New dynamic critical phenomena in nuclear and quark superfluids

We study the dynamic critical phenomena near the possible high-density QCD critical point inside the superfluid phase of nuclear and quark matter. We find that this critical point belongs to a new dynamic universality class beyond the conventional classification by Hohenberg and Halperin. We show that the speed of the superfluid phonon vanishes at the critical point and that the dynamic critical index is $z\approx 2$.

Figure 1

A schematic QCD phase structure with the high-temperature critical point A and high-density critical point B [8, 9]. The double and single lines denote the first-order transition associated with chiral symmetry breaking/restoration and the second-order transition associated with $\mathrm{U}(1{)}_{\mathrm{B}}$ symmetry breaking/restoration, respectively.