Hyperfine splitting and leptonic decay rates in heavy quarkonia

Abstract

The hyperfine splitting in heavy quarkonia is considered in its relation to the leptonic decay rates with the account of relativistic and radiative corrections. The calculated decay rates agree well with the available experimental data, while the predicted \eta_c(2S) mass is significantly smaller than the value measured recently by the Belle Collaboration.

Comments: 4 pages, misprint in Table 2 corrected