5,452 research outputs found
Asymptotically flat spacetimes in 3D bigravity
We report that a class of three-dimensional bimetric theories contain
asymptotically flat solutions. These spacetimes can be cast in a set of
asymptotic conditions at null infinity which are preserved under the infinite
dimensional BMS group. Moreover, the algebra of the canonical generators
exhibits a central extension. The possibility that these solutions describe
regular black holes is also discussed.Comment: 6 page
Boundary dynamics of asymptotically flat 3D gravity coupled to higher spin fields
We construct a two-dimensional action principle invariant under a spin-three
extension of BMS group. Such a theory is obtained through a reduction of
Chern-Simons action with a boundary. This procedure is carried out by imposing
a set of boundary conditions obtained from asymptotically flat spacetimes in
three dimensions. When implementing part of this set, we obtain an analog of
chiral WZW model based on a contraction of . The remaining part of the boundary conditions imposes
constraints on the conserved currents of the model, which allows to further
reduce the action principle. It is shown that a sector of this latter theory is
related to a flat limit of Toda theory.Comment: 16 pages, no figure
Quasi-Exactly Solvable Potentials on the Line and Orthogonal Polynomials
In this paper we show that a quasi-exactly solvable (normalizable or
periodic) one-dimensional Hamiltonian satisfying very mild conditions defines a
family of weakly orthogonal polynomials which obey a three-term recursion
relation. In particular, we prove that (normalizable) exactly-solvable
one-dimensional systems are characterized by the fact that their associated
polynomials satisfy a two-term recursion relation. We study the properties of
the family of weakly orthogonal polynomials defined by an arbitrary
one-dimensional quasi-exactly solvable Hamiltonian, showing in particular that
its associated Stieltjes measure is supported on a finite set. From this we
deduce that the corresponding moment problem is determined, and that the -th
moment grows like the -th power of a constant as tends to infinity. We
also show that the moments satisfy a constant coefficient linear difference
equation, and that this property actually characterizes weakly orthogonal
polynomial systems.Comment: 22 pages, plain TeX. Please typeset only the file orth.te
Supertranslations and Superrotations at the Black Hole Horizon
We show that the asymptotic symmetries close to nonextremal black hole
horizons are generated by an extension of supertranslations. This group is
generated by a semidirect sum of Virasoro and Abelian currents. The charges
associated with the asymptotic Killing symmetries satisfy the same algebra.
When considering the special case of a stationary black hole, the zero mode
charges correspond to the angular momentum and the entropy at the horizon.Comment: 6 pages, references added, published versio
Trade and Morality: Preserving Public Morals Without Sacrificing the Global Economy
The World Trade Organization (WTO) exists for the purpose of promoting and facilitating trade amongst its member nations. When those member nations acceded to the WTO\u27s agreements, however, they acknowledged that sometimes trade barriers are useful tools in protecting themselves from certain evils. This Note addresses one of those useful tools--the public morals exception--which allows a member nation to maintain trade barriers with respect to certain goods or services.
Since the WTO agreements have been in effect, the public morals has lacked two critical things.: a definition and boundaries. This Note will attempt to define the public morals exception in a way that preserves the spirit of the WTO agreements. Furthermore, this Note will propose a test that will allow future WTO panels to decide whether a country\u27s law or regulation, justified under the public morals exception, can legitimately fall within the ambit of the WTO agreements
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