New insights into the Ds0(2317) and other charm scalar mesons

Through the scattering of light-pseudoscalar mesons ([pi],K,[pi],[pi]') off charmed mesons (D,Ds), we study the Ds0*(2317) state and other relevant charm scalar mesons in a unitarized chiral effective field theory approach. We investigate the charm scalar meson poles with different strangeness (S) and isospin (I) quantum numbers as well as their corresponding residues, which provide the coupling strengths of the charm scalar mesons. Both the light-quark mass and NC dependences of the pole positions of the Ds0*(2317) and the poles with (S,I)=(0,1/2) are analyzed in detail in this work. Interestingly we observe quite similar pion mass trajectories for the resonance pole at around 2.1 GeV with (S,I)=(0,1/2) to those of the f0(500) given in the literature. When increasing the values of NC we find that a bound state and a virtual state in the (S,I)=(1,0) channel asymmetrically approach the DK threshold for NC6, the bound and virtual states move into the complex plane on the second Riemann sheet and become a symmetric pair of resonance poles. For large enough values of NC, neither the Ds0*(2317) pole nor the poles with (S,I)= (0,1/2) tend to fall down to the real axis, indicating that they do not behave like a standard quark-antiquark meson at large NC.