# Single photo and electroproduction of pions at EBAC@JLAB - Nuclear Theory

Abstract: Within the Excited Baryon Analysis Center we have performed a dynamicalcoupled-channels analysis of the available $pe,e- \piN$ data in the region of$W \leq$ 1.6 GeV and $Q^2 \leq$ 1.45 GeV-c$^2$. The channels included are$\gamma^* N$, $\pi N$, $\eta N$, and $\pi\pi N$ which has $\pi\Delta$, $hoN$, and $\sigma N$ components. With the hadronic parameters of the modeldetermined in our previous investigations of $\pi N\to \pi N$ reaction, we havefound that the available data in the considered $W \leq$ 1.6 GeV region can befitted well by only adjusting the bare $\gamma^* N \to N^*$ helicity amplitudesfor the lowest $N^*$ states in $P {33}$, $P {11}$, $S {11}$ and $D {13}$partial waves. The meson cloud effect, as required by the unitarity conditions,on the $\gamma^* N \to N^*$ form factors are examined.

Author: B. Julia-Diaz

Source: https://arxiv.org/