Understanding exotic hadrons from the first-principle calculation in lattice QCD*

The first-principle calculation using lattice QCD plays an important role in hadron physics. In particular, hadron interactions, for which the calculation methods in lattice QCD have been developed together with increasing computer resources in recent years, are vital inputs for understanding exotic hadrons through scattering processes. The HAL QCD method, one of the methods to extract hadron interactions, has the advantage that it provides us with an understanding of the structure of exotic hadrons via the corresponding hadron interaction potentials. 

In this presentation, after a brief review of the HAL QCD method, we overview the recent studies of exotic hadrons in the HAL QCD method, such as P_c pentaquark, Ω_cccΩ_ccc dibaryon, and Τ_cc tetraquark. Furthermore, we present one of our recent projects, the analyses of hadron scatterings containing light quark-antiquark pair creation and annihilation processes, which are essential to investigate hadron resonances and the exotic hadrons that appear in such scattering processes. We first show the results of the studies on ρ and Δ resonances and then report the preliminary results of our current study in this project: Λ(1405) from the meson-baryon interactions in flavor SU(3) limit.