191 research outputs found
Representations of Composite Braids and Invariants for Mutant Knots and Links in Chern-Simons Field Theories
We show that any of the new knot invariants obtained from Chern-Simons theory
based on an arbitrary non-abelian gauge group do not distinguish isotopically
inequivalent mutant knots and links. In an attempt to distinguish these knots
and links, we study Murakami (symmetrized version) -strand composite braids.
Salient features of the theory of such composite braids are presented.
Representations of generators for these braids are obtained by exploiting
properties of Hilbert spaces associated with the correlators of Wess-Zumino
conformal field theories. The -composite invariants for the knots are given
by the sum of elementary Chern-Simons invariants associated with the
irreducible representations in the product of representations (allowed by
the fusion rules of the corresponding Wess-Zumino conformal field theory)
placed on the individual strands of the composite braid. On the other hand,
composite invariants for links are given by a weighted sum of elementary
multicoloured Chern-Simons invariants. Some mutant links can be distinguished
through the composite invariants, but mutant knots do not share this property.
The results, though developed in detail within the framework of
Chern-Simons theory are valid for any other non-abelian gauge group.Comment: Latex, 25pages + 16 diagrams available on reques
Chirality of Knots and and Chern-Simons Theory
Upto ten crossing number, there are two knots, and whose
chirality is not detected by any of the known polynomials, namely, Jones
invariants and their two variable generalisations, HOMFLY and Kauffman
invariants. We show that the generalised knot invariants, obtained through
Chern-Simons topological field theory, which give the known polynomials
as special cases, are indeed sensitive to the chirality of these knots.Comment: 15 pages + 7 diagrams (available on request
Multiparametric and coloured extensions of the quantum group and the Yangian algebra through a symmetry transformation of the Yang-Baxter equation
Inspired by Reshetikhin's twisting procedure to obtain multiparametric
extensions of a Hopf algebra, a general `symmetry transformation' of the
`particle conserving' -matrix is found such that the resulting
multiparametric -matrix, with a spectral parameter as well as a colour
parameter, is also a solution of the Yang-Baxter equation (YBE). The
corresponding transformation of the quantum YBE reveals a new relation between
the associated quantized algebra and its multiparametric deformation. As
applications of this general relation to some particular cases, multiparametric
and coloured extensions of the quantum group and the Yangian algebra
are investigated and their explicit realizations are also discussed.
Possible interesting physical applications of such extended Yangian algebras
are indicated.Comment: 21 pages, LaTeX (twice). Interesting physical applications of the
work are indicated. To appear in Int. J. Mod. Phys.
Medical Diagnosis with Multimodal Image Fusion Techniques
Image Fusion is an effective approach utilized to draw out all the significant information from the source images, which supports experts in evaluation and quick decision making. Multi modal medical image fusion produces a composite fused image utilizing various sources to improve quality and extract complementary information. It is extremely challenging to gather every piece of information needed using just one imaging method. Therefore, images obtained from different modalities are fused Additional clinical information can be gleaned through the fusion of several types of medical image pairings. This study's main aim is to present a thorough review of medical image fusion techniques which also covers steps in fusion process, levels of fusion, various imaging modalities with their pros and cons, and the major scientific difficulties encountered in the area of medical image fusion. This paper also summarizes the quality assessments fusion metrics. The various approaches used by image fusion algorithms that are presently available in the literature are classified into four broad categories i) Spatial fusion methods ii) Multiscale Decomposition based methods iii) Neural Network based methods and iv) Fuzzy Logic based methods. the benefits and pitfalls of the existing literature are explored and Future insights are suggested. Moreover, this study is anticipated to create a solid platform for the development of better fusion techniques in medical applications
Boosts, Schwarzschild Black Holes and Absorption cross-sections in M theory
dimensional neutral black strings wrapped on a circle are related to
dimensional charged black holes by boosts. We show that the boost has
to be performed in the covering space and the boosted coordinate has to be
compactified on a circle with a Lorentz contracted radius. Using this fact we
show that the transition between Schwarzschild black holes to black p-branes
observed recently in M theory is the well-known black hole- black string
transition viewed in a boosted frame. In a similar way the correspondence point
where an excited string state goes over to a neutral black hole is mapped
exactly to the correspondence point for black p-branes. In terms of the
brane quantities the equation of state for an excited string state becomes
identical to that of a 3+1 dimensional massless gas for all . Finally, we
show how boosts can be used to relate Hawking radiation rates. Using the known
microscopic derivation of absorption by extremal 3-branes and near-extremal 5D
holes with three large charges we provide a microscopic derivation of
absorption of 0-branes by seven and five dimensional Schwarzschild black holes
in a certain regime.Comment: Some references added, minor clarifications (harvmac, 16 pages
Hawking Radiation from Four-dimensional Schwarzschild Black Holes in M-theory
Recently a method has been developed for relating four dimensional Schwarzschild black holes in M-theory to near-extremal black holes in string theory with four charges, using suitably defined ``boosts'' and T-dualities. We show that this method can be extended to obtain the emission rate of low energy massless scalars for the four dimensional Schwarzschild hole from the microscopic picture of radiation from the near extremal hole
Spectral solutions for the Schr\"odinger equation with a regular singularity
We propose a modification in the Bethe-like ansatz to reproduce the hydrogen
atom spectrum and the wave functions. Such a proposal provided a clue to
attempt the exact quantization conditions (EQC) for the quantum periods
associated with potentials V (x) which are singular at the origin. In a
suitable limit of the parameters, the potential can be mapped to |x| potential.
We validate our EQC proposition by numerically computing the Voros spectrum and
matching it with the true spectrum for |x| potential. Thus we have given a
route to obtain the spectral solution for the one dimensional Schr\"odinger
equation involving potentials with regular singularity at the origin.Comment: 26 pages, 6 figures, 5 tables; A mathematica file is attached as an
ancillary fil
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