Exclusive Hard Processes for Studying Hadron Structures at J-PARC.

With an appropriate hard scale, exclusive hadronic processes could provide novel information of the internal quark-gluon configurations of hadrons. The availability of 10-20 GeV secondary meson beam in the coming high-momentum beam line of Hadron Hall at J-PARC offers an unique opportunity to carry out the measurements of the exclusive hard processes. We address this interesting approach by two possibilities: (a) $\pi^- p \to K^0 \Lambda(1405)$ for the constituent quark structure of $\Lambda(1405)$, and (b) exclusive pion-induced Drell-Yan process $\pi^- p \to \gamma^* n \to l^+ l^- n$ for the generalized parton distributions (GPDs) of nucleons. Realization of such measurements at J-PARC will open up a new way of accessing the internal quark structure of exotic hadrons and also the nucleon GPDs based on a solid theoretical foundation of perturbative QCD.