Leptonic widths of high excitations in heavy quarkonia

Agreement with the measured electronic widths of the resonances psi (4040), psi (4415) and Y (11 019) is shown to be obtained if two effects are taken into account: (i) a flattening of the confining potential at distances r >= 1.2 fm, which gives a drop in the leptonic widths of high excitations of about 10-20 %, but does not affect low-lying states, and (ii) switching off the gluon-exchange (GE) interaction for those nS states which have a rms radius r(n) >= 1.4 fm. We also show that an exponential type of screening of the GE interaction barely changes the leptonic widths, Gamma (n S), for n <= 5. The leptonic widths of Gamma(e+e-)(Y(7S)) = 0.11 keV and Gamma(psi(5S)) approximate to 0.54 keV are predicted.