Vanishing bulk viscosities and conformal invariance of unitary Fermi gas

By requiring general-coordinate and conformal invariance of the hydrodynamic equations, we show that the unitary Fermi gas has zero bulk viscosity, zeta=0, in the normal phase. In the superfluid phase, two of the bulks viscosities have to vanish, zeta_1=zeta_2=0, while the third one zeta_3 is allowed to be nonzero.Comment: 4 page

Berry Curvature, Triangle Anomalies, and the Chiral Magnetic Effect in Fermi Liquids

In a three-dimensional Fermi liquid, quasiparticles near the Fermi surface may possess a Berry curvature. We show that if the Berry curvature has a nonvanishing flux through the Fermi surface, the particle number associated with this Fermi surface has a triangle anomaly in external electromagnetic fields. We show how Landau's Fermi liquid theory should be modified to take into account the Berry curvature. We show that the "chiral magnetic effect" also emerges from the Berry curvature flux.Comment: 5 pages, published versio

Chiral Vortical Effect in Superfluid

We consider rotating superfluid pionic liquid, with superfluidity being induced by isospin chemical potential. The rotation is known to result in a chiral current flowing along the axis of the rotation. We argue that in case of superfluidity the chiral current is realized on fermionic zero modes propagating along vortices. The current evaluated in this way differs by a factor of two from the standard one. The reason is that the chiral charge is carried by zero modes which propagate with speed of light, and thus the liquid cannot be described by a single (local) velocity, like it is assumed in standard derivations.Comment: 10 pages. To be published in PRD. Minor changes added; typos fixe

Charged and superconducting vortices in dense quark matter

Quark matter at astrophysical densities may contain stable vortices due to the spontaneous breaking of hypercharge symmetry by kaon condensation. We argue that these vortices could be both charged and electrically superconducting. Current carrying loops (vortons) could be long lived and play a role in the magnetic and transport properties of this matter. We provide a scenario for vorton formation in protoneutron stars.Comment: Replaced with the published version. A typographical error in Eq. 2 is correcte

Suppression of Landau damping via electron band gap

The pondermotive potential in the X-ray Raman compression can generate an electron band gap which suppresses the Landau damping. The regime is identified where a Langmuir wave can be driven without damping in the stimulated Raman compression. It is shown that the partial wave breaking and the frequency detuning due to the trapped particles would be greatly reduced.Comment: 4 pages, 5 figure

Hydrodynamics with Triangle Anomalies

We consider the hydrodynamic regime of theories with quantum anomalies for global currents. We show that a hitherto discarded term in the conserve current is not only allowed by symmetries, but is in fact required by triangle anomalies and the second law of thermodynamics. This term leads to a number of new effects, one of which is chiral separation in a rotating fluid at nonzero chemical potential. The new kinetic coefficients can be expressed, in a unique fashion, through the anomalies coefficients and the equation of state. We briefly discuss the relevance of this new hydrodynamic term for physical situations, including heavy ion collisions.Comment: 4 pages; v2: error in Eq.(4) correcte

Real-time pion propagation in finite-temperature QCD

We argue that in QCD near the chiral limit, at all temperatures below the chiral phase transition, the dispersion relation of soft pions can be expressed entirely in terms of three temperature-dependent quantities: the pion screening mass, a pion decay constant, and the axial isospin susceptibility. The definitions of these quantities are given in terms of equal-time (static) correlation functions. Thus, all three quantities can be determined directly by lattice methods. The precise meaning of the Gell-Mann--Oakes--Renner relation at finite temperature is given.Comment: 25 pages, 2 figures; v2: discussion on the region of applicability expanded, to be published in PR

Pion Propagation near the QCD Chiral Phase Transition

We point out that, in analogy with spin waves in antiferromagnets, all parameters describing the real-time propagation of soft pions at temperatures below the QCD chiral phase transition can be expressed in terms of static correlators. This allows, in principle, the determination of the soft pion dispersion relation on the lattice. Using scaling and universality arguments, we determine the critical behavior of the parameters of pion propagation. We predict that when the critical temperature is approached from below, the pole mass of the pion drops despite the growth of the pion screening mass. This fact is attributed to the decrease of the pion velocity near the phase transition.Comment: 8 pages (single column), RevTeX; added references, version to be published in PR