THE RATIO (F(BS) F(B))/(F(DS)/F(D)) AND ITS IMPLICATIONS FOR B-(B)OVER-BAR MIXING/

We observe that quantities like (f(B)s/f(B))/(f(D)s/f(D)) are predicte d to be unity both by heavy quark and by light quark flavor symmetries . Hence, the deviation from the symmetry prediction must be simultaneo usly small in both symmetry breaking parameters, i.e., order of the ra tio of light to heavy quark masses. We estimate the size of the correc tion. We observe that the ratio of (DELTAM/GAMMA) for B(s)-BBAR(s) to B-BBAR mixing can be expressed in terms of the measurable ratio f(D)s/ f(D) with good precision. We comment on applications of these ideas to other processes.