There has been a lot of theoretical effort to unmask the pentaquark candidates, the $P_c^+$, since they were reported by LHCb collaboration in 2015. However, lack of knowledge in charmed-hadron interactions seems to be causing controversy on this issue; some argue that they are loosely-bound meson-baryon state, while others consider them as tightly-bound states, threshold cusps, and so forth. In this talk, we present our recent result on the $J/\psi-N$ and $\eta_c-N$ single-channel interactions from lattice QCD first-principle calculation. We update a previously reported result by Kawanai and Sasaki by using the time-dependent HAL QCD method and by employing dynamical fermions.

Hadron Spectroscopy and Interactions