SCALING RELATION FOR THE $\Upsilon (4S)\to B\bar{B}$ AND $\psi (3770)\to D\bar{D}$ DECAY CONSTANTS FROM PHENOMENOLOGICAL SUM RULES

The sum rules for exclusive production of heavy meson pairs in e+e− annihilation are used to evaluate the [Formula: see text] and [Formula: see text] decay widths. Infinitely heavy quark limit is discussed, and the scaling relation for the quarkonium-meson coupling constant is derived. The [Formula: see text] pair contribution into the leptonic constant fϒ(4S) is estimated.