Constraints on charged Higgs bosons from D?s ? ??? and D?s ? ???

The decays D?s ? ???? and D?s ? ???? have traditionally been used to measure the D?s meson decay constant fDs. Recent measurements at CLEO-c and the B factories suggest a branching ratio for both decays somewhat higher than the Standard Model prediction using fDs from unquenched lattice calculations. The charged Higgs boson (H?) in the Two Higgs Doublet Model (Type II) would also mediate these decays, but any sizeable contribution from H? can only suppress the branching ratios and consequently is now slightly disfavoured. It is shown that constraints on the parameters tan ? and mH? from such decays can be competitive with and complementary to analogous constraints derived from the leptonic meson decays B? ? ???? and K? ? ????, especially if lattice calculations eventually prefer fDs < 250 MeV.