113 research outputs found
A case of pleural mesothelioma with effusive-constrictive pericarditis.
A case report is presented of pleural mesothelioma with simultaneous development of benign effusive-constrictive pericarditis
A Cohomological Perspective on Algebraic Quantum Field Theory
Algebraic quantum field theory is considered from the perspective of the Hochschild cohomology bicomplex. This is a framework for studying deformations and symmetries. Deformation is a possible approach to the fundamental challenge of constructing interacting QFT models. Symmetry is the primary tool for understanding the structure and properties of a QFT model. This perspective leads to a generalization of the algebraic quantum field theory framework, as well as a more general definition of symmetry. This means that some models may have symmetries that were not previously recognized or exploited. To first order, a deformation of a QFT model is described by a Hochschild cohomology class. A deformation could, for example, correspond to adding an interaction term to a Lagrangian. The cohomology class for such an interaction is computed here. However, the result is more general and does not require the undeformed model to be constructed from a Lagrangian. This computation leads to a more concrete version of the construction of perturbative algebraic quantum field theory
The gl(M|N) Super Yangian and Its Finite Dimensional Representations
Methods are developed for systematically constructing the finite dimensional
irreducible representations of the super Yangian Y(gl(M|N)) associated with the
Lie superalgebra gl(M|N). It is also shown that every finite dimensional
irreducible representation of Y(gl(M|N)) is of highest weight type, and is
uniquely characterized by a highest weight. The necessary and sufficient
conditions for an irrep to be finite dimensional are given.Comment: 14 pages plain late
The Principal Element of a Frobenius Lie Algebra
We introduce the notion of the \textit{principal element} of a Frobenius Lie
algebra \f. The principal element corresponds to a choice of F\in \f^* such
that non-degenerate. In many natural instances, the principal element
is shown to be semisimple, and when associated to \sl_n, its eigenvalues are
integers and are independent of . For certain ``small'' functionals , a
simple construction is given which readily yields the principal element. When
applied to the first maximal parabolic subalgebra of \sl_n, the principal
element coincides with semisimple element of the principal three-dimensional
subalgebra. We also show that Frobenius algebras are stable under deformation.Comment: 10 page
Direct Detection of Electroweak-Interacting Dark Matter
Assuming that the lightest neutral component in an SU(2)L gauge multiplet is
the main ingredient of dark matter in the universe, we calculate the elastic
scattering cross section of the dark matter with nucleon, which is an important
quantity for the direct detection experiments. When the dark matter is a real
scalar or a Majorana fermion which has only electroweak gauge interactions, the
scattering with quarks and gluon are induced through one- and two-loop quantum
processes, respectively, and both of them give rise to comparable contributions
to the elastic scattering cross section. We evaluate all of the contributions
at the leading order and find that there is an accidental cancellation among
them. As a result, the spin-independent cross section is found to be
O(10^-(46-48)) cm^2, which is far below the current experimental bounds.Comment: 19 pages, 7 figures, published versio
Phase Space Reduction for Star-Products: An Explicit Construction for CP^n
We derive a closed formula for a star-product on complex projective space and
on the domain using a completely elementary
construction: Starting from the standard star-product of Wick type on and performing a quantum analogue of Marsden-Weinstein
reduction, we can give an easy algebraic description of this star-product.
Moreover, going over to a modified star-product on ,
obtained by an equivalence transformation, this description can be even further
simplified, allowing the explicit computation of a closed formula for the
star-product on \CP^n which can easily transferred to the domain
.Comment: LaTeX, 17 page
Operadic formulation of topological vertex algebras and Gerstenhaber or Batalin-Vilkovisky algebras
We give the operadic formulation of (weak, strong) topological vertex
algebras, which are variants of topological vertex operator algebras studied
recently by Lian and Zuckerman. As an application, we obtain a conceptual and
geometric construction of the Batalin-Vilkovisky algebraic structure (or the
Gerstenhaber algebra structure) on the cohomology of a topological vertex
algebra (or of a weak topological vertex algebra) by combining this operadic
formulation with a theorem of Getzler (or of Cohen) which formulates
Batalin-Vilkovisky algebras (or Gerstenhaber algebras) in terms of the homology
of the framed little disk operad (or of the little disk operad).Comment: 42 page
Unbraiding the braided tensor product
We show that the braided tensor product algebra
of two module algebras of a quasitriangular Hopf algebra is
equal to the ordinary tensor product algebra of with a subalgebra of
isomorphic to , provided there exists a
realization of within . In other words, under this assumption we
construct a transformation of generators which `decouples' (i.e.
makes them commuting). We apply the theorem to the braided tensor product
algebras of two or more quantum group covariant quantum spaces, deformed
Heisenberg algebras and q-deformed fuzzy spheres.Comment: LaTex file, 29 page
Algebraic properties of Gardner's deformations for integrable systems
An algebraic definition of Gardner's deformations for completely integrable
bi-Hamiltonian evolutionary systems is formulated. The proposed approach
extends the class of deformable equations and yields new integrable
evolutionary and hyperbolic Liouville-type systems. An exactly solvable
two-component extension of the Liouville equation is found.Comment: Proc. conf. "Nonlinear Physics: Theory and Experiment IV" (Gallipoli,
2006); Theor. Math. Phys. (2007) 151:3/152:1-2, 16p. (to appear
Peripheric Extended Twists
The properties of the set L of extended jordanian twists are studied. It is
shown that the boundaries of L contain twists whose characteristics differ
considerably from those of internal points. The extension multipliers of these
"peripheric" twists are factorizable. This leads to simplifications in the
twisted algebra relations and helps to find the explicit form for coproducts.
The peripheric twisted algebra U(sl(4)) is obtained to illustrate the
construction. It is shown that the corresponding deformation U_{P}(sl(4))
cannot be connected with the Drinfeld--Jimbo one by a smooth limit procedure.
All the carrier algebras for the extended and the peripheric extended twists
are proved to be Frobenius.Comment: 16 pages, LaTeX 209. Some misprints have been corrected and new
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