Role of final-state interactions in the calculation of the hadronic tensor of nuclear matter.

Abstract

We develop methods for the calculation of the hadronic tensor that describes the response of nuclear matter to an electromagnetic probe and study the role of final-state interactions, making use of the theory of Horikawa, Lenz, and Mukhopadhyay. Recently, extensive calculations of such final-state interaction effects in quasielastic ({ital e},{ital e}{prime}) reactions have been performed by Chinn, Picklesimer, and Van Orden for finite nuclei. Our nuclear matter calculations reproduce the qualitative features found by those authors, including a significant quenching'' of the longitudinal response, if one uses a relativistic description of the process. While we are able to achieve an improved fit to a body of experimental data for the longitudinal response using this formalism, definitive conclusions cannot be drawn without performing a gauge-invariant calculation. We also find quenching of the transverse response in the region of the quasielastic peak; however, it is unclear as to whether that creates a problem for the theory, since the transverse response is known to have contributions from the excitation of the delta resonance and various multinucleon processes. As part of our study, we provide a spectral representation of the Green's function of a nucleon propagating in relativistic nuclear matter.