5,908 research outputs found
The Structure of Worker Compensation in Brazil, With a Comparison to France and the United States
Chern-Simons theory and atypical Hall conductivity in the Varma phase
In this letter, we analyze the topological response of a fermionic model
defined on the Lieb lattice in presence of an electromagnetic field. The
tight-binding model is built in terms of three species of spinless fermions and
supports a topological Varma phase due to the spontaneous breaking of
time-reversal symmetry. In the low-energy regime, the emergent effective
Hamiltonian coincides with the so-called Duffin-Kemmer-Petiau (DKP)
Hamiltonian, which describes relativistic pseudospin-0 quasiparticles. By
considering a minimal coupling between the DKP quasiparticles and an external
Abelian gauge field, we calculate both the Landau-level spectrum and the
emergent Chern-Simons theory. The corresponding Hall conductivity reveals an
atypical quantum Hall effect, which can be simulated in an artificial Lieb
lattice.Comment: 5 pages, 3 figures; New version with an improved discussion about our
finding
Markovian versus non-Markovian stochastic quantization of a complex-action model
We analyze the Markovian and non-Markovian stochastic quantization methods
for a complex action quantum mechanical model analog to a Maxwell-Chern-Simons
eletrodynamics in Weyl gauge. We show through analytical methods convergence to
the correct equilibrium state for both methods. Introduction of a memory kernel
generates a non-Markovian process which has the effect of slowing down
oscillations that arise in the Langevin-time evolution toward equilibrium of
complex action problems. This feature of non-Markovian stochastic quantization
might be beneficial in large scale numerical simulations of complex action
field theories on a lattice.Comment: Accepted for publication in the International Journal of Modern
Physics
Conformal QED in two-dimensional topological insulators
It has been shown recently that local four-fermion interactions on the edges
of two-dimensional time-reversal-invariant topological insulators give rise to
a new non-Fermi-liquid phase, called helical Luttinger liquid (HLL). In this
work, we provide a first-principle derivation of this non-Fermi-liquid phase
based on the gauge-theory approach. Firstly, we derive a gauge theory for the
edge states by simply assuming that the interactions between the Dirac fermions
at the edge are mediated by a quantum dynamical electromagnetic field. Here,
the massless Dirac fermions are confined to live on the one-dimensional
boundary, while the (virtual) photons of the U(1) gauge field are free to
propagate in all the three spatial dimensions that represent the physical space
where the topological insulator is embedded. We then determine the effective
1+1-dimensional conformal field theory (CFT) given by the conformal quantum
electrodynamics (CQED). By integrating out the gauge field in the corresponding
partition function, we show that the CQED gives rise to a 1+1-dimensional
Thirring model. The bosonized Thirring Hamiltonian describes exactly a HLL with
a parameter K and a renormalized Fermi velocity that depend on the value of the
fine-structure constant .Comment: (5+4) pages, 2 figure
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