  The electromagnetic and pionic transitions in mesons with heavy flavor quarks
are calculated within the framework of the covariant Blankenbecler-Sugar
equation. The M1 transitions in the charmonium system are shown to be sensitive
to the relativistic aspect of the spin-flip magnetic moment operator, and the
Lorentz structure of the Q\bar Q interaction. The observed rate for the M1
transition J/psi -> eta_c gamma is shown to provide strong evidence for a
scalar confining interaction.
  The single pion and dipion widths are calculated for the heavy-light D
mesons, by employment of the pseudovector pion-quark coupling suggested by
chiral perturbation theory. The pionic transitions D* -> D pi are shown to
provide constraining information on the pion-quark axial coupling g_A^q. It is
also shown that axial exchange charge contributions associated with the Q\bar q
interaction suppress the axial charge amplitude for pion emission by an order
of magnitude. The models for pi and M1 transitions also make it possible to
estimate the eta-nucleon coupling from the transition Ds* -> D_s pi0, once the
value of the pi^0 - eta mixing angle is known.
  Finally, the dipion transition rates of the L=1 D mesons are calculated, and
are shown to make up a significant fraction of their total widths for strong
decay. The pipi transitions between S-wave charmonium and bottomonium states
are modeled in terms of a broad sigma meson with derivative couplings to pions.
