886 research outputs found
Analogies between the Black Hole Interior and the Type II Weyl Semimetals
In the Painleve--Gullstrand (PG) reference frame, the description of
elementary particles in the background of a black hole (BH) is similar to the
description of non-relativistic matter falling toward the BH center. The
velocity of the fall depends on the distance to the center, and it surpasses
the speed of light inside the horizon.~Another analogy to non-relativistic
physics appears in the description of the massless fermionic particle. Its
Hamiltonian inside the BH, when written in the PG reference frame, is identical
to the Hamiltonian of the electronic quasiparticles in type~II Weyl semimetals
(WSII) that reside in the vicinity of a type~II Weyl point. When these
materials are in the equilibrium state, the type II Weyl point becomes the
crossing point of the two pieces of the Fermi surface called Fermi pockets. {It
was previously stated} that there should be a Fermi surface inside a black hole
in equilibrium. In real materials, type II Weyl points come in pairs, and the
descriptions of the quasiparticles in their vicinities are, to a certain
extent, inverse. Namely, the directions of their velocities are opposite. In
line with the mentioned analogy, we propose the hypothesis that inside the
equilibrium BH there exist low-energy excitations moving toward the exterior of
the BH. These excitations are able to escape from the BH, unlike ordinary
matter that falls to its center. The important consequences to the quantum
theory of black holes follow.Comment: Latex, 7 page
Absence of equilibrium chiral magnetic effect
We analyse the D equilibrium chiral magnetic effect (CME). We apply
derivative expansion to the Wigner transform of the two - point Green function.
This technique allows us to express the response of electric current to
external electromagnetic field strength through the momentum space topological
invariant. We consider the wide class of the lattice regularizations of quantum
field theory (that includes, in particular, the regularization with Wilson
fermions) and also certain lattice models of solid state physics (including
those of Dirac semimetals). It appears, that in these models the mentioned
topological invariant vanishes identically at nonzero chiral chemical
potential. That means, that the bulk equilibrium CME is absent in those
systems.Comment: Latex, 18 pages. arXiv admin note: substantial text overlap with
arXiv:1603.0366
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