Effect of H on Ds -> and Ds ->

We investigate the effect of a charged Higgs boson (H^\pm) on the decaysD^\pm_s\to \mu^\pm\nu and D^\pm_s\to \tau^\pm\nu, which will be measured withhigh precision at forthcoming CLEO-c. We show that a H^\pm can suppress thebranching ratios by 10% \to 15% from the Standard Model prediction, and weemphasize that such contributions should not be overlooked when comparinglattice calculations of f_{D_s} to the values obtained from these decays.Comment: 5 pages, 1 figur