92,822 research outputs found
Higher-spin Realisations of the Bosonic String
It has been shown that certain algebras can be linearised by the
inclusion of a spin--1 current. This provides a way of obtaining new
realisations of the algebras. Recently such new realisations of were
used in order to embed the bosonic string in the critical and non-critical
strings. In this paper, we consider similar embeddings in and
strings. The linearisation of is already known, and can be
achieved for all values of central charge. We use this to embed the bosonic
string in critical and non-critical strings. We then derive the
linearisation of using a spin--1 current, which turns out to be
possible only at central charge . We use this to embed the bosonic
string in a non-critical string.Comment: 8 pages. CTP TAMU-10/95
Quantum Corrals, Eigenmodes and Quantum Mirages in s-wave Superconductors
We study the electronic structure of magnetic and non-magnetic quantum
corrals embedded in s-wave superconductors. We demonstrate that a quantum
mirage of an impurity bound state peak can be projected from the occupied into
the empty focus of a non-magnetic quantum corral via the excitation of the
corral's eigenmodes. We observe an enhanced coupling between magnetic
impurities inside the corral, which can be varied through oscillations in the
corral's impurity potential. Finally, we discuss the form of eigenmodes in
magnetic quantum corrals.Comment: 4 pages, 4 figure
From the Complete Yang Model to Snyder's Model, de Sitter Special Relativity and Their Duality
By means of Dirac procedure, we re-examine Yang's quantized space-time model,
its relation to Snyder's model, the de Sitter special relativity and their
UV-IR duality. Starting from a dimensionless dS_5-space in a 5+1-d Mink-space a
complete Yang model at both classical and quantum level can be presented and
there really exist Snyder's model, the dS special relativity and the duality.Comment: 7 papge
Liouville and Toda Solitons in M-theory
We study the general form of the equations for isotropic single-scalar,
multi-scalar and dyonic -branes in superstring theory and M-theory, and show
that they can be cast into the form of Liouville, Toda (or Toda-like)
equations. The general solutions describe non-extremal isotropic -branes,
reducing to the previously-known extremal solutions in limiting cases. In the
non-extremal case, the dilatonic scalar fields are finite at the outer event
horizon.Comment: Latex, 10 pages. Minor corrections to text and titl
Hydrogen Embrittlement of Aluminum: the Crucial Role of Vacancies
We report first-principles calculations which demonstrate that vacancies can
combine with hydrogen impurities in bulk aluminum and play a crucial role in
the embrittlement of this prototypical ductile solid. Our studies of
hydrogen-induced vacancy superabundant formation and vacancy clusterization in
aluminum lead to the conclusion that a large number of H atoms (up to twelve)
can be trapped at a single vacancy, which over-compensates the energy cost to
form the defect. In the presence of trapped H atoms, three nearest-neighbor
single vacancies which normally would repel each other, aggregate to form a
trivacancy on the slip plane of Al, acting as embryos for microvoids and cracks
and resulting in ductile rupture along the these planes.Comment: To appear in Phys. Rev. Let
Higher-spin strings and W minimal models
We study the spectrum of physical states for higher-spin generalisations of
string theory, based on two-dimensional theories with local spin-2 and spin-
symmetries. We explore the relation of the resulting effective Virasoro string
theories to certain minimal models. In particular, we show how the
highest-weight states of the minimal models decompose into Virasoro
primaries.Comment: 13 pages, CTP TAMU-43/93, KUL-TF-93/9
The Poisson geometry of SU(1,1)
We study the natural Poisson structure on the Lie group SU(1,1) and related
questions. In particular, we give an explicit description of the
Ginzburg-Weinstein isomorphism for the sets of admissible elements. We also
establish an analogue of Thompson's conjecture for this group.Comment: 11 pages, minor correction
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