36,961 research outputs found
q-Deformation of the Krichever-Novikov Algebra
The recent focus on deformations of algebras called quantum algebras can be
attributed to the fact that they appear to be the basic algebraic structures
underlying an amazingly diverse set of physical situations. To date many
interesting features of these algebras have been found and they are now known
to belong to a class of algebras called Hopf algebras [1]. The remarkable
aspect of these structures is that they can be regarded as deformations of the
usual Lie algebras. Of late, there has been a considerable interest in the
deformation of the Virasoro algebra and the underlying Heisenberg algebra
[2-11]. In this letter we focus our attention on deforming generalizations of
these algebras, namely the Krichever-Novikov (KN) algebra and its associated
Heisenberg algebra.Comment: AmsTex. To appear in Letters in Mathematical Physic
A Comparison of Different Machine Transliteration Models
Machine transliteration is a method for automatically converting words in one
language into phonetically equivalent ones in another language. Machine
transliteration plays an important role in natural language applications such
as information retrieval and machine translation, especially for handling
proper nouns and technical terms. Four machine transliteration models --
grapheme-based transliteration model, phoneme-based transliteration model,
hybrid transliteration model, and correspondence-based transliteration model --
have been proposed by several researchers. To date, however, there has been
little research on a framework in which multiple transliteration models can
operate simultaneously. Furthermore, there has been no comparison of the four
models within the same framework and using the same data. We addressed these
problems by 1) modeling the four models within the same framework, 2) comparing
them under the same conditions, and 3) developing a way to improve machine
transliteration through this comparison. Our comparison showed that the hybrid
and correspondence-based models were the most effective and that the four
models can be used in a complementary manner to improve machine transliteration
performance
Symmetric Multiplets in Quantum Algebras
We consider a modified version of the coproduct for \U(\su_q(2)) and show
that in the limit when , there exists an essentially
non-cocommutative coproduct. We study the implications of this
non-cocommutativity for a system of two spin- particles. Here it is shown
that, unlike the usual case, this non-trivial coproduct allows for symmetric
and anti-symmetric states to be present in the multiplet. We surmise that our
analysis could be related to the ferromagnetic and antiferromagnetic cases of
the Heisenberg magnets.Comment: Needs subeqnarray.sty. To be published in Mod Phys Lett.
SQCD Vacua and Geometrical Engineering
We consider the geometrical engineering constructions for the N = 1 SQCD
vacua recently proposed by Giveon and Kutasov. After one T-duality, the
geometries with wrapped D5 branes become N = 1 brane configurations with NS
branes and D4 branes. The field theories encoded by the geometries contain
extra massive adjoint fields for the flavor group. After performing a flop, the
geometries contain branes, antibranes and branes wrapped on non-holomorphic
cycles. The various tachyon condensations between pairs of wrapped D5 branes
and anti D5 branes together with deformations of the cycles give rise to a
variety of supersymmetric and metastable non-supersymmetric vacua.Comment: 21 Pages, Latex, 8 Figure
On the sign of the pi-rho-omega coupling constant
It is shown that the relative sign between the and
coupling constants can be determined most sensitively from production
processes in collisions. Recent data on these reactions clearly favor the
sign of the coupling constant which is opposite to that
inferred from studies of the photoproduction reaction in combination with the
vector meson dominance assumption and used by many authors. Implication of this
finding in the description of other reactions is discussed.Comment: 6 pages, 4 figures, REVTeX, to be published in Phys. Lett.
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