Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons

We present preliminary results on an experimental study of the nuclear modification of the longitudinal (${\sigma }_L$) and transverse (${\sigma }_T$) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= ${\sigma }_L\mathrm{/}{\sigma }_T$ for nuclei ($R_A$) and for deuterium ($R_D$) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, $R_A<R_D$.