Near threshold charmed-strange meson states

Early theoretical studies and lattice simulations predicted the scalar and axial-vector D_s charmed-strange mesons to be broad states lying above the thresholds, DK and D*K respectively. Experiments found narrow states D_s0^*(2317) and D_s1(2460) below threshold. We present lattice results of a high statistics N_f = 2 study with a lattice spacing of approximately 0.071 fm, taking explicitly into account the thresholds by including four quark operators. We find a lowering of the meson's masses relative to the two quark operator results. Two pion masses of 290 and 150 MeV with multiple volumes up to 4.5 fm were employed. The volume dependence of the resulting spectrum is investigated according to Luescher's formula.