Study of the scalar charmed-strange meson D^∗ _{s 0}(2317) with chiral fermions

The recently discovered charmed-strange meson D^∗ _{s 0}(2317) has been speculated to be a tetraquark mesonium. We study this suggestion with overlap fermions on 2+1 flavor domain wall fermion configurations. We use 4-quark interpolating operators with Z₄ grid sources on two lattices (16³ × 32 and 24³ ×64) to study the volume dependence of the states in an attempt to discern the nature of the states in the four-quark correlator to see if they are all two-meson scattering states or if one is a tetraquark mesonium. We also use the hybrid boundary condition method for this purpose which is designed to lift the two-meson states in energy while leaving the tetraquark mesonium unchanged. We find that the volume method is not effective in the present case due to the fact that the scattering states spectrum is closely packed for such heavy states so that one cannot separate out individual scattering states since the volume dependence is skewed as a result. However, the hybrid boundary condition method works and we found that the four-quark correlators can be fitted with a tower of two-meson scattering states. We conclude that we do not see a tetraquark mesonium in the D^∗ _{s 0}(2317) meson region.