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Single photo and electroproduction of pions at EBAC@JLAB

Within the Excited Baryon Analysis Center we have performed a dynamical coupled-channels analysis of the available $p(e,e' π)N$ data in the region of $W \leq $ 1.6 GeV and $Q^2 \leq$ 1.45 (GeV/c)$^2$. The channels included are $γ^* N$, $πN$, $ηN$, and $ππN$ which has $πΔ$, $ρN$, and $σN$ components. With the hadronic parameters of the model determined in our previous investigations of $πN\to πN$ reaction, we have found that the available data in the considered $W \leq $ 1.6 GeV region can be fitted well by only adjusting the bare $γ^* N \to N^*$ helicity amplitudes for 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 $γ^* N \to N^*$ form factors are examined.