Investigation of Medium Modifications to ${}^{12}$C Structure Functions in the Resonance Region

We present results from a high precision experimental study of the nuclear modification of the longitudinal ($F_L$) to transverse ($F_1$) structure function ratio for bound nucleons in the resonance region. The inclusive electron scattering cross sections were measured in Jefferson Lab Experimental Hall C on carbon and deuterium nuclei for a large range of kinematics, allowing for separations of the longitudinal and transverse structure functions to be performed at a range of four-momentum transfer values $0.5\le Q^2\le$ 3.75 GeV${}^2$. In contrast to the significant body of measurements of the nuclear modification of the $F_2$ structure function in the deep inelastic scattering region, there is very little on $F_L$ and $R=F_L\mathrm{/}2x{F}_1$ in the region of the nucleon resonances. In this paper we present measurements of the nuclear effect on $R$ for ${}^{12}$C ($R_C$) relative to deuterium ($R_D$). These results indicate regions in which in $R_C>R_D$, requiring that the nuclear modifications be different in all three structure functions, $F_2$, $F_1$ and $F_L$.