Results for "Michael D. Albrow"

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Early Estimation of Microlensing Event MagnificationsFeb 13 2004Gravitational microlensing events with high peak magnifications provide a much enhanced sensitivity to the detection of planets around the lens star. However, estimates of peak magnification during the early stages of an event by means of chi^2 minimization ... More
Microlensing Observations Rapid Search for Exoplanets: MORSE code for GPUsNov 03 2015The rapid analysis of ongoing gravitational microlensing events has been integral to the successful detection and characterisation of cool planets orbiting low mass stars in the Galaxy. In this paper we present an implementation of search and fit techniques ... More
Precision proton spectrometers for CMSOct 16 2013Oct 30 2013We plan to add high precision tracking- and timing-detectors at z = +/- 240 m to CMS to study exclusive processes p + p -- p + X + p at high luminosity. This enables the LHC to be used as a tagged photon-photon collider, with X = l+l- and W+W-, and as ... More
Double Pomeron Exchange: from the ISR to the LHCOct 04 2010I discuss Double Pomeron Exchange processes from their first observation at the CERN Intersecting Storage Rings, focusing on glueball searches, through the observations of exclusive chi_c, photon-photon, and di-jets at the Tevatron, to prospects at the ... More
Exclusive High Mass Di-leptons in CDFSep 18 2009In the Collider Detector at Fermilab, CDF, we have measured central exclusive production, p+pbar --> p+X+pbar, where X is a pair of leptons or photons and nothing else. In this talk I focus on central masses M(X) > 8 GeV/c2. We measured QED production ... More
Summary of the EDS Blois 2013 WorkshopOct 25 2013I give a personal overview of some highlights of the EDS Blois 2013 Conference on elastic and diffractive scattering in Saariselka, Finland.
Fast timing detectors for forward protons at the LHCApr 07 2011I discuss the development of high precision timing detectors for high momentum protons at the LHC, and their application in studying exclusive Higgs boson production.
Simulating the Role of Stellar Rotation in the Spectroscopic Effects of Differential Limb MagnificationSep 24 2013Finite-source effects of gravitationally microlensed stars have been well discussed in the literature, but the role that stellar rotation plays has been neglected. A differential magnification map applied to a differentially Doppler-shifted surface alters ... More
Stellar rotation and the extended main sequence turnoff in the open cluster NGC 5822Apr 06 2019The origin of extended main sequence turnoffs (eMSTOs) in intermediate-age (1-3 Gyr) clusters is one of the most intriguing questions in current star cluster research. Unlike the split main sequences found in some globular clusters. which are caused by ... More
The Spatially-Resolved Mass Function of the Globular Cluster M22Jul 12 2002HST imaging of M22 has allowed, for the first time, a detailed and uniform mapping of mass segregation in a globular cluster. Luminosity and mass functions from the turnoff down to the mid to lower main sequence are presented for M22 in annular bins from ... More
The White Pomeron, Color Sextet Quarks and Cosmic Ray AnomaliesSep 27 2004I introduce the critical pomeron theory ("white pomeron") proposed by Alan White, with its prediction of excessive WW and ZZ production at the LHC especially by double pomeron exchange (DPE), which is a crucial test. This theory implies dramatic effects ... More
Diffractive Structure Functions at the TevatronFeb 08 2001We have studied events with a high-x_F antiproton and two central jets with E_T>7 GeV in CDF, in p+p_bar collisions at sqrt(s) = 1800 GeV. From the di-jet kinematics we derive the diffractive structure function of the antiproton. We also find an excess ... More
Central exclusive production at the TevatronDec 02 2008In CDF we have observed several exclusive processes: 2-photon --> e+e- and --> mu+mu-, photon+pomeron --> J/psi and psi(2S), and pomeron+pomeron --> chi_c. The cross sections agree with QED, HERA photoproduction data, and theoretical estimates of gg --> ... More
QCD and Hard Diffraction at the LHCSep 26 2005As an introduction to QCD at the LHC I give an overview of QCD at the Tevatron, emphasizing the high Q^2 frontier which will be taken over by the LHC. After describing briefly the LHC detectors I discuss high mass diffraction, in particular central exclusive ... More
Central exclusive production at the TevatronSep 01 2014The Collider Detector at Fermilab, CDF, observed for the first time in hadron-hadron collisions photon-photon to e+e- and mu+mu-, photon-pomeron to J/psi and psi(2S), and pomeron-pomeron to photon+photon and to chi_c. Exclusive pi+pi- production by double ... More
Double Pomeron Physics at the LHCJul 25 2005I discuss central exclusive production, otherwise known as Double Pomeron Exchange, DPE, from the ISR through the Tevatron to the LHC. There I emphasize the interest of exclusive Higgs and WW/ZZ production.
The Frequency of Binary Stars in the Core of 47 TucanaeMay 24 2001Differential time series photometry has been derived for 46422 main-sequence stars in the core of 47 Tucanae. The observations consisted of near-continuous 160-s exposures alternating between the F555W and F814W filters for 8.3 days in 1999 July with ... More
Exclusive Central pi+pi- production in CDFOct 14 2013Using the Collider Detector at Fermilab, CDF, we have measured exclusive pi+pi- production at sqrt(s) = 900 GeV and 1960 GeV. The pi+pi- pair is central, |y| < 1.0, and there are no other particles detected in |eta| < 5.9. We discuss the mass spectrum, ... More
Diffractive Interactions at DIS99: Experimental SummaryMay 28 1999Experimental results on diffraction, which were presented at the 7th International Workshop on Deep Inelastic Scattering and QCD (DIS99), are summarized.
Central Exclusive Particle Production at High Energy Hadron CollidersJun 07 2010We review the subject of central exclusive particle production at high energy hadron colliders. In particular we consider reactions of the type A + B -> A + X + B, where X is a fully specified system of particles that is well separated in rapidity from ... More
1318 New Variable Stars in a 0.25 Square Degree Region of the Galactic PlaneJul 15 2010We have conducted a deep photometric survey of a 0.5 deg x 0.5 deg area of the Galactic Plane using the WFI instrument on the 2.2-m ESO telescope on La Silla, Chile. The dataset comprises a total of 267 R-band images, 204 from a 16 day observation run ... More
Forward Physics with Rapidity Gaps at the LHCNov 02 2008Aug 03 2009A rapidity gap program with great potential can be realized at the Large Hadron Collider, LHC, by adding a few simple forward shower counters (FSCs) along the beam line on both sides of the main central detectors, such as CMS. Measurements of single diffractive ... More
The Korea Microlensing Telescope Network (KMTNet) Alert Algorithm and Alert SystemJun 20 2018We describe a new microlensing-event alert algorithm that is tailored to the Korea Microlensing Telescope Network (KMTNet) multi-observatory system. The algorithm focuses on detecting "rising" events, i.e., events whose brightness is increasing as a function ... More
Kmt-2016-blg-1397b: Kmtnet-only discovery of a microlens giant planetOct 25 2018We report the discovery of a giant planet in the KMT-2016-BLG-1397 microlensing event, which was found by The Korea Microlensing Telescope Network (KMTNet) alone. The time scale of this event is t_E = 40.0 +- 0.5 days and the mass ratio between the lens ... More
KMT-2018-BLG-1990Lb: A Nearby Jovian Planet From A Low-Cadence Microlensing FieldMay 14 2019We report the discovery and characterization of KMT-2018-BLG-1990Lb, a Jovian planet $(m_p=0.57_{-0.25}^{+0.79}\,M_J)$ orbiting a late M dwarf $(M=0.14_{-0.06}^{+0.20}\,M_\odot)$, at a distance $(D_L=1.23_{-0.43}^{+1.06}\,\kpc)$, and projected at $2.6\pm ... More
KMT-2016-BLG-1107: A New Hollywood-Planet Close/Wide DegeneracyMay 22 2018Nov 13 2018We show that microlensing event KMT-2016-BLG-1107 displays a new type of degeneracy between wide-binary and close-binary Hollywood events in which a giant-star source envelops the planetary caustic. The planetary anomaly takes the form of a smooth, two-day ... More
KMT-2016-BLG-1820 and KMT-2016-BLG-2142: Two Microlensing Binaries Composed of Planetary-mass Companions and Very-Low-Mass PrimariesMay 25 2018Sep 18 2018We present the analyses of two short-timescale $(t_{\rm E} \sim 5~{\rm days})$ microlensing events, KMT-2016-BLG-1820 and KMT-2016-BLG-2142. In both light curves, the brief anomalies were clearly captured and densely covered by the Korea Microlensing ... More
Q-switched Dy:ZBLAN fiber lasers beyond 3 μm: comparison of pulse generation using acousto-optic modulation and inkjet-printed black phosphorusFeb 19 2019May 11 2019We report high-energy mid-infrared pulse generation by Q-switching of dysprosium-doped fiber lasers for the first time. Two different modulation techniques are demonstrated. Firstly, using active acousto-optic modulation, pulses are produced with up to ... More
Accelerator Data for Cosmic Ray PhysicsSep 21 2010I present selected examples of accelerator data, mainly from hadron colliders, that are relevant for understanding cosmic ray showers. I focus on the forward region, $x_{Feynman} > 0.05$, where high energy data are scarce, since the emphasis in collider ... More
Q-switched Dy:ZBLAN fiber lasers beyond 3 μm: comparison of pulse generation using acousto-optic modulation and inkjet-printed black phosphorusFeb 19 2019We report high-energy mid-infrared pulse generation by Q-switching of dysprosium-doped fiber lasers for the first time. Two different modulation techniques are demonstrated. Firstly, using active acousto-optic modulation, pulses are produced with up to ... More
Physics at Future Hadron CollidersJan 23 2002We discuss the physics opportunities and detector challenges at future hadron colliders. As guidelines for energies and luminosities we use the proposed luminosity and/or energy upgrade of the LHC (SLHC), and the Fermilab design of a Very Large Hadron ... More
Observation of the Narrow State $X(3872)\to J/ψπ^{+}π^{-}$ in $\bar{p}p$ Collisions at $\sqrt{s}=1.96 \TeV$Dec 05 2003We report the observation of a narrow state decaying into $J/\psi\pi^+\pi^-$ and produced in $220 pb^{-1}$ of $\bar{p} p $ collisions at $\sqrt{s}=1.96 TeV$ in the CDF II experiment. We observe $ 730 \pm 90 $ decays. The mass is measured to be $3871.3 ... More
KMT-2018-BLG-1292: A Super-Jovian Microlens Planet in the Galactic PlaneMay 13 2019We report the discovery of KMT-2018-BLG-1292Lb, a super-Jovian $M_{\rm planet} = 4.5\pm 1.3\,M_J$ planet orbiting an F or G dwarf $M_{\rm host} = 1.5\pm 0.4\,M_\odot$, which lies physically within ${\cal O}(10\,\pc)$ of the Galactic plane. The source ... More
KMT-2016-BLG-2052L: Microlensing Binary Composed of M Dwarfs Revealed from a Very Long Time-scale EventJul 30 2018We present the analysis of a binary microlensing event KMT-2016-BLG-2052, for which the lensing-induced brightening of the source star lasted for 2 seasons. We determine the lens mass from the combined measurements of the microlens parallax $\pie$ and ... More
KMT-2017-BLG-0165Lb: A Super-Neptune mass planet Orbiting a Sun-like Host StarSep 05 2018Dec 27 2018We report the discovery of a low mass-ratio planet $(q = 1.3\times10^{-4})$, i.e., 2.5 times higher than the Neptune/Sun ratio. The planetary system was discovered from the analysis of the KMT-2017-BLG-0165 microlensing event, which has an obvious short-term ... More
Difference Image Analysis: Extension to a Spatially Varying Photometric Scale Factor and Other ConsiderationsOct 10 2012We present a general framework for matching the point-spread function (PSF), photometric scaling, and sky background between two images, a subject which is commonly referred to as difference image analysis (DIA). We introduce the new concept of a spatially ... More
KMT-2018-BLG-0029Lb: A Very Low Mass-Ratio Spitzer Microlens PlanetJun 26 2019At $q=1.81\pm 0.20 \times 10^{-5}$, KMT-2018-BLG-0029Lb has the lowest planet-host mass ratio $q$ of any microlensing planet to date by more than a factor of two. Hence, it is the first planet that probes below the apparent "pile-up" at $q=5$--10 $\times ... More
Searching for the Higgs Boson at Hadron Colliders using the Missing Mass MethodSep 28 2000If the Higgs is produced with a large enough cross section in the {\em exclusive} reaction $p + \bar{p} \to p + H + \bar{p}$ it will give rise to a peak at $M_H$ in the {\em missing mass} ($MM$) spectrum, calculated from the 4-momenta of the beam particles ... More
KELT-22Ab: A Massive Hot Jupiter Transiting a Near Solar TwinMar 20 2018We present the discovery of KELT-22Ab, a hot Jupiter from the KELT-South survey. KELT-22Ab transits the moderately bright ($V\sim 11.1$) Sun-like G2V star TYC 7518-468-1. The planet has an orbital period of $P = 1.3866529 \pm 0.0000027 $ days, a radius ... More
MOA-2016-BLG-319Lb: Microlensing Planet Subject to Rare Minor-Image Perturbation Degeneracy in Determining Planet ParameterSep 21 2018We present the analysis of the planetary microlensing event MOA-2016-BLG-319. The event light curve is characterized by a brief ($\sim 3$ days) anomaly near the peak produced by minor-image perturbations. From modeling, we find two distinct solutions ... More
NASA ExoPAG Study Analysis Group 11: Preparing for the WFIRST Microlensing SurveySep 09 2014NASA's proposed WFIRST-AFTA mission will discover thousands of exoplanets with separations from the habitable zone out to unbound planets, using the technique of gravitational microlensing. The Study Analysis Group 11 of the NASA Exoplanet Program Analysis ... More
Lorentz violation and topological defectsMar 13 2014If Lorentz symmetry is broken, it must have occurred dynamically, via a vector or tensor field whose potential energy forces it to take on a non-zero background expectation value "in vacuum". If the set of minima of this potential (the vacuum manifold) ... More
Embedding Graphs into the Extended GridFeb 28 2007Let $G=(V,E)$ be an arbitrary undirected source graph to be embedded in a target graph $EM$, the extended grid with vertices on integer grid points and edges to nearest and next-nearest neighbours. We present an algorithm showing how to embed $G$ into ... More
Extending the graviton propagator with a Lorentz-violating vector fieldAug 04 2016I discuss progress towards "bootstrapping" a Lorentz-violating gravity theory: namely, extending a linear Lorentz-violating theory of a rank-2 tensor to a non-linear theory by coupling this field to its own stress-energy tensor.
The Infrared Diameter -- Velocity Dispersion Relation for Elliptical GalaxiesJun 28 1995Using single channel infrared photometry from the literature, a provisional K-band diameter--velocity dispersion relation for elliptical galaxies in the Coma and Virgo clusters is derived. The Coma cluster relation has \~1.5 times lower scatter at K than ... More
Constraints and degrees of freedom in Lorentz-violating field theoriesOct 22 2018Nov 05 2018Many current models which "violate Lorentz symmetry" do so via a vector or tensor field which takes on a vacuum expectation value, thereby spontaneously breaking the underlying Lorentz symmetry of the Lagrangian. To obtain a tensor field with this behavior, ... More
A Statistical Approach to Crime LinkageOct 08 2014The object of this paper is to develop a statistical approach to criminal linkage analysis that discovers and groups crime events that share a common offender and prioritizes suspects for further investigation. Bayes factors are used to describe the strength ... More
Stochastic Optics: A Scattering Mitigation Framework for Radio Interferometric ImagingOct 17 2016Just as turbulence in the Earth's atmosphere can severely limit the angular resolution of optical telescopes, turbulence in the ionized interstellar medium fundamentally limits the resolution of radio telescopes. We present a scattering mitigation framework ... More
Hereditary unigraphs and Erdős--Gallai equalitiesFeb 12 2013We give characterizations of the structure and degree sequences of hereditary unigraphs, those graphs for which every induced subgraph is the unique realization of its degree sequence. The class of hereditary unigraphs properly contains the threshold ... More
The place of exceptional covers among all diophantine relationsOct 17 2009A cover of normal varieties is exceptional over a finite field if the map on points over infinitely many extensions of the field is one-one. A cover over a number field is exceptional if it is exceptional over infinitely many residue class fields. The ... More
OGLE-2018-BLG-0532Lb: Cold Neptune With Possible Jovian SiblingMay 15 2019We report the discovery of the planet OGLE-2018-BLG-0532Lb, with very obvious signatures in the light curve that lead to an estimate of the planet-host mass ratio $q=M_{\rm planet}/M_{\rm host}\simeq 1\times10^{-4}$. Although there are no obvious systematic ... More
Bosonic construction of vertex operator para-algebras from symplectic affine Kac-Moody algebrasJun 22 1994Jun 27 1994The representation theory of affine Kac-Moody Lie algebras has grown tremendously since their independent introduction by Robert V. Moody and Victor G. Kac in 1968. Inspired by mathematical structures found by theoretical physicists, and by the desire ... More
Noise control in gene regulatory networks with negative feedbackMar 08 2016Genes and proteins regulate cellular functions through complex circuits of biochemical reactions. Fluctuations in the components of these regulatory networks result in noise that invariably corrupts the signal, possibly compromising function. Here, we ... More
A survey of spinning test particle orbits in Kerr spacetimeFeb 25 2003We investigate the dynamics of the Papapetrou equations in Kerr spacetime. These equations provide a model for the motion of a relativistic spinning test particle orbiting a rotating (Kerr) black hole. We perform a thorough parameter space search for ... More
Lyapunov exponents in constrained and unconstrained ordinary differential equationsMar 20 2003May 05 2003We discuss several numerical methods for calculating Lyapunov exponents (a quantitative measure of chaos) in systems of ordinary differential equations. We pay particular attention to constrained systems, and we introduce a variety of techniques to address ... More
Dynamics of spinning test particles in Kerr spacetimeOct 14 2002Feb 12 2003We investigate the dynamics of relativistic spinning test particles in the spacetime of a rotating black hole using the Papapetrou equations. We use the method of Lyapunov exponents to determine whether the orbits exhibit sensitive dependence on initial ... More
How Uniform is the Uniform Distribution on Permutations?Jan 10 2019For large $q$, does the (discrete) uniform distribution on the set of $q!$ permutations of the vector $(1,2,\dots,q)$ closely approximate the (continuous) uniform distribution on the $(q-2)$-sphere that contains them? These permutations comprise the vertices ... More
The derivative expansion of the exact renormalization groupAug 06 2001We formulate a method of performing non-perturbative calculations in quantum field theory, based upon a derivative expansion of the exact renormalization group. We then proceed to apply this method to the calculation of critical exponents for three dimensional ... More
The LKPY Package for Recommender Systems Experiments: Next-Generation Tools and Lessons Learned from the LensKit ProjectSep 10 2018Since 2010, we have built and maintained LensKit, an open-source toolkit for building, researching, and learning about recommender systems. We have successfully used the software in a wide range of recommender systems experiments, to support education ... More
Probing Dark Energy with Lensing Magnification in Photometric SurveysJan 02 2014I present an estimator for the angular cross-correlation of two tracers of the cosmological large-scale structure that utilizes redshift information to isolate separate physical contributions. The estimator is derived by solving the Limber equation for ... More
Bayesian Linking of Geosynchronous Orbital Debris Tracks as seen by the Large Synoptic Survey TelescopeNov 10 2011We describe a Bayesian sampling model for linking and constraining orbit models from angular observations of "streaks" in optical telescope images. Our algorithm is particularly suited to situations where the observation times are small fractions of the ... More
Discussion of "Calibrated Bayes, for Statistics in General, and Missing Data in Particular" by R. J. A. LittleAug 17 2011Discussion of "Calibrated Bayes, for Statistics in General, and Missing Data in Particular" by R. Little [arXiv:1108.1917]
Etale Homotopy Types and Bisimplicial HypercoversFeb 18 2010Feb 04 2011An \'etale homotopy type $T(X, z)$ associated to any pointed locally fibrant connected simplicial sheaf $(X, z)$ on a pointed locally connected small Grothendieck site $(\mc{C}, x)$ is studied. It is shown that this type $T(X, z)$ specializes to the \'etale ... More
On realization graphs of degree sequencesMar 20 2015Mar 15 2016Given the degree sequence $d$ of a graph, the realization graph of $d$ is the graph having as its vertices the labeled realizations of $d$, with two vertices adjacent if one realization may be obtained from the other via an edge-switching operation. We ... More
On fractional realizations of graph degree sequencesOct 03 2013We introduce fractional realizations of a graph degree sequence and a closely associated convex polytope. Simple graph realizations correspond to a subset of the vertices of this polytope. We describe properties of the polytope vertices and characterize ... More
Variables separated equations: Strikingly different roles for the Branch Cycle Lemma and the Finite Simple Group ClassificationDec 23 2010Aug 11 2011H. Davenport's Problem asks: What can we expect of two polynomials, over the integers, with the same ranges on almost all residue class fields? This stood out among many separated variable problems posed by Davenport, D.J. Lewis and A. Schinzel. By bounding ... More
An Experiment with Hierarchical Bayesian Record LinkageDec 20 2012In record linkage (RL), or exact file matching, the goal is to identify the links between entities with information on two or more files. RL is an important activity in areas including counting the population, enhancing survey frames and data, and conducting ... More
Dynamical Lorentz symmetry breaking and topological defectsAug 10 2010Aug 13 2010I discuss the possibility of topological defect solutions in field theories containing a tensor field which spontaneously breaks Lorentz symmetry. I find that for theories of a tensor with rank r <= 5 and for which the vacuum manifold consists of the ... More
How Uniform is the Uniform Distribution on Permutations?Jan 10 2019Feb 26 2019For large $q$, does the (discrete) uniform distribution on the set of $q!$ permutations of the vector $(1,2,\dots,q)$ closely approximate the (continuous) uniform distribution on the $(q-2)$-sphere that contains them? These permutations comprise the vertices ... More
Singular Hamiltonians in models with spontaneous Lorentz symmetry breakingMar 14 2019Many current models which "violate Lorentz symmetry" do so via a vector or tensor field which takes on a vacuum expectation value, thereby spontaneously breaking the underlying Lorentz symmetry of the Lagrangian. One common way to construct such a model ... More
The Main Conjecture of Modular Towers and its higher rank generalizationNov 20 2006The genus of projective curves discretely separates decidedly different two variable algebraic relations. So, we can focus on the connected moduli M_g of genus g curves. Yet, modern applications require a data variable (function) on such curves. The resulting ... More
A monopole solution in a Lorentz-violating field theoryAug 02 2010I present a topological defect solution that arises in a theory where Lorentz symmetry is spontaneously broken by a rank-two antisymmetric tensor field, and I discuss its observational signatures.
The Coma - Leo I Distance Ratio and the Hubble ConstantMar 05 1997The diameter - velocity dispersion relation in B, V, and K for three early-type galaxies in the Leo I (M96) group is derived from published photometry and kinematic data. The relations in all three colors have slopes which agree well with those for the ... More
Introduction to moduli, l-adic representations and the Regular Version of the Inverse Galois ProblemMar 28 2018Sect 1 introduces Nielsen classes attached to (G,C), where C is r conjugacy classes in a finite group G, and a braid action on them. These give reduced Hurwitz spaces, denoted H(G,C)^rd. The section concludes with a braid formula for the genus of these ... More
How Uniform is the Uniform Distribution on Permutations?Jan 10 2019Mar 05 2019For large $q$, does the (discrete) uniform distribution on the set of $q!$ permutations of the vector $(1,2,\dots,q)$ closely approximate the (continuous) uniform distribution on the $(q-2)$-sphere that contains them? These permutations comprise the vertices ... More
Moduli of relatively nilpotent extensionsOct 22 2009Gives the most precise available description of the p-Frattini module for any p-perfect finite group G=G_0 (Thm. 2.8), and therefore of the groups G_{k,ab}, k \ge 0, from which we form the abelianized M(odular) T(ower). \S 4 includes a classification ... More
Relating two genus 0 problems of John ThompsonOct 20 2009The "relating" entwines three problems: 1. Davenport's Problem, describing pairs of polynomials over Q whose ranges on Z/p are the same for almost all p. 2. Showing that the monodromy groups of rational function maps over the complexes are limited to ... More
Alternating groups and moduli space lifting InvariantsNov 20 2006Nov 07 2009Main Theorem: Spaces of r-branch point 3-cycle covers, degree n or Galois of degree n!/2 have one (resp. two) component(s) if r=n-1 (resp. r\ge n). Improves Fried-Serre on deciding when sphere covers with odd-order branching lift to unramified Spin covers. ... More
Cellular signaling networks function as generalized Wiener-Kolmogorov filters to suppress noiseJun 12 2014Aug 19 2014Cellular signaling involves the transmission of environmental information through cascades of stochastic biochemical reactions, inevitably introducing noise that compromises signal fidelity. Each stage of the cascade often takes the form of a kinase-phosphatase ... More
Stability of spherically symmetric solutions in modified theories of gravityMar 08 2007Aug 08 2007In recent years, a number of alternative theories of gravity have been proposed as possible resolutions of certain cosmological problems or as toy models for possible but heretofore unobserved effects. However, the implications of such theories for the ... More
Generalized bumblebee models and Lorentz-violating electrodynamicsSep 17 2009Feb 05 2010The breaking of Lorentz symmetry via a dynamical mechanism, with a tensor field which takes on a non-zero expectation value in vacuum, has been a subject of significant research activity in recent years. In certain models of this type, the perturbations ... More
Vector models of gravitational Lorentz symmetry breakingMar 12 2009Jun 08 2009Spontaneous Lorentz symmetry breaking can occur when the dynamics of a tensor field cause it to take on a non-zero expectation value in vacuo, thereby providing one or more "preferred directions" in spacetime. Couplings between such fields and spacetime ... More
Designs for a large-aperture telescope to map the CMB 10X fasterNov 14 2015Feb 24 2016Current large-aperture cosmic microwave background (CMB) telescopes have nearly maximized the number of detectors that can be illuminated while maintaining diffraction-limited image quality. The polarization-sensitive detector arrays being deployed in ... More
Using Red Clump Stars to Decompose the Galactic Magnetic Field with DistanceJul 27 2014A new method for measuring the large-scale structure of the Galactic magnetic field is presented. The Galactic magnetic field has been probed through the Galactic disk with near-infrared starlight polarimetry, however the distance to each background star ... More
Weakly threshold graphsAug 03 2016We define a weakly threshold sequence to be a degree sequence $d=(d_1,\dots,d_n)$ of a graph having the property that $\sum_{i \leq k} d_i \geq k(k-1)+\sum_{i > k} \min\{k,d_i\} - 1$ for all positive $k \leq \max\{i:d_i \geq i-1\}$. The weakly threshold ... More
Nonabelian $H^1$ and the Étale van Kampen TheoremFeb 18 2010Generalized \'etale homotopy pro-groups $\pi_1^{\ets}(\mc{C}, x)$ associated to pointed connected small Grothendieck sites $(\mc{C}, x)$ are defined and their relationship to Galois theory and the theory of pointed torsors for discrete groups is explained. ... More
On 2-switches and isomorphism classesOct 22 2011A 2-switch is an edge addition/deletion operation that changes adjacencies in the graph while preserving the degree of each vertex. A well known result states that graphs with the same degree sequence may be changed into each other via sequences of 2-switches. ... More
Weakly threshold graphsAug 03 2016May 21 2018We define a weakly threshold sequence to be a degree sequence $d=(d_1,\dots,d_n)$ of a graph having the property that $\sum_{i \leq k} d_i \geq k(k-1)+\sum_{i > k} \min\{k,d_i\} - 1$ for all positive $k \leq \max\{i:d_i \geq i-1\}$. The weakly threshold ... More
Adjacency relationships forced by a degree sequenceJul 31 2015There are typically several nonisomorphic graphs having a given degree sequence, and for any two degree sequence terms it is often possible to find a realization in which the corresponding vertices are adjacent and one in which they are not. We provide ... More
Lorentz-violating gravity and the bootstrap procedureJul 29 2019In conventional gravitational physics, the so-called "bootstrap procedure" can be used to extrapolate from a linear model of a rank-2 tensor to a full non-linear theory of gravity (i.e., general relativity) via a coupling to the stress-energy of the model. ... More
KMT-2015-1b: a Giant Planet Orbiting a Low-mass Dwarf Host Star Discovered by a New High-cadence Microlensing Survey with a Global Telescope NetworkJul 20 2015We report the discovery of an extrasolar planet, KMT-2015-1b, that was detected using the microlensing technique. The planetary lensing event was observed by KMTNet survey that has commenced in 2015. With dense coverage by using network of globally distributed ... More
Galaxy Disruption as the Origin of Intracluster Light in the Coma ClusterDec 02 1998Although the existence of a faint background of starlight in the core of the Coma cluster has been well established (1,2), its origin is uncertain. This vast sea of stars could have formed outside the galaxies, using gas left over from the time of the ... More
The Ghosts of Galaxies: Tidal Debris in ClustersOct 16 2003Gravitational interactions in rich clusters can strip material from the outer parts of galaxies or even completely disrupt entire systems, giving rise to large scale, low surface brightness ghostly features stretching across intergalactic space. The nearby ... More
Physics at a Fermilab Proton DriverSep 16 2005This report documents the physics case for building a 2 MW, 8 GeV superconducting linac proton driver at Fermilab.
Multilevel quadrature for elliptic parametric partial differential equations in case of polygonal approximations of curved domainsSep 30 2015Dec 31 2018Multilevel quadrature methods for parametric operator equations such as the multilevel (quasi-) Monte Carlo method are closely related to the sparse tensor product approximation between the spatial variable and the parameter. In this article, we employ ... More
H-alpha Equivalent Width Variations across the Face of a Microlensed K Giant in the Galactic BulgeNov 21 2000Mar 25 2001We present VLT FORS1 spectroscopy that temporally resolves the second caustic crossing of the Bulge K giant source of microlensing event EROS 2000-BLG-5, the first time this has been accomplished for several phases of a caustic transit. The ~1 angstrom ... More
A Lack of Planets in 47 Tucanae from an HST SearchSep 25 2000Oct 11 2000We report results from a large Hubble Space Telescope project to observe a significant (~34,000) ensemble of main sequence stars in the globular cluster 47 Tucanae with a goal of defining the frequency of inner-orbit, gas-giant planets. Simulations based ... More
OGLE-2008-BLG-513Lb: The Orbital Solution for a Microlensing PlanetJun 20 2011Jul 11 2011A static binary star solution for OGLE-2008-BLG-513 has been found. The mass ratio and separation for this solution are q~0.28, s~0.86. This model has a chi^2 comparable to the chi^2 of the model with a planetary mass ratio and orbital motion that was ... More
Hadamard Conjugation for the Kimura 3ST Model: Combinatorial Proof using PathsetsMay 28 2005Nov 03 2005In most stochastic models of molecular sequence evolution the probability of each possible pattern of homologous characters at a site is estimated numerically. However in the case of Kimura's three-substitution-types (K3ST) model, these probabilities ... More
Network Models of Photonic Floquet Topological InsulatorsNov 19 2013A recently-proposed class of photonic topological insulators is shown to map onto Chalker-Coddington-type networks, which were originally formulated to study disordered quantum Hall systems. Such network models are equivalent to the Floquet states of ... More