Spectroscopic Study of Quark Dynamics in Baryons at J-PARC

Through spectroscopy of hadrons, we could study internal motions of quarks, which reflect dynamics of quarks and gluons characterized by non-perturbative nature in low-energy QCD. Internal motions of quarks, in particular quark-quark correlations, can be disentangled by introducing different flavors, such as charm and strangeness, in a baryon. They are reflected not only in excitation energies but also in production rates and/or decay branching ratios. The spin-dependent interactions between quarks are usually described by the one-gluon exchange potential. The instanton induced interaction related to the non-trivial vacuum of gluon field in low-energy QCD can also contribute to the spin-dependent interactions. We discuss how the instanton induced interaction affects the level structure of excited singly heavy baryons in terms of level splittings by the spin-orbit interaction. Mechanism of color confinement has yet to be clarified. We recall a “string tension puzzle” shown in excited heavy baryons, which may suggest that the confinement potential in baryons is not always compatible with that in mesons. Studies of internal structure of excited heavy baryons are necessary to understand what happen in highly excited states. The J-PARC Hadron Experimental Facility (HEF) provides a unique platform to study quark dynamics in low-energy QCD though spectroscopy of excited baryons with heavy flavors.