Particle Formation and Ordering in Strongly Correlated Fermionic Systems: Solving a Model of Quantum Chromodynamics

Abstract

In this paper we study a (1+1)-dimensional version of the famous Nambu-Jona-Lasinio model of Quantum Chromodynamics (QCD2) both at zero and finite hadron density. We use non-perturbative techniques (non-Abelian bosonization and Truncated Conformal Space Approach). At zero density we describe a formation of fermion three-quark (nucleons and $\Delta$-baryons) and boson (two-quark mesons, six-quark deuterons) bound states and also a formation of a topologically nontrivial phase. At finite hadron density, the model has a rich phase diagram which includes phases with density wave and superfluid quasi-long-range (QLR) order and also a phase of a baryon Tomonaga-Luttinger liquid (strange metal). The QLR order results as a condensation of scalar mesons (the density wave) or six-quark bound states (deuterons).