Magnetic Response in Anyon Fluid at High Temperature

The magnetic response of the charged anyon fluid at temperatures lower and larger than the fermion enery gap $\omega_{c}$ is investigated in the self-consistent field approximation. We prove that the anyon system with boundaries exhibits a total Meissner effect at temperatures smaller than the fermion energy gap ($T\ll \omega_{c}$). The London penetration length at $T$ $\sim 200K$ is of the order $\lambda \sim 10^{-5}cm$. At $T\gg \omega_{c}$ a new phase, characterized by an inhomogeneous magnetic penetration, is found. We conclude that the energy gap, $\omega_{c},$ defines a scale that separates two phases: a superconducting phase at $T\ll \omega_{c}$, and a non-superconducting one at $T\gg \omega_{c}$.Comment: 7 pages, Talk presented at SILAFAE'98. April 8-11, 1998, San Juan, Puerto Ric

No Net Charge Separation in Hot QCD in a Magnetic Field

We study the realization of axion electrodynamics in QCD in the presence of a background magnetic field at temperatures high enough for the occurrence of topological charge transitions that are reflected in the presence of a $\theta$-vacuum term in the action. We show that in this system, the Maxwell equations contain two equal and opposite electric currents that are proportional to the time derivative of the axion field $\theta$. One of these currents comes directly from the Abelian chiral anomaly term in the action and can be interpreted as a polarization current due to the magnetoelectricity of the system with CP-broken symmetry. The other current is obtained from the regular tadpole diagrams and can be understood as produced by the medium chiral imbalance and the single spin projection of the quarks in the lowest Landau level. Since the two currents cancel out, the net electric charge separation along the magnetic field, a phenomenon known as the Chiral Magnetic Effect, does not take place in hight-T QCD at least in equilibrium, in sharp contrast with many claims in the literature. We discuss the similarities and differences with Weyl semimetals in a magnetic field.Comment: 17 page

Novel Topological Effects in Dense QCD in a Magnetic Field

We study the electromagnetic properties of dense QCD in the so-called Magnetic Dual Chiral Density Wave phase. This inhomogeneous phase exhibits a nontrivial topology that comes from the fermion sector due to the asymmetry of the lowest Landau level modes. The nontrivial topology manifests in the electromagnetic effective action via a chiral anomaly term $~\theta F^{\mu\nu}\tilde{F}_{\mu\nu}$, with a dynamic axion field $\theta$ given by the phase of the dual chiral density wave condensate. The coupling of the axion with the electromagnetic field leads to several macroscopic effects that include, among others, an anomalous, nondissipative Hall current, an anomalous electric charge, magnetoelectricity, and the formation of a hybridized propagating mode known as an axion polariton. Connection to topological insulators and Weyls semimetals, as well as possible implications for heavy-ion collisions and neutron stars are all highlighted.Comment: Section 3 completely revised, discussions added, and typos correcte

Spontaneous CPT Violation in Confined QED

Symmetry breaking induced by untwisted fermions in QED in a nonsimply connected spacetime with topology $S^{1}\times R^{3}$ is investigated. It is found that the discrete CPT symmetry of the theory is spontaneously broken by the appearance of a constant vacuum expectation value of the electromagnetic potential along the direction of space periodicity. The constant potential is shown to be gauge nonequivalent to zero in the nonsimply connected spacetime under consideration. Due to the symmetry breaking, one of the electromagnetic modes of propagation is massive with a mass that depends on the inverse of the compactification length. As a result, the system exhibits a sort of topological directional superconductivity.Comment: 6 pages, revte