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Results for "Benjamin V. Rackham"

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The Transit Light Source Effect II: The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like StarsDec 14 2018Transmission spectra probe exoplanetary atmospheres, but they can also be strongly affected by heterogeneities in host star photospheres through the transit light source effect. Here we build upon our recent study of the effects of unocculted spots and ... More
Retrieval of planetary and stellar properties in transmission spectroscopy with AuraAug 29 2018Transmission spectroscopy provides a powerful probe of the atmospheric properties of transiting exoplanets. To date, studies of exoplanets in transit have focused on inferring their atmospheric properties such as chemical compositions, cloud/haze properties, ... More
The Near-Infrared Transmission Spectra of TRAPPIST-1 Planets b, c, d, e, f, and g and Stellar Contamination in Multi-Epoch Transit SpectraFeb 06 2018Aug 31 2018The seven approximately Earth-sized transiting planets in the \object{TRAPPIST-1} system provide a unique opportunity to explore habitable zone and non-habitable zone small planets within the same system. Its habitable zone exoplanets -- due to their ... More
ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar PhotosphereDec 01 2016GJ 1214b is the most studied sub-Neptune exoplanet to date. Recent measurements have shown its near-infrared transmission spectrum to be flat, pointing to a high-altitude opacity source in the exoplanet's atmosphere, either equilibrium condensate clouds ... More
ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4bDec 18 2018We present an optical transmission spectrum of the atmosphere of WASP-4b obtained through observations of four transits with Magellan/IMACS. Using a Bayesian approach to atmospheric retrieval, we find no evidence for scattering or absorption features ... More
ACCESS: A featureless optical transmission spectrum for WASP-19b from Magellan/IMACSJul 27 2018Oct 02 2018The short period ($0.94$-day) transiting exoplanet WASP-19b is an exceptional target for transmission spectroscopy studies, due to its relatively large atmospheric scale-height ($\sim 500$ km) and equilibrium temperature ($\sim 2100$ K). Here we report ... More
Understanding Stellar Contamination in Exoplanet Transmission Spectra as an Essential Step in Small Planet CharacterizationMar 23 2018Transmission spectroscopy during planetary transits is expected to be a major source of information on the atmospheres of small (approximately Earth-sized) exoplanets in the next two decades. This technique, however, is intrinsically affected by stellar ... More
Constraining Stellar Photospheres as an Essential Step for Transmission Spectroscopy of Small ExoplanetsMar 14 2019Transmission spectra probe the atmospheres of transiting exoplanets, but these observations are also subject to signals introduced by magnetic active regions on host stars. Here we outline scientific opportunities in the next decade for providing useful ... More
A Statistical Comparative Planetology Approach to Maximize the Scientific Return of Future Exoplanet Characterization EffortsMar 12 2019Provided that sufficient resources are deployed, we can look forward to an extraordinary future in which we will characterize potentially habitable planets. Until now, we have had to base interpretations of observations on habitability hypotheses that ... More
On Permutiples Having a Fixed Set of DigitsNov 06 2015A permutiple is the product of a digit preserving multiplication, that is, a number which is an integer multiple of some permutation of its digits. Certain permutiple problems, particularly transposable, cyclic, and, more recently, palintiple numbers, ... More
Digit Preserving Multiplication in Continued Fraction RepresentationsFeb 15 2017A permutiple is a number which is an integer multiple of some permutation of its digits. A well-known example is 9801 since it is an integer multiple of its reversal, 1089. In this paper, we consider the permutiple problem in an entirely different setting: ... More
Some Thoughts on Determining Symmetric PalintiplesOct 09 2014Mar 28 2015A palintiple is a natural number which is an integer multiple of its digit reversal. A previous paper partitions all palintiples into three distinct classes according to patterns in the carries and then determines all palintiples belonging to the shifted-symmetric ... More
Derived Palintiple Families and Their PalinomialsNov 30 2014Mar 28 2015We consider several families of palintiples (also known as reverse multiples) whose carries themselves are digits of lower-base palintiples and give some methods for constructing them from fundamental palintiple types. We also continue the study of palinomials ... More
Erdos-Szekeres tableauxJul 02 2014We explore a question related to the celebrated Erd\H{o}s-Szekeres Theorem and develop a geometric approach to answer it. Our main object of study is the Erd\H{o}s-Szekeres tableau, or EST, of a number sequence. An EST is the sequence of integral points ... More
Back to "Normal" for the Disintegrating Planet Candidate KIC 12557548 bOct 23 2018Nov 11 2018KIC 12557548 b is first of a growing class of intriguing disintegrating planet candidates, which lose mass in the form of a metal rich vapor that condenses into dust particles. Here, we follow up two perplexing observations of the system: 1) the transits ... More
Helium in the eroding atmosphere of an exoplanetMay 03 2018Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres ... More
The Near-Infrared Transmission Spectra of TRAPPIST-1 Planets b, c, d, e, f, and g and Stellar Contamination in Multi-Epoch Transit SpectraFeb 06 2018The seven approximately Earth-sized transiting planets in the TRAPPIST-1 system provide a unique opportunity to explore habitable zone and non-habitable zone small planets within the same system. Its habitable zone exoplanets -- due to their favorable ... More
Pro-aperiodic monoids via saturated modelsSep 25 2016Aug 28 2017We apply Stone duality and model theory to study the structure theory of free pro-aperiodic monoids. Stone duality implies that elements of the free pro-aperiodic monoid may be viewed as elementary equivalence classes of pseudofinite words. Model theory ... More
Alfven Wave Reflection and Turbulent Heating in the Solar Wind from 1 Solar Radius to 1 AU: an Analytical TreatmentNov 05 2009We study the propagation, reflection, and turbulent dissipation of Alfven waves in coronal holes and the solar wind. We start with the Heinemann-Olbert equations, which describe non-compressive magnetohydrodynamic fluctuations in an inhomogeneous medium ... More
Epidemiological consequences of an ineffective Bordetella pertussis vaccineFeb 28 2014The recent increase in Bordetella pertussis incidence (whooping cough) presents a challenge to global health. Recent studies have called into question the effectiveness of acellular B. pertussis vaccination in reducing transmission. Here we examine the ... More
On the rational subset problem for groupsFeb 21 2006We use language theory to study the rational subset problem for groups and monoids. We show that the decidability of this problem is preserved under graph of groups constructions with finite edge groups. In particular, it passes through free products ... More
Merge decompositions, two-sided Krohn-Rhodes, and aperiodic pointlikesAug 27 2017This paper provides short proofs of two fundamental theorems of finite semigroup theory whose previous proofs were significantly longer, namely the two-sided Krohn-Rhodes decomposition theorem and Henckell's aperiodic pointlike theorem, using a new algebraic ... More
Torus Principal Component Analysis with an Application to RNA StructuresNov 16 2015There are several cutting edge applications needing PCA methods for data on tori and we propose a novel torus-PCA method with important properties that can be generally applied. There are two existing general methods: tangent space PCA and geodesic PCA. ... More
Connecting direct and indirect detection with a dark spike in the cosmic-ray electron spectrumMar 17 2019Multiple space-borne cosmic ray detectors have detected line-like features in the electron and positron spectra. Most recently, the DAMPE collaboration reported the existence of such a feature at 1.4 TeV, sparking interest in a potential dark matter origin. ... More
Dynamic polarizabilities and magic wavelengths for dysprosiumNov 22 2010We theoretically study dynamic scalar polarizabilities of the ground and select long-lived excited states of dysprosium, a highly magnetic atom recently laser cooled and trapped. We demonstrate that there are a set of magic wavelengths of the unpoarized ... More
Nonparametric Covariate Adjustment for Receiver Operating Characteristic CurvesMay 04 2009The accuracy of a diagnostic test is typically characterised using the receiver operating characteristic (ROC) curve. Summarising indexes such as the area under the ROC curve (AUC) are used to compare different tests as well as to measure the difference ... More
Resolving the Solar Neutrino Problem with KamLANDNov 20 2000Feb 26 2001We study how well KamLAND, the first terrestrial neutrino experiment capable of addressing the solar neutrino problem, will perform in ascertaining whether or not the large mixing angle MSW solution (with $10^{-5}<\Delta m_{21}^2< 10^{-4} eV^2$ and oscillation ... More
Numerical hydrodynamic simulations based on semi-analytic galaxy merger trees: method and Milky-Way like galaxiesOct 19 2012We present a new approach to study galaxy evolution in a cosmological context. We combine cosmological merger trees and semi-analytic models of galaxy formation to provide the initial conditions for multi-merger hydrodynamic simulations. In this way we ... More
Gaussianisation for fast and accurate inference from cosmological dataSep 30 2015Jun 13 2016We present a method to transform multivariate unimodal non-Gaussian posterior probability densities into approximately Gaussian ones via non-linear mappings, such as Box--Cox transformations and generalisations thereof. This permits an analytical reconstruction ... More
Heating of Milky Way disc Stars by Dark Matter Fluctuations in Cold Dark Matter and Fuzzy Dark Matter ParadigmsSep 13 2018Feb 21 2019Although highly successful on cosmological scales, Cold Dark Matter (CDM) models predict unobserved over-dense `cusps' in dwarf galaxies and overestimate their formation rate. We consider an ultra-light axion-like scalar boson which promises to reduce ... More
The Origins Space Telescope: Towards An Understanding of Temperate Planetary AtmospheresMar 21 2018The Origins Space Telescope (OST) is one of four mission concepts currently being studied by NASA in preparation for the Astrophysics 2020 Decadal Survey. With active cooling (~4 K), OST will be sensitive in mid- to far-IR wavelengths, using imaging and ... More
Transits of Inclined Exomoons - Hide and Seek and an Application to Kepler-1625Jan 18 2019A Neptune-sized exomoon candidate was recently announced by Teachey & Kipping (2018), orbiting a 287-day gas giant in the Kepler-1625 system. However, the system is poorly characterized and needs more observations to be confirmed, with the next potential ... More
Signatures of Chaos in Time Series Generated by Many-Spin Systems at High TemperaturesMay 23 2011Sep 18 2014Extracting reliable indicators of chaos from a single experimental time series is a challenging task, in particular, for systems with many degrees of freedom. The techniques available for this purpose often require unachievably long time series. In this ... More
Optimal bounds for the colored Tverberg problemOct 26 2009Nov 17 2014We prove a "Tverberg type" multiple intersection theorem. It strengthens the prime case of the original Tverberg theorem from 1966, as well as the topological Tverberg theorem of Barany et al. (1980), by adding color constraints. It also provides an improved ... More
Chandra X-ray Imaging Spectroscopy of the Young Supernova Remnant Kesteven 75Sep 18 2002We present a spatially resolved spectroscopic analysis of the young Galactic supernova remnant Kes 75 (SNR G29.7-0.3) using the Chandra X-ray Observatory. Kes 75 is one of an increasing number of examples of a shell-type remnant with a central pulsar ... More
The Dust Content of Galaxy ClustersNov 07 2007We report on the detection of reddening toward z ~ 0.2 galaxy clusters. This is measured by correlating the Sloan Digital Sky Survey cluster and quasar catalogs and by comparing the photometric and spectroscopic properties of quasars behind the clusters ... More
A tight colored Tverberg theorem for maps to manifoldsJul 10 2011We prove that any continuous map of an N-dimensional simplex Delta_N with colored vertices to a d-dimensional manifold M must map r points from disjoint rainbow faces of Delta_N to the same point in M: For this we have to assume that N \geq (r-1)(d+1), ... More
Searching for Scalar Dark Matter in Atoms and Astrophysical Phenomena: Variation of Fundamental ConstantsNov 12 2015We propose to search for scalar dark matter via its effects on the electromagnetic fine-structure constant and particle masses. Scalar dark matter that forms an oscillating classical field produces `slow' linear-in-time drifts and oscillating variations ... More
Model Independent Expansion History from Supernovae: Deviation from $Λ$CDM?Dec 10 2018We examine the Pantheon supernovae distance data compilation in a model independent analysis to test the validity of cosmic history reconstructions beyond the concordance $\Lambda$CDM cosmology. Strong deviations are allowed by the data at $z\gtrsim1$ ... More
From Discs to Bulges: effect of mergers on the morphology of galaxiesJul 16 2015We study the effect of mergers on the morphology of galaxies by means of the simulated merger tree approach first proposed by Moster et al. This method combines N-body cosmological simulations and semi-analytic techniques to extract realistic initial ... More
Model Independent Expansion History from Supernovae: Cosmology versus SystematicsDec 10 2018Mar 03 2019We examine the Pantheon supernovae distance data compilation in a model independent analysis to test the validity of cosmic history reconstructions beyond the concordance $\Lambda$CDM cosmology. Strong deviations are allowed by the data at $z\gtrsim1$ ... More
Generating topological order from a 2D cluster state using a duality mappingMay 11 2011In this paper we prove, extend and review possible mappings between the two-dimensional Cluster state, Wen's model, the two-dimensional Ising chain and Kitaev's toric code model. We introduce a two-dimensional duality transformation to map the two-dimensional ... More
Discriminants of stable rank two sheaves on some general type surfacesDec 05 2018Jan 10 2019We prove sharp bounds on the discriminants of stable rank two sheaves on surfaces in three-dimensional projective space. The key technical ingredient is to study them as torsion sheaves in projective space via tilt stability in the derived category. We ... More
Graphene on a hydrophobic substrate: Doping reduction and hysteresis suppression under ambient conditionsOct 14 2009The intrinsic doping level of graphene prepared by mechanical exfoliation and standard lithography procedures on thermally oxidized silicon varies significantly and seems to depend strongly on processing details and the substrate morphology. Moreover, ... More
Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic FieldNov 17 2014Jun 16 2015Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for limiting differential ... More
Interaction between dark matter sub-halos & galactic gaseous diskJul 12 2011Nov 04 2011We investigate the idea that the interaction of Dark Matter (DM) sub-halos with the gaseous disk of galaxies can be the origin for the observed holes and shells found in their neutral hydrogen (HI) distributions. We use high resolution hydrodynamic simulations ... More
Observations of the Ultraviolet-Bright Star Y453 in the Globular Cluster M4 (NGC 6121)Aug 03 2017We present a spectral analysis of the UV-bright star Y453 in M4. Model fits to the star's optical spectrum yield T_eff ~ 56,000 K. Fits to the star's FUV spectrum, obtained with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope, ... More
Particle-in-cell study of the ion-to-electron sheath transitionApr 27 2016The form of a sheath near a small electrode, with bias changing from below to above the plasma potential is studied using 2D particle-in-cell (PIC) simulations. Five cases are studied: (A) an electrode biased more than the electron temperature ($T_e/e$) ... More
Structural and electronic properties of $α,β$-(BEDT-TTF)$_2$I$_3$ and $κ$-(BEDT-TTF)$_2$X$_3$ (X=I,F,Br,Cl) organic charge transfer saltsMay 30 2017Aug 21 2017(BEDT-TFF)$_2$I$_3$ charge transfer salts are reported to show superconductivity and pressure induced quasi two-dimensional Dirac cones at the Fermi level. By performing state of the art ab initio calculations in the framework of density functional theory, ... More
The Concentration Dependence of the Galaxy-Halo Connection: Modeling Assembly Bias with Abundance MatchingOct 19 2015Jun 28 2016Empirical methods for connecting galaxies to their dark matter halos have become essential in interpreting measurements of the spatial statistics of galaxies. In this work, we present a novel approach for parameterizing the degree of concentration dependence ... More
Dense monoenergetic proton beams from chirped laser-plasma interactionJul 06 2011Oct 27 2011Interaction of a frequency-chirped laser pulse with single protons and a hydrogen plasma cell is studied analytically and by means of particle-in-cell simulations, respectively. Feasibility of generating ultra-intense (10^7 particles per bunch) and phase-space ... More
FUSE, STIS, and Keck spectroscopic analysis of the UV-bright star vZ 1128 in M3 (NGC 5272)Jun 30 2015We present a spectral analysis of the UV-bright star vZ 1128 in M3 based on observations with the Far Ultraviolet Spectroscopic Explorer (FUSE), the Space Telescope Imaging Spectrograph (STIS), and the Keck HIRES echelle spectrograph. By fitting the H ... More
The Concentration Dependence of the Galaxy-Halo Connection: Modeling Assembly Bias with Abundance MatchingOct 19 2015Dec 02 2016Empirical methods for connecting galaxies to their dark matter halos have become essential for interpreting measurements of the spatial statistics of galaxies. In this work, we present a novel approach for parameterizing the degree of concentration dependence ... More
Nanoscale Mapping of Nanosecond Time-scale Electro-Mechanical Phenomena in Graphene NEMSSep 02 2015Atomically thin layers of two-dimensional (2D) materials such as graphene, MoS2 and h-BN have immense potential as sensors and electronic devices thanks to their highly desirable electronic, mechanical, optical and heat transport properties. In particular ... More
The Turbulent Heating Rate in Strong MHD Turbulence with Nonzero Cross HelicityMay 20 2009Different results for the cascade power in strong, incompressible MHD turbulence with nonzero cross helicity appear in the literature. In this paper, we discuss the conditions under which these different results are valid. We define z+ to be the rms amplitude ... More
Bilayer fractional quantum Hall states with ultracold dysprosiumMay 12 2015We show how dipolar interactions between dysprosium atoms in an optical lattice can be used to obtain fractional quantum Hall states. In our approach, dysprosium atoms are trapped one atom per site in a deep optical lattice with negligible tunneling. ... More
The effects of a hot gaseous halo in galaxy major mergersApr 01 2011Cosmological hydrodynamical simulations as well as observations indicate that spiral galaxies are comprised of five different components: dark matter halo, stellar disc, stellar bulge, gaseous disc and gaseous halo. While the first four components have ... More
Quantitative Measures of Equity in Small GroupsOct 31 2017This project investigates how to quantitatively measure equity in small student groups. We follow several student groups to operationalize how discourse may be equitable or inequitable. The groups came from a two week, pre-college program that prepares ... More
Learning Based Segmentation of CT Brain Images: Application to Post-Operative Hydrocephalic ScansDec 11 2017Objective: Hydrocephalus is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid (CSF) in the brain. Segmentation of brain imagery into brain tissue and CSF (before and after surgery, i.e. pre-op vs. postop) plays a crucial ... More
Star formation in mergers with cosmologically motivated initial conditionsJul 06 2015We use semi-analytic models and cosmological merger trees to provide the initial conditions for multi-merger numerical hydrodynamic simulations, and exploit these simulations to explore the effect of galaxy interaction and merging on star formation (SF). ... More
Electron Preheaths: The Outsized Influence of Positive Boundaries on PlasmasAug 24 2015Oct 04 2016Electron sheaths form near the surface of objects biased more positive than the plasma potential, such as in the electron saturation region of a Langmuir probe trace. Generally, the formation of electron sheaths requires that the electron-collecting area ... More
Quantum spin pumping with adiabatically modulated magnetic barrier'sMar 29 2003Dec 09 2003A quantum pump device involving magnetic barriers produced by the deposition of ferro magnetic stripes on hetero-structure's is investigated. The device for dc- transport does not provide spin-polarized currents, but in the adiabatic regime, when one ... More
On smooth Gorenstein polytopesMar 08 2013A Gorenstein polytope of index r is a lattice polytope whose r-th dilate is a reflexive polytope. These objects are of interest in combinatorial commutative algebra and enumerative combinatorics, and play a crucial role in Batyrev's and Borisov's computation ... More
Path-by-path well-posedness of nonlinear diffusion equations with multiplicative noiseJul 11 2018We prove the path-by-path well-posedness of stochastic porous media and fast diffusion equations driven by linear, multiplicative noise. As a consequence, we obtain the existence of a random dynamical system. This solves an open problem raised in [Barbu, ... More
A bound for the splitting of smooth Fano polytopes with many verticesSep 25 2014Aug 10 2015The classification of toric Fano manifolds with large Picard number corresponds to the classification of smooth Fano polytopes with large number of vertices. A smooth Fano polytope is a polytope that contains the origin in its interior such that the vertex ... More
Vacua and correlators in hyperbolic de Sitter spaceJan 31 2015Feb 23 2015We study the power - and bi -spectrum of vacuum fluctuations in a hyperbolic section of de Sitter space, comparing two states of physical interest: the Bunch-Davies and hyperbolic vacuum. We introduce a one -parameter family of de Sitter hyperbolic sections ... More
Ferroics: magnetic-compass lattice and optical phonon dispersions of dipolar crystalsDec 22 2005Jan 03 2006We report a simple safe and attractive pedagogic demonstration with magnetic compasses that facilitates an intuitive understanding of the concept that ferromagnetism and ferroelectricity do not result from dipole-dipole interactions alone. Phonon dispersion ... More
Leveraging the ALICE/L3 cavern for long-lived exoticsOct 08 2018Run 5 of the HL-LHC era (and beyond) may provide new opportunities to search for physics beyond the standard model (BSM) at interaction point 2 (IP2). In particular, taking advantage of the existing ALICE detector and infrastructure provides an opportunity ... More
The effects of a hot gaseous halo on disc thickening in galaxy minor mergersAug 08 2011We employ hydrodynamical simulations to study the effects of dissipational gas physics on the vertical heating and thickening of disc galaxies during minor mergers. For the first time we present a suite of simulations that includes a diffuse, rotating, ... More
Can Gas prevent the Destruction of Thin Stellar Discs by Minor Mergers?Jun 03 2009Dec 14 2009We study the effect of dissipational gas physics on the vertical heating and thickening of disc galaxies during minor mergers. We produce a suite of minor merger simulations for Milky Way-like galaxies. This suite consists of collisionless simulations ... More
Sign-changing photon-mediated atom interactions in multimode cavity QEDOct 25 2018Sign-changing interactions constitute a crucial ingredient in the creation of frustrated many-body systems such as spin glasses. We present here the demonstration of a photon-mediated sign-changing interaction between Bose-Einstein condensed (BEC) atoms ... More
A New Channel for the Formation of Kinematically Decoupled Cores in Early-type galaxiesFeb 02 2015We present the formation of a Kinematically Decoupled Core (KDC) in an elliptical galaxy, resulting from a major merger simulation of two disk galaxies. We show that although the two progenitor galaxies are initially following a prograde orbit, strong ... More
Games and Meta-Games: Pricing Rules for Combinatorial MechanismsMar 20 2015In settings where full incentive-compatibility is not available, such as core-constraint combinatorial auctions and budget-balanced combinatorial exchanges, we may wish to design mechanisms that are as incentive-compatible as possible. This paper offers ... More
Homogenization of Hamilton-Jacobi equations with rough time dependenceFeb 16 2016We consider viscosity solutions of Hamilton-Jacobi equations with oscillatory spatial dependence and rough time dependence. The time dependence is in the form of the derivative of a continuous path that converges to a possibly nowhere-differentiable path, ... More
A simple proof of Brown's diagonalizability theoremOct 04 2010We present here a simple proof of Brown's diagonalizability theorem for certain elements of the algebra of a left regular band, including probability measures.
Yet another solution to the Burnside problem for matrix semigroupsNov 16 2008We use the kernel category to give a finiteness condition for semigroups. As a consequence we provide yet another proof that finitely generated periodic semigroups of matrices are finite.
SO(2)-congruent projections of convex bodies with rotation about the originSep 27 2013We prove that if two convex bodies $ K, L \subset \mathbb{R}^3$ satisfy the property that the orthogonal projections of $K$ and $L$ onto every plane containing the origin are roations of each other, then either $K$ and $L$ coincide or $L$ is the image ... More
Bipartite Euler systemsFeb 28 2012If E is an elliptic curve over Q and K is an imaginary quadratic field, there is an Iwasawa main conjecture predicting the behavior of the Selmer group of E over the anticyclotomic Z_p-extension of K. The main conjecture takes different forms depending ... More
Special cohomology classes for modular Galois representationsFeb 28 2012Building on ideas of Vatsal, Cornut proved a conjecture of Mazur asserting the generic nonvanishing of Heegner points on an elliptic curve E as one ascends the anticyclotomic Z_p-extension of a quadratic imaginary extension K/Q. In the present article ... More
Opportunities with top quarks at future circular collidersDec 04 2014We describe various studies relevant for top physics at future circular collider projects currently under discussion. We show how highly-massive top-antitop systems produced in proton-proton collisions at a center-of-mass energy of 100 TeV could be observed ... More
Beyond the Minimal Supersymmetric Standard Model: from theory to phenomenologyFeb 21 2012Thanks to the latest development in the field of Monte Carlo event generators and satellite programs allowing for a straightforward implementation of any beyond the Standard Model theory in those tools, studying the property of any softly-broken supersymmetric ... More
Transverse-momentum, threshold and joint resummations for slepton pair production at hadron collidersOct 10 2007We present precision calculations of the transverse-momentum spectrum and the invariant-mass distribution for slepton pair production at hadron colliders. We implement the transverse-momentum, threshold and joint resummation formalisms at the next-to-leading ... More
Slepton pair production at hadron collidersOct 24 2006In R-parity conserving supersymmetric models, sleptons are produced in pairs at hadron colliders. We show that measurements of the longitudinal single-spin asymmetry at possible polarization upgrades of existing colliders allow for a direct extraction ... More
Twisted derived equivalences for affine schemesNov 11 2013We show how work of Rickard and To\"en completely resolves the question of when two twisted affine schemes are derived equivalent.
On the integral Tate conjecture for finite fields and representation theoryApr 19 2015May 28 2015We describe a new source of counterexamples to the so-called integral Hodge and integral Tate conjectures. As in the other known counterexamples to the integral Tate conjecture over finite fields, ours are approximations of the classifying space of some ... More
On a theorem of Hazrat and HooblerApr 05 2011We use cycle complexes with coefficients in an Azumaya algebra, as developed by Kahn and Levine, to compare the G-theory of an Azumaya algebra to the G-theory of the base scheme. We obtain a sharper version of a theorem of Hazrat and Hoobler in certain ... More
Jet Charge with the ATLAS Detector using $\sqrt{s}=8$ TeV $pp$ Collision DataSep 01 2014The momentum-weighted sum of the charges of tracks associated to a jet provides an experimental handle on the electric charge of fundamental strongly-interacting particles. An overview of a study of this jet charge observable for jets produced in dijet ... More
Summary of progress on the Blaschke conjectureSep 05 2013Aug 03 2015The Blaschke conjecture claims that every compact Riemannian manifold whose injectivity radius equals its diameter is, up to constant rescaling, a compact rank one symmetric space. We summarize the intuition behind this problem, the proof that such manifolds ... More
Analogues elliptiques des nombres multizétasJan 14 2013Jan 12 2015We study functions of an elliptic parameter, which are defined as iterated integrals of elliptic functions. We establish their relation with the "elliptic associators" of our previous work, by means of a functional realization of Lie algebras appearing ... More
Holomorphic Cartan geometries on uniruled surfacesMay 24 2011We classify holomorphic Cartan geometries on every compact complex curve, and on every compact complex surface which contains a rational curve.
Characteristic forms of complex Cartan geometriesApr 19 2007Dec 09 2008We calculate relations on characteristic classes which are obstructions preventing closed K\"ahler manifolds from carrying holomorphic Cartan geometries. We apply these relations to give global constraints on the phase spaces of complex analytic determined ... More
Determination of all rational preperiodic points for morphisms of PNOct 23 2012Jul 03 2013For a morphism $f:\P^N \to \P^N$, the points whose forward orbit by $f$ is finite are called preperiodic points for $f$. This article presents an algorithm to effectively determine all the rational preperiodic points for $f$ defined over a given number ... More
Computing Hybridization Networks for Multiple Rooted Binary Phylogenetic Trees by Maximum Acyclic Agreement ForestsAug 13 2014Dec 17 2015It is a known fact that, given two rooted binary phylogenetic trees, the concept of maximum acyclic agreement forests is sufficient to compute hybridization networks with minimum hybridization number. In this work, we demonstrate by first presenting an ... More
Einstein-aether as a quantum effective field theoryMay 14 2009The possibility that Lorentz symmetry is violated in gravitational processes is relatively unconstrained by experiment, in stark contrast with the level of accuracy to which Lorentz symmetry has been confirmed in the matter sector. One model of Lorentz ... More
(2+3) dimensional geometrical dual of the complex Klein-Gordon equationJan 30 2008Jan 22 2009In this paper it is shown that an equivalent to the complex Klein-Gordon equation can be obtained from the (2+3) dimensional Einstein equations coupled to a conserved energy momentum tensor. In an explicit toy model we give matching conditions for what ... More
The Brownian Frame Process as a Rough PathFeb 01 2006We introduce the (path-valued) Brownian frame process whose evaluation at time t is the sample path of the underlying Brownian motion run from time t-1 to t. Due to its connections with Gaussian Volterra processes and SDDEs this is an interesting object ... More
The flux-tube model of particle creation in nuclear collisionsJul 08 1999I review some of the history of the flux-tube model, concentrating on work done by the Los Alamos-Tel Aviv collaboration on particle creation and back-reaction in uniform fields and in the central rapidity region. I discuss the incorporation of more realistic ... More
Tangent Lie algebra of derived Artin stacksDec 11 2013Jun 21 2016Since the work of Mikhail Kapranov in [Kap], it is known that the shifted tangent complex $\mathbb{T}_X[-1]$ of a smooth algebraic variety $X$ is endowed with a weak Lie structure. Moreover any complex of quasi-coherent sheaves on $X$ is endowed with ... More
New method for studying steady states in quantum impurity problems: The interacting resonant level modelMar 09 2007Aug 31 2007We develop a new perturbative method for studying any steady states of quantum impurities, in or out of equilibrium. We show that steady-state averages are completely fixed by basic properties of the steady-state (Hershfield's) density matrix along with ... More
Hypotrochoids in conformal restriction systems and Virasoro descendantsSep 21 2012A conformal restriction system is a commutative, associative, unital algebra equipped with a representation of the groupoid of univalent conformal maps on connected open sets of the Riemann sphere, and a family of linear functionals on subalgebras, satisfying ... More