In this paper, we study the chiral symmetry restoration in the hadronic spectrum in the framework of generalized Nambu–Jona-Lasinio quark models with instantaneous confining quark kernels. We investigate a heavy-light quarkonium and derive its bound-state equation in the form of a Schrödinger-like equation and, after the exact inverse Foldy-Wouthuysen transformation, in the form of a Diraclike equation. We discuss the Lorentz nature of confinement for such a system and demonstrate explicitly the effective chiral symmetry restoration for highly excited states in the mesonic spectrum. We give an estimate for the scale of this restoration.

• Received 30 June 2005

DOI:https://doi.org/10.1103/PhysRevD.72.034020