Results for "Joseph A. Ferrar"

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Capillary-driven binding of thin triangular prisms at fluid interfacesFeb 08 2018We observe capillary-driven binding between thin, equilateral triangular prisms at a flat air-water interface. The edge length of the equilateral triangle face is 120 $\mu m$, and the thickness of the prism is varied between 2 and 20 $\mu m$. For thickness ... More
Supergraphs and the cubic Leigh-Strassler modelAug 07 2011Oct 22 2011We discuss supergraphs and their relation to "chiral functions" in N=4 Super Yang-Mills. Based on the magnon dispersion relation and an explicit three-loop result of Sieg's we make an all loop conjecture for the rational contributions of certain classes ... More
A Second Order Ensemble Timestepping Algorithm for Natural ConvectionAug 01 2017This paper presents an algorithm for calculating an ensemble of solutions to natural convection problems. The ensemble average is the most likely temperature distribution and its variance gives an estimate of prediction reliability. Solutions are calculated ... More
Localizing gauge theories on $S^d$Dec 22 2015Apr 29 2016We conjecture the form of the one-loop determinants for localized gauge theories with eight supersymmetries on $d$-dimensional spheres. Combining this with results for the localized action, we investigate the strong coupling behavior in the large $N$ ... More
Glueball Mass Spectra and Other Issues for Supergravity Duals of QCD ModelsNov 16 1998Dec 01 1998We derive WKB expressions for glueball masses of various finite temperature supergravity models. The results are very close to recent numerical computations. We argue that the spectra has some universality that depends only on the dimension of the AdS ... More
Quark-Monopole Potentials in Large N Super Yang-MillsMar 14 1998Apr 27 1998We compute the quark-monopole potential for ${\cal N}=4$ super Yang-Mills in the large $N$ limit. We find an attractive potential that falls off as 1/L and is manifestly invariant under $g\to 1/g$. The strength of the potential is less than the quark-antiquark ... More
Summing Over Inequivalent Maps in the String Theory Interpretation of Two Dimensional QCDJan 02 1993Following some recent work by Gross, we consider the partition function for QCD on a two dimensional torus and study its stringiness. We present strong evidence that the free energy corresponds to a sum over branched surfaces with small handles mapped ... More
Flows and Solitary Waves in Unitary Matrix Models with Logarithmic PotentialsNov 05 1991We investigate unitary one-matrix models coupled to bosonic quarks. We derive a flow equation for the square-root of the specific heat as a function of the renormalized quark mass. We show numerically that the flows have a finite number of solitary waves, ... More
Solvability, Structure and Analysis for Minimal Parabolic SubgroupsOct 25 2016We examine the structure of the Levi component $MA$ in a minimal parabolic subgroup $P = MAN$ of a real reductive Lie group $G$, work out the cases where $M$ is commutative, verify that $P$ is solvable if and only if $M$ is commutative, and work out the ... More
Stepwise Square Integrability for Nilradicals of Parabolic Subgroups and Maximal Amenable SubgroupsMay 20 2016In a series of recent papers we extended the notion of square integrability, for representations of nilpotent Lie groups, to that of stepwise square integrability. There we discussed a number of applications based on the fact that nilradicals of minimal ... More
Buried and accessible surface area control intrinsic protein flexibilityJun 12 2013Aug 13 2013Proteins experience a wide variety of conformational dynamics that can be crucial for facilitating their diverse functions. How is the intrinsic flexibility required for these motions encoded in their three-dimensional structures? Here, the overall flexibility ... More
Stepwise Square Integrable Representations: the Concept and Some ConsequencesNov 29 2015There are some new developments on Plancherel formula and growth of matrix coefficients for unitary representations of nilpotent Lie groups. These have several consequences for the geometry of weakly symmetric spaces and analysis on parabolic subgroups ... More
Classical Analysis and Nilpotent Lie GroupsDec 06 2010Classical Fourier analysis has an exact counterpart in group theory and in some areas of geometry. Here I'll describe how this goes for nilpotent Lie groups and for a class of Riemannian manifolds closely related to a nilpotent Lie group structure. There ... More
Stepwise Square Integrability for Nilradicals of Parabolic Subgroups and Maximal Amenable SubgroupsMay 20 2016Feb 15 2017In a series of recent papers we extended the notion of square integrability, for representations of nilpotent Lie groups, to that of stepwise square integrability. There we discussed a number of applications based on the fact that nilradicals of minimal ... More
On the Analytic Structure of Commutative NilmanifoldsJul 01 2014In the classification theorems of Vinberg and Yakimova for commutative nilmanifolds, the relevant nilpotent groups have a very surprising analytic property. The manifolds are of the form $G/K = N \rtimes K/K$ where, in all but three cases, the nilpotent ... More
The Plancherel Formula for Minimal Parabolic SubgroupsJun 27 2013Dec 18 2013In a recent paper we found conditions for a nilpotent Lie group to be foliated into subgroups that have square integrable unitary representations that fit together to form a filtration by normal subgroups. That resulted in explicit character formulae, ... More
The SU(2) sector in AdS/CFTMar 18 2005Apr 24 2005In the large N limit of N=4 Super Yang-Mills, the mixing under dilatations of the SU(2) sector, single trace operators composed of L complex scalar fields of two types, is closed to all orders in perturbation theory. By relying on the AdS/CFT correspondence, ... More
Higher Loops Beyond the SU(2) SectorMay 26 2004Oct 10 2005We consider the case of coherent gauge invariant operators in the SU(3) and SO(4) sectors. We argue that in many cases, these sectors can be closed in the thermodynamic limit, even at higher loops. We then use a modification of the Bethe equations which ... More
Matrix Models and One Dimensional Open String Theory (Revised)Apr 06 1992Apr 10 1992We propose a random matrix model as a representation for $D=1$ open strings. We show that the model is equivalent to $N$ fermions with spin in a central potential that also includes a long-range ferromagnetic interaction between the fermions that falls ... More
Ultrafast Calculation of Diffuse Scattering from Atomistic ModelsSep 19 2018Dec 20 2018Diffuse scattering is a rich source of information about disorder in crystalline materials, which can be modelled using atomistic techniques such as Monte Carlo and molecular dynamics simulations. Modern X-ray and neutron scattering instruments can rapidly ... More
Simulating the Ridesharing Economy: The Individual Agent Metro-Washington Area Ridesharing ModelFeb 19 2018The ridesharing economy is experiencing rapid growth and innovation. Companies such as Uber and Lyft are continuing to grow at a considerable pace while providing their platform as an organizing medium for ridesharing services, increasing consumer utility ... More
Infinite Dimensional Multiplicity Free Spaces II: Limits of Commutative NilmanifoldsJan 25 2008We study direct limits $(G,K) = \varinjlim (G_n,K_n)$ of Gelfand pairs of the form $G_n = N_n\rtimes K_n$ with $N_n$ nilpotent, in other words pairs $(G_n,K_n)$ for which $G_n/K_n$ is a commutative nilmanifold. First, we extend the criterion of \cite{W3} ... More
Complex Forms of Quaternionic Symmetric SpacesAug 28 2003Oct 02 2003This is a complete classification of the complex forms of quaternionic symmetric spaces
Representations on Partially Holomorphic Cohomology Spaces, RevisitedAug 01 2017This is a semi--expository update and rewrite of my 1974 AMS AMS Memoir describing Plancherel formulae and partial Dolbeault cohomology realizations for standard tempered representations for general real reductive Lie groups. Even after so many years, ... More
Ensemble Timestepping Algorithms for the Heat Equation with Uncertain ConductivityAug 02 2017Motivated by applications to 3D printing, this paper presents two algorithms for calculating an ensemble of solutions to heat conduction problems. The ensemble average is the most likely temperature distribution and its variance gives an estimate of prediction ... More
A Monte Carlo Approach to the 4D Scattering EquationsJun 07 2018Jul 17 2018The scattering equation formalism is a general framework for calculation of amplitudes in theories of massless particles. We provide a detailed introduction to the 4D scattering equation framework accessible to non-experts, outline current difficulties ... More
Matrix models for 5d super Yang-MillsAug 09 2016Oct 15 2016In this contribution to the review on localization in gauge theories we investigate the matrix models derived from localizing N=1 super Yang-Mills on S^5. We consider the large-N limit and attempt to solve the matrix model by a saddle-point approximation. ... More
Rolling the tachyon in super BSFTMay 10 2002May 14 2002We investigate the rolling of the tachyon on the unstable D9 brane in Type IIA string theory by studying the BSFT action. The action is known for linear profiles of the tachyon, which is the expected asymptotic behavior of the tachyon as it approaches ... More
Stretched strings in tachyon condensation modelsMar 12 2002May 14 2002In this note, we consider the two derivative truncation of boundary string field theory for unstable D9 branes in Type IIA string theory. We construct multiples of the stable codimension 1 solitons that correspond to stacks of D8 branes. We find the fluctuation ... More
Asymptotic Freedom and Confinement from Type 0 String TheoryFeb 10 1999Feb 22 1999We argue that there are generic solutions to the type 0 gravity equations of motion that are confining in the infrared and have log scaling in the ultraviolet. The background curvature generically diverges in the IR. Nevertheless, there exist solutions ... More
Duality Symmetries for N=2 Supersymmetric QCD with Vanishing beta-FunctionsJun 30 1998Jul 07 1998We construct the duality groups for N=2 Supersymmetric QCD with gauge group SU(2n+1) and N_f=4n+2 hypermultiplets in the fundamental representation. The groups are generated by two elements $S$ and $T$ that satisfy a relation $(STS^{-1}T)^{2n+1}=1$. Thus, ... More
Analytical Modeling of Galaxies at z>~6: Star Formation and Black Hole GrowthAug 03 2012Galaxies at z>~6 represent an important evolutionary link between the first galaxies and their modern counterparts. Modeling both the global and internal properties of these recently discovered objects can lead us to understand how they relate to even ... More
Unitary Representations, $L^2$ Dolbeault Cohomology, and Weakly Symmetric Pseudo--Riemannian NilmanifoldsOct 12 2018We combine recent developments on weakly symmetric pseudo--riemannian nilmanifolds with with geometric methods for construction of unitary representations on square integrable Dolbeault cohomology spaces. This runs parallel to construction of discrete ... More
Solvability, Structure and Analysis for Minimal Parabolic SubgroupsOct 25 2016Jan 22 2017We examine the structure of the Levi component $MA$ in a minimal parabolic subgroup $P = MAN$ of a real reductive Lie group $G$ and work out the cases where $M$ is metabelian, equivalently where $\mathfrak{p}$ is solvable. When $G$ is a linear group we ... More
Review of AdS/CFT Integrability, Chapter I.1: Spin Chains in N=4 Super Yang-MillsDec 17 2010Jul 15 2011In this chapter of "Review of AdS/CFT Integrability" we introduce N=4 Super Yang-Mills. We discuss the global superalagebra PSU(2,2|4) and its action on gauge invariant operators. We then discuss the computation of the correlators of certain gauge invariant ... More
Homogeneity for a Class of Riemannian Quotient ManifoldsSep 19 2016We study riemannian coverings $\varphi: \widetilde{M} \to \Gamma\backslash \widetilde{M}$ where $\widetilde{M}$ is a normal homogeneous space $G/K_1$ fibered over another normal homogeneous space $M = G/K$ and $K$ is locally isomorphic to a nontrivial ... More
Principal series representations of infinite dimensional Lie groups, II: Construction of induced representationsAug 20 2012Oct 19 2012We study representations of the classical infinite dimensional real simple Lie groups $G$ induced from factor representations of minimal parabolic subgroups $P$. This makes strong use of the recently developed structure theory for those parabolic subgroups ... More
Principal Series Representations of Infinite Dimensional Lie Groups, I: Minimal Parabolic SubgroupsApr 05 2012We study the structure of minimal parabolic subgroups of the classical infinite dimensional real simple Lie groups, corresponding to the classical simple direct limit Lie algebras. This depends on the recently developed structure of parabolic subgroups ... More
Gauge Fields and Fermions in Tachyon Effective Field TheoriesNov 24 2000In this paper we incorporate gauge fields into the tachyon field theory models for unstable D-branes in bosonic and in Type II string theories. The chosen couplings yield massless gauge fields and an infinite set of equally spaced massive gauge fields ... More
Invariants of the Haldane-Shastry $SU(N)$ ChainAug 25 1992Using a formalism developed by Polychronakos, we explicitly construct a set of invariants of the motion for the Haldane-Shastry $SU(N)$ chain.
Field theory models for tachyon and gauge field string dynamicsAug 30 2000Sep 13 2000In hep-th/0008227, the unstable lump solution of \phi^3 theory was shown to have a spectrum governed by the solvable Schroedinger equation with the \ell=3 reflectionless potential and was used as a model for tachyon condensation in string theory. In this ... More
A Discrete Hopf Interpolant and Stability of the Finite Element Method for Natural ConvectionOct 06 2017The temperature in natural convection problems is, under mild data assumptions, uniformly bounded in time. This property has not yet been proven for the standard finite element method (FEM) approximation of natural convection problems with nonhomogeneous ... More
Hardy-space function theory, operator model theory, and dissipative linear systems: the multivariable, free-noncommutative, weighted Bergman-space settingJun 06 2019Jun 10 2019It is known that (i) a subspace ${\mathcal N}$ of the Hardy space $H^2$ which is invariant under the backward shift operator can be represented as the range of the observability operator of a conservative discrete-time linear system, (ii) the transfer-function ... More
Covers of generalized quadranglesJul 20 2016We solve a problem posed by Cardinali and Sastry [2] about factorization of $2$-covers of finite classical generalized quadrangles. To that end, we develop a general theory of cover factorization for generalized quadrangles, and in particular we study ... More
Fractionalized Topological InsulatorsMay 06 2015Oct 30 2015Topological insulators have emerged as a major topic of condensed matter physics research with several novel applications proposed. Although there are now a number of established experimental examples of materials in this class, all of them can be described ... More
Effective Tachyon Dynamics in Superstring TheorySep 29 2000A recently proposed \ell=\infty field theory model of tachyon dynamics for unstable bosonic D-branes has been shown to arise as the two-derivative truncation of (boundary)-string field theory. Using an \ell\to \infty limit appropriate to stable kinks ... More
The Density Contrast of the Shapley SuperclusterMay 05 2008May 19 2008We calculate the density contrast of the Shapley Supercluster (SSC) based on the enhanced abundance of X-ray clusters in it using the extended Press-Schechter formalism. We derive a total SSC mass of M_tot=(4.4+-0.44)x10^{16} M_sun within a sphere of ... More
Killing Vector Fields of Constant Length on Riemannian Normal Homogeneous SpacesDec 10 2014Apr 06 2016Killing vector fields of constant length correspond to isometries of constant displacement. Those in turn have been used to study homogeneity of Riemannian and Finsler quotient manifolds. Almost all of that work has been done for group manifolds or, more ... More
Extension of Symmetric Spaces and Restriction of Weyl Groups and Invariant PolynomialsDec 02 2010Polynomial invariants are fundamental objects in analysis on Lie groups and symmetric spaces. Invariant differential operators on symmetric spaces are described by Weyl group invariant polynomial. In this article we give a simple criterion that ensure ... More
Static and Dynamical Properties of Antiferromagnetic Skyrmions in the Presence of Applied Current and TemperatureMay 22 2015Apr 08 2016Skyrmions are topologically protected entities in magnetic materials which have the potential to be used in spintronics for information storage and processing. However, Skyrmions in ferromagnets have some intrinsic difficulties which must be overcome ... More
Locally symmetric homogeneous Finsler spacesJun 16 2012Let $(M,F)$ be a connected Finsler space and $d$ the distance function of $(M,F)$. A Clifford translation is an isometry $\rho$ of $(M,F)$ of constant displacement, in other words such that $d(x,\rho(x))$ is a constant function on $M$. In this paper we ... More
Geometry of the Borel -- de Siebenthal Discrete SeriesJan 28 2009Let $G_0$ be a connected, simply connected real simple Lie group. Suppose that $G_0$ has a compact Cartan subgroup $T_0$, so it has discrete series representations. Relative to $T_0$ there is a distinguished positive root system $\Delta^+$ for which there ... More
Zero-pole interpolation for matrix meromorphic functions on a compact Riemann surface, and a matrix Fay trisecant identityDec 23 1997Feb 08 1999This paper presents a new approach to constructing a meromorphic bundle map between flat vector bundles over a compact Riemann surface having a prescribed Weil divisor (i.e., having prescribed zeros and poles with directional as well as multiplicity information ... More
An Artificial Compressibility Ensemble Timestepping Algorithm for Flow ProblemsDec 18 2017Ensemble calculations are essential for systems with uncertain data but require substantial increase in computational resources. This increase severely limits ensemble size. To reach beyond current limits, we present a first-order artificial compressibility ... More
Gauge theories with 16 supersymmetries on spheresFeb 25 2015Aug 14 2016We give a unified approach to localization of maximally symmetric gauge theories on spheres, including $S^6$ and $S^7$. The approach follows Pestun's method of dimensionally reducing from 10 dimensional super Yang-Mills. The resulting theories have a ... More
Hyperelliptic curves for Supersymmetric Yang-MillsJul 06 1995In this paper we discuss the hyperelliptic curve for $N=2$ $SU(3)$ super Yang-Mills with six flavors of hypermultiplets. We start with a generic genus two surface and construct the curve in terms of genus two theta functions. From this one can construct ... More
Equilibrium circulation and stress distribution in viscoelastic creeping flowDec 10 2015Jan 13 2016An analytic, asymptotic approximation of the nonlinear steady-state equations for viscoelastic creeping flow, modeled by the Oldroyd-B equations with polymer stress diffusion, is derived. Near the extensional stagnation point the flow stretches and aligns ... More
Sp(2)/U(1) and a Positive Curvature ProblemFeb 10 2015Mar 10 2015A compact Riemannian homogeneous space $G/H$, with a bi--invariant orthogonal decomposition $\mathfrak{g}=\mathfrak{h}+\mathfrak{m}$ is called positively curved for commuting pairs, if the sectional curvature vanishes for any tangent plane in $T_{eH}(G/H)$ ... More
Electron acceleration in SNR and diffuse gamma-rays above 1 GeVJun 11 1998The recently observed X-ray synchrotron emission from four supernova remnants (SNR) has strengthened the evidence that cosmic ray electrons are accelerated in SNR. We show, that if this is indeed the case, the local electron spectrum will be strongly ... More
Inner Functions with Derivatives in the Weak Hardy SpaceJun 14 2012It is proved that exponential Blaschke products are the inner functions whose derivative is in the weak Hardy space. Exponential Blaschke products are described in terms of their logarithmic means and also in terms of the behavior of the derivatives of ... More
Constraining the Minimum Mass of High-Redshift Galaxies and Their Contribution to the Ionization State of the IGMOct 11 2010We model the latest HST WFPC3/IR observations of > 100 galaxies at redshifts z=7-8 in terms of a hierarchical galaxy formation model with starburst activity. Our model provides a distribution of UV luminosities per dark matter halo of a given mass and ... More
Functional Models and Invariant Subspaces for Pairs of Commuting ContractionsSep 26 2018Sep 28 2018The goal of the present paper is to push Sz.-Nagy--Foias model theory for a completely nonunitary Hilbert-space contraction operator $T$, to the case of a commuting pair of contraction operators $(T_1, T_2)$ having product $T = T_1 T_2$ which is completely ... More
Weighted Bergman spaces: shift-invariant subspaces and input/state/output linear systemsSep 17 2012It is well known that subspaces of the Hardy space over the unit disk which are invariant under the backward shift occur as the image of an observability operator associated with a discrete-time linear system with stable state-dynamics, as well as the ... More
de Branges-Rovnyak spaces and norm-constraint interpolationMay 12 2014For $S$ a contractive analytic operator-valued function on the unit disk ${\mathbb D}$, de Branges and Rovnyak associate a Hilbert space of analytic functions ${\mathcal H}(S)$. A companion survey provides equivalent definitions and basic properties of ... More
Weakly Symmetric Pseudo-Riemannian NilmanifoldsJun 20 2018Nov 13 2018In an earlier paper we developed the classification of weakly symmetric pseudo--riemannian manifolds $G/H$ where $G$ is a semisimple Lie group and $H$ is a reductive subgroup. We derived the classification from the cases where $G$ is compact. As a consequence ... More
Ensemble Timestepping Algorithms for Natural ConvectionAug 01 2017This paper presents two algorithms for calculating an ensemble of solutions to laminar natural convection problems. The ensemble average is the most likely temperature distribution and its variance gives an estimate of prediction reliability. Solutions ... More
The inverse commutant lifting problem: characterization of associated Redheffer linear-fractional mapsApr 03 2010It is known that the set of all solutions of a commutant lifting and other interpolation problems admits a Redheffer linear-fractional parametrization. The method of unitary coupling identifies solutions of the lifting problem with minimal unitary extensions ... More
Can the excess in the FeXXVI Ly gamma line from the Galactic Center provide evidence for 17 keV sterile neutrinos?Jan 01 2010The standard model of particle physics assumes that neutrinos are massless, although adding non-zeros is required by the experimentally established phenomenon of neutrino oscillations requires neutrinos to have non-zero mass. Sterile neutrinos (or right-handed ... More
SoundSignaling: Realtime, Stylistic Modification of a Personal Music Corpus for Information DeliveryNov 16 2018Drawing inspiration from the notion of cognitive incongruence associated with Stroop's famous experiment, from musical principles, and from the observation that music consumption on an individual basis is becoming increasingly ubiquitous, we present the ... More
$N=2$ Super Yang-Mills and Subgroups of $SL(2,Z)$Jan 12 1996Feb 01 1996We discuss $SL(2,Z)$ subgroups appropriate for the study of $N=2$ Super Yang-Mills with $N_f=2n$ flavors. Hyperelliptic curves describing such theories should have coefficients that are modular forms of these subgroups. In particular, uniqueness arguments ... More
Three-point correlators from string amplitudes: Mixing and Regge spinsOct 17 2014Jan 20 2016This paper has two parts. We first compute the leading contribution to the strong-coupling mixing between the Konishi operator and a double-trace operator composed of chiral primaries by using flat-space vertex operators for the string-duals of the operators. ... More
de Branges-Rovnyak spaces: basics and theoryMay 12 2014For $S$ a contractive analytic operator-valued function on the unit disk ${\mathbb D}$, de Branges and Rovnyak associate a Hilbert space of analytic functions ${\mathcal H}(S)$ and related extension space ${\mathcal D(S)}$ consisting of pairs of analytic ... More
Interpolation in the noncommutative Schur-Agler classJun 26 2005The class of Schur-Agler functions over a domain ${\mathcal D} \subset {\mathbb C}^{d}$ is defined as the class of holomorphic operator-valued functions on ${\mathcal D}$ for which a certain von Neumann inequality is satisfied when a commuting tuple of ... More
Light-Cone Distortion of the Clustering and Abundance of Massive Galaxies at High-RedshiftsNov 15 2007Mar 13 2008Observational surveys of galaxies are not trivially related to single-epoch snapshots from computer simulations. Observationally, an increase in the distance along the line-of-sight corresponds to an earlier cosmic time at which the properties of the ... More
Hardy-space function theory, operator model theory, and dissipative linear systems: the multivariable, free-noncommutative, weighted Bergman-space settingJun 06 2019It is known that (i) a subspace ${\mathcal N}$ of the Hardy space $H^2$ which is invariant under the backward shift operator can be represented as the range of the observability operator of a conservative discrete-time linear system, (ii) the transfer-function ... More
Pseudo-Riemannian Weakly Symmetric ManifoldsJul 22 2011There is a well developed theory of weakly symmetric Riemannian manifolds. Here it is shown that several results in the Riemannian case are also valid for weakly symmetric pseudo-Riemannian manifolds, but some require additional hypotheses. The topics ... More
Semisimple Weakly Symmetric Pseudo--Riemannian ManifoldsJul 04 2017Jan 10 2018We develop the classification of weakly symmetric pseudo--riemannian manifolds $G/H$ where $G$ is a semisimple Lie group and $H$ is a reductive subgroup. We derive the classification from the cases where $G$ is compact, and then we discuss the (isotropy) ... More
Approximating Minimum-Cost k-Node Connected Subgraphs via Independence-Free GraphsDec 17 2012We present a 6-approximation algorithm for the minimum-cost $k$-node connected spanning subgraph problem, assuming that the number of nodes is at least $k^3(k-1)+k$. We apply a combinatorial preprocessing, based on the Frank-Tardos algorithm for $k$-outconnectivity, ... More
Cycle Space Constructions for Exhaustions of Flag DomainsJul 13 2008In the study of complex flag manifolds, flag domains and their cycle spaces, a key point is the fact that the cycle space $\mathcal M_D$ of a flag domain $D$ is a Stein manifold. That fact has a long history. The earliest approach relied on construction ... More
Integrable Systems for Particles with Internal Degrees of FreedomJun 10 1992We show that a class of models for particles with internal degrees of freedom are integrable. These systems are basically generalizations of the models of Calogero and Sutherland. The proofs of integrability are based on a recently developed exchange ... More
Theory of coexistence of superconductivity and ferroelectricityJan 18 2006A new investigation of the coexistence and competition of ferroelectricity and superconductivity is reported. In particular we show that the starting Hamiltonian of a previous study by Birman and Weger (2001) can be exactly diagonalized. The result differs ... More
Geodesic Orbit Metrics on Compact Simple Lie Groups arising from Generalized Flag ManifoldsMay 04 2018In this paper, we investigate left-invariant geodesic orbit metrics on connected simple Lie groups, where the metrics are formed by the structures of generalized flag manifolds. We prove that all these left-invariant geodesic orbit metrics on simple Lie ... More
Transfer-function realization for multipliers of the Arveson spaceOct 20 2006An interesting and recently much studied generalization of the classical Schur class is the class of contractive operator-valued multipliers for the reproducing kernel Hilbert space ${\mathcal H}(k_{d})$ on the unit ball ${\mathbb B}^{d} \subset {\mathbb ... More
Multivariable backward-shift-invariant subspaces and observability operatorsOct 20 2006It is well known that subspaces of the Hardy space over the unit disk which are invariant under the backward shift occur as the image of an observability operator associated with a discrete-time linear system with stable state-dynamics, as well as the ... More
Exponentially Localized Magnetic Fields for Single-Spin Quantum Logic GatesOct 15 2003Feb 03 2004An infinite array of parallel current-carrying wires is known, from the field of neutral particle optics, to produce an exponentially localized magnetic field when the current direction is antiparallel in adjacent wires. We show that a finite array of ... More
Tunneling and delocalization in hydrogen bonded systems: a study in position and momentum spaceApr 29 2009Novel experimental and computational studies have uncovered the proton momentum distribution in hydrogen bonded systems. In this work, we utilize recently developed open path integral Car-Parrinello molecular dynamics methodology in order to study the ... More
Characterizing the Shapes of Galaxy Clusters Using Moments of the Gravitational Lensing ShearAug 03 2005Nov 07 2005We explore the use of the tangential component of weak lensing shear to characterize the ellipticity of clusters of galaxies. We introduce an ellipticity estimator, and quantify its properties for isolated clusters from LCDM N-body simulations. We compare ... More
Direct Systems of Spherical Functions and RepresentationsOct 04 2011Nov 09 2012Spherical representations and functions are the building blocks for harmonic analysis on riemannian symmetric spaces. In this paper we consider spherical functions and spherical representations related to certain infinite dimensional symmetric spaces ... More
Extension of the $ν$-metricFeb 27 2010We extend the $\nu$-metric introduced by Vinnicombe in robust control theory for rational plants to the case of infinite-dimensional systems/classes of nonrational transfer functions.
Incoherent digital holograms acquired by interferenceless coded aperture correlation holography system without refractive lensesAug 01 2017We present a lensless, interferenceless incoherent digital holography technique based on the principle of coded aperture correlation holography. The acquired digital hologram by this technique contains a three-dimensional image of some observed scene. ... More
Test functions, Schur-Agler classes and transfer-function realizations: the matrix-valued settingSep 17 2011Given a collection of test functions, one defines the associated Schur-Agler class as the intersection of the contractive multipliers over the collection of all positive kernels for which each test function is a contractive multiplier. We indicate extensions ... More
Schur-class multipliers on the Arveson space: de Branges-Rovnyak reproducing kernel spaces and commutative transfer-function realizationsOct 20 2006An interesting and recently much studied generalization of the classical Schur class is the class of contractive operator-valued multipliers $S$ for the reproducing kernel Hilbert space ${\mathcal H}(k_{d})$ on the unit ball ${\mathbb B}^{d} \subset {\mathbb ... More
Convexity analysis and matrix-valued Schur class over finitely connected planar domainsSep 17 2011We identify the set of extreme points and apply Choquet theory to a normalized matrix-measure ball subject to finitely many linear side constraints. As an application we obtain integral representation formulas for the Herglotz class of matrix-valued functions ... More
Linearized force constants method for lattice dynamics in mixed semiconductorsSep 19 2007A simple and accurate method of calculating phonon spectra in mixed semiconductors alloys, on the basis of preliminarily (from first principles) relaxed atomic structure, is proposed and tested for (Zn,Be)Se and (Ga,In)As solid solutions. The method uses ... More
Overcoming efficiency constraints on blind quantum computationNov 18 2014Blind quantum computation allows a user to delegate a computation to an untrusted server while keeping the computation hidden. A number of recent works have sought to establish bounds on the communication requirements necessary to implement blind computation, ... More
Programmable Extreme Pseudomagnetic Fields in Graphene by a Uniaxial StretchNov 07 2015Many of the properties of graphene are tied to its lattice structure, allowing for tuning of charge carrier dynamics through mechanical strain. The graphene electro-mechanical coupling yields very large pseudomagnetic fields for small strain fields, up ... More
Probing Vortex Unbinding via Dipole FluctuationsAug 21 2002We develop a numerical method for detecting a vortex unbinding transition in a two-dimensional system by measuring large scale fluctuations in the total vortex dipole moment ${\vec P}$ of the system. These are characterized by a quantity $\cal F$ which ... More
Dynamical formation & scattering of hierarchical triples: Cross sections, Kozai-Lidov oscillations, and collisionsJul 13 2015Dec 11 2015Dynamical scattering of binaries and triple systems of stars, planets, and compact objects may produce highly inclined triple systems subject to Kozai-Lidov (KL) oscillations, potentially leading to collisions, mergers, Type Ia supernovae, and other phenomena. ... More
Isometric Equivalence of Isometries on $ H^p $May 27 2015We consider a natural notion of equivalence for bounded linear operators on $H^p,$ for $p\neq 2.$ We determine which isometries of finite codimension are equivalent. For these isometries , we classify those which have the Crownover property.
On the Theory of Quantum Oscillations of the Elastic Moduli in Layered ConductorsMar 30 2000Aug 24 2005In this paper we study theoretically how the local geometry of the Fermi surface (FS) of a layered conductor can affect quantum oscillations in the thermodynamic observables. We introduce a concrete model of the FS of a layered conductor. The model permits ... More