How tetraquarks can generate a second chiral phase transition

TL;DR

This paper explores how tetraquark fields influence the chiral phase transition in QCD-like theories, revealing potential multiple first-order transitions and connections to color superconductivity, with implications for multi-flavor quark systems.

Contribution

It introduces the role of tetraquarks in generating multiple chiral phase transitions and links these to phenomena like color superconductivity in multi-flavor QCD.

Findings

Tetraquarks can induce two first-order chiral phase transitions for three flavors.

Lattice results suggest the tetraquark condensate transition is a smooth crossover.

A possible formation of hexaquarks from triquark fields in four-flavor scenarios.

Abstract

We consider how tetraquarks can affect the chiral phase transition in theories like QCD, with light quarks coupled to three colors. For two flavors the tetraquark field is an isosinglet, and its effect is minimal. For three flavors, however, the tetraquark field transforms in the same representation of the chiral symmetry group as the usual chiral order parameter, and so for very light quarks there may be two chiral phase transitions, which are both of first order. In QCD, results from the lattice indicate that any transition from the tetraquark condensate is a smooth crossover. In the plane of temperature and quark chemical potential, though, a crossover line for the tetraquark condensate is naturally related to the transition line for color superconductivity. For four flavors we suggest that a triquark field, antisymmetric in both flavor and color, combine to form hexaquarks.