Pionic transparency in semi-exclusive electroproduction off nuclei

TL;DR

This paper studies the early appearance of pionic color transparency in semi-exclusive pion electroproduction off nuclei, emphasizing the importance of distinguishing soft and hard components for accurate modeling.

Contribution

It introduces a coupled-channel approach to final state interactions and highlights the role of point-like configurations in explaining nuclear transparency data.

Findings

Data are well reproduced with point-like configurations dominating the transverse channel.

Proper separation of soft and hard components is crucial for quantitative agreement.

The coupled-channel treatment improves understanding of final state interactions.

Abstract

We investigate the early onset of pionic color transparency ($\pi$CT) observed at Jefferson Laboratory (JLAB) in semi--exclusive pion electroproduction reaction $A(e,e'\pi^+)$ off nuclei. In the present description the primary $\gamma^*p \to \pi^+ n$ interaction is described very well both for the longitudinal and the transverse polarizations. For the final state interactions a coupled--channel treatment of the interactions of transmitted hadrons allows to go beyond the Glauber approximation. We show that a proper distinction between the soft hadronic and hard partonic components of the electroproduction amplitude is essential for a quantitative description of the measured nuclear transparency. The data are well reproduced if one assumes that point--like configurations are produced in the regime of hard deep--inelastic scattering (DIS) off partons and dominate the transverse channel.