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

TL;DR

This paper investigates a (1+1)-dimensional QCD-like model using non-perturbative methods, revealing complex phase structures including bound states, topological phases, and density wave and superfluid orders at various densities.

Contribution

It provides a detailed analysis of a simplified QCD model, uncovering novel phases and bound state formations using advanced non-perturbative techniques.

Findings

Formation of fermion and boson bound states at zero density

Identification of a topologically nontrivial phase

Rich phase diagram with density wave and superfluid phases

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).