Nuclear final-state interactions in deep inelastic scattering off the lightest nuclei

Abstract

We review recent progress in studies of nuclear final-state interactions in deep inelastic scattering (DIS) off the lightest nuclei tagged by a recoil nucleon. These processes hold a lot of potential for resolving the outstanding issues related to the dynamics of hadronization in QCD. Within the minimal Fock component framework, valid at large Bjorken x, the main features of the theoretical approach based on the virtual nucleon approximation are elaborated. In this approach, the strong final-state interaction of the DIS products with the nuclear fragments is described by an effective eikonal amplitude, whose parameters can be extracted from the analysis of semi-inclusive DIS off the deuteron target. The extraction of the Q 2 and W mass dependences of these parameters gives a new observable in studying the QCD structure of DIS final states. Another important feature of tagged DIS off the lightest nuclei is the possibility of performing pole extrapolation with a high degree of accuracy. Such extrapolation allows an extraction of the neutron structure function in a model independent way due to suppression of the final-state interaction in the on-shell limit of the struck nucleon propagator. We review the first application of the pole extrapolation to recent experimental data. Finally, we outline the extension of the framework to inclusive DIS, including a polarized deuteron target as well as its application to the tagged DIS reactions for future experiments at fixed target and collider energies.

Measurement of deeply virtual Compton scattering off Helium-4 with CLAS at Jefferson Lab

“…Modern calculations exist for such effects in deep inelastic scattering [16] and quasi-elastic scattering [17], and we can expect them to be extended to the DVCS process as more data become available. Another avenue of progress on this topic will be the use of experimental techniques like tagging.…”

Neutron spin structure from polarized deuteron DIS with proton tagging

“…The tagged DIS cross section is generally affected by initialstate nuclear modifications of the structure functions and finalstate interactions of the DIS products with the spectator. These effects can be described by dynamical models and added to the impulse approximation [19,26]. An alternative approach is to eliminate them using the analytic properties of the proton momentum dependence [10].…”

Electron scattering from a deeply bound nucleon on the light-front

“…Using the explicit forms of the currents from Eqs. (26), (27) we calculate the above structure functions expressing them through the off-shell parameter η (Eq. (30)) as follows [49]:…”

“…Refs. [18][19][20][21][22][23][24][25][26][27]). One of the approaches, referred to as generalized eikonal approximation [18,25], selfconsiestently treated the relativistic effects associated with the large momentum of bound nucleon involved in the reaction, as such these approach provided a theoretical framework for calculating FSI effects relevant to studies of the nuclear structure at short distances.…”