Exclusive pion electroproduction off nucleons and nuclei

TL;DR

This paper investigates exclusive pion electroproduction on nucleons and nuclei at high Q^2, emphasizing the importance of nucleon models for understanding color transparency effects observed at JLAB, and develops theoretical models for these processes.

Contribution

It introduces new models combining Regge theory and nucleon resonances to describe pion production at JLAB and HERMES, enhancing understanding of color transparency phenomena.

Findings

Successful description of pion production data at JLAB and HERMES

Evidence supporting the role of nucleon resonances in exclusive processes

Insights into the mechanisms behind color transparency effects

Abstract

We present our results for the exclusive electroproduction of pions off nucleons and nuclei at high values of $Q^2$. In electroproduction of nuclei $A(e,e'\pi)$ we consider the Color Transparency (CT) effect recently observed at JLAB. It is shown that the description of $\pi$ production off nucleons is mandatory for the proof of the CT signal at JLAB. We further develop the models for exclusive production of $\pi$ off nucleons at JLAB and HERMES. At first we describe a model based on exclusive-inclusive connection. In the second approach we combine a Regge pole approach with the residual effect of nucleon resonances. The nucleon resonances are described using a dual connection between the exclusive form factors and inclusive deep inelastic structure functions. We present the results for the beam spin azimuthal asymmetries measured at JLAB in exclusive electroproduction of charged and neutral pions.