545 research outputs found
Poisson-Lie T-dual sigma models on supermanifolds
We investigate Poisson-Lie symmetry for T-dual sigma models on supermanifolds
in general and on Lie supergroups in particular. We show that the integrability
condition on this super Poisson-Lie symmetry is equivalent to the super Jacobi
identities of the Lie super-bialgebras. As examples we consider models related
to four dimensional Lie super-bialgebras and
. Then generally it is shown that for Abelian case (g, I)
the super Poisson-Lie T-duality transforms the role of fermionic (bosonic)
fields in the model to bosonic (fermionic) fields on the dual model and vice
versa.Comment: 13 pages, Revised and accepted for publication in JHE
Super Poisson-Lie symmetry of the GL(1|1) WZNW model and worldsheet boundary conditions
We show that the WZNW model on the Lie supergroup GL(1|1) has super
Poisson-Lie symmetry with the dual Lie supergroup B + A + A1;1|.i. Then, we
discuss about D-branes and worldsheet boundary conditions on supermanifolds, in
general, and obtain the algebraic relations on the gluing supermatrix for the
Lie supergroup case. Finally, using the supercanonical transformation
description of the super Poisson-Lie T-duality transformation, we obtain
formula for the description of the dual gluing supermatrix, then, we find the
gluing supermatrix for the WZNW model on GL(1|1) and its dual model. We also
discuss about different boundary conditions.Comment: 19 pages, two Refs. have adde
Poisson Lie symmetry and D-branes in WZW model on the Heisenberg Lie group
We show that the WZW model on the Heisenberg Lie group has Poisson-Lie
symmetry only when the dual Lie group is . In this way,
we construct the mutual T-dual sigma models on Drinfel'd double generated by
the Heisenberg Lie group and its dual pair, , as
the target space in such a way that the original model is the same as the
WZW model. Furthermore, we show that the dual model is conformal up to two
loops order. Finally, we discuss -branes and the worldsheet boundary
conditions defined by a gluing matrix on the WZW model. Using the duality
map obtained from the canonical transformation description of the Poisson-Lie
T-duality transformations for the gluing matrix which locally defines the
properties of the -brane, we find two different cases of the gluing matrices
for the WZW model based on the Heisenberg Lie group and its dual model.Comment: 17 page
String cosmology from Poisson-Lie T-dual sigma models on supermanifolds
We generalize the formulation of Poisson-Lie T-dual sigma models on manifolds
to supermanifolds. In this respect, we formulate 1+1 dimensional string
cosmological models on the Lie supergroup C^3 and its dual (A_1,1 +
2A)^0_(1,0,0), which are coupled to two fermionic fields. Then, we solve the
equations of motion of the models and show that there is a essential
singularity for the metric of the original model and its dual.Comment: 17 pages, Appendix and three references have adde
BTZ black hole from Poisson-Lie T-dualizable sigma models with spectators
The non-Abelian T-dualization of the BTZ black hole is discussed in detail by
using the Poisson-Lie T-duality in the presence of spectators. We explicitly
construct a dual pair of sigma models related by Poisson-Lie symmetry. The
original model is built on a -dimensional manifold , where as a two-dimensional real non-Abelian Lie group
acts freely on , while is the orbit of in . The
findings of our study show that the original model indeed is canonically
equivalent to the Wess-Zumino-Witten (WZW) model for a given
value of the background parameters. Moreover, by a convenient coordinate
transformation we show that this model describes a string propagating in a
spacetime with the BTZ black hole metric in such a way that a new family of the
solutions to low energy string theory with the BTZ black hole vacuum metric,
constant dilaton field and a new torsion potential is found. The dual model is
built on a -dimensional target manifold with
two-dimensional real Abelian Lie group acting freely on it.
We further show that the dual model yields a three-dimensional charged black
string for which the mass and axion charge per unit length are
calculated. After that, the structure and asymptotic nature of the dual
space-time including the horizon and singularity are determined.Comment: 20 page
Improved Energy Detector for Wideband Spectrum Sensing in Cognitive Radio Networks
In this paper, an improved energy detector for a wideband spectrum sensing is proposed. For a better detection of the spectrum holes the overall band is divided into equal non-overlapping sub-bands. The main objective is to determine the detection thresholds for each of these subbands jointly. By defining the problem as an optimization problem, we aim to find the maximum aggregated opportunistic throughput of cognitive radio networks. Introducing practical constraints to this optimization problem will change the problem into a convex and solvable one. The results of this paper show that the proposed improved energy detector will increase the aggregated throughput considerably
Classification of two and three dimensional Lie super-bialgebras
Using adjoint representation of Lie superalgebras, we obtain the matrix form
of super-Jacobi and mixed super-Jacobi identities of Lie superbialgebras. By
direct calculations of these identities, and use of automorphism supergroups of
two and three dimensional Lie superalgebras, we obtain and classify all two and
three dimensional Lie superbialgebras.Comment: 15 page
The gl(1|1) Lie superbialgebras
By direct calculations of matrix form of super Jacobi and mixed super Jacobi
identities which are obtained from adjoint representation, and using the
automorphism supergroup of the gl(1|1) Lie superalgebra, we determine and
classify all gl(1|1) Lie superbialgebras. Then, by calculating their classical
r-matrices, the gl(1j1) coboundary Lie superbialgebras and their types
(triangular, quasi-triangular or factorizable) are determined, furthermore in
this way super Poisson structures on the GL(1|1) Lie supergroup are obtained.
Also, we classify Drinfeld superdoubles based on the gl(1|1) as a theorem.
Afterwards, as a physical application of the coboundary Lie superbialgebras, we
construct a new integrable system on the homogeneous superspace OSp(1|2)/U(1).
Finally, we make use of the Lyakhovsky and Mudrov formalism in order to build
up the deformed gl(1|1) Lie superalgebra related to all gl(1|1) coboundary Lie
superbialgebras. For one case, the quantization at the supergroup level is also
provided, including its quantum R-matrix.Comment: Section 8 and 2 references have adde
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