Chiral perturbation theory for {f D S}/{F D} and {B B S}/{B B}

The decay constants for D and D _s mesons, denoted f_D and f_{D S} respectively, are equal in the SU(3) _V limit, as are the hadronic amplitudes for B _S- overlineB_S and B⁰- overlineB⁰ mixing. The leading SU(3) _V violating contribution to ( F_{D S}/ F_D) and to the ration of hadronic matrix elements relevant for B _S - overlineB_S and B ⁰ - overlineB⁰ mixing amplitudes are calculated in chiral perturbatiion theory. We discuss the formalism needed to include both meson and anti-meson fields in the heavy quark effective theory.