Entropy Wave Instability in Dirac and Weyl Semimetals.

Hydrodynamic instabilities driven by a direct current are analyzed in 2D and 3D relativisticlike systems with the Dyakonov-Shur boundary conditions supplemented by a boundary condition for temperature. Besides the conventional Dyakonov-Shur instability for plasmons, we find an entropy wave instability in both 2D and 3D systems. The entropy wave instability is a manifestation of the relativisticlike nature of electron quasiparticles and a nontrivial role of the energy current in such systems.

Inter-node superconductivity in strained Weyl semimetals.

The effects of a strain-induced pseudomagnetic field on inter-node spin-triplet superconducting states in Weyl semimetals are studied by using the quasiclassical Eilenberger formalism. It is found that the Cooper pairing with spins parallel to the pseudomagnetic field has the lowest energy among the spin-triplet states and its gap does not depend on the strength of the field. In such a state, both electric and chiral superconducting currents are absent.

Collective excitations in Weyl semimetals in the hydrodynamic regime.

The spectrum of collective excitations in Weyl materials is studied by using consistent hydrodynamics. The corresponding framework includes the vortical and chiral anomaly effects, as well as the dependence on the separations between the Weyl nodes in energy b and momentum [Formula: see text]. The latter are introduced via the Chern-Simons contributions to the electric current and charge densities in Maxwell's equations.

Consistent Chiral Kinetic Theory in Weyl Materials: Chiral Magnetic Plasmons.

We argue that the correct definition of the electric current in the chiral kinetic theory for Weyl materials should include the Chern-Simons contribution that makes the theory consistent with the local conservation of the electric charge in electromagnetic and strain-induced pseudoelectromagnetic fields. By making use of such a kinetic theory, we study the plasma frequencies of collective modes in Weyl materials in constant magnetic and pseudomagnetic fields, taking into account the effects of dynamical electromagnetism. We show that the collective modes are chiral plasmons.

Fast equilibration of hadrons in an expanding fireball.

Because of long chemical equilibration times for standard hadronic reactions in a hadron gas in relativistic heavy ion collisions, it was suggested that hadrons are born into equilibrium after the quark gluon plasma is formed. We develop a dynamical scheme, using master equations, in which Hagedorn states contribute to fast chemical equilibration times of baryons and kaons, just below the critical temperature, estimates of which are derived analytically. The hadrons quickly equilibrate for an initial over- or underpopulation of Hagedorn states.

Pulsar kicks via spin-1 color superconductivity.

We propose a new neutrino propulsion mechanism for neutron stars which can lead to strong velocity kicks, needed to explain the observed bimodal velocity distribution of pulsars. The spatial asymmetry in the neutrino emission is naturally provided by a stellar core containing spin-1 color-superconducting quark matter in the A phase. The neutrino propulsion mechanism switches on when the stellar core temperature drops below the transition temperature of this phase.

Spontaneous symmetry breaking with abnormal number of Nambu-Goldstone bosons and kaon condensate.

We describe a class of relativistic models incorporating a finite density of matter in which spontaneous breakdown of continuous symmetries leads to a lesser number of Nambu-Goldstone bosons than that required by the Goldstone theorem. This class, in particular, describes the dynamics of the kaon condensate in the color-flavor locked phase of high density QCD. We describe the spectrum of low energy excitations in this dynamics and show that, despite the presence of a condensate and gapless excitations, this system is not a superfluid.