Exotic baryons in two-dimensional QCD and the generalized sine-Gordon solitons

Abstract

The solitons and kinks of the SU(3) generalized sine-Gordon model (GSG) are shown to describe the baryonic spectrum of two-dimensional quantum chromodynamics (QCD$_{2}$). The GSG model arises in the low-energy effective action of bosonized QCD$_{2}$ with unequal quark mass parameters. The GSG potential for $N_{f}=3$ flavors resembles the potential of the effective chiral lagrangian proposed by Witten to describe low-energy behavior of four dimensional QCD. Among the attractive features of the GSG model are the variety of soliton and kink type solutions for QCD$_{2}$ unequal quark mass parameters [JHEP(0701)(2007)(027)]. Exotic baryons in QCD$_{2}$ [J. Ellis et al JHEP0508(2005)081] are discussed in the context of the GSG model. Various semi-classical computations are performed improving the results of this reference and clarifying the role of unequal quark masses. The remarkable double sine Gordon model also arises as a reduced GSG model bearing a kink($K$) type solution describing a multi-baryon; so, the description of some resonances in QCD$_{2}$ may take advantage of the properties of the $K\bar{K}$ system.