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
Understanding the Observed Evolution of the Galaxy Luminosity Function from z=6-10 in the Context of Hierarchical Structure FormationApr 05 2011Mar 15 2012Recent observations of the Lyman-break galaxy (LBG) luminosity function (LF) from z~6-10 show a steep decline in abundance with increasing redshift. However, the LF is a convolution of the mass function of dark matter halos (HMF)--which also declines ... 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
Bounded Isometries and Homogeneous QuotientsFeb 15 2015Nov 26 2015In this paper we give an explicit description of the bounded displacement isometries of a class of spaces that includes the Riemannian nilmanifolds. The class of spaces consists of metric spaces (and thus includes Finsler manifolds) on which an exponential ... More
Spherical Functions on Euclidean SpaceSep 20 2005We study special functions on euclidean spaces from the viewpoint of riemannian symmetric spaces. Here the euclidean space $E^n = G/K$ where $G$ is the semidirect product $R^n \cdot K$ of the translation group with a closed subgroup $K$ of the orthogonal ... More
Infinite Dimensional Multiplicity Free Spaces III: Matrix Coefficients and Regular FunctionsSep 09 2009In earlier papers we studied direct limits $(G,K) = \varinjlim (G_n,K_n)$ of two types of Gelfand pairs. The first type was that in which the $G_n/K_n$ are compact Riemannian symmetric spaces. The second type was that in which $G_n = N_n\rtimes K_n$ with ... More
Stepwise Square Integrable Representations for Locally Nilpotent Lie GroupsFeb 16 2014In a recent paper we found conditions for a nilpotent Lie group $N$ to have a filtration by normal subgroups whose successive quotients have square integrable representations, and such that these square integrable representations fit together nicely to ... More
Principal Series Representations of Direct Limit GroupsFeb 17 2004We combine the geometric realization of principal series representations of the author, with the Bott--Borel--Weil Theorem for direct limits of compact groups of Natarajan, Rodriguez-Carrington and the author, obtaining limits of principal series representations ... More
Plancherel Formulae associated to Filtrations of Nilpotent Lie GroupsDec 09 2012Dec 29 2012We study the conditions for a nilpotent Lie group to be foliated into subgroups that have square integrable (relative discrete series) unitary representations, that fit together to form a filtration by normal subgroups. Then we use that filtration to ... 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
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
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
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
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
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
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
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
Complex Forms of Quaternionic Symmetric SpacesAug 28 2003Oct 02 2003This is a complete classification of the complex forms of quaternionic symmetric spaces
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
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 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
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
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
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
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
Relativistic Cyclotron Radiation Detection of Tritium Decay Electrons as a New Technique for Measuring the Neutrino MassApr 18 2009The shape of the beta decay energy distribution is sensitive to the mass of the electron neutrino. Attempts to measure the endpoint shape of tritium decay have so far seen no distortion from the zero-mass form, thus placing an upper limit of m_nu_beta ... 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
Separating Vector Bundle Sections by Invariant MeansOct 19 2012We sharpen the construction of representation space in the paper "Principal Series Representations of Infinite Dimensional Lie Groups II: Construction of Induced Representations". We show that the principal series representation spaces constructed there, ... More
The Paley-Wiener Theorem and Limits of Symmetric SpacesJan 24 2011We extend the Paley--Wiener theorem for riemannian symmetric spaces to an important class of infinite dimensional symmetric spaces. For this we define a notion of propagation of symmetric spaces and examine the direct (injective) limit symmetric spaces ... More
Weyl Group Invariants and Application to Spherical Harmonic Analysis on Symmetric SpacesJan 29 2009Oct 24 2009Polynomial 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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Ionization Sources and Physical Conditions in the Diffuse Ionized Gas Halos of Four Edge-On GalaxiesNov 29 2000Dec 01 2000Deep long-slit spectra of the diffuse ionized gas halos of the edge-on spiral galaxies NGC 4302 and UGC 10288 are presented. These data, along with previously presented data for NGC 5775 and NGC 891, are used to address the issue of how DIG halos are ... 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
Modelling the angle-dependent magnetoresistance oscillations of Fermi surfaces with hexagonal symmetryJun 03 2016By solving the Boltzmann transport equation we investigate theoretically the general form of oscillations in the resistivity caused by varying the direction of an applied magnetic field for the case of quasi-two dimensional systems on hexagonal lattices. ... 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
Object-image correspondence for curves under projectionsFeb 06 2012Mar 15 2013We present a novel algorithm for deciding whether a given planar curve is an image of a given spatial curve, obtained by a central or a parallel projection with unknown parameters. A straightforward approach to this problem consists of setting up a system ... More
The Canonical Perfect Bose Gas in Casimir BoxesMay 14 2004We study the problem of Bose-Einstein condensation in the perfect Bose gas in the canonical ensemble, in anisotropically dilated rectangular parallelpipeds (Casimir boxes). We prove that in the canonical ensemble for these anisotropic boxes there is the ... More
Recommender Systems Notation: Proposed Common Notation for Teaching and ResearchFeb 04 2019As the field of recommender systems has developed, authors have used a myriad of notations for describing the mathematical workings of recommendation algorithms. These notations ap-pear in research papers, books, lecture notes, blog posts, and software ... 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
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
Direct calculation of lattice Green function with arbitrary interactions for general crystalsFeb 24 2012Efficient computation of lattice defect geometries such as point defects, dislocations, disconnections, grain boundaries, interfaces and free surfaces requires accurate coupling of displacements near the defect to the long-range elastic strain. Flexible ... More
Electrodynamics of Nearly-Ferroelectric SuperconductorsJun 17 2005We report here the frequency-dependent optical response of a nearly ferroelectric superconductor (NFE-SC), like Na$_{x}$WO$_3$, or n-SrTiO$_3$. From $\omega =0$, up to a critical frequency $ \omega_{c1}$, Meissner-like field extinction occurs as in a ... More
Geometric Resonance in Modulated Quantum Hall Systems Near $ ν= 1/2$Aug 12 1999Oct 12 1999We propose a theory for the new effects recently observed by Willett et al [1] in the magnetoresistance of a weakly modulated two dimensional electron gas near filling factor 1/2. Minima in transverse magnetoresistance and maxima in longitudinal magnetoresistance ... More
Cold atom guidance in a capillary using blue-detuned, hollow optical modesMay 17 2012We demonstrate guiding of cold 85Rb atoms through a 100-micron-diameter hollow core dielectric waveguide using cylindrical hollow modes. We have transported atoms using blue-detuned light in the 1st order, azimuthally-polarized TE01 hollow mode, and the ... More
Coupling spans of the Higgs-like bosonOct 11 2012Feb 27 2013Using the LHC and Tevatron data, we set upper and lower limits on the total width of the Higgs-like boson. The upper limit is based on the well-motivated assumption that the Higgs coupling to a W or Z pair is not much larger than in the Standard Model. ... More
Non-Pauli Transitions From Spacetime NoncommutativityMar 11 2010Mar 20 2010There are good reasons to suspect that spacetime at Planck scales is noncommutative. Typically this noncommutativity is controlled by fixed "vectors" or "tensors" with numerical entries. For the Moyal spacetime, it is the antisymmetric matrix $\theta_{\mu\nu}$. ... More
Causality and statistics on the Groenewold-Moyal planeMay 06 2009Quantum theories constructed on the noncommutative spacetime called the Groenewold-Moyal plane exhibit many interesting properties such as Lorentz and CPT noninvariance, causality violation and twisted statistics. We show that such violations lead to ... More
Quantum Fields on the Groenewold-Moyal PlaneMar 30 2008Jun 24 2008We give an introductory review of quantum physics on the noncommutative spacetime called the Groenewold-Moyal plane. Basic ideas like star products, twisted statistics, second quantized fields and discrete symmetries are discussed. We also outline some ... More
Density Functional Theory of Hard Sphere Condensation Under GravityMar 01 2001The onset of condensation of hard spheres in a gravitational field is studied using density functional theory. In particular, we find that the local density approximation yields results identical to those obtained previously using the kinetic theory [Physica ... More
Controlling the Size of PopcornMay 22 2000Oct 11 2000We present a thermo-statistical model of popcorn production and propose a way to control the final size of the popcorn by monitoring only the chamber pressure.
Extreme Galaxies During Reionization: Testing ISM and Disk ModelsSep 25 2013Dec 10 2013We test the ability of equilibrium galactic disk and one-zone interstellar medium models to describe the physical and emission properties of quasar hosts, submillimeter galaxies, and Lyman-alpha emitters at z>~6. The size, line widths, star formation ... More
Molecular Cloud Properties and CO Line Emission in z >~ 6 GalaxiesJan 03 2013Aug 01 2013We explore molecular cloud properties and the physics of CO transition lines in z >~ 6 Lyman-break galaxies and predict their CO fluxes using an analytic formalism built from global models of star formation in high-redshift galaxies that minimizes our ... More