FINITE CHARM-MASS EFFECTS IN F-DS DETERMINATION WITHIN THE HEAVY-QUARK EFFECTIVE THEORY

Within the framework of the heavy quark effective theory, the O(($) ov er bar Lambda/m(c)) (($) over bar Lambda equivalent to m(D)-m(c)) effe cts are studied in determination of f(Ds), (D-s decay constant) via B nonleptonic decays. These effects are found to be sizable and the corr ected f(Ds), is consistent with its direct experimental measurement, t hough the results depend to a certain extent on the form of the Isgur- Wise function.