Existence of chiral density wave phases in QCD at high density and low temperature

Establish whether chiral density wave phases actually occur in quantum chromodynamics at low temperature and large baryon chemical potential and delineate their region of stability in the (μB,T) phase diagram using first-principles or otherwise robust methods.

Background

The authors employ a nucleon–meson model to probe whether chiral density wave (CDW) phases can affect cosmological phase transitions. They note, however, that the existence of the CDW phase in real QCD remains unconfirmed and is currently a theoretical possibility due to limitations such as the lattice QCD sign problem at finite baryon chemical potential.

Determining the existence and extent of CDW phases in QCD is a prerequisite for assessing their cosmological implications, including the feasibility of QCD-induced little inflation and associated gravitational-wave signals.

References

Although the existence of the CDW phase in QCD matter has not yet been fully established and still remains a theoretical possibility, we find that, in the nucleon-meson model, its phase transition can be strongly first-order when the saturation mass M0 is large and the self-interaction of the ω meson is strong.

— Revisiting QCD-induced little inflation with chiral density wave state and its implications on pulsar timing array gravitational-wave signals  (2603.29772 - Jung et al., 31 Mar 2026) in Section "Summary" (Section 5)