Leptonic widths of high excitations in heavy quarkonia

Abstract

Agreement with the measured electronic widths of the $ψ(4040)$, $ψ(4415)$, and $Υ(11019)$ resonances is shown to be reached if two effects are taken into account: a flattening of the confining potential at large distances and a total screening of the gluon-exchange interaction at $r\ga 1.2$ fm. The leptonic widths of the unobserved $Υ(7S)$ and $ψ(5S)$ resonances: $Γ_{e^+e^-}(Υ(7S))=0.11$ keV and $Γ(ψ(5S))\approx 0.54$ keV are predicted.