  In the context of gauge/gravity duals with flavor, we examine heavy-light
mesons which involve a heavy and a light quark. For this purpose we embed two
D7 brane probes at different positions into the gravity background. We
establish the non-Abelian Dirac-Born-Infeld (DBI) action for these probes, in
which the U(2) matrix describing the embedding is diagonal. The fluctuations of
the brane probes correspond to the mesons. In particular, the off-diagonal
elements of the U(2) fluctuation matrix correspond to the heavy-light mesons,
while the diagonal elements correspond to the light-light and heavy-heavy
mesons, respectively. The heavy-light mesons scale differently with the 't
Hooft coupling than the mesons involving quarks of equal mass. The model
describes both scalar and vector mesons. For different dilaton-deformed gravity
backgrounds, we also calculate the Wilson loop energy, and compare with the
meson masses.
