Selected Topics in High Energy Semi-Exclusive Electro-Nuclear Reactions

Abstract

We review the present status of the theory of high energy reactions with semi-exclusive nucleon electro-production from nuclear targets. We demonstrate how the increase of transferred energies in these reactions opens a complete new window in studying the microscopic nuclear structure at small distances. The simplifications in theoretical descriptions associated with the increase of the energies are discussed. The theoretical framework for calculation of high energy nuclear reactions based on the effective Feynman diagram rules is described in details. The result of this approach is the generalized eikonal approximation (GEA), which is reduced to Glauber approximation when nucleon recoil is neglected. The method of GEA is demonstrated in the calculation of high energy electro-disintegration of the deuteron and A = 3 targets. Subsequently we generalize the obtained formulae for A > 3 nuclei. The relation of GEA to the Glauber theory is analyzed. Then based on the GEA framework we discuss some of the phenomena which can be studied in exclusive reactions, these are: nuclear transparency and short-range correlations in nuclei. We illustrate how light-cone dynamics of high-energy scattering emerge naturally in high energy electro-nuclear reactions.

Exclusive electrodisintegration ofHe3at highQ2. I. Generalized eikonal approximation

“…The contribution of the second diagram in Fig.2 can be calculated by interchanging the momenta of "2" and "3" nucleons in Eq. (20). Doing this and changing the integration variables d 3 p 3 to d 3 p 23 (similar to Sec.III A) for complete single rescattering amplitude one obtains: …”

“…We will perform the calculation within the generalized eikonal approximation (GEA), [19,20]. In this approach, the interaction of the fast, knocked-out nucleon with slow spectator nucleons is calculated based on the eikonal approximation for the corresponding covariant diagrams.…”

“…In this approach, the interaction of the fast, knocked-out nucleon with slow spectator nucleons is calculated based on the eikonal approximation for the corresponding covariant diagrams. The reduction theorem [20] derived for this approximation allows us to reduce an infinite sum of rescattering diagrams to a finite set of covariant Feynman diagrams. In these diagrams, soft NN reinteractions are described through phenomenological NN interaction vertices which can be parameterized using experimental data on the small angle NN scattering amplitudes.…”

A Measurement of the neutron electric form factor at very large momentum transfer using polaried electrions scattering from a polarized helium-3 target

“…The method used is the Generalized Eikonal Approximation (GEA) [111]. This is a general form of the eikonal approximation introduced by R. Glauber [112,113].…”

“…It cannot re-interact, so the potentially infinite series of scattering amplitudes is truncated after double scattering. These amplitudes can then be calculated from the well known proton-proton or proton-neutron scattering cross sections [111].…”