Coupled-channel analysis of hadronic and electromagnetic $\pi$, $\eta$, two-$\pi$ production reactions*

Recent high precision data of the electromagnetic meson production reactions off nucleons from Bonn, GRAAL, JLab, Mainz and Spring-8 make possible to extract $Q^2$ dependence of the electromagnetic $N$-$N^\ast$ transition form factors. To extract such information on the quark-gluon structures of the $N^\ast$ states, a comprehensive analysis of the hadronic and electromagnetic meson production reactions is ongoing in Excited Baryon Analysis Center (EBAC) at JLab. The analysis is based on the dynamical coupled-channel model which properly describes correlations among all relevant reaction channels required from unitarity and can treat non-resonant and resonant processes in a unified manner. In this talk, we will report current status on the analysis of $\gamma N \to \pi N$, $\gamma N \to \eta N$ and $e N \to e' \pi N$ reactions. The main purpose is to determine parameters associated with the electromagnetic interactions by this combined analysis of the electromagnetic meson production reactions. We will also discuss the $N$-$N^\ast$ electromagnetic form factors extracted from the analysis of the $e N \to e' \pi N$ reaction.