets.