High Energy Break-Up of Few-Nucleon Systems

TL;DR

This paper reviews recent theoretical advances in high-energy two-body break-up reactions of few-nucleon systems, emphasizing the hard rescattering model and its experimental validation, providing insights into the underlying quark dynamics.

Contribution

It introduces the hard rescattering model (HRM) for describing high-energy break-up reactions and predicts a new helicity selection mechanism confirmed by experiments.

Findings

Validation of HRM in $^2D$ and $^3He$ break-up reactions

Prediction and experimental confirmation of helicity selection mechanism

Clarification of the separation between hard and soft subprocesses

Abstract

We discus recent developments in theory of high energy two-body break-up reactions of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon by the outgoing two nucleons. Within HRM we discuss hard break-up reactions involving $^2D$ and $^3He$ targets. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.