Scalar meson properties from D-meson decays⁎

Decay amplitudes of D ( D s ) → f 0 ( 980 ) X , X = π , K , are compared to experimental branching ratios with the aim of singling out the poorly known D → f 0 ( 980 ) transition form factor in these amplitudes. Since the other elements of the amplitudes are either calculable in an effective QCD theory using operator product expansion or are known from experiment (e.g. the pion and kaon decay constants), we can take advantage of these reactions to constrain the transition form factors obtained in relativistic quark models [O.M.A. Leitner, B. El-Bennich, B. Loiseau and J.-P. Dedonder, hep-ph/0609062 ; B. El-Bennich, O.M.A. Leitner, B. Loiseau and J.-P. Dedonder, hep-ph/0609154 ]. In these models, the f 0 ( 980 ) wavefunction requires an unknown size parameter for both its non-strange u ¯ u ( d ¯ d ) and strange s ¯ s components, which we fit to the D ( D s ) decay data.