CHIRAL PERTURBATION-THEORY FOR SU(3) BREAKING IN HEAVY-MESON SYSTEMS

The SU(3)-breaking effects due to light-quark masses on heavy-meson masses, decay constants (F(D), F(D)s), and the form factor for semileptonic BBAR --> D(*)lnu(l)BAR transitions are formulated in chiral perturbation theory, using a heavy-meson effective Lagrangian and expanding in inverse powers of the heavy-meson mass. To leading order in this expansion, the leading chiral logarithms and the required counterterms are determined. At this level, a nonanalytic correction to the mass splittings of O(p3) appears, similar to the one found in light baryons. The correction to F(D)s/F(D) is roughly estimated to be of the order of 10% and, therefore, experimentally accessible, while the correction to the form factor is likely to be substantially smaller. We explicitly check that the heavy-quark symmetry is preserved by the chiral loops.