Chiral symmetry breaking with no bilinear condensate revisited

Abstract

While chiral symmetry breaking in the QCD vacuum is attributed to nonzero chiral condensate, an alternative symmetry breaking pattern with no chiral condensate is also possible, as pointed out by Stern. This hypothetical phase was excluded in QCD at zero density long time ago, but nothing forbids it at finite baryon density. In this work, we study the $\theta$ dependence of this unorthodox phase on the basis of chiral perturbation theory. Physical observables such as energy density, topological susceptibility, non-local chiral order parameter and meson masses are computed analytically in the epsilon-regime. At nonzero $\theta$ we find an exotic phase that breaks vectorial flavor symmetries in a way analogous to the Aoki phase in lattice QCD.

27 pages, 8 figures. v2: minor revisions, published version

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Cited by in corpus (12)

• Recent Progress in QCD Condensate Evaluations and Sum Rules
• Anomaly constraint on massless QCD and the role of Skyrmions in chiral symmetry breaking
• Fractional $\theta$ angle, 't Hooft anomaly, and quantum instantons in charge-$q$ multi-flavor Schwinger model
• Fermion masses through four-fermion condensates
• A pseudo-conformal structure in dense baryonic matter
• 't Hooft anomaly matching condition and chiral symmetry breaking without bilinear condensate
• U(1) axial symmetry and Dirac spectra in QCD at high temperature
• Poincare covariant pseudoscalar and scalar meson spectroscopy in Wigner-Weyl phase
• Heavy-tailed chiral random matrix theory
• Metal or Insulator? Dirac operator spectrum in holographic QCD
• Chiral random matrix theory for colorful quark-antiquark condensates
• Nonrelativistic Banks-Casher relation and random matrix theory for multi-component fermionic superfluids