Measurement of the interference structure functionRLTfor the12C(e,e′p)reaction in the quasielastic region

The coincidence cross section and the interference structure function, $R_{\mathrm{LT}},$ were measured for the ${}^{12}\mathrm{C}{(e,e}^{\prime }p){}^{11}\mathrm{B}$ reaction at quasielastic kinematics and central momentum transfer of $|\overrightarrow{q}|=400\mathrm{}\mathrm{M}\mathrm{e}\mathrm{V}/\mathrm{c}.$ The measurement was at an opening angle of ${\theta }_{\mathrm{pq}}=11\mathrm{}°,$ covering a range in missing energy of $E_m=0\mathrm{}$ to 65 MeV. The $R_{\mathrm{LT}}$ structure function is found to be consistent with zero for $E_m>50\mathrm{}\mathrm{MeV},$ confirming an earlier study which indicated that $R_L$ vanishes in this region. The integrated strengths of the $p$- and $s$-shell are compared with a distorted wave impulse approximation (DWIA) calculation. The $s$-shell strength and shape are also compared with a Hartree Fock–random phase approximation (HF-RPA) calculation. The DWIA calculation does not succeed in giving a consistent description of both the cross section data and the extracted $R_{\mathrm{LT}}$ response for either shell. The HF-RPA calculation describes the data more consistently, which may be due to the inclusion of 2-body currents in this calculation.