2,793 research outputs found
Gravitational Lorentz anomaly from the overlap formula in 2-dimensions
In this letter we show that the overlap formulation of chiral gauge theories
correctly reproduces the gravitational Lorentz anomaly in 2-dimensions. This
formulation has been recently suggested as a solution to the fermion doubling
problem on the lattice. The well known response to general coordinate
transformations of the effective action of Weyl fermions coupled to gravity in
2-dimensions can also be recovered.Comment: 7 pages, late
Nonlocal lattice fermion models on the 2d torus
Abelian fermion models described by the SLAC action are considered on a
finite 2d lattice. It is shown that modification of these models by introducing
additional Pauli - Villars regularization supresses nonlocal effects and
provides agreement with the continuum results in vectorial U(1) models. In the
case of chiral fermions the phase of the determinant differs from the continuum
one.Comment: 16 pages, LaTeX, 5 eps figures, uses epsf.sty, rotate.st
Interlayer interaction and electronic screening in multilayer graphene
The unusual transport properties of graphene are the direct consequence of a
peculiar bandstructure near the Dirac point. We determine the shape of the pi
bands and their characteristic splitting, and the transition from a pure 2D to
quasi-2D behavior for 1 to 4 layers of graphene by angle-resolved
photoemission. By exploiting the sensitivity of the pi bands to the electronic
potential, we derive the layer-dependent carrier concentration, screening
length and strength of interlayer interaction by comparison with tight binding
calculations, yielding a comprehensive description of multilayer graphene's
electronic structure
Density-functional theory investigation of oxygen adsorption at Pd(11N)(N=3,5,7) vicinal surfaces
We present a density-functional theory study addressing the on-surface
adsorption of oxygen at the Pd(11N) (N =3,5,7) vicinal surfaces, which exhibit
(111) steps and (100) terraces of increasing width. We find the binding to be
predominantly governed by the local coordination at the adsorption site. This
leads to very similar bonding properties at the threefold step sites of all
three vicinal surfaces, while the binding at the central fourfold hollow site
in the four atomic row terrace of Pd(117) is already very little disturbed by
the presence of the neighboring steps.Comment: 9 pages including 4 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Scaling of energy spreading in strongly nonlinear disordered lattices
To characterize a destruction of Anderson localization by nonlinearity, we
study the spreading behavior of initially localized states in disordered,
strongly nonlinear lattices. Due to chaotic nonlinear interaction of localized
linear or nonlinear modes, energy spreads nearly subdiffusively. Based on a
phenomenological description by virtue of a nonlinear diffusion equation we
establish a one-parameter scaling relation between the velocity of spreading
and the density, which is confirmed numerically. From this scaling it follows
that for very low densities the spreading slows down compared to the pure power
law.Comment: 4 pages, 4 figure
Constraints on the Existence of Chiral Fermions in Interacting Lattice Theories
It is shown that an interacting theory, defined on a regular lattice, must
have a vector-like spectrum if the following conditions are satisfied:
(a)~locality, (b)~relativistic continuum limit without massless bosons, and
(c)~pole-free effective vertex functions for conserved currents.
The proof exploits the zero frequency inverse retarded propagator of an
appropriate set of interpolating fields as an effective quadratic hamiltonian,
to which the Nielsen-Ninomiya theorem is applied.Comment: LaTeX, 9 pages, WIS--93/56--JUNE--P
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