37 research outputs found
Numerical study of chiral plasma instability within the classical statistical field theory approach
We report on a numerical study of real-time dynamics of electromagnetically
interacting chirally imbalanced lattice Dirac fermions within the classical
statistical field theory approach. Namely, we perform exact simulations of the
real-time quantum evolution of fermionic fields coupled to classical
electromagnetic fields, which are in turn coupled to the vacuum expectation
value of the fermionic electric current. We use Wilson-Dirac Hamiltonian for
fermions, and non-compact action for the gauge field. In general, we observe
that the backreaction of fermions on the electromagnetic field prevents the
system from acquiring chirality imbalance. In the case of chirality pumping in
parallel electric and magnetic fields, electric field is screened by the
produced on-shell fermions and the accumulation of chirality is hence stopped.
In the case of evolution with initially present chirality imbalance, axial
charge tends to transform to helicity of electromagnetic field. By performing
simulations on large lattices we show that in most cases this decay process is
accompanied by the inverse cascade phenomenon which transfers energy from
short-wavelength to long-wavelength electromagnetic fields. In some
simulations, however, we observe a very clear signature of inverse cascade for
the helical magnetic fields which is not accompanied by the axial charge decay.
This suggests that the relation between inverse cascade and axial charge decay
is not as straightforward as predicted by the simplest form of anomalous
Maxwell equations.Comment: 22 pages RevTeX, 14 figures; v4: published version, updated
references, new physical results on large lattice
Applications of lattice QCD techniques for condensed matter systems
We review the application of lattice QCD techniques, most notably the Hybrid
Monte-Carlo (HMC) simulations, to first-principle study of tight-binding models
of crystalline solids with strong inter-electron interactions. After providing
a basic introduction into the HMC algorithm as applied to condensed matter
systems, we review HMC simulations of graphene, which in the recent years have
helped to understand the semi-metal behavior of clean suspended graphene at the
quantitative level. We also briefly summarize other novel physical results
obtained in these simulations. Then we comment on the applicability of Hybrid
Monte-Carlo to topological insulators and Dirac and Weyl semi-metals and
highlight some of the relevant open physical problems. Finally, we also touch
upon the lattice strong-coupling expansion technique as applied to condensed
matter systems.Comment: 20 pages, 5 figures, Contribution to IJMPA special issue "Lattice
gauge theory beyond QCD". List of references update
Magnetism and interaction-induced gap opening in graphene with vacancies or hydrogen adatoms: Quantum Monte Carlo study
We study electronic properties of graphene with finite concentration of
vacancies or other resonant scatterers by a straightforward lattice Quantum
Monte Carlo calculations. Taking into account realistic long-range Coulomb
interaction we calculate distribution of spin density associated to midgap
states and demonstrate antiferromagnetic ordering. Energy gaps are open due to
the interaction effects, both in the bare graphene spectrum and in the
vacancy/impurity bands. In the case of 5 % concentration of resonant scatterers
the latter gap is estimated as 0.7 eV and 1.1 eV for graphene on boron nitride
and freely suspended graphene, respectively.Comment: Text is substantially updated, temperature dependence of order
parameter is added. Accepted for publication in PR
Green functions in graphene monolayer with Coulomb interactions taken into account
We consider the low energy effective field model of graphene monolayer.
Coulomb interactions are taken into account. The model is simulated numerically
using the lattice discretization with staggered fermions. The two point
fermionic Green functions are calculated. We find that in the insulator phase
these Green functions almost do not depend on energy. This indicates that the
effective field model (in its insulator phase) does not correspond to the real
graphene.Comment: Latex, 9 pages, accepted for publication in Solid State
Communication