22,086 research outputs found
A Note on the Stringy Embeddings of Certain N = 2 Dualities
Seiberg-Witten theory can be embedded in F-theory using D3 branes probing an
orientifold geometry. The non-perturbative corrections in the orientifold
picture map directly to the instanton corrections in the corresponding gauge
theory that convert the classical moduli space to the quantum one. In this
short review we argue that the recently proposed class of conformal Gaiotto
models may also be embedded in F-theory. The F-theory constructions help us not
only to understand the Gaiotto dualities but also to extend to the
non-conformal cases with and without cascading behaviors. For the conformal
cases, the near horizon geometries in F-theory capture both the UV and IR
behaviors succinctly.Comment: 6 pages, LaTeX, Based on the talk given by K. D at the Theory Canada
Conference June 2012; v2: Typos corrected and references adde
An optimal property of sequential decision procedures related to Bayes solutions
Optimal property of sequential decision procedure
A modification of the kuhn-tucker theorem technical report no. 1, 1 jun. - 31 dec. 1964
Modification of Kuhn-Tucker theorem for maximizing set of concave function
Quantum Melting of Charge Order due to Frustration in Two-Dimensional Quarter-Filled Systems
The effect of geometrical frustration in a two-dimensional 1/4-filled
strongly correlated electron system is studied theoretically, motivated by
layered organic molecular crystals. An extended Hubbard model on the square
lattice is considered, with competing nearest neighbor Coulomb interaction, V,
and that of next-nearest neighbor along one of the diagonals, V', which favor
different charge ordered states. Based on exact diagonalization calculations,
we find a metallic phase stabilized over a broad window at V' ~ V even for
large Coulomb repulsion strengths as a result of frustrating the charge ordered
states. Slightly modifying the lattice geometry relevant to the actual organic
compounds does not alter the results, suggesting that this `quantum melting' of
charge order is a robust feature of frustrated strongly correlated 1/4-filled
systems.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Unified Heat Kernel Regression for Diffusion, Kernel Smoothing and Wavelets on Manifolds and Its Application to Mandible Growth Modeling in CT Images
We present a novel kernel regression framework for smoothing scalar surface
data using the Laplace-Beltrami eigenfunctions. Starting with the heat kernel
constructed from the eigenfunctions, we formulate a new bivariate kernel
regression framework as a weighted eigenfunction expansion with the heat kernel
as the weights. The new kernel regression is mathematically equivalent to
isotropic heat diffusion, kernel smoothing and recently popular diffusion
wavelets. Unlike many previous partial differential equation based approaches
involving diffusion, our approach represents the solution of diffusion
analytically, reducing numerical inaccuracy and slow convergence. The numerical
implementation is validated on a unit sphere using spherical harmonics. As an
illustration, we have applied the method in characterizing the localized growth
pattern of mandible surfaces obtained in CT images from subjects between ages 0
and 20 years by regressing the length of displacement vectors with respect to
the template surface.Comment: Accepted in Medical Image Analysi
Complementary Pair Density Wave and d-wave Checkerboard Order in High Temperature Superconductors
The competing orders in the particle-particle (P-P) channel and the
particle-hole (P-H) channel have been proposed separately to explain the
pseudogap physics in cuprates. By solving the Bogoliubov-deGennes equation
self-consistently, we show that there is a general complementary connection
between the d-wave checkerboard order (DWCB) in the particle-hole (P-H) channel
and the pair density wave order (PDW) in the particle-particle (P-P) channel. A
small pair density localization generates DWCB and PDW orders simultaneously.
The result suggests that suppressing superconductivity locally or globally
through phase fluctuation should induce both orders in underdoped cuprates. The
presence of both DWCB and PDW orders with periodicity can
explain the checkerboard modulation observed in FT-STS from STM and the
puzzling dichotomy between the nodal and antinodal regions as well as the
characteristic features such as non-dispersive Fermi arc in the pseudogap
state
Formulating the Net Gain of MISO-SFN in the Presence of Self-Interferences
In this study, an analytical formula for multiple-input single-output single frequency network gain (MISO-SFNG) is investigated. To formulate the net MISO-SFNG, we derived the average signal to interference plus noise ratio (SINR) where the gain achieved by the distributed MISO diversity as a function of power imbalance is curve-fitted. Further, we analyzed the losses owing to self-interferences resulting from the delay spread and imperfect channel estimation. We verified the accuracy and effectiveness of the derived formula by comparing the measurement results with the analytical results. The derived formula helps to understand how various system factors affect the gain under a given condition. The formula can be used to evaluate the MISO-SFNG and to predict the MISO-SFN coverage in various system configurations
A New Phase at Finite Quark Density from AdS/CFT
We explore phases of N=2 super Yang-Mills theory at finite quark density by
introducing quark chemical potential in a D3-D7 setup. We formulate the
thermodynamics of brane embeddings and find that we need to renormalize the
finite chemical potential due to the divergence of the thermodynamic potentials
and we find that the density versus chemical potential equation of state has
rich structure. This yields two distinct first order phase transitions in a
small window of quark density. In order words, there is a new first order phase
transition in the region of deconfined quarks. In this new phase, the chemical
potential is a decreasing function of the density. We suggest that this might
be relevant to the difference in sQGP--wQGP phases of QCD.Comment: 4 pages, revte
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