Results for "Jessie Shelton"

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Polarized tops from new physics: signals and observablesNov 04 2008Jan 08 2009Top quarks may be produced in large numbers in association with new physics at the LHC. The polarization of these top quarks probes the chiral structure of the new physics. We discuss several kinematic distributions which are sensitive to the polarization ... More
Closed Superstring Emission from Rolling Tachyon BackgroundsNov 03 2004We compute the lowest components of the Type II Ramond-Ramond boundary state for the tachyon profile $T (X) = \lambda e ^{X ^ 0/\sqrt{2}}$ by direct path integral evaluation. The calculation is made possible by noting that the integrals involved in the ... More
TASI Lectures on Jet SubstructureFeb 01 2013Feb 09 2013Jet physics is a rich and rapidly evolving field, with many applications to physics in and beyond the Standard Model. These notes, based on lectures delivered at the June 2012 Theoretical Advanced Study Institute, provide an introduction to jets at the ... More
Composite Octet Searches with Jet SubstructureJul 18 2011Many new physics models with strongly interacting sectors predict a mass hierarchy between the lightest vector meson and the lightest pseudoscalar mesons. We examine the power of jet substructure tools to extend the 7 TeV LHC sensitivity to these new ... More
A Solar System Test of Self-Interacting Dark MatterNov 01 2018Dark matter (DM) self-interactions affect the gravitational capture of DM in the Sun and Earth differently as a simple consequence of the differing kinematics of collisions within the two potential wells: the dominant effect of self-interactions in the ... More
Probing Supersymmetry With Third-Generation Cascade DecaysNov 26 2008Jan 20 2009The chiral structure of supersymmetric particle couplings involving third generation Standard Model fermions depends on left-right squark and slepton mixings as well as gaugino-higgsino mixings. The shapes and intercorrelations of invariant mass distributions ... 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
Gamma Lines without a Continuum: Thermal Models for the Fermi-LAT 130 GeV Gamma LineAug 20 2012Recent claims of a line in the Fermi-LAT photon spectrum at 130 GeV are suggestive of dark matter annihilation in the galactic center and other dark matter-dominated regions. If the Fermi feature is indeed due to dark matter annihilation, the best-fit ... More
Hunting Asymmetric StopsDec 18 2012Oct 06 2013We point out that in the irreducible natural SUSY spectrum, stops have comparable branching fractions to chargino-bottom and neutralino-top in the vast bulk of parameter space, provided only that both decay modes are kinematically accessible. The total ... More
Long-Lived Staus and Displaced Leptons at the LHCJan 06 2016Apr 14 2016As the majority of LHC searches are focused on prompt signatures, specific long-lived particles have the potential to be overlooked by the otherwise systematic new physics programs at ATLAS and CMS. While in many cases long-lived superparticles are now ... More
A Theory for Maximal Flavor ViolationJan 27 2011Jul 18 2011Theories of flavor violation beyond the Standard Model typically suppose that the new contributions must be small, for example suppressed by Yukawa couplings, as in Minimal Flavor Violation. We show that this need not be true, presenting a case for flavor ... More
Weak annihilation cusp inside the dark matter spike about a black holeJun 03 2016We reinvestigate the effect of annihilations on the distribution of collisionless dark matter (DM) in a spherical density spike around a massive black hole. We first construct a very simple, pedagogic, analytic model for an isotropic phase space distribution ... More
DarkogenesisAug 11 2010In standard models of baryogenesis and of dark matter, the mechanisms which generate the densities in both sectors are unrelated to each other. In this paper we explore models which generate the baryon asymmetry through the dark matter sector, simultaneously ... More
Open windows for a light axigluon explanation of the top forward-backward asymmetryDec 07 2012Feb 09 2013The top forward-backward asymmetry (tAFB) measured at the Tevatron remains one of the most puzzling outstanding collider anomalies. After two years of LHC running, however, few models for tAFB remain consistent with LHC data. In this paper we take a detailed ... More
Measuring the Invisible Higgs Width at the 7 and 8 TeV LHCDec 19 2011Aug 21 2012The LHC is well on track toward the discovery or exclusion of a light Standard Model (SM)-like Higgs boson. Such a Higgs has a very small SM width and can easily have large branching fractions to physics beyond the SM, making Higgs decays an excellent ... More
Warping and Supersymmetry BreakingApr 30 2007Jan 28 2008We analyze supersymmetry breaking by anti-self-dual flux in the deformed conifold. This theory has been argued to be a dual realization of susy breaking by antibranes. As such, one might expect it to lead to a hierarchically small breaking scale, but ... More
Measuring the Polarization of Boosted Hadronic TopsSep 22 2009Jun 23 2010We propose a new technique for measuring the polarization of hadronically decaying boosted top quarks. In particular, we apply a subjet-based technique to events where the decay products of the top are clustered within a single jet. The technique requires ... More
Tadpoles and Closed String Backgrounds in Open String Field TheoryApr 30 2003Jun 04 2003We investigate the quantum structure of Witten's cubic open bosonic string field theory by computing the one-loop contribution to the open string tadpole using both oscillator and conformal field theory methods. We find divergences and a breakdown of ... More
Multi-Lepton Signals of Top-Higgs Associated ProductionAug 04 2013We evaluate the potential to measure ttbar H associated production at the LHC using non-resonant multi-lepton final states in conjunction with two or more b-tags. The multi-lepton ttbar H signal arises predominantly from H to tau tau and H to WW^* alongside ... More
Dark Matter Through the Neutrino PortalAug 13 2009We consider a model of dark matter whose most prominent signature is a monochromatic flux of TeV neutrinos from the galactic center. As an example of a general scenario, we consider a specific model where the dark matter is a fermion in the adjoint representation ... More
Kinematics of Top Quark Final States: A Snowmass White PaperSep 11 2013Oct 08 2013This is the summary report of the Top Quark Kinematics working group prepared for Snowmass 2013. We survey the current state of theoretical predictions for top pair differential distributions, in both boosted and un-boosted regimes, and present an overview ... More
Nongeometric Flux CompactificationsAug 18 2005Jul 03 2006We investigate a simple class of type II string compactifications which incorporate nongeometric "fluxes" in addition to "geometric flux" and the usual H-field and R-R fluxes. These compactifications are nongeometric analogues of the twisted torus. We ... More
Generalized Flux VacuaJul 04 2006Aug 11 2006We consider type II string theory compactified on a symmetric T^6/Z_2 orientifold. We study a general class of discrete deformations of the resulting four-dimensional supergravity theory, including gaugings arising from geometric and "nongeometric'' fluxes, ... More
Direct and indirect detection of dissipative dark matterDec 04 2013Jul 02 2014We study the constraints from direct detection and solar capture on dark matter scenarios with a subdominant dissipative component. This dissipative dark matter component in general has both a symmetric and asymmetric relic abundance. Dissipative dynamics ... More
Chilly Dark Sectors and Asymmetric ReheatingApr 08 2016Jun 01 2016In a broad class of theories, the relic abundance of dark matter is determined by interactions internal to a thermalized dark sector, with no direct involvement of the Standard Model (SM). We point out that these theories raise an immediate cosmological ... More
Fitting the Galactic Center Gamma-Ray Excess with Cascade AnnihilationsMay 01 2014Oct 20 2014The apparent excess of gamma rays in an extended region in the direction of the galactic center has a spatial distribution and amplitude that are suggestive of dark matter annihilations. If this excess is indeed due to dark matter annihilations, it would ... More
Splitting Algebras II: The Cohomology AlgebraAug 10 2012Gelfand, Retakh, Serconek and Wilson, in \cite{GRSW}, defined a graded algebra $A_\Gamma$ attached to any finite ranked poset $\Gamma$ - a generalization of the universal algebra of pseudo-roots of noncommutative polynomials. This algebra has since come ... More
Illuminating Dark Photons with High-Energy CollidersNov 28 2014Feb 27 2015High-energy colliders offer a unique sensitivity to dark photons, the mediators of a broken dark U(1) gauge theory that kinetically mixes with the Standard Model (SM) hypercharge. Dark photons can be detected in the exotic decay of the 125 GeV Higgs boson, ... More
A black hole window into p-wave dark matter annihilationJun 12 2015We present a new method to measure or constrain p-wave-suppressed cross sections for dark matter (DM) annihilations inside the steep density spikes induced by supermassive black holes. We demonstrate that the high DM densities, together with the increased ... More
Galactic Center Gamma-Ray Excess from Dark Matter Annihilation: Is There A Black Hole Spike?Jun 18 2014If the supermassive black hole Sgr A* at the center of the Milky Way grew adiabatically from an initial seed embedded in an NFW dark matter (DM) halo, then the DM profile near the hole has steepened into a spike. We calculate the dramatic enhancement ... More
Tests of Neutrino and Dark Radiation Models from Galaxy and CMB surveysDec 21 2016Feb 02 2017We analyze the ability of galaxy and CMB lensing surveys to constrain massive neutrinos and new models of dark radiation. We present a Fisher forecast analysis for neutrino mass constraints with the LSST galaxy survey and the CMB S4 survey. A joint analysis ... More
A Polarized View of the Top AsymmetryMay 18 2011Nov 11 2011Recent experimental results from the CDF collaboration which study the top forward-backward asymmetry have strengthened the case that new physics is playing a role in t-tbar production. Here we propose a set of measurements, built from the charged lepton ... More
Gamma Ray Spectra from Dark Matter Annihilation and DecayAug 17 2009In this paper, we study gamma ray spectra for various scenarios of dark matter annihilation and decay. We focus on processes which generate only high-energy photons or leptons and photons, but no proton-antiproton pairs, to be compatible with PAMELA's ... More
PBW-deformation theory and regular central extensionsMar 15 2006Mar 27 2006A deformation $U$, of a graded $K$-algebra $A$ is said to be of PBW type if $grU$ is $A$. It has been shown for Koszul and $N$-Koszul algebras that the deformation is PBW if and only if the relations of $U$ satisfy a Jacobi type condition. In particular, ... More
Simulations of Supernova Remnants in Diffuse Media III. The Population of Buoyant Remnants Above the Milky Way's DiskNov 08 2005We model SNRs at a variety of heights above the disk. Our detailed numerical simulations include non-equilibrium ionization and recombination and follow the remnants' evolution until their hot bubbles have cooled. We analytically calculate the bubbles' ... More
Simulations of Supernova Remnants in Diffuse Media. II. Three Remnants and Their X-Ray EmissionApr 28 1999Apr 30 1999This paper describes the X-ray emission from supernova remnants evolving in warm, low density, nonthermal pressure dominated regions. Non-equilibrium ionization hydrocode simulations are used to predict the high resolution spectra, ROSAT PSPC countrates, ... More
Report from Sessions 1 and 3, including the Local Bubble DebateApr 15 2008This report summarizes the discussions in the Session 1 and Session 3 groups which met to discuss the questions: ``What Physical Processes Drive the Multiphase Interstellar Medium in the Local Bubble?'', and ``What are the Energy and Pressure Balances ... More
Generalizing the notion of Koszul algebraApr 27 2007We introduce a generalization of the notion of a Koszul algebra, which includes graded algebras with relations in different degrees, and we establish some of the basic properties of these algebras. This class is closed under twists, twisted tensor products, ... More
Revising the Local Bubble Model due to Solar Wind Charge Exchange X-ray EmissionApr 15 2008The hot Local Bubble surrounding the solar neighborhood has been primarily studied through observations of its soft X-ray emission. The measurements were obtained by attributing all of the observed local soft X-rays to the bubble. However, mounting evidence ... More
Surprisingly Little O VI Emission Arises in the Local BubbleFeb 25 2003Mar 27 2003This paper reports the first study of the O VI resonance line emission (1032, 1038 Angstroms) originating in the Local Bubble (or Local Hot Bubble) surrounding the solar neighborhood. In spite of the fact that O VI absorption within the Local Bubble has ... More
The RR Lyrae Period-Amplitude Relation as a Clue to the Origin of the Oosterhoff DichotomyFeb 19 1999An examination of the period-V amplitude relation for RRab stars (fundamental mode pulsators) with `normal' light curves in the Oosterhoff type I clusters M3 and M107 and in the Oosterhoff type II clusters M9 and M68 reveals that the V amplitude for a ... More
Unburied HiggsJun 08 2010Many models of physics beyond the Standard Model yield exotic Higgs decays. Some of these, particularly those in which the Higgs decays to light quarks or gluons, can be very difficult to discover experimentally. Here we introduce a new set of jet substructure ... More
Searching for Inflation in Simple String Theory Models: An Astrophysical PerspectiveSep 03 2007Nov 13 2007Attempts to connect string theory with astrophysical observation are hampered by a jargon barrier, where an intimidating profusion of orientifolds, Kahler potentials, etc. dissuades cosmologists from attempting to work out the astrophysical observables ... More
$A^t_{FB}$ Meets LHCMar 23 2011Apr 12 2011The recent Tevatron measurement of the forward-backward asymmetry of the top quark shows an intriguing discrepancy with Standard Model expectations, particularly at large $\ttbar$ invariant masses. Measurements of this quantity are subtle at the LHC, ... More
Data-driven Model-independent Searches for Long-lived Particles at the LHCMay 09 2016Neutral long-lived particles (LLPs) are highly motivated by many BSM scenarios, such as theories of supersymmetry, baryogenesis, and neutral naturalness, and present both tremendous discovery opportunities and experimental challenges for the LHC. A major ... More
SO(5)-Symmetric Description of the Low Energy Sector of a Ladder SystemOct 23 1997Apr 03 1998We study a system of two Tomonaga-Luttinger models coupled by a small transverse hopping (a two-chain ladder). We use Abelian and non-Abelian bosonisation to show that the strong coupling regime at low energies can be described by an SO(5)$_1$ WZW model ... More
Intrusion Detection using Continuous Time Bayesian NetworksJan 16 2014Intrusion detection systems (IDSs) fall into two high-level categories: network-based systems (NIDS) that monitor network behaviors, and host-based systems (HIDS) that monitor system calls. In this work, we present a general technique for both systems. ... More
Visualization of Collaborative DataJun 27 2012Collaborative data consist of ratings relating two distinct sets of objects: users and items. Much of the work with such data focuses on filtering: predicting unknown ratings for pairs of users and items. In this paper we focus on the problem of visualizing ... More
Collisions between Dark Matter Confined High Velocity Clouds and Magnetized Galactic Disks: The Smith CloudNov 18 2015The Galaxy's population of High Velocity Clouds (HVCs) may include a subpopulation that is confined by dark matter minihalos and falling toward the Galactic disk. We present the first magnetohydrodynamic simulational study of dark matter-dominated HVCs ... More
On Removing Interloper Contamination from Intensity Mapping Power Spectrum MeasurementsApr 19 2016Line intensity mapping experiments seek to trace large scale structure by measuring the spatial fluctuations in the combined emission, in some convenient spectral line, from individually unresolved galaxies. An important systematic concern for these surveys ... More
Discrete Cosmological Models in the Brans-Dicke Theory of GravityMar 07 2019We consider the problem of building inhomogeneous cosmological models in scalar-tensor theories of gravity. This starts by splitting the field equations of these theories into constraint and evolution equations, and then proceeds by identifying exact ... More
Tropical Severi VarietiesAug 30 2011May 13 2013We study the tropicalizations of Severi varieties, which we call tropical Severi varieties. In this paper, we give a partial answer to the following question, ``describe the tropical Severi varieties explicitly.'' We obtain a description of tropical Severi ... More
Of puzzles and partitions: Introducing PartitiOct 05 2017We introduce Partiti, the puzzle that will run in Mathematics Magazine in 2018, and use the opportunity to recall some basic properties of integer partitions.
Identification of Signal, Noise, and Indistinguishable Subsets in High-Dimensional Data AnalysisMay 01 2013Motivated by applications in high-dimensional data analysis where strong signals often stand out easily and weak ones may be indistinguishable from the noise, we develop a statistical framework to provide a novel categorization of the data into the signal, ... More
Numerical Study of Turbulent Mixing Layers with Non-Equilibrium Ionization CalculationsJun 18 2010Highly ionized species such as C IV, N V, and O VI, are commonly observed in diffuse gas in various places in the universe, such as in our Galaxy's disk and halo, high velocity clouds (HVCs), external galaxies, and the intergalactic medium. One possible ... More
Superconducting Instability in a 1D lattice of Berry Phase MoleculesFeb 06 1995We study the 1D model of conduction electrons interacting with local vibronic modes. States in the conduction band are two-fold degenerate both in orbital index and spin. It is shown that such 1D system has a strong tendency to superconductivity. The ... More
Secondary fans and Tropical Severi varietiesJul 10 2013Apr 05 2015This article studies the relationship between tropical Severi varieties and secondary fans. In the case when tropical Severi varieties are hypersurfaces this relationship is very well known; specifically, in this case, a tropical Severi variety of codimension ... More
What do observations of the Lyman-alpha fraction tell us about reionization?Aug 28 2013Dec 04 2013An appealing approach for studying the reionization history of the Universe is to measure the redshift evolution of the Lyman-alpha fraction, the percentage of Lyman-break selected galaxies that emit appreciably in the Ly-alpha line. This fraction is ... More
Publish or Patent: Bibliometric evidence for empirical trade-offs in national funding strategiesFeb 15 2011Multivariate linear regression models suggest a trade-off in allocations of national R&D investments. Government funding, and spending in the higher education sector, seem to encourage publications, whereas other components such as industrial funding, ... More
Expectation Maximization and Complex Duration Distributions for Continuous Time Bayesian NetworksJul 04 2012Continuous time Bayesian networks (CTBNs) describe structured stochastic processes with finitely many states that evolve over continuous time. A CTBN is a directed (possibly cyclic) dependency graph over a set of variables, each of which represents a ... More
Comparing Suzaku and XMM-Newton Observations of the Soft X-ray Background: Evidence for Solar Wind Charge Exchange EmissionDec 20 2007We present an analysis of a pair of Suzaku spectra of the soft X-ray background (SXRB), obtained from pointings on and off a nearby shadowing filament in the southern Galactic hemisphere. Because of the different Galactic column densities in the two pointing ... More
An XMM-Newton Survey of the Soft X-ray Background. I. The O VII and O VIII Lines Between l=120 and l=240Feb 24 2010We present measurements of the soft X-ray background (SXRB) O VII and O VIII intensity between $l = 120\degr$ and $l = 240\degr$, the first results of a survey of the SXRB using archival XMM-Newton observations. We do not restrict ourselves to blank-sky ... More
Is the Milky Way's Hot Halo Convectively Unstable?Jan 30 2014We investigate the convective stability of two popular types of model of the gas distribution in the hot Galactic halo. We first consider models in which the halo density and temperature decrease exponentially with height above the disk. These halo models ... More
An XMM-Newton Survey of the Soft X-ray Background. II. An All-Sky Catalog of Diffuse O VII and O VIII Emission IntensitiesAug 21 2012Sep 05 2012We present an all-sky catalog of diffuse O VII and O VIII line intensities, extracted from archival XMM observations. The O VII and O VIII intensities are typically ~2-11 and <~3 ph/cm^2/s/sr (LU), respectively, although much brighter intensities were ... More
Superconductivity in a spin liquid - a one dimensional exampleSep 12 1995We study a one-dimensional model of interacting conduction electrons with a two-fold degenerate band away from half filling. The interaction includes an on-site Coulomb repulsion and Hund's rule coupling. We show that such one-dimensional system has a ... More
Simple and open 4f Koehler transmitted illumination system for low-cost microscopic imaging and teachingJan 06 2019Koehler transillumination is a powerful imaging method, yet commercial Koehler condensers are difficult to integrate into tabletop systems and make learning the concepts of Koehler illumination difficult. We propose a simple 4f Koehler illumination system ... More
Continuous Time Bayesian NetworksDec 12 2012In this paper we present a language for finite state continuous time Bayesian networks (CTBNs), which describe structured stochastic processes that evolve over continuous time. The state of the system is decomposed into a set of local variables whose ... More
The Trouble with the Local BubbleJun 16 2009The model of a Local Hot Bubble has been widely accepted as providing a framework that can explain the ubiquitous presence of the soft X-ray background diffuse emission. We summarize the current knowledge on this local interstellar region, paying particular ... More
A Possible Supernova Remnant high above the Galactic DiskJun 26 2009We present the analysis of three Suzaku observations of a bright arc in the ROSAT All-Sky Survey 1/4 keV maps at $l \approx 247\degr$, $b \approx -64\degr$. In particular, we have tested the hypothesis that the arc is the edge of a bubble blown by an ... More
Half-metallic ferromagnetism in Sr$_3$Ru$_2$O$_7$Feb 21 2017The bilayered member of the Ruddesden-Popper family of ruthenates, Sr$_3$Ru$_2$O$_7$, has received an increasing attention due to its interesting properties and phases. By using first principle calculations we find that the ground-state is characterized ... More
Uniaxial pressure induced half-metallic ferromagnetic phase transition in LaMnO$_3$Feb 25 2016We use first-principles theory to predict that the application of uniaxial compressive strain leads to a transition from an antiferromagnetic insulator to a ferromagnetic half-metal phase in LaMnO$_3$. We identify the Q2 Jahn-Teller mode as the primary ... More
Variable Selection via Adaptive False Negative Control in High-Dimensional RegressionApr 20 2018In high-dimensional regression, variable selection methods have been developed to provide sparse solutions. However, how to further interpret the sparse solutions in terms of false positive and false negative control remains largely an open question. ... More
Efficient Predictor Ranking and False Discovery Proportion Control in High-Dimensional RegressionApr 09 2018Dec 11 2018We propose a ranking and selection procedure to prioritize relevant predictors and control false discovery proportion (FDP) of variable selection. Our procedure utilizes a new ranking method built upon the de-sparsified Lasso estimator. We show that the ... More
Newton-Okounkov bodies of Bott-Samelson varieties and Grossberg-Karshon twisted cubesApr 04 2015Apr 18 2015We describe, under certain conditions, the Newton-Okounkov body of a Bott-Samelson variety as a lattice polytope defined by an explicit list of inequalities. The valuation that we use to define the Newton-Okounkov body is different from that used previously ... More
Singular string polytopes and functorial resolutions from Newton-Okounkov bodiesDec 28 2017The main result of this note is that the toric degenerations of flag varieties associated to string polytopes and certain Bott-Samelson resolutions of flag varieties fit into a commutative diagram which gives a resolution of singularities of singular ... More
Tropical geometry and Newton-Okounkov cones for Grassmannian of planes from compactificationsJun 18 2018Jan 13 2019We construct a family of compactifications of the affine cone of the Grassmannian variety of 2-planes. We show that both the tropical variety of the Pl\"ucker ideal and familiar valuations associated to the construction of Newton-Okounkov bodies for the ... More
Grossberg-Karshon twisted cubes and basepoint-free divisorsJul 15 2014Jul 17 2014Let $G$ be a complex semisimple simply connected linear algebraic group. The main result of this note is to give several equivalent criteria for the untwistedness of the twisted cubes introduced by Grossberg and Karshon. In certain cases arising from ... More
Noncommutative Koszul Algebras from Combinatorial TopologyNov 21 2008Associated to any uniform finite layered graph Gamma there is a noncommutative graded quadratic algebra A(Gamma) given by a construction due to Gelfand, Retakh, Serconek and Wilson. It is natural to ask when these algebras are Koszul. Unfortunately, a ... More
Suzaku Observations of the Soft X-ray BackgroundMar 08 2007We have analyzed a pair of Suzaku XIS1 spectra of the soft X-ray background, obtained by observing towards and to the side of a nearby (d = 230 pc) absorbing filament in the southern Galactic hemisphere. We fit multicomponent spectral models to the spectra ... More
The Yoneda algebra of a K_2 algebra need not be another K_2 algebraOct 26 2008Nov 11 2008The Yoneda algebra of a Koszul algebra or a D-Koszul algebra is Koszul. K_2 algebras are a natural generalization of Koszul algebras, and one would hope that the Yoneda algebra of a K_2 algebra would be another K_2 algebra. We show that this is not necessarily ... More
An XMM-Newton Survey of the Soft X-ray Background. III. The Galactic Halo X-ray EmissionJun 10 2013We present measurements of the Galactic halo's X-ray emission for 110 XMM-Newton sight lines, selected to minimize contamination from solar wind charge exchange emission. We detect emission from few million degree gas on ~4/5 of our sight lines. The temperature ... More
An Effective Theory for Midgap States in Doped Spin Ladder and Spin-Peierls Systems: Liouville Quantum MechanicsApr 14 1997In gapped spin ladder and spin-Peierls systems the introduction of disorder, for example by doping, leads to the appearance of low energy midgap states. The fact that these strongly correlated systems can be mapped onto one dimensional noninteracting ... More
Learning Continuous Time Bayesian NetworksOct 19 2012Continuous time Bayesian networks (CTBNs) describe structured stochastic processes with finitely many states that evolve over continuous time. A CTBN is a directed (possibly cyclic) dependency graph over a set of variables, each of which represents a ... More
Expectation Propagation for Continuous Time Bayesian NetworksJul 04 2012Continuous time Bayesian networks (CTBNs) describe structured stochastic processes with finitely many states that evolve over continuous time. A CTBN is a directed (possibly cyclic) dependency graph over a set of variables, each of which represents a ... More
Exotic Decays of the 125 GeV Higgs BosonDec 17 2013Sep 02 2015We perform an extensive survey of non-standard Higgs decays that are consistent with the 125 GeV Higgs-like resonance. Our aim is to motivate a large set of new experimental analyses on the existing and forthcoming data from the Large Hadron Collider ... More
Exotic Decays of the 125 GeV Higgs BosonDec 17 2013Oct 09 2017We perform an extensive survey of non-standard Higgs decays that are consistent with the 125 GeV Higgs-like resonance. Our aim is to motivate a large set of new experimental analyses on the existing and forthcoming data from the Large Hadron Collider ... More
Stochastic Coherence in an Oscillatory Gene Circuit ModelAug 03 2009We show that noise-induced oscillations in a gene circuit model display stochastic coherence, that is, a maximum in the regularity of the oscillations as a function of noise amplitude. The effect is manifest as a system-size effect in a purely stochastic ... More
The orientation dependence of quasar spectral energy distributionsSep 01 2013We investigate the orientation dependence of the spectral energy distributions in a sample of radio-loud quasars. Selected specifically to study orientation issues, the sample contains 52 sources with redshifts in the range 0.16<z<1.4 and measurements ... More
Convergence of Magnus integral addition theorems for confluent hypergeometric functionsJan 11 2016In 1946, Magnus presented an addition theorem for the confluent hypergeometric function of the second kind $U$ with argument $x+y$ expressed as an integral of a product of two $U$'s, one with argument $x$ and another with argument $y$. We take advantage ... More
Cosmological Solutions with Charged Black HolesMay 04 2017Jun 30 2017We consider the problem of constructing cosmological solutions of the Einstein-Maxwell equations that contain multiple charged black holes. By considering the field equations as a set of constraint and evolution equations, we construct exact initial data ... More
Some Two-Step Procedures for Variable Selection in High-Dimensional Linear RegressionOct 09 2008We study the problem of high-dimensional variable selection via some two-step procedures. First we show that given some good initial estimator which is $\ell_{\infty}$-consistent but not necessarily variable selection consistent, we can apply the nonnegative ... More
Maximum Number of Minimum Dominating and Minimum Total Dominating SetsAug 14 2013Given a connected graph with domination (or total domination) number \gamma>=2, we ask for the maximum number m_\gamma and m_{\gamma,T} of dominating and total dominating sets of size \gamma. An exact answer is provided for \gamma=2and lower bounds are ... More
Orientation and quasar black hole mass estimationSep 22 2015Oct 08 2015We have constructed a sample of 386 radio-loud quasars with z < 0.75 from the Sloan Digital Sky Survey in order to investigate orientation effects on black hole mass estimates. Orientation is estimated using radio core dominance measurements based on ... More
A Study of the Vertical Motion of Supernova Remnant Bubbles in the Interstellar Medium Drawn from the Results of Three-Dimensional MHD SimulationsJul 20 2007In order to determine the circumstances under which isolated SNRs are capable of rising into and enriching the thick disk and galactic halo, simulations of supernova remnants are performed with the FLASH magnetohydrodynamic code. We performed simulations ... More
The X-ray Structure and Spectrum of the Pulsar Wind Nebula Surrounding PSR B1853+01 in W44Jul 03 2002We present the result of a Chandra ACIS observation of the pulsar PSR B1853+01 and its associated pulsar wind nebula (PWN), embedded within the supernova remnant W44. A hard band ACIS map cleanly distinguishes the PWN from the thermal emission of W44. ... More
Hot Gas in the Galactic Thick Disk and Halo Near the Draco CloudAug 17 2010This paper examines the ultraviolet and X-ray photons generated by hot gas in the Galactic thick disk or halo in the Draco region of the northern hemisphere. Our analysis uses the intensities from four ions, C IV, O VI, O VII, and O VIII, sampling temperatures ... More
The Origin of the X-ray Emission from the High-velocity Cloud MS30.7-81.4-118Jun 24 2014A soft X-ray enhancement has recently been reported toward the high-velocity cloud MS30.7-81.4-118 (MS30.7), a constituent of the Magellanic Stream. In order to investigate the origin of this enhancement, we have analyzed two overlapping XMM-Newton observations ... More
The Effect of Mixing on the Observed Metallicity of the Smith CloudFeb 02 2017Measurements of high-velocity clouds' metallicities provide important clues about their origins, and hence on whether they play a role in fueling ongoing star formation in the Galaxy. However, accurate interpretation of these measurements requires compensating ... More
Antiferromagnetic spin ladders: crossover between spin S = 1/2 and S = 1 chainsAug 14 1995Aug 15 1995We study a model of two weakly coupled isotropic spin-1/2 Heisenberg chains with an antiferromagnetic coupling along the chains. It is shown that the system always has a spectral gap. For the case of identical chains the model in the continuous limit ... More
Factored Filtering of Continuous-Time SystemsFeb 14 2012We consider filtering for a continuous-time, or asynchronous, stochastic system where the full distribution over states is too large to be stored or calculated. We assume that the rate matrix of the system can be compactly represented and that the belief ... More