Pionic transparency in semi-exclusive electroproduction off nuclei

Understand

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.