  A phenomenological analysis of the scalar meson f0(980) is performed that
relies on the quasi-two body decays D and Ds -> f0(980)P, with P=pi, K. The
two-body branching ratios are deduced from experimental data on D or Ds -> pi
pi pi, K Kbar pi and from the f0(980) -> pi+ pi- and f0(980) -> K+ K- branching
fractions. Within a covariant quark model, the scalar form factors F0(q2) for
the transitions D and Ds -> f0(980) are computed. The weak D decay amplitudes,
in which these form factors enter, are obtained in the naive factorization
approach assuming a quark-antiquark state for the scalar and pseudoscalar
mesons. They allow to extract information on the f0(980) wave function in terms
of u-ubar, d-dbar and s-sbar pairs as well as on the mixing angle between the
strange and non-strange components. The weak transition form factors are
modeled by the one-loop triangular diagram using two different relativistic
approaches: covariant light-front dynamics and dispersion relations. We use the
information found on the f0(980) structure to evaluate the scalar and vector
form factors in the transitions D and Ds -> f0(980), as well as to make
predictions for B and Bs -> f0(980), for the entire kinematically allowed
momentum range of q2.
