1,576 research outputs found
Noncommutative Novikov algebras
The class of Novikov algebras is a popular object of study among classical
nonassociative algebras. The generic example of a Novikov algebra may be
obtained from a differential associative and commutative algebra. We consider a
more general class of linear algebras which may be obtained in the same way
from not necessarily commutative associative algebras with a derivation.Comment: 18 page
Short-time critical dynamics of the three-dimensional systems with long-range correlated disorder
Monte Carlo simulations of the short-time dynamic behavior are reported for
three-dimensional Ising and XY models with long-range correlated disorder at
criticality, in the case corresponding to linear defects. The static and
dynamic critical exponents are determined for systems starting separately from
ordered and disordered initial states. The obtained values of the exponents are
in a good agreement with results of the field-theoretic description of the
critical behavior of these models in the two-loop approximation and with our
results of Monte Carlo simulations of three-dimensional Ising model in
equilibrium state.Comment: 24 RevTeX pages, 12 figure
Interface states in junctions of two semiconductors with intersecting dispersion curves
A novel type of shallow interface state in junctions of two semiconductors
without band inversion is identified within the envelope function
approximation, using the two-band model. It occurs in abrupt junctions when the
interband velocity matrix elements of the two semiconductors differ and the
bulk dispersion curves intersect. The in-plane dispersion of the interface
state is found to be confined to a finite range of momenta centered around the
point of intersection. These states turn out to exist also in graded junctions,
with essentially the same properties as in the abrupt case.Comment: 1 figur
Planar Heterostructure Graphene -- Narrow-Gap Semiconductor -- Graphene
We investigate a planar heterostructure composed of two graphene films
separated by a narrow-gap semiconductor ribbon. We show that there is no the
Klein paradox when the Dirac points of the Brillouin zone of graphene are in a
band gap of a narrow-gap semiconductor. There is the energy range depending on
an angle of incidence, in which the above-barrier damped solution exists.
Therefore, this heterostructure is a "filter" transmitting particles in a
certain range of angles of incidence upon a potential barrier. We discuss the
possibility of an application of this heterostructure as a "switch".Comment: 9 pages, 2 figure
Graded associative conformal algebras of finite type
In this paper, we consider graded associative conformal algebras. The class
of these objects includes pseudo-algebras over non-cocommutative Hopf algebras
of regular functions on some linear algebraic groups. In particular, an
associative conformal algebra which is graded by a finite group is a
pseudo-algebra over the coordinate Hopf algebra of a linear algebraic group
such that the identity component is the affine line and . A classification of simple and semisimple graded associative
conformal algebras of finite type is obtained
On pre-Novikov algebras and derived Zinbiel variety
For a non-associative algebra with a derivation , its derived algebra
is the same space equipped with new operations ,
, . Given a variety Var of algebras, its derived
variety is generated by all derived algebras for all in Var and
for all derivations of . The same terminology is applied to binary
operads governing varieties of non-associative algebras. For example, the
operad of Novikov algebras is the derived one for the operad of (associative)
commutative algebras. We state a sufficient condition for every algebra from a
derived variety to be embeddable into an appropriate differential algebra of
the corresponding variety. We also find that for the variety Zinb of Zinbiel
algebras, there exist algebras from the derived variety (which coincides with
the class of pre-Novikov algebras) that cannot be embedded into a Zinbiel
algebra with a derivation.Comment: 14 pages, minor revisio
Singlet-Triplet Excitations in the Unconventional Spin-Peierls System TiOBr
We have performed time-of-flight neutron scattering measurements on powder
samples of the unconventional spin-Peierls compound TiOBr using the
fine-resolution Fermi chopper spectrometer (SEQUOIA) at the SNS. These
measurements reveal two branches of magnetic excitations within the
commensurate and incommensurate spin-Peierls phases, which we associate with n
= 1 and n = 2 triplet excitations out of the singlet ground state. These
measurements represent the first direct measure of the singlet-triplet energy
gap in TiOBr, which is determined to be Eg = 21.2 +/- 1.0 meV.Comment: 5 pages, 4 figures, submitted for publicatio
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