An incompatibility in calculation of quarkonium masses and leptonic decay widths in potential models

Masses and leptonic decay widths of charmonium and upsilon states are reanalyzed using a QQ-potential, whose confining part is of a general power-law type i.e. βrn. Treating the exponent n and the strength β of this confining part as free parameters, the authors show that the masses and leptonic widths prefer mutually exclusive regions in the β-n parametric space. Some ways to resolve this incompatibility are discussed. (author)