On chiral extrapolations of charmed meson masses and coupled-channel reaction dynamics

We perform an analysis of QCD lattice data on charmed-meson masses. The quark-mass dependence of the data set is used to gain information on the size of counterterms of the chiral Lagrangian formulated with opencharm states with JP = 0− and JP = 1− quantum numbers. Of particular interest are those counterterms that are active in the exotic flavor sextet channel. A chiral expansion scheme in which physical masses enter the extrapolation formulas is developed and applied to the lattice data set. Good convergence properties are demonstrated, and an accurate reproduction of the lattice data based on ensembles of PACS-CS, MILC, ETMC, and HSC with pion and kaon masses smaller than 600 MeV is achieved. It is argued that a unique set of lowenergy parameters is obtainable only if additional information from HSC on some scattering observables is included in our global fits. The elastic and inelastic s-wave πD and ηD scattering as considered by HSC is reproduced faithfully. Based on such low-energy parameters, we predict 15 phase shifts and inelasticities at physical quark masses but also for an additional HSC ensemble at smaller pion mass. In addition, we find a clear signal for a member of the exotic flavor sextet states in the ηD channel, below the KD¯ s threshold. For the isospin-violating strong decay width of the D* s0(2317), we obtain the range (104–116) keV.