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

TL;DR

This paper analyzes lattice QCD data on charmed meson masses using a chiral extrapolation scheme, accurately reproduces the data, predicts scattering observables, and identifies exotic states with implications for meson decay widths.

Contribution

It develops a physical-mass-based chiral expansion scheme for charmed mesons and extracts low-energy parameters, including signals for exotic states, from lattice data.

Findings

Accurate reproduction of lattice data with pion and kaon masses below 600 MeV.

Prediction of 15 phase shifts and inelasticities at physical and smaller pion masses.

Identification of a potential exotic flavour sextet state below the K D_s threshold.

Abstract

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 counter terms of the chiral Lagrangian formulated with open-charm states with J^P= 0^- and J^P =1^- quantum numbers. Of particular interest are those counter terms that are active in the exotic flavour sextet channel. A chiral expansion scheme where physical masses enter the extrapolation formulae 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 low-energy 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 pi D and eta D scattering as considered by HSC is reproduced faithfully. Based on such low-energy parameters we predict 15 phase shifts and in-elasticities 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 flavour sextet states in the eta D channel, below the bar K D_s threshold. For the isospin violating strong decay width of the D_{s0}(2317) we obtain the range (104-116) keV.