Results for "Sean Bryan"

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Half-wave Plates for the Spider Cosmic Microwave Background PolarimeterFeb 11 2014Spider is a balloon-borne array of six telescopes that will observe the Cosmic Microwave Background. The 2400 antenna-coupled bolometers in the instrument will make a polarization map of the CMB with ~degree resolution at 150 GHz and 95 GHz. Polarization ... More
WSPEC: A waveguide filter-bank focal plane array spectrometer for millimeter wave astronomy and cosmologySep 15 2015Imaging and spectroscopy at (sub-)millimeter wavelengths are key frontiers in astronomy and cosmology. Large area spectral surveys with moderate spectral resolution (R=50-200) will be used to characterize large scale structure and star formation through ... More
The Donaldson-Thomas theory of $K3\times E$ via the topological vertexApr 11 2015Oberdieck and Pandharipande conjectured that the curve counting invariants of $S\times E$, the product of a $K3$ surface and an elliptic curve, is given by minus the reciprocal of the Igusa cusp form of weight 10. For a fixed primitive curve class in ... More
The Ihara zeta function of the infinite gridJun 23 2013The infinite grid is the Cayley graph of $\mathbb{Z} \times \mathbb{Z}$ with the usual generators. In this paper, the Ihara zeta function for the infinite grid is computed using elliptic integrals and theta functions. The zeta function of the grid extends ... More
Anomalous X-ray pulsars and soft gamma-ray repeaters - the connection with supernova remnantsDec 03 2002Many of the properties of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are still a matter of much debate, as is the connection (if any) between these two groups of sources. In cases where we can identify the supernova remnant (SNR) ... More
Radio Emission from the Milky WayJan 13 2004In the last 5-10 years, wide-field imaging capabilities and effective mosaicing algorithms have made possible a variety of ambitious interferometric surveys of the Galaxy, resulting in images of unprecedented sensitivity and resolution. Here I discuss ... More
Evidence for a conjecture of PandharipandeAug 03 2000In his paper "Hodge integrals and degenerate contributions", Pandharipande studied the relationship between the enumerative geometry of certain 3-folds and the Gromov-Witten invariants. In some good cases, enumerative invariants (which are manifestly ... More
The Donaldson-Thomas partition function of the banana manifoldFeb 22 2019A banana manifold is a compact Calabi-Yau threefold, fibered by Abelian surfaces, whose singular fibers have a singular locus given by a "banana configuration of curves". A basic example is given by $X_{ban}$, the blowup along the diagonal of the fibered ... More
Navigating the Topology of 2x2 Games: An Introductory Note on Payoff Families, Normalization, and Natural OrderOct 22 2010The Robinson-Goforth topology of swaps in adjoining payoffs elegantly arranges 2x2 ordinal games in accordance with important properties including symmetry, number of dominant strategies and Nash Equilibria, and alignment of interests. Adding payoff families ... More
Algebraic subgroups of acylindrically hyperbolic groupsNov 26 2015Feb 05 2017A subgroup of a group $G$ is called algebraic if it can be expressed as a finite union of solution sets to systems of equations. We prove that a non-elementary subgroup $H$ of an acylindrically hyperbolic group $G$ is algebraic if and only if there exists ... More
Zeta functions of graphs with $\mathbb{Z}$ actionsJul 26 2006Suppose $Y$ is a regular covering of a graph $X$ with covering transformation group $\pi = \mathbb{Z}$. This paper gives an explicit formula for the $L^2$ zeta function of $Y$ and computes examples. When $\pi = \mathbb{Z}$, the $L^2$ zeta function is ... More
Threshold Logical Clocks for Asynchronous Distributed Coordination and ConsensusJul 16 2019Consensus protocols for asynchronous networks are usually complex and inefficient, leading practical systems to rely on synchronous protocols. This paper attempts to simplify asynchronous consensus by building atop a novel threshold logical clock abstraction, ... More
Packrat Parsing: Simple, Powerful, Lazy, Linear TimeMar 18 2006Packrat parsing is a novel technique for implementing parsers in a lazy functional programming language. A packrat parser provides the power and flexibility of top-down parsing with backtracking and unlimited lookahead, but nevertheless guarantees linear ... More
Scale-invariant gravity: Spacetime recoveredJul 21 2003Jul 28 2004The configuration space of general relativity is superspace - the space of all Riemannian 3-metrics modulo diffeomorphisms. However, it has been argued that the configuration space for gravity should be conformal superspace - the space of all Riemannian ... More
Escaping Prisoner's Dilemmas: From Discord to Harmony in the Landscape of 2x2 GamesJun 08 2012Changes in payoffs can transform Prisoner's Dilemma and other social dilemmas into harmonious win-win games. Using the Robinson-Goforth topology of 2x2 games, this paper analyzes how payoff swaps turn Prisoner's Dilemma into other games, compares Prisoner's ... More
The Atacama Large Aperture Submillimeter Telescope (AtLAST)Jul 10 2019The sub-mm sky is a unique window for probing the architecture of the Universe and structures within it. From the discovery of dusty sub-mm galaxies, to the ringed nature of protostellar disks, our understanding of the formation, destruction, and evolution ... More
Development of dual-polarization LEKIDs for CMB observationsJul 12 2016We discuss the design considerations and initial measurements from arrays of dual-polarization, lumped element kinetic inductance detectors (LEKIDs) nominally designed for cosmic microwave background (CMB) studies. The detectors are horn-coupled, and ... More
Modeling dielectric half-wave plates for cosmic microwave background polarimetry using a Mueller matrix formalismJun 17 2010Jun 22 2011We derive an analytic formula using the Mueller matrix formalism that parameterizes the nonidealities of a half-wave plate (HWP) made from dielectric antireflection-coated birefringent slabs. This model accounts for frequency-dependent effects at normal ... More
X-Rays from Superbubbles in the Large Magellanic Cloud. VI. A Sample of Thirteen SuperbubblesApr 11 2001We present ROSAT observations and analysis of thirteen superbubbles in the Large Magellanic Cloud. Eleven of these observations have not been previously reported. We have studied the X-ray morphology of the superbubbles, and have extracted and analyzed ... More
A Compact Filter-Bank Waveguide Spectrometer for Millimeter WavelengthsFeb 09 2015May 13 2015We present the design and measurements of a 90GHz prototype of a millimeter-wave channelizing spectrometer realized in rectangular waveguide for astronomical instrumentation. The device was fabricated using conventional high-precision metal machining, ... More
A Texture BestiaryDec 09 1993Jul 25 1995Textures are topologically nontrivial field configurations which can exist in a field theory in which a global symmetry group $G$ is broken to a subgroup $H$, if the third homotopy group $\p3$ of $G/H$ is nontrivial. We compute this group for a variety ... More
The Science Advantage of a Redder Filter for WFIRSTJun 01 2018WFIRST will be capable of providing Hubble-quality imaging performance over several thousand square degrees of the sky. The wide-area, high spatial resolution survey data from WFIRST will be unsurpassed for many decades into the future. With the current ... More
The Log-Convex Density Conjecture and vertical surface area in warped productsJul 22 2011Dec 22 2014We examine the vertical component of surface area in the warped product of a Euclidean interval and a fiber manifold with product density. We determine general conditions under which vertical fibers minimize vertical surface area among regions bounding ... More
Gravitino dark matter and the lithium primordial abundance within a pre-BBN modified expansionAug 17 2010Mar 23 2011We present supersymmetric scenarios with gravitino LSP and stau NLSP in the case of a non-standard model of cosmology with the addition of a dark component in the pre-BBN era. In the context of the standard model of cosmology, gravitino LSP has drawn ... More
Percival's Conjecture for the Bunimovich Mushroom BilliardApr 28 2015Jan 09 2016The Laplace-Beltrami eigenfunctions on a compact Riemannian manifold $M$ whose geodesic billiard flow has mixed character have been conjectured by Percival to split into two complementary families, with all semiclassical mass supported in the completely ... More
SL(3,C)-Character Varieties and RP2-Structures on a TrinionJul 03 2014Denote the free group on two letters by F2 and the SL(3,C)-representation variety of F2 by R = Hom(F2, SL(3, C)). There is a SL(3,C)-action on the coordinate ring of R, and the geometric points of the subring of invariants is an affine variety X. We determine ... More
Exact Solutions and Black Hole Stability in Higher Dimensional Supergravity TheoriesSep 12 2012This thesis examines exact solutions to gauged and ungauged supergravity theories in space-time dimensions $D\ge5$ as well as various instabilities of such solutions.
Solution-free sets for sums of binary formsOct 10 2011We obtain quantitative estimates for the asymptotic density of subsets of the two-dimensional integer lattice which contain only trivial solutions to an additive equation involving binary forms. In the process we develop an analogue of Vinogradov's mean ... More
Production & Decay of QuarkoniumDec 04 2001In this talk I review NRQCD predictions for the production of charmonium at the Tevatron. After a quick presentation of the NRQCD factorization formalism for production and decay I review some old results and discuss how they compare to recent data. Following ... More
Traces of Thermalization at RHICApr 18 2004I argue that measurements of Au+Au collisions at 20, 130 and 200 GeV of the centrality dependence of the mean p_t together with p_t and net-charge fluctuations reflect the approach to local thermal equilibrium.
Fluctuations from Thermalization at RHICMay 07 2004The centrality dependence of dynamic fluctuations of the transverse momentum and the net charge can signal the approach to local thermal equilibrium in nuclear collisions. I explore this signal by comparing transport-theory calculations to STAR and PHENIX ... More
Transcendence of the Hodge-Tate filtrationOct 17 2016For $C$ a complete algebraically closed extension of $\mathbb{Q}_p$, we show that a one-dimensional $p$-divisible group $G/ \mathcal{O}_C$ can be defined over a complete discretely valued subfield $L \subset C$ with Hodge-Tate period ratios contained ... More
Kottwitz's nearby cycles conjecture for a class of unitary Shimura varietiesDec 01 2011Oct 22 2016This paper proves that the nearby cycles complexes on a certain family of PEL local models are central with respect to the convolution product of sheaves on the corresponding affine flag varieties. As a corollary, the semisimple trace functions defined ... More
Circulant preconditioners for functions of Hermitian Toeplitz matricesJul 28 2018Circulant preconditioners for functions of matrices have been recently of interest. In particular, several authors proposed the use of the optimal circulant preconditioners as well as the superoptimal circulant preconditioners in this context and numerically ... More
Generators, Relations and Symmetries in Pairs of 3x3 Unimodular MatricesJan 06 2006Jan 23 2007Denote the free group on two letters by F2 and the SL(3,C)-representation variety of F2 by R = Hom(F2, SL(3,C)). There is a SL(3,C)-action on the coordinate ring of R, and the geometric points of the subring of invariants is an affine variety X. We determine ... More
BiLipschitz decomposition of Lipschitz maps between Carnot groupsJan 19 2015Aug 29 2015Let $f : G \to H$ be a Lipschitz map between two Carnot groups. We show that if $B$ is ball of $G$, then there exists a subset $Z \subset B$, whose image in $H$ under $f$ has small Hausdorff content, such that $B \backslash Z$ can be decomposed into a ... More
On the geometry of almost $\mathcal{S}$-manifoldsMar 23 2011Oct 20 2011An $f$-structure on a manifold $M$ is an endomorphism field $\phi$ satisfying $\phi^3+\phi=0$. We call an $f$-structure {\em regular} if the distribution $T=\ker\phi$ is involutive and regular, in the sense of Palais. We show that when a regular $f$-structure ... More
Commuting probabilities of finite groupsNov 04 2014Jun 24 2015The commuting probability of a finite group is defined to be the probability that two randomly chosen group elements commute. Let P \subset (0,1] be the set of commuting probabilities of all finite groups. We prove that every point of P is nearly an Egyptian ... More
Optimal preconditioners for systems defined by functions of Toeplitz matricesFeb 10 2018We propose several circulant preconditioners for systems defined by some functions $g$ of Toeplitz matrices $A_n$. In this paper we are interested in solving $g(A_n)\mathbf{x}=\mathbf{b}$ by the preconditioned conjugate method or the preconditioned minimal ... More
Basepoint freeness for big line bundles in positive characteristic, with applications to M_g and to 3-fold MMPMar 03 1997Mar 13 1998I give a necessary and sufficient condition for a nef and big line bundle in positive characteristic to be semi-ample, and then give two applications: I show that the relative dualizing sheaf of the universal curve is semi-ample, in positive characteristic, ... More
A Tale of Two HorizonsFeb 09 2015I revisit the fate of coinciding horizons and the volume between them in the extremal limit of spherically symmetric black holes in four spacetime dimensions, focusing on the Schwarzschild de Sitter black hole for concreteness. The two Killing horizons ... More
Is Spacetime Countable?Jan 12 2015Is there a number for every bit of spacetime, or is spacetime smooth like the real line? The ultimate fate of a quantum theory of gravity might depend on it. The troublesome infinities of quantum gravity can be cured by assuming that spacetime comes in ... More
$CP$ violation in $B_s^0$ decays at LHCbAug 30 2014Latest LHCb measurements of $CP$ violation in the interference between mixing and decay are presented based on $pp$ collision data collected during LHC Run I, corresponding to an integrated luminosity of $3.0\, {\rm fb}^{-1}$. Approximately $27\, 000$ ... More
Observing Shape in SpacetimeAug 18 2014The notion of "reference frame" is a central theoretical construct for interpreting the physical implications of spacetime diffeomorphism invariance in General Relativity. However, the alternative formulation of classical General Relativity known as Shape ... More
Shape dynamics and Mach's principles: Gravity from conformal geometrodynamicsApr 03 2012In this PhD thesis, we develop a new approach to classical gravity starting from Mach's principles and the idea that the local shape of spatial configurations is fundamental. This new theory, "shape dynamics", is equivalent to general relativity but differs ... More
Følner sequences and sum-free setsJan 24 2014Erd\H{o}s showed that every set of $n$ positive integers contains a subset of size at least $n/(k+1)$ containing no solutions to $x_1 + \cdots + x_k = y$. We prove that the constant $1/(k+1)$ here is best possible by showing that if $(F_m)$ is a multiplicative ... More
Percival's Conjecture for the Bunimovich Mushroom BilliardApr 28 2015Nov 28 2016The Laplace-Beltrami eigenfunctions on a compact Riemannian manifold $M$ whose geodesic billiard flow has mixed character have been conjectured by Percival to split into two complementary families, with all semiclassical mass supported in the completely ... More
Valence bond solid formalism for d-level one-way quantum computationDec 19 2005Mar 06 2006The d-level or qudit one-way quantum computer (d1WQC) is described using the valence bond solid formalism and the generalised Pauli group. This formalism provides a transparent means of deriving measurement patterns for the implementation of quantum gates ... More
An Explicit Determination of the Springer MorphismJan 06 2017Let $G$ be a simply connected semisimple algebraic group over $\mathbb{C}$ and let $\rho :G\rightarrow GL(V_\lambda)$ be an irreducible representation of highest weight $\lambda$. Suppose that $\rho$ has finite kernel. Springer defined adjoint-invariant ... More
Deriving Dagger CompactnessJul 11 2019Dagger compact structure is a common assumption in the study of physical process theories, but lacks a clear interpretation. Here we derive dagger compactness from more operational axioms on a category. We first characterise the structure in terms of ... More
Relative Categoricity and Abstraction PrinciplesSep 11 2014Jan 24 2015Many recent writers in the philosophy of mathematics have put great weight on the relative categoricity of the traditional axiomatizations of our foundational theories of arithmetic and set theory (\cite{Parsons1990a}, \cite{Parsons2008} \S{49}, \cite{McGee1997aa}, ... More
An equivariant index formula for almost-CR manifoldsOct 02 2008Feb 01 2009We consider a consider the case of a compact manifold M, together with the following data: the action of a compact Lie group H and a smooth H-invariant distribution E, such that the H-orbits are transverse to E. These data determine a natural equivariant ... More
Power operations in the Kunneth spectral sequence and commutative HFp-algebrasFeb 22 2016In this paper, we prove the multiplicativity of the K\"unneth spectral sequence. This is established by an analogue of the Comparison Theorem from homological algebra, which we suspect may be useful for other spectral sequences. This multiplicativity ... More
Tree Oriented Data AnalysisSep 19 2014Sep 22 2014Complex data objects arise in many areas of modern science including evolutionary biology, nueroscience, dynamics of gene expression and medical imaging. Object oriented data analysis (OODA) is the statistical analysis of datasets of complex objects. ... More
Charmonium Suppression in Nuclear CollisionsSep 25 1996Measurements of $\psi$ and $\psi'$ production from experiment NA50 at the CERN SPS are compared to predictions based on a hadronic model of charmonium suppression by Vogt and myself. Data on centrality dependence and total cross sections are in good accord ... More
Extraordinary Baryon Fluctuations and the QCD Tricritical PointAug 24 1999The dynamic separation into phases of high and low baryon density in a heavy ion collision can enhance fluctuations of the net rapidity density of baryons compared to model expectations. We show how these fluctuations arise and how they can survive through ... More
Soft Collinear Effective Theory: An OverviewJul 22 2009In this talk I give an overview of soft collinear effective theory (SCET), including a discussion of some recent advances. First, I briefly cover the foundation upon which SCET is built, namely QCD factorization, and review the theoretical framework of ... More
Determining Color-Octet psi-Production Matrix Elements from gamma p and e p ProcessesOct 15 1996We calculated, within the NRQCD factorization formalism, the leading color-octet contributions to psi production in photon-nucleon and electron-nucleon collisions. The expressions obtained depend on the NRQCD matrix elements <O^{psi}_8(^1S_0)> and <O^{psi}_8(^3P_J)>. ... More
NRQCD Prediction for the Polarization of the J/psi Produced from b-decayAug 27 1996Presented at the Meeting of the Division of Particles and Fields, August 1996, in Minneapolis. The work presented here is based upon a recent paper (hep-ph/9608413) done in collaboration with Oscar F. Hernandez, Ivan Maksymyk, and Helene Nadeau. The NRQCD ... More
Optimal angle of the holomorphic functional calculus for the classical Ornstein-Uhlenbeck operator on $L^p$Dec 20 2018We give a simple proof of the fact that the classical Ornstein-Uhlenbeck operator $L$ is R-sectorial of angle $arcsin|1-2/p|$ on $L^{p}(\mathbb{R}^{n},\exp(-|x|^2/2)dx)$ (for $1<p<\infty$). Applying the abstract holomorphic functional calculus theory ... More
From Lab Testing to Science: Applying SAPHIRA HgCdTe L-APD Detectors to Adaptive OpticsJul 13 2018Due to their high frame rates, high sensitivity, low noise, and low dark current, SAPHIRA detectors provide new capabilities for astronomical observations. The SAPHIRA detector is a 320x256@24 $\mu$m pixel HgCdTe linear avalanche photodiode array manufactured ... More
Equivalence of continuous, local and infinitesimal rigidity in normed spacesSep 06 2018We present a rigorous study of framework rigidity in general finite dimensional normed spaces from the perspective of Lie group actions on smooth manifolds. As an application, we prove an extension of Asimow and Roth's 1978/9 result establishing the equivalence ... More
Conjugation of Transitive Permutation Pairs and Dessins d'EnfantsJan 31 2017Apr 06 2017Let E be a finite set. Given permutations x and y of E that together generate a transitive subgroup, for which s is it true that x and the conjugate of y by s also generate a transitive subgroup? Such transitive permutation pairs encode dessins d'enfants, ... More
On the Canonical Representatives of a Finite Weyl GroupMay 27 2015Apr 18 2016Let K be a field and G a split connected reductive affine algebraic K-group. Let T be a split maximal torus of G, W its finite Weyl group, and R its root system. After fixing a realization of R in G and choosing a simple system for R, one gets a system ... More
Predicativity, the Russell-Myhill Paradox, and Church's Intensional LogicJun 07 2015This paper sets out a predicative response to the Russell-Myhill paradox of propositions within the framework of Church's intensional logic. A predicative response places restrictions on the full comprehension schema, which asserts that every formula ... More
Sharp regularity near an absorbing boundary for solutions to second order SPDEs in a half-line with constant coefficientsMar 27 2013Jul 23 2015We prove that the weak version of the SPDE problem \begin{align*} dV_{t}(x) & = [-\mu V_{t}'(x) + \frac{1}{2} (\sigma_{M}^{2} + \sigma_{I}^{2})V_{t}"(x)]dt - \sigma_{M} V_{t}'(x)dW^{M}_{t}, \quad x > 0, \\ V_{t}(0) &= 0 \end{align*} with a specified bounded ... More
Remarks on Realizing Inflation in String and Particle Physics ModelsJan 30 2014The recent measurements of cosmological parameters by the Planck collaboration favors inflationary models with a redshifted spectrum and a very low tensor-to-scalar ratio. Two well-studied scenarios in the particle physics/string theory literature -- ... More
Compression bounds for wreath productsJul 29 2009Dec 06 2009We show that if $G$ and $H$ are finitely generated groups whose Hilbert compression exponent is positive, then so is the Hilbert compression exponent of the wreath $G \wr H$. We also prove an analogous result for coarse embeddings of wreath products. ... More
Soft Collinear Effective TheoryJan 30 2006In this talk I review soft collinear effective theory. After a discussion of the formalism and properties of the effective field theory, I turn to phenomenology. I present results on color-suppressed B to D decays, and on the Upsilon radiative decay spectrum. ... More
A Categorical Reconstruction of Quantum TheoryApr 06 2018Feb 26 2019We reconstruct finite-dimensional quantum theory from categorical principles. That is, we provide properties ensuring that a given physical theory described by a dagger compact category in which one may 'discard' objects is equivalent to a generalised ... More
Quotient Categories and PhasesJan 29 2018Jan 07 2019We study properties of a category after quotienting out a suitable chosen group of isomorphisms on each object. Coproducts in the original category are described in its quotient by our new weaker notion of a 'phased coproduct'. We examine these and show ... More
Motivic random variables and representation stability I: Configuration spacesOct 18 2016We prove a motivic stabilization result for the cohomology of the local systems on configuration spaces of varieties over $\mathbb{C}$ attached to character polynomials. Our approach interprets the stabilization as a probabilistic phenomenon based on ... More
Product mixing in the alternating groupDec 11 2015Feb 11 2017We prove the following one-sided product-mixing theorem for the alternating group: Given subsets $X,Y,Z \subset A_n$ of densities $\alpha,\beta,\gamma$ satisfying $\min(\alpha\beta,\alpha\gamma,\beta\gamma)\gg n^{-1}(\log n)^7$, there are at least $ (1+o(1))\alpha\beta\gamma ... More
Obtaining the One-Holed Torus from Pants: Duality in an SL(3,C)-Character VarietyMar 25 2008The SL(3,C)-representation variety R of a free group F arises naturally by considering surface group representations for a surface with boundary. There is a SL(3,C)-action on the coordinate ring of R. The geometric points of the subring of invariants ... More
Poisson Geometry of SL(3,C)-Character Varieties Relative to a Surface with BoundaryMar 09 2007Mar 03 2008The SL(3,C)-representation variety R of a free group F arises naturally by considering surface group representations for a surface with boundary. There is a SL(3,C)-action on the coordinate ring of R by conjugation. The geometric points of the subring ... More
Fragments of Frege's Grundgesetze and Gödel's Constructible UniverseJul 15 2014Jun 07 2015Frege's Grundgesetze was one of the 19th century forerunners to contemporary set theory which was plagued by the Russell paradox. In recent years, it has been shown that subsystems of the Grundgesetze formed by restricting the comprehension schema are ... More
Conjugacy classes of non-translations in affine Weyl groups and applications to Hecke algebrasJun 21 2013Nov 11 2014Let W be an Iwahori-Weyl group of a connected reductive group G over a non-archimedean local field. I prove that if w is an element of W that does not act on the corresponding apartment of G by a translation then one can apply to w a sequence of conjugations ... More
Stratified $β$-numbers and traveling salesman in Carnot groupsFeb 08 2019We introduce a modified version of P. Jones's $\beta$-numbers for Carnot groups which we call stratified $\beta$-numbers. We show that an analogue of Jones's traveling salesman theorem on 1-rectifiability of sets holds for any Carnot group if we replace ... More
On the geometric quantization of contact manifoldsSep 10 2009Mar 24 2011Suppose that $(M,E)$ is a compact contact manifold, and that a compact Lie group $G$ acts on $M$ transverse to the contact distribution $E$. In an earlier paper, we defined a $G$-transversally elliptic Dirac operator $\dirac$, constructed using a Hermitian ... More
Spontaneously broken Standard Model (SM) symmetries and the Goldstone theorem protect the Higgs mass and ensure that it has no Higgs Fine Tuning Problem (HFTP)Jun 30 2011Aug 08 2012B.W.Lee/K.Symanzik proved that Ward-Takahashi identities and tadpole renormalization force all ultra-violet quadratic divergences (UV-QD) to be absorbed into the physical renormalized pseudo-scalar pion mass in O(4)LSM (linear sigma models) across the ... More
Minimizing Close-k Aggregate Loss Improves ClassificationNov 01 2018Nov 03 2018In classification, the de facto method for aggregating individual losses is the average loss. When the actual metric of interest is 0-1 loss, it is common to minimize the average surrogate loss for some well-behaved (e.g. convex) surrogate. Recently, ... More
A comparison theorem for the isoperimetric profile under curve shortening flowApr 05 2011We prove a comparison theorem for the isoperimetric profiles of simple closed curves evolving by the normalized curve shortening flow: If the isoperimetric profile of the region enclosed by the initial curve is greater than that of some `model' convex ... More
A Generalized Method for Measuring Weak Lensing Magnification With Weighted Number CountsJul 07 2015Nov 19 2015We present a derivation of a generalized optimally-weighted estimator for the weak lensing magnification signal, including a calculation of errors. With this estimator, we present a local method for optimally estimating the local effects of magnification ... More
Searching for Topological Degeneracy in the Hubbard Model with Quantum Monte CarloMay 01 2013Z2 spin liquids have topological order. One manifestation of this is that a Z2 spin liquid on a torus exhibits a four-fold degeneracy. Recent numerical evidence has argued for the existence of a spin liquid ground state in the Hubbard model on a honeycomb ... More
Curve-counting invariants for crepant resolutionsAug 04 2012Jul 01 2014We construct curve counting invariants for a Calabi-Yau threefold $Y$ equipped with a dominant birational morphism $\pi:Y \to X$. Our invariants generalize the stable pair invariants of Pandharipande and Thomas which occur for the case when $\pi:Y\to ... More
Matroids, antimatroids, and the generalized external orderDec 12 2017Las Vergnas's active orders are a collection of partial orders on the bases of a matroid which are derived from the classical notion of matroid activity. In this paper, we construct a generalization of Las Vergnas's external order which is defined on ... More
Geolocation of Multiple Noncooperative Emitters Using Received Signal Strength: Sparsity, Resolution, and DetectabilityJul 02 2019In this paper we investigate the problem of locating multiple non-cooperative radio frequency (RF) emitters using only received signal strength (RSS) data. We assume that the number of emitters is unknown and that individual emitters cannot be distinguished ... More
Shocks, Outflows and Bubbles: New Views on Pulsars and their WindsMar 18 2003A typical young pulsar slows down at an imperceptible rate, its spin period increasing by less than 10 microseconds over the course of a year. However, the inertia of a pulsar is so extreme that to effect this tiny change in rotation rate, the star must ... More
Cosmic Magnetism with the Square Kilometre Array and its PathfindersJan 19 2009One of the five key science projects for the Square Kilometre Array (SKA) is "The Origin and Evolution of Cosmic Magnetism", in which radio polarimetry will be used to reveal what cosmic magnets look like and what role they have played in the evolving ... More
The Square Kilometre Array: A new probe of cosmic magnetismMar 02 2006Magnetic fields are a fundamental part of many astrophysical phenomena, but the evolution, structure and origin of magnetic fields are still unresolved problems in physics and astrophysics. When and how were the first fields generated? Are present-day ... More
Three myths about time reversal in quantum theoryJul 25 2016Many have suggested that the transformation standardly referred to as 'time reversal' in quantum theory is not deserving of the name. I argue on the contrary that the standard definition is perfectly appropriate, and is indeed forced by basic considerations ... More
Curvature bound for curve shortening flow via distance comparison and a direct proof of Grayson's theoremAug 19 2009A new isoperimetric estimate is proved for embedded closed curves evolving by curve shortening flow, normalized to have total length $2\pi$. The estimate bounds the length of any chord from below in terms of the arc length between its endpoints and elapsed ... More
The Constructive Standard Model: Part IFeb 01 2018Jul 26 2018In this paper, we construct the complete set of minimal 3-point vertices for the massive Standard Model (SM) based purely on symmetry principles, mass dimension and high-energy behavior and without any recourse to field theory, gauge symmetries or Feynman ... More
Foundations of an Alternative Approach to Reification in RDFJun 13 2014Mar 19 2019This document defines extensions of the RDF data model and of the SPARQL query language that capture an alternative approach to represent statement-level metadata. While this alternative approach is backwards compatible with RDF reification as defined ... More
A Simple Optimal Binary Representation of Mosaic Floorplans and Baxter PermutationsNov 21 2011Nov 22 2011A "floorplan" is a rectangle subdivided into smaller rectangular sections by horizontal and vertical line segments. Each section in the floorplan is called a "block". Two floorplans are considered equivalent if and only if there is a one-to-one correspondence ... More
Donaldson-Thomas invariants of local elliptic surfaces via the topological vertexAug 26 2016We compute the Donaldson-Thomas invariants of a local elliptic surface with section. We introduce a new computational technique which is a mixture of motivic and toric methods. This allows us to write the partition function for the invariants in terms ... More
The Rank Stable Topology of Instantons on $\cpbar$Oct 09 1996Let $\M_{k}^{n}$ be the moduli space of based (anti-self-dual) instantons on $\cpbar$ of charge $k$ and rank $n$. There is a natural inclusion of rank $n$ instantons into rank $n+1$. We show that the direct limit space is homotopy equivalent to $BU(k)\times ... More
The Quantum McKay Correspondence for polyhedral singularitiesMar 26 2008Jul 31 2009Let G be a polyhedral group, namely a finite subgroup of SO(3). Nakamura's G-Hilbert scheme provides a preferred Calabi-Yau resolution Y of the polyhedral singularity C^3/G. The classical McKay correspondence describes the classical geometry of Y in terms ... More
The Crepant Resolution ConjectureOct 03 2006Jan 07 2007For orbifolds admitting a crepant resolution and satisfying a hard Lefschetz condition, we formulate a conjectural equivalence between the Gromov-Witten theories of the orbifold and the resolution. We prove the conjecture for the equivariant Gromov-Witten ... More
On the rigidity of stable maps to Calabi-Yau threefoldsMay 11 2004Mar 13 2009If X is a nonsingular curve in a Calabi--Yau threefold Y whose normal bundle N_{X/Y} is a generic semistable bundle, are the local Gromov-Witten invariants of X well defined? For X of genus two or higher, the issues are subtle. We will formulate a precise ... More