Color transparency and short-range correlations in exclusive pion photo- and electroproduction from nuclei

TL;DR

This paper develops a relativistic quantum framework to analyze nuclear transparency in pion photo- and electroproduction, accounting for color transparency and short-range correlations, with applications to Jefferson Lab experiments.

Contribution

It introduces a flexible relativistic model that incorporates both color transparency and short-range correlations in nuclear reactions, adaptable to different energy regimes.

Findings

Both CT and SRC increase nuclear transparency.

The two mechanisms have distinct dependence on the hard scale.

Model comparisons show consistent trends in transparency results.

Abstract

A relativistic and quantum mechanical framework to compute nuclear transparencies for pion photo- and electroproduction reactions is presented. Final-state interactions for the ejected pions and nucleons are implemented in a relativistic eikonal approach. At sufficiently large ejectile energies, a relativistic Glauber model can be adopted. At lower energies, the framework possesses the flexibility to use relativistic optical potentials. The proposed model can account for the color-transparency (CT) phenomenon and short-range correlations (SRC) in the nucleus. Results are presented for kinematics corresponding to completed and planned experiments at Jefferson Lab. The influence of CT and SRC on the nuclear transparency is studied. Both the SRC and CT mechanisms increase the nuclear transparency. The two mechanisms can be clearly separated, though, as they exhibit a completely different dependence on the hard scale parameter. The nucleon and pion transparencies as computed in the relativistic Glauber approach are compared with optical-potential and semi-classical calculations. The similarities in the trends and magnitudes of the nuclear transparencies indicate that they are not subject to strong model dependencies.