Nonrelativistic Heavy Quarkonium Model Descended from a Quasi-Particle Approach.

A Schrödinger-type equation for a heavy quarkonium in terms of the dynamical quark mass is obtained in a quasi-particle approach by Llanes-Estrada and Cotanch. To observe the relationship between the obtained equation and the constituent quark (potential) model equation, we treat the dynamical quark mass by a constant parameter M and expand the equation in 1/M up to order (1/M). The equation reduces to that of the traditional nonrelativistic constituent quark model when a nonlocal interaction is neglected. We investigate the nonrelativistic model where the dynamical quark mass M in the Schrödinger-type equation is treated as a free parameter and call it the quasi-quark (QQ) model. To elucidate the role of the nonlocal interaction and to observe the reliability of the QQ model, we studied the charmonium S-wave states. [ABSTRACT FROM AUTHOR]