Holographic heavy-light chiral effective action

We propose a variant of the D4-D8 construction to describe the low-energy effective theory of heavy-light mesons, interacting with the lowest lying pseudoscalar and vector mesons. The heavy degrees of freedom are identified with the D8L-D8H string low-energy modes, and are approximated near the world volume of Nf-1 light D8L branes, by fundamental vector field valued in U(Nf-1). The effective action follows from the reduction of the bulk Dirac-Born-Infeld and Chern-Simons actions, and is shown to exhibit both chiral and heavy-quark symmetry. The action interpolates continuously between the U(Nf) case with massless mesons, and the U(Nf-1) case with heavy-light mesons. The heavy-light meson radial spectrum is Regge-like. The one-pion and two-pion couplings to the heavy-light multiplets are evaluated. The partial widths for the charged decays G→H+π are shown to be comparable to the recently reported full widths for both the charm and bottom mesons.