Results for "Chris Karwin"

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Fermi-LAT Observations of Gamma-Ray Emission Towards the Outer Halo of M31Mar 25 2019The Andromeda Galaxy is the closest spiral galaxy to us and has been the subject of numerous studies. It harbors a massive dark matter (DM) halo which may span up to ~600 kpc across and comprises ~90% of the galaxy's total mass. This halo size translates ... More
Fermi-LAT Observations of Gamma-Ray Emission Towards the Outer Halo of M31Dec 07 2018The Andromeda Galaxy is the closest spiral galaxy to us and has been the subject of numerous studies. It harbors a massive dark matter (DM) halo which may span up to ~600 kpc across and comprises ~90% of the galaxy's total mass. This halo size translates ... More
Fermi-LAT Observations of Gamma-Ray Emission Towards the Outer Halo of M31Mar 25 2019Jun 13 2019The Andromeda Galaxy is the closest spiral galaxy to us and has been the subject of numerous studies. It harbors a massive dark matter (DM) halo which may span up to ~600 kpc across and comprises ~90% of the galaxy's total mass. This halo size translates ... More
Search for gamma-ray emission from $p$-wave dark matter annihilation in the Galactic CenterApr 12 2019Indirect searches for dark matter through Standard Model products of its annihilation generally assume a cross-section which is dominated by a term independent of velocity ($s$-wave annihilation). However, in many DM models an $s$-wave annihilation cross-section ... More
Generic transversality for unbranched covers of closed pseudoholomorphic curvesJul 02 2014Dec 12 2014We prove that in closed almost complex manifolds of any dimension, generic perturbations of the almost complex structure suffice to achieve transversality for all unbranched multiple covers of simple pseudoholomorphic curves with deformation index zero. ... More
Generic transversality for unbranched covers of closed pseudoholomorphic curvesJul 02 2014Nov 03 2016We prove that in closed almost complex manifolds of any dimension, generic perturbations of the almost complex structure suffice to achieve transversality for all unbranched multiple covers of simple pseudoholomorphic curves with deformation index zero. ... More
Light Will be Thrown: The Emerging Science of Cultural EvolutionSep 08 2016Culture evolves, not just in the trivial sense that cultures change over time, but also in the strong sense that such change is governed by Darwinian principles. Both biological and cultural evolution are essentially cumulative selection processes in ... More
The adiabatic/entropy decomposition in $P(φ^I,X^{IJ})$ theories with multiple sound speedsNov 08 2016We consider $P(\phi^I,X^{IJ})$ theories of multi-field inflation and ask the question of how to define the adiabatic and entropy perturbations, widely used in calculating the curvature and isocurvature power spectra, in this general context. It is found ... More
Lifting non-ordinary cohomology classes for SL(3)Feb 19 2016In this paper, we present a generalisation of a theorem of David and Rob Pollack. In 'A construction of rigid analytic cohomology classes for congruence subgroups of SL(3,Z)', they give a very general argument for lifting ordinary eigenclasses (with respect ... More
Hadronic transitions from the latticeOct 03 2003I discuss strategies to determine hadronic decay couplings from lattice studies. As a check of the methods, I explore the decay of a vector meson to two pseudoscalar mesons with $N_f=2$ flavours of sea quark. Although we are working with quark masses ... More
Glueballs and Hybrid MesonsSep 08 1992We discuss states in the meson spectrum which have explicit gluonic components. Glueballs (with no valence quarks) and hybrid mesons (with valence quarks) are both reviewed. We present in some detail lattice simulation results. ( to appear in proceedings ... More
Model Building with Multiple Dependent Variables and ConstraintsSep 04 2011The most widely used method for finding relationships between several quantities is multiple regression. This however is restricted to a single dependent variable. We present a more general method which allows models to be constructed with multiple variables ... More
Iterates of mappings which are almost continuous and openOct 06 2010Nov 20 2010This note presents an approach to studying the iterates of a mapping whose restriction to the complement of a finite set is continuous and open. The main examples to which the approach can be applied are piecewise monotone mappings defined on an interval ... More
Computing with EquationsAug 06 2010The intention of these notes is to give a mathematical account of how I believe students could be taught to think about functional programming languages and to explain how such languages work.
Refining quasi-probability kernelsMar 16 2010We consider the problem of modifying a quasi-probability kernel in order to improve its properties without changing the set of measures whose conditional probabilities it specifies.
Existence of monoids compatible with a family of mappingsMar 05 2009Aug 02 2010These notes present an approach to obtaining monoid operations which are compatible with a given family of mappings in the sense that the mappings become left translations in the monoid. This can be applied to various situations such as the addition on ... More
Hilbert-space factorization is a limited and expensive information-processing resourceJan 20 2014Feb 05 2014By taking the need for quantum reference frames into account, it is shown that Hilbert-space factorization is a dissipative process requiring on the order of kT to reduce by one bit an observer's uncertainty in the provenance of a classically-recorded ... More
Quantum mechanics from five physical assumptionsFeb 03 2011Five physical assumptions are proposed that together entail the general qualitative results, including the Born rule, of non-relativistic quantum mechanics by physical and information-theoretic reasoning alone. Two of these assumptions concern fundamental ... More
Classical system boundaries cannot be determined within quantum DarwinismAug 02 2010May 19 2011Multiple observers who interact with environmental encodings of the states of a macroscopic quantum system S as required by quantum Darwinism cannot demonstrate that they are jointly observing S without a joint a priori assumption of a classical boundary ... More
Morse Theory on 1-SkeletaJun 05 2014Guillemin and Zara gave necessary and sufficient conditions under which Morse theoretic techniques could be used to construct an additive basis for the equivariant cohomology of a 1-skeleton that is either 3-independent or GKM. We show that their conditions ... More
The Kaon B-parameter from Two-Flavour Dynamical Domain Wall FermionsOct 26 2004We report on the calculation of the kaon B-parameter using two dynamical flavours of domain wall fermions. Our analysis is based on three ensembles of configurations, each consisting of about 5,000 HMC trajectories, with a lattice spacing of approximately ... More
Beaming models and the correlations between the core dominance parameter and the core and extended powers of quasarsAug 20 1998We investigate the recent claim by Qin et al. that the observed correlations (or lack thereof) between the core dominance parameter and the core and extended powers of samples of lobe- and core-dominated quasars is in contradiction with beaming models. ... More
On the equivariant algebraic Jacobian for curves of genus twoNov 11 2011We present a treatment of the algebraic description of the Jacobian of a generic genus two plane curve which exploits an SL2(k) equivariance and clarifes the structure of E.V.Flynn's 72 defining quadratic relations. The treatment is also applied to the ... More
Stochastic HPSGFeb 17 1995In this paper we provide a probabilistic interpretation for typed feature structures very similar to those used by Pollard and Sag. We begin with a version of the interpretation which lacks a treatment of re-entrant feature structures, then provide an ... More
Completing CVA and Liquidity: Firm-Level Positions and Collateralized TradesSep 17 2010Bilateral CVA as currently implement has the counterintuitive effect of profiting from one's own widening CDS spreads, i.e. increased risk of default, in practice. The unified picture of CVA and liquidity introduced by Morini & Prampolini 2010 has contributed ... More
Scaling accretion flow models from BHB to AGN - Why doesn't it work?May 12 2014Black holes depend only on mass and spin, while what we see from the accretion flow in steady state depends also on mass accretion rate and (weakly) inclination. Hence we should be able to scale the accretion flow properties from the stellar to the supermassive ... More
Gasdynamics and Starbursts in Interacting GalaxiesNov 10 1997The onset of gaseous inflows and central activity in interacting galaxies is driven largely by induced bars in the host galaxies. The stability of galaxies against growing bar modes is a direct function of their structural properties --- galaxies with ... More
Power-law tails in probability density functions of molecular cloud column densityMar 04 2015Power-law tails are often seen in probability density functions (PDFs) of molecular cloud column densities, and have been attributed to the effect of gravity. We show that extinction PDFs of a sample of five molecular clouds obtained at a few tenths of ... More
When can perfect state transfer occur?Nov 01 2010Jan 04 2011Let $X$ be a graph on $n$ vertices with with adjacency matrix $A$ and let $H(t)$ denote the matrix-valued function $\exp(iAt)$. If $u$ and $v$ are distinct vertices in $X$, we say perfect state transfer from $u$ to $v$ occurs if there is a time $\tau$ ... More
Controllable Subsets in GraphsOct 15 2010Let $X$ be a graph on $v$ vertices with adjacency matrix $A$, and let let $S$ be a subset of its vertices with characteristic vector $z$. We say that the pair $(X,S)$ is controllable if the vectors $A^rz$ for $r=1,\ldots,v-1$ span $\mathbb{R}^v$. Our ... More
TeV-scale gravity in Horava-Witten theory on a compact complex hyperbolic threefoldApr 11 2007Aug 19 2012The field equations and boundary conditions of Horava-Witten theory, compactified on a smooth compact spin quotient of CH^3, where CH^3 denotes the hyperbolic cousin of CP^3, are studied in the presence of Casimir energy density terms. If the Casimir ... More
A BPHZ convergence proof in Euclidean position spaceJan 23 2006Two BPHZ convergence theorems are proved directly in Euclidean position space, without exponentiating the propagators, making use of the Cluster Convergence Theorem presented previously. The first theorem proves the absolute convergence of arbitrary BPHZ-renormalized ... More
Improvement of a provisional solution of the quantum-corrected field equations of d = 11 supergravity on flat R^4 times a compact hyperbolic 7-manifold, and modes that decay along the beam line outside the interaction region at the LHCMar 14 2012Mar 15 2012A recent provisional solution of the quantum-corrected field equations of d = 11 supergravity on flat R^4 times a compact hyperbolic 7-manifold \bar{H}^7, in the presence of magnetic 4-form fluxes wrapping 4-cycles of \bar{H}^7, is improved by showing ... More
Some Remarks on Watanabe's Bold ConjectureMar 30 2016At the 2015 Workshop on Lefschetz Properties of Artinian Algebras, Junzo Watanabe conjectured that every graded Artinian complete intersection algebra with the standard grading can be embedded into another such algebra cut out by quadratic generators. ... More
Closed sets of Mahler measuresJun 14 2016Given a $k$-variable Laurent polynomial $F$, any $l\times k$ integer matrix $A$ naturally defines an $l$-variable Laurent polynomial $F_A.$ I prove that for fixed $F$ the set $\mathcal M(F)$ of all the logarithmic Mahler measures $m(F_A)$ of $F_A$ for ... More
State Transfer on GraphsFeb 24 2011Jun 27 2011If $X$ is a graph with adjacency matrix $A$, then we define $H(t)$ to be the operator $\exp(itA)$. We say that we have perfect state transfer in $X$ from the vertex $u$ to the vertex $v$ at time $\tau$ if the $uv$-entry of $|H(\tau)_{u,v}|=1$. This concept ... More
Effective dark energy from decoherenceFeb 11 2015Apr 17 2016Within the quantum Darwinist framework introduced by W. H. Zurek ({\em Nat. Phys.}, 5:181-188, 2009), observers obtain pointer-state information about quantum systems by interacting with a local sample of the surrounding environment, e.g. a local sample ... More
The Index Bundle for a Family of Dirac-Ramond OperatorsFeb 09 2012We study the index bundle of the Dirac-Ramond operator associated with a family $\pi: Z \to X$ of compact spin manifolds. We view this operator as the formal twisted Dirac operator $\dd \otimes \bigotimes_{n=1}^{\infty}S_{q^n}TM_{\C}$ so that its index ... More
A Dynamical Key to the Riemann HypothesisMay 11 2011Oct 25 2011We investigate a dynamical basis for the Riemann hypothesis (RH) that the non-trivial zeros of the Riemann zeta function lie on the critical line x = 1/2. In the process we graphically explore, in as rich a way as possible, the diversity of zeta and L-functions, ... More
State Transfer on GraphsFeb 24 2011Jun 17 2017If $X$ is a graph with adjacency matrix $A$, then we define $H(t)$ to be the operator $\exp(itA)$. We say that we have perfect state transfer in $X$ from the vertex $u$ to the vertex $v$ at time $\tau$ if the $uv$-entry of $|H(\tau)_{u,v}|=1$. This concept ... More
Circle and sphere blending with conformal geometric algebraOct 09 2003Blending schemes based on circles provide smooth `fair' interpolations between series of points. Here we demonstrate a simple, robust set of algorithms for performing circle blends for a range of cases. An arbitrary level of G-continuity can be achieved ... More
Extensions of Abelian Automata GroupsMar 16 2019A longstanding problem in understanding abelian automata groups comes from a seemingly unnecessary parameter in the classification given by Nekrashevich and Sidki. In this paper, we show that this parameter corresponds to the presence of certain fractional ... More
Enumerating Unique Computational Graphs via an Iterative Graph InvariantFeb 17 2019In this report, we describe a novel graph invariant for computational graphs (colored directed acylic graphs) and how we used it to generate all distinct computational graphs up to isomorphism for small graphs. The algorithm iteratively applies isomorphism-invariant ... More
Lessons from the History of European EMUMay 25 2018This paper examines the history of previous examples of EMU from the viewpoint that state actors make decisions about whether to participate in a monetary union based on rational self-interest concerning costs and benefits to their national economies. ... More
Implications of EMU for the European CommunityMay 25 2018Monetary integration has both costs and benefits. Europeans have a strong aversion to exchange rate instability. From this perspective, the EMS has shown its limits and full monetary union involving a single currency appears to be a necessity. This is ... More
The Mahler measure of algebraic numbers: a surveyJan 14 2007Jan 28 2008A survey of results for Mahler measure of algebraic numbers, and one-variable polynomials with integer coefficients is presented. Related results on the maximum modulus of the conjugates (`house') of an algebraic integer are also discussed. Some generalisations ... More
Closed sets of Mahler measuresJun 14 2016Jan 23 2018Given a $k$-variable Laurent polynomial $F$, any $l\times k$ integer matrix $A$ naturally defines an $l$-variable Laurent polynomial $F_A.$ I prove that for fixed $F$ the set $\mathcal M(F)$ of all the logarithmic Mahler measures $m(F_A)$ of $F_A$ for ... More
On rigidity of locally symmetric spacesApr 11 2017In this note I generalize the classical results of Calabi-Vesentini to certain non-compact locally symmetric domains, namely those that are quotients of a hermitian symmetric domain by a neat arithmetic subgroup of the group of its holomorphic automorphisms. ... More
Measurements of photon and jet production properties with ATLASOct 13 2016Summary of recent ATLAS measurements of jet and photon production using proton-proton (pp) collisions from the Large Hadron Collider. The charged-particle multiplicity in jets, and jet charge measurements are presented using 8 TeV pp collisions. Differential ... More
Quantifiers for quantum logicNov 10 2008Apr 23 2009We consider categorical logic on the category of Hilbert spaces. More generally, in fact, any pre-Hilbert category suffices. We characterise closed subobjects, and prove that they form orthomodular lattices. This shows that quantum logic is just an incarnation ... More
Uniform Random Planar Graphs with Degree ConstraintsJul 22 2013Random planar graphs have been the subject of much recent work. Many basic properties of the standard uniform random planar graph P_{n}, by which we mean a graph chosen uniformly at random from the set of all planar graphs with vertex set {1,2,...,n}, ... More
The evolution of uniform random planar graphsJan 26 2011Let P_{n,m} denote the graph taken uniformly at random from the set of all planar graphs on {1,2,..., n} with exactly m(n) edges. We use counting arguments to investigate the probability that P_{n,m} will contain given components and subgraphs, finding ... More
An Introduction to the Moebius FunctionMar 18 2018This is an introduction to the M\"obius function of a poset. The chief novelty is in the exposition. We show how order-preserving maps from one poset to another can be used to relate their M\"obius functions. We derive the basic results on the M\"obius ... More
Sharkovsky's Theorem and one-dimensional combinatorial dynamicsJan 17 2012A proof of Sharkovsky's Theorem is given. It is shown how this proof naturally generalizes to looking at maps on graphs and to Sharkovsky-type theorems for these maps. The paper is written at an elementary level and is meant as an introduction to one-dimensional ... More
Non-Exact Symplectic Cobordisms Between Contact 3-ManifoldsAug 14 2010Feb 05 2013We show that the pre-order defined on the category of contact manifolds by arbitrary symplectic cobordisms is considerably less rigid than its counterparts for exact or Stein cobordisms: in particular, we exhibit large new classes of contact 3-manifolds ... More
A Hierarchy of Local Symplectic Filling Obstructions for Contact 3-ManifoldsSep 14 2010Feb 05 2013We generalize the familiar notions of overtwistedness and Giroux torsion in 3-dimensional contact manifolds, defining an infinite hierarchy of local filling obstructions called planar torsion, whose integer-valued order $k \ge 0$ can be interpreted as ... More
Finite Energy Foliations on Overtwisted Contact ManifoldsNov 17 2006Mar 12 2008We develop a method for preserving pseudoholomorphic curves in contact 3-manifolds under surgery along transverse links. This makes use of a geometrically natural boundary value problem for holomorphic curves in a 3-manifold with stable Hamiltonian structure, ... More
Contact 3-manifolds, holomorphic curves and intersection theoryJun 17 2017This is a slight revision of some expository lecture notes written originally for a 5-hour minicourse on the intersection theory of punctured holomorphic curves and its applications in 3-dimensional contact topology, given by the author as part of the ... More
Compactly accessible categories and quantum key distributionNov 13 2008Apr 19 2016Compact categories have lately seen renewed interest via applications to quantum physics. Being essentially finite-dimensional, they cannot accomodate (co)limit-based constructions. For example, they cannot capture protocols such as quantum key distribution, ... More
Accretion Flows in X--Ray Binaries and Active Galactic NucleiMay 29 2001Hard X-ray emission is ubiquitous in accreting black holes, both in Galactic binary systems and in Active Galactic Nuclei. I review the different spectra which can be seen from these systems, and possible ways of producing this emission. X-ray reflection ... More
On Modelling LifeMay 16 1994We present a theoretical as well as experimental investigation of a population of self-replicating segments of code subject to random mutation and survival of the fittest. Under the assumption that such a system constitutes a minimal system with characteristics ... More
The commuting graph of a soluble groupSep 11 2012The commuting graph of a finite soluble group with trivial centre is investigated. It is shown that the diameter of such a graph is at most 8 or the graph is disconnected. Examples of soluble groups with trivial centre and commuting graph of diameter ... More
The Development of Gas/Star Offsets in Tidal TailsNov 06 2000We present models of interacting galaxies in order to study the development of spatial offsets between the gaseous and stellar components in tidal tails. Observationally, such offsets are observed to exist over large scales (e.g., NGC 3690; Hibbard et ... More
Gas/Star Offsets in Tidal TailsAug 09 2000We use numerical simulations to study the development of gas/star offsets in the tidal tails of merging galaxies. These offsets are shown to be a natural consequence of the radially extended HI spatial distribution in disk galaxies, coupled with internal ... More
Morphology of Galaxy Mergers at Intermediate RedshiftOct 14 1994Using a combination of numerical simulation and synthesized Hubble Space Telescope Wide Field Camera 2 (HST WFC2) images, we follow the detectability of morphological signatures of disk galaxy mergers at intermediate redshifts z=0.4 and z=1.0. Rapid evolution ... More
Do mergers make (normal) ellipticals?Sep 06 2000Under the merger hypothesis, elliptical galaxies are built through mergers of gas-rich spirals. However, the relative paucity of HI in most normal ellipticals demands significant processing of atomic gas into other forms if this process is to be viable. ... More
Specifying Data Objects with Initial AlgebrasSep 19 2009This study presents a systematic approach to specifying data objects with the help of initial algebras. The primary aim is to describe the set-up to be found in modern functional programming languages such as Haskell and ML, although it can also be applied ... More
Investment Volatility: A Critique of Standard Beta Estimation and a Simple Way ForwardSep 20 2011Beta is a widely used quantity in investment analysis. We review the common interpretations that are applied to beta in finance and show that the standard method of estimation - least squares regression - is inconsistent with these interpretations. We ... More
A quantum Fourier transform algorithmApr 09 2004Jun 17 2004Algorithms to compute the quantum Fourier transform over a cyclic group are fundamental to many quantum algorithms. This paper describes such an algorithm and gives a proof of its correctness, tightening some claimed performance bounds given earlier. ... More
Computational costs of data definition at the quantum - classical interfaceMay 26 2010Model-independent semantic requirements for user specification and interpretation of data before and after quantum computations are characterized. Classical computational costs of assigning classical data values to quantum registers and to run-time parameters ... More
Generalized 1-skeleta and a lifting resultMar 17 2012Jul 01 2013In their paper "1-skeleta, Betti numbers, and equivariant cohomology" Guillemin and Zara described some beautiful constructions enabling them to use Morse theory on a certain class 1-skeleta including 1-skeleta of simple polytopes. In this paper we extend ... More
Dynamical Domain Wall FermionsOct 23 2003We report on an exploratory study of N_f=2 dynamical domain wall fermions and the DBW2 gauge action at weak coupling. Details of improved simulation algorithms and preliminary results for the hadron spectrum and renormalised light and strange quark masses ... More
Non-perturbative Renormalisation with Domain Wall FermionsNov 06 2000Nov 07 2000We present results from a study of the renormalisation of both quark bilinear and four-quark operators for the domain wall fermion action, using the non-perturbative renormalisation technique of the Rome-Southampton group. These results are from a quenched ... More
Light quark masses from Domain Wall FermionsOct 03 2002Oct 09 2002We present results for the renormalised light and strange quark masses calculated using Domain Wall Fermions in quenched QCD. New results using the DBW2 gauge action at inverse lattice spacings of approximately 2 GeV and 1.3 GeV will be presented and ... More
A new look at the isotropy of narrow line emission in extragalactic radio sourcesMar 03 1998We undertake a quantitative investigation, using Monte Carlo simulations, of the amount by which quasars are expected to exceed radio galaxies in optical luminosity in the context of the `receding torus' model. We compare these simulations with the known ... More
The luminosity dependence of the Type 1 AGN fractionMar 23 2005Using a complete, magnitude-limited sample of active galaxies from the Sloan Digital Sky Survey (SDSS) we show that the fraction of broad-line (Type 1) active galactic nuclei increases with luminosity of the isotropically-emitted [O III] narrow emission ... More
Earth's Stopping Effect in Directional Dark Matter DetectorsSep 29 2015We explore the stopping effect that results from interactions between dark matter and nuclei as the dark matter particles travel undergound towards the detector. Although this effect is negligible for heavy dark matter particles, there is parameter phase ... More
Some Notes on Finite SetsSep 09 2015Oct 05 2016These notes aim to give a gentle account to one approach to the theory of finite sets without making use of the natural numbers. They were written to be used as the basis for a student seminar. There are no real prerequisites except for a certain familiarity ... More
Accretion disc viscosity: a limit on the anisotropyApr 20 2015Observations of warped discs can give insight into the nature of angular momentum transport in accretion discs. Only a few objects are known to show strong periodicity on long timescales, but when such periodicity is present it is often attributed to ... More
An Ultradiscrete QRT mapping from Tropical Elliptic CurvesSep 22 2006Recently the area of tropical geometry has introduced the concept of the tropical elliptic group law associated with a tropical elliptic curve. This gives rise to a notion of the tropical QRT mapping. We compute the explicit tropically birational expressions ... More
The light quark coupling of the E(38) boson candidateAug 31 2012Sep 04 2012Assuming that the E(38) boson candidate recently observed at the JINR Nuclotron is produced in a bremsstrahlung-like manner and decays only to two photons, its coupling constant to light quarks is estimated to be $\sim 10^{-4}$.
Cluster Convergence TheoremSep 04 2005A power-counting theorem is presented, that is designed to play an analogous role, in the proof of a BPHZ convergence theorem, in Euclidean position space, to the role played by Weinberg's power-counting theorem, in Zimmermann's proof of the BPHZ convergence ... More
Lower bounds on the two-sided inhomogeneous approximation constantMar 20 2016We give lower bounds on the case of worst inhomogeneous approximation.
On the inhomogeneous spectrum of period two quadraticsMar 20 2016We give a complete description of the inhomogeneous spectrum of period two quadratics down to the first limit point.
Secure message transmission in the presence of a fully generalised adversaryDec 14 2015We investigate the problem of secure message transmission in the presence of a "fully generalised" adversary, who disrupts and listens to separate sets of communication wires. We extend previous results by considering the case when these sets may have ... More
Holonomy and Symmetry in M-theoryMay 05 2003May 07 2003Supersymmetric solutions of 11-dimensional supergravity can be classified according to the holonomy of the supercovariant derivative arising in the Killing spinor condition. It is shown that the holonomy must be contained in $\SL(32,\R)$. The holonomies ... More
Factored Latent Analysis for far-field tracking dataJul 11 2012This paper uses Factored Latent Analysis (FLA) to learn a factorized, segmental representation for observations of tracked objects over time. Factored Latent Analysis is latent class analysis in which the observation space is subdivided and each aspect ... More
Leptonic Decays of Heavy-Light SystemsSep 26 1995Oct 20 1995Results from recent lattice calculations of the decay constants $f_B$ and $f_D$ are reviewed. A discussion of the methods currently used is presented, together with an outline of the various systematic effects involved.
The Early Universe as a Probe of New PhysicsDec 24 2008The Standard Model of Particle Physics has been verified to unprecedented precision in the last few decades. However there are still phenomena in nature which cannot be explained, and as such new theories will be required. Since terrestrial experiments ... More
A Noisy-Influence Regularity Lemma for Boolean FunctionsOct 21 2016We present a regularity lemma for Boolean functions $f:\{-1,1\}^n \to \{-1,1\}$ based on noisy influence, a measure of how locally correlated $f$ is with each input bit. We provide an application of the regularity lemma to weaken the conditions on the ... More
Keeping It Real: Revisiting a Real-Space Approach to Running Ensembles of Cosmological N-body SimulationsJan 10 2012Apr 17 2013In setting up initial conditions for ensembles of cosmological N-body simulations there are, fundamentally, two choices: either maximizing the correspondence of the initial density field to the assumed fourier-space clustering or, instead, matching to ... More
Glueballs, hybrid and exotic mesonsJan 25 2001We review lattice QCD results for glueballs (including a discussion of mixing with scalar mesons), hybrid mesons and exotic mesons (such as $B_s B_s$ molecules).
Adiabatic surfaces from the lattice: excited gluonic potentialsSep 01 1998I describe the results from lattice studies of probing the vacuum with static colour sources. Topics include (i) Twang the flux tube: string models and hybrid mesons. (ii) Charge up the flux tube: adjoint and sextet sources. (iii) Several sources: how ... More
Electric-Magnetic Duality in Massless QED?Sep 08 2009Sep 09 2009The possibility that QED and recently developed non-Hermitian, or magnetic, versions of QED are equivalent is considered. Under this duality the Hamiltonians and anomalous axial currents of the two theories are identified. A consequence of such a duality ... More
Madeup: A Mobile Development Environment for Programming 3-D ModelsSep 27 2013Constructionism is a learning theory that states that we learn more when we construct tangible objects. In the process of building and presenting our work, we make concrete the abstract mental models we've formed, see where they breakdown through the ... More
The Variation of Rotation Curve Shapes as a Signature of the Effects of Baryons on Dark Matter Density ProfilesMay 31 2015Oct 16 2015Rotation curves of galaxies show a wide range of shapes, which can be paramaterized as scatter in Vrot(1kpc)/Vmax i.e.the ratio of the rotation velocity measured at 1kpc and the maximum measured rotation velocity. We examine whether the observed scatter ... More
Some Consequences of the Thermodynamic Cost of System IdentificationFeb 02 2019The concept of a ``system'' is foundational to physics, but the question of how observers identify systems is seldom addressed. Classical thermodynamics restricts observers to finite, finite-resolution observations with which to identify the systems on ... More
Stable TetraquarksApr 13 2018Apr 17 2018For very heavy quarks, relations derived from heavy-quark symmetry imply novel narrow doubly heavy tetraquark states containing two heavy quarks and two light antiquarks. We predict that double-beauty states will be stable against strong decays, whereas ... More
No homotopy 4-sphere invariants using ECH = SWFMay 27 2019In relation to the 4-dimensional smooth Poincar\'e conjecture we construct an invariant of smooth homotopy 4-spheres using embedded contact homology (and Seiberg-Witten theory). But they turn out to vanish, for good reason.