Charmonium and UPSILON systems with small hyperfine splittings

The parameters of the simple Coulomb plus linear effective potential with lowest-order relativistic corrections are determined by the charmonium states other than the 1S0 states and by the leptonic decay widths of J/psi and psi'. The effective coupling constant α/sub s/ is found to be 0.21. Within this framework the hyperfine splittings are small and so are the consequent M1 transitions (well below the experimental upper limit of 1.2 keV). The 1S0 partners of psi and psi' are predicted to be eta/sub c/(3020) and eta/sub c/' (3638) and are not to be identified with the experimentally uncertain X (2830) and chi (3450). The same effective potential, changing only the constituent quark mass, gives a good description of the UPSILON system. The spin-independent relativistic corrections play an important role in obtaining the equality m/sub Upsilonprime/ - m/sub Upsilon/ approx. = m/sub psiprime/ - m/sub psi/