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Eigenvectors of random graphs: Nodal domainsJul 23 2008Nov 02 2009We initiate a systematic study of eigenvectors of random graphs. Whereas much is known about eigenvalues of graphs and how they reflect properties of the underlying graph, relatively little is known about the corresponding eigenvectors. Our main focus ... More

Finding Hidden Cliques in Linear Time with High ProbabilityOct 14 2010We are given a graph $G$ with $n$ vertices, where a random subset of $k$ vertices has been made into a clique, and the remaining edges are chosen independently with probability $\tfrac12$. This random graph model is denoted $G(n,\tfrac12,k)$. The hidden ... More

Determining Omega from Peculiar VelocitiesSep 19 1993The large-scale dynamics of matter is inferred from the observed peculiar velocities of galaxies via the POTENT procedure. The smoothed fields of velocity and mass-density fluctuations are recovered from the current data of about 3000 galaxies. The cosmological ... More

Non abelian cohomology of extensions of Lie algebras as Deligne groupoidOct 02 2013In this note we show that the theory of non abelian extensions of a Lie algebra $\mathfrak{g}$ by a Lie algebra $\mathfrak{h}$ can be understood in terms of a differential graded Lie algebra $L$. More precisely we show that the non-abelian cohomology ... More

Tribute to an astronomer: the work of Max Ernst on Wilhelm TempelDec 17 2015Jan 11 2016In 1964-1974, the German artist Max Ernst created, with the help of two friends, a series of works (books, movie, paintings) related to the astronomer Wilhelm Tempel. Mixing actual texts by Tempel and artistic features, this series pays homage to the ... More

Spectroscopy of Massive StarsApr 27 2006Dec 06 2006Although rare, massive stars, being the main sources of ionizing radiation, chemical enrichment and mechanical energy in the Galaxy, are the most important objects of the stellar population. This review presents the many different aspects of the main ... More

Hot stars observed by XMM-Newton I. The catalog and the properties of OB starsAug 11 2009Aims : Following the advent of increasingly sensitive X-ray observatories, deep observations of early-type stars became possible. However, the results for only a few objects or clusters have until now been reported and there has been no large survey comparable ... More

Deformation of the Heisenberg Algebra inside $gl(3,\mathbb{K})$Mar 24 2004We study non-trivial deformations of the natural imbedding of the Lie algebra $\fh_1$ of lower triangular matrices (the Heisenberg Lie algebra) into $gl(3,\mathbb{K})$, where $\mathbb{K}=\mathbb{R}$ or $|mathbb{C}$. Our first result is the calculation ... More

Periodic Hamiltonian flows on four dimensional manifoldsOct 13 1995Apr 07 1998We classify the periodic Hamiltonian flows on compact four dimensional symplectic manifolds up to isomorphism of Hamiltonian S^1 spaces. Additionally, we show that all these spaces are Kaehler, that every such space is obtained from a simple model by ... More

Optimization and Reoptimization in Scheduling ProblemsSep 04 2015Parallel machine scheduling has been extensively studied in the past decades, with applications ranging from production planning to job processing in large computing clusters. In this work we study some of these fundamental optimization problems, as well ... More

Moment maps and non-compact cobordismsJan 19 1997We define a moment map associated to a smooth torus action on a smooth manifold, without a two-form. We define cobordisms of such structures, allowing non compact manifolds as long as the moment maps are proper. We prove that a compact manifold with a ... More

A new cohomology theory associated to deformations of Lie algebra morphismsApr 22 2003We introduce a new cohomology theory related to deformations of Lie algebra morphisms. This notion involves simultaneous deformations of two Lie algebras and a homomorphism between them.

Astronomical arguments in Newton's ChronologyDec 20 2012Nov 19 2013In his Chronology, Newton uses astronomical "evidence" to support its extreme rejuvenation of ancient times. These elements, having a scientific varnish, provide some credibility to the work. They have been fiercely debated for a century, with a gradual ... More

Metastable Rank-Condition Supersymmetry Breaking in a Chiral ExampleJul 18 2011We discuss generalizations of Intriligator-Seiberg-Shih (ISS) vacua to chiral models. We study one example, of an s-confining theory, in detail. In the IR, this example reduces to two ISS-like sectors, and exhibits a supersymmetry-breaking vacuum with ... More

Supersymmetry breakingJan 12 2006These lectures provide a simple introduction to supersymmetry breaking. After presenting the basics of the subject and illustrating them in tree-level examples, we discuss dynamical supersymmetry breaking, emphasizing the role of holomorphy and symmetries ... More

Maximal tori in the symplectomorphism groups of Hirzebruch surfacesApr 30 2002We count the conjugacy classes of maximal tori in the groups of symplectomorphisms of S^2 \times S^2 and of the blow-up of CP^2 at a point.

Structure de l'univers - quand l'observation guide la theorie... ou pasJun 05 2015The scientific method is often presented, e.g. to children, as a linear process, starting by a question and ending by the elaboration of a theory, with a few experiments in-between. The reality of the building of science is much more complex, with back-and-forth ... More

Flavor and LHC Searches for New PhysicsJan 25 2012Uncovering the physics of electroweak symmetry breaking (EWSB) is the raison-d'etre of the LHC. Flavor questions, it would seem, are of minor relevance for this quest, apart from their role in constraining the possible structure of EWSB physics. In this ... More

X-ray stellar population of the LMCAug 28 2008Sep 08 2008In the study of stars, the high energy domain occupies a place of choice, since it is the only one able to directly probe the most violent phenomena: indeed, young pre-main sequence objects, hot massive stars, or X-ray binaries are best revealed in X-rays. ... More

Magnetic fields in O starsJun 28 2013Over the last decade, large-scale, organized (generally dipolar) magnetic fields with a strength between 0.1 and 20 kG were detected in dozens of OB stars. This contribution reviews the impact of such magnetic fields on the stellar winds of O-stars, with ... More

Competing first passage percolation on random regular graphsSep 12 2011Aug 04 2014We consider two competing first passage percolation processes started from uniformly chosen subsets of a random regular graph on $N$ vertices. The processes are allowed to spread with different rates, start from vertex subsets of different sizes or at ... More

Galaxy Biasing: Nonlinear, Stochastic and MeasurableSep 23 1998I describe a general formalism for galaxy biasing (Dekel & Lahav 1998) and its application to measurements of beta (=Omega^0.6/b), e.g. via direct comparisons of light and mass and via redshift distortions. The linear and deterministic relation g=b*d ... More

Characteristic Scales in Galaxy FormationJan 23 2004Recent data, e.g. from SDSS and 2dF, reveal a robust bi-modality in the distribution of galaxy properties, with a characteristic transition scale at stellar mass M_*~3x10^{10} Msun (near L_*), corresponding to virial velocity V~100 km/s. Smaller galaxies ... More

Faster parameterized algorithm for Cluster Vertex DeletionJan 22 2019In the Cluster Vertex Deletion problem the input is a graph $G$ and an integer $k$. The goal is to decide whether there is a set of vertices $S$ of size at most $k$ such that the deletion of the vertices of $S$ from $G$ results a graph in which every ... More

Dual conformal transformations of smooth holographic Wilson loopsOct 23 2016We study dual conformal transformations of minimal area surfaces in $AdS_5 \times S^5$ corresponding to holographic smooth Wilson loops and some other related observables. To act with dual conformal transformations we map the string solutions to the dual ... More

Succinct data-structure for nearest colored node in a treeSep 06 2016We give a succinct data-structure that stores a tree with color for each node, and allows finding, given a node x and a color alpha, the nearest node to x with color alpha. This results improves the O(n log n)-bits structure of Gawrychowski et al.~[CPM ... More

Algebraic Curves for Factorized String SolutionsFeb 04 2013We show how to construct an algebraic curve for factorized string solution in the context of the AdS/CFT correspondence. We define factorized solutions to be solutions where the flat-connection becomes independent of one of the worldsheet variables by ... More

Phase-Space Structure & Substructure of Dark HalosMar 07 2004A method is presented for computing the 6-D phase-space density f(x,v) and its PDF v(f) in an N-body system. It is based on Delaunay tessellation, yielding v(f) with a fixed smoothing window over a wide f range, independent of the sampling resolution. ... More

Do Spirals and Ellipticals Trace the Same Velocity Field?Sep 27 1993We test the hypothesis that the velocity field derived from Tully-Fisher measurements of spiral galaxies, and that derived independently from Dn-sigma measurements of ellipticals and S0s, are noisy versions of the same underlying velocity field. The radial ... More

Correlation Function of Circular Wilson Loops at Strong CouplingSep 12 2013Sep 23 2013We study the correlation function of two circular Wilson loops at strong coupling in N=4 super Yang-Mills theory. Using the AdS/CFT correspondence, the problem maps to finding the minimal surface between two circles defined on the boundary of AdS, and ... More

Gravitational Quenching by Clumpy Accretion in Cool Core Clusters: Convective Dynamical Response to OverheatingAug 05 2010Dec 09 2011Many galaxy clusters pose a "cooling-flow problem", where the observed X-ray emission from their cores is not accompanied by enough cold gas or star formation. A continuous energy source is required to balance the cooling rate over the whole core volume. ... More

Gravitational Quenching in Massive Galaxies and Clusters by Clumpy AccretionJul 09 2007Nov 05 2007We consider a simple gravitational-heating mechanism for the long-term quenching of cooling flows and star formation in massive dark-matter haloes hosting ellipticals and clusters. The virial shock heating in haloes >10^12 Mo triggers quenching in 10^12-13 ... More

Galaxy Bimodality due to Cold Flows and Shock HeatingDec 13 2004Dec 17 2005We address the origin of the robust bi-modality observed in galaxy properties about a characteristic stellar mass ~3x10^{10}Msun. Less massive galaxies tend to be ungrouped blue star-forming discs, while more massive galaxies are typically grouped red ... More

Virial shocks in galactic haloes?Feb 08 2003Jul 14 2003We investigate the conditions for the existence of an expanding virial shock in the gas falling within a spherical dark-matter halo. The shock relies on pressure support by the shock-heated gas behind it. When the radiative cooling is efficient compared ... More

Centered complexity one Hamiltonian torus actionsNov 23 1999Feb 23 2000We consider symplectic manifolds with Hamiltonian torus actions which are "almost but not quite completely integrable": the dimension of the torus is one less than half the dimension of the manifold. We provide a complete set of invariants for such spaces ... More

The flavor of product-group GUTsJan 06 2006The doublet-triplet splitting problem can be simply solved in product-group GUT models, using a global symmetry that distinguishes the doublets from the triplets. Apart from giving the required mass hierarchy, this ``triplet symmetry'' can also forbid ... More

Counting to Ten with Two Fingers: Compressed Counting with Spiking NeuronsFeb 27 2019We consider the task of measuring time with probabilistic threshold gates implemented by bio-inspired spiking neurons. In the model of spiking neural networks, network evolves in discrete rounds, where in each round, neurons fire in pulses in response ... More

The Gromov width of complex GrassmanniansMay 20 2004Aug 24 2005We show that the Gromov width of the Grassmannian of complex k-planes in C^n is equal to one when the symplectic form is normalized so that it generates the integral cohomology in degree 2. We deduce the lower bound from more general results. For example, ... More

The Morse-Bott-Kirwan condition is localJul 14 2014Nov 09 2016Kirwan identified a condition on a smooth function under which the usual techniques of Morse-Bott theory can be applied to this function. We prove that if a function satisfies this condition locally then it also satisfies the condition globally. As an ... More

The Graver Complexity of Integer ProgrammingSep 10 2007Nov 22 2007In this article we establish an exponential lower bound on the Graver complexity of integer programs. This provides new type of evidence supporting the presumable intractability of integer programming. Specifically, we show that the Graver complexity ... More

Gauge Theories in $AdS_5$ and Fine-Lattice DeconstructionSep 22 2004Sep 23 2004The logarithmic energy dependence of gauge couplings in AdS_5 emerges almost automatically when the theory is deconstructed on a coarse lattice. Here we study the theory away from the coarse-lattice limit. While we cannot analytically calculate individual ... More

Structure-Aware Classification using Supervised Dictionary LearningSep 29 2016In this paper, we propose a supervised dictionary learning algorithm that aims to preserve the local geometry in both dimensions of the data. A graph-based regularization explicitly takes into account the local manifold structure of the data points. A ... More

X-ray and optical spectroscopy of the massive young open cluster IC1805Aug 16 2016Very young open clusters are ideal places to study the X-ray properties of a homogeneous population of early-type stars. In this respect, the IC1805 open cluster is very interesting as it hosts the O4If$^+$ star HD15570 thought to be in an evolutionary ... More

Convexity package for momentum maps on contact manifoldsOct 29 2009Mar 10 2010Let a torus T act effectively on a compact connected cooriented contact manifold, and let Psi be the natural momentum map on the symplectization. We prove that, if dim T > 2, the union of the origin with the image of Psi is a convex polyhedral cone, the ... More

A geometric characterization of the classical Lie algebrasJul 07 2017A nonzero element x in a Lie algebra g over a field F with Lie product [ , ] is called a extremal element if [x, [x, g]] is contained in Fx. Long root elements in classical Lie algebras are examples of extremal elements. Arjeh Cohen et al. initiated the ... More

Localization for equivariant cohomology with varying polarizationDec 16 2010Jun 21 2012The main contribution of this paper is a generalization of several previous localization theories in equivariant symplectic geometry, including the classical Atiyah-Bott/Berline-Vergne localization theorem, as well as many cases of the localization via ... More

The Metric Completion of Outer SpaceFeb 28 2012Nov 15 2013We develop the theory of a metric completion of an asymmetric metric space. We characterize the points on the boundary of Outer Space that are in the metric completion of Outer Space with the Lipschitz metric. We prove that the simplicial completion, ... More

Simultaneous deformations of algebras and morphisms via derived bracketsJan 21 2013Sep 09 2015We present a method to construct explicitly L-infinity algebras governing simultaneous deformations of various kinds of algebraic structures and of their morphisms. It is an alternative to the heavy use of the operad machinery of the existing approaches. ... More

High-resolution X-ray spectroscopy of Theta CarAug 25 2008Context : The peculiar hot star Theta Car in the open cluster IC2602 is a blue straggler as well as a single-line binary of short period (2.2d). Aims : Its high-energy properties are not well known, though X-rays can provide useful constraints on the ... More

Nonlinear Bipartite MatchingMay 23 2006We study the problem of optimizing nonlinear objective functions over bipartite matchings. While the problem is generally intractable, we provide several efficient algorithms for it, including a deterministic algorithm for maximizing convex objectives, ... More

A geometric characterization of the symplectic Lie algebraJul 07 2017A nonzero element $x$ in a Lie algebra $\mathfrak{g}$ with Lie product $[ , ]$ is called extremal if $[x,[x,y]]$ is a multiple of $x$ for all $y$. In this paper we characterize the (finitary) symplectic Lie algebras as simple Lie algebras generated by ... More

Distinguishing symplectic blowups of the complex projective planeJul 20 2014A symplectic manifold that is obtained from the complex projective plane by k blowups is encoded by k+1 parameters: the size of the initial complex projective plane, and the sizes of the blowups. We determine which values of these parameters yield symplectomorphic ... More

Reconstruction of the Path GraphDec 31 2017Let $P$ be a set of $n \geq 5$ points in convex position in the plane. The path graph $G(P)$ of $P$ is an abstract graph whose vertices are non-crossing spanning paths of $P$, such that two paths are adjacent if one can be obtained from the other by deleting ... More

Blockers for Triangulations of a Convex Polygon and a Geometric Maker-Breaker GameDec 31 2017Let $G$ be a complete convex geometric graph whose vertex set $P$ forms a convex polygon $C$, and let $F$ be a family of subgraphs of $G$. A blocker for $F$ is a set of edges, of smallest possible size, that contains a common edge with every element of ... More

An astronomical survey conducted in BelgiumAug 19 2013This article presents the results of the first survey conducted in Belgium about the interest and knowledge in astronomy. Two samples were studied, the public at large (667 questionnaires) and students (2589 questionnaires), but the results are generally ... More

Strongly Contracting Geodesics in Outer SpaceDec 08 2008Jun 18 2010We study the Lipschitz metric on Outer Space and prove that fully irreducible elements of Out(F_n) act by hyperbolic isometries with axes which are strongly contracting. As a corollary, we prove that the axes of fully irreducible automorphisms in the ... More

Revisiting Tietze-Nakajima - Local and Global Convexity for MapsJan 25 2007Nov 19 2009A theorem of Tietze and Nakamija, from 1928, asserts that if a subset X of R^n is closed, connected, and locally convex, then it is convex. We give an analogous "local to global convexity" theorem when the inclusion map of X to R^n is replaced by a map ... More

Basic Forms and Orbit Spaces: a Diffeological ApproachAug 07 2014Mar 08 2016If a Lie group acts on a manifold freely and properly, pulling back by the quotient map gives an isomorphism between the differential forms on the quotient manifold and the basic differential forms upstairs. We show that this result remains true for actions ... More

Shortening the Hofer length of Hamiltonian circle actionsDec 04 2009Dec 09 2013A Hamiltonian circle action on a compact symplectic manifold is known to be a closed geodesic with respect to the Hofer metric on the group of Hamiltonian diffeomorphisms. If the momentum map attains its minimum or maximum at an isolated fixed point with ... More

Non-Compact Symplectic Toric ManifoldsJul 16 2009Jul 22 2015A key result in equivariant symplectic geometry is Delzant's classification of compact connected symplectic toric manifolds. The moment map induces an embedding of the quotient of the manifold by the torus action into the dual of the Lie algebra of the ... More

The Morse-Bott-Kirwan condition is localJul 14 2014Kirwan identified a condition on a smooth function under which the usual techniques of Morse-Bott theory can be applied to this function. We prove that if a function satisfies this condition locally then it also satisfies the condition globally. As an ... More

Simultaneous deformations and Poisson geometryFeb 13 2012Oct 07 2014We consider the problem of deforming simultaneously a pair of given structures. We show that such deformations are governed by an L-infinity algebra, which we construct explicitly. Our machinery is based on Th. Voronov's derived bracket construction. ... More

Lorentz Violation and Superpartner MassesMay 19 2006Jan 09 2007We consider Lorentz violation in supersymmetric extensions of the standard model. We perform a spurion analysis to show that, in the simplest natural constructions, the resulting supersymmetry-breaking masses are tiny. In the process, we argue that one ... More

Collective excitations of hydrodynamically coupled driven colloidal particlesDec 23 2013Aug 21 2014Two colloidal particles, driven around an optical vortex trap, have been recently shown to pair due to an interplay between hydrodynamic interactions and the curved path they are forced to follow. We demonstrate here, that this pairing interaction can ... More

Circle and torus actions on equal symplectic blow-ups of CP^2Jan 02 2005A manifold obtained by k simultaneous symplectic blow-ups of CP^2 of equal sizes epsilon (where the size of CP^1 \subset CP^2 is one) admits an effective two dimensional torus action if k <= 3 and admits an effective circle action if (k-1)epsilon < 1. ... More

The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR21aApr 06 2016Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase ... More

Spin Correlations in Top-Quark Pair Production at $e^+e^-$ CollidersJun 24 1996Aug 30 1996We show that top-quark pairs are produced in an essentially unique spin configuration in polarized $e^+e^-$ colliders at all energies above the threshold region. Since the directions of the electroweak decay products of polarized top-quarks are strongly ... More

Deep penetration fluorescence imaging through dense yeast cells suspensions using Airy beamsFeb 24 2019We propose a new method to image fluorescent objects through turbid media base on Airy beam scanning. This is achieved by using the non-diffractive nature of Airy beams, namely their ability to maintain their shape while penetrating through a highly scattering ... More

Counting to Ten with Two Fingers: Compressed Counting with Spiking NeuronsFeb 27 2019Mar 03 2019We consider the task of measuring time with probabilistic threshold gates implemented by bio-inspired spiking neurons. In the model of spiking neural networks, network evolves in discrete rounds, where in each round, neurons fire in pulses in response ... More

X-ray emission from interacting massive binaries: a review of 15 years of progressSep 22 2015Previous generations of X-ray observatories revealed a group of massive binaries that were relatively bright X-ray emitters. This was attributed to emission of shock-heated plasma in the wind-wind interaction zone located between the stars. With the advent ... More

On unitality conditions for Hom-associative algebrasApr 30 2009Jul 21 2009In hom-associative structures, the associativity condition $(xy)z=x(yz)$ is twisted to $\alpha(x)(yz) = (xy)\alpha(z)$, with $\alpha$ a map in the appropriate category. In the present paper, we consider two different unitality conditions for hom-associative ... More

Complete invariants for Hamiltonian torus actions with two dimensional quotientsFeb 18 2002Dec 14 2003We study torus actions on symplectic manifolds with proper moment maps in the case that each reduced space is two-dimensional. We provide a complete set of invariants for such spaces. Our proof uses sheaves of groupoids of Hamiltonian spaces.

Hamiltonian group actions on exact symplectic manifolds with proper momentum maps are standardJul 13 2016We give a complete characterization of Hamiltonian actions of compact Lie groups on exact symplectic manifolds with proper momentum maps. We deduce that every Hamiltonian action of a compact Lie group on a contractible symplectic manifold with a proper ... More

Cosmological Parameters and Power Spectrum from Peculiar VelocitiesSep 29 1999The power spectrum of mass density fluctuations is evaluated from the Mark III and the SFI catalogs of peculiar velocities by a maximum likelihood analysis, using parametric models for the power spectrum and for the errors. The applications to the two ... More

Integrability of Green-Schwarz Sigma Models with BoundariesJun 17 2011Nov 08 2011We construct integrability preserving boundary conditions for Green-Schwarz sigma-models on semi-symmetric spaces. The boundary conditions are expressed as gluing conditions of the flat-connection, using an involutive metric preserving automorphism. We ... More

Cosmic Flows: A Status ReportMay 27 2001Jun 03 2001We give a brief review of recent developments in the study of the large-scale velocity field of galaxies since the international workshop on Cosmic Flows held in July 1999 in Victoria, B.C. Peculiar velocities (PVs) yield a tight and unique constraint ... More

Self-Duality of Green-Schwarz Sigma-ModelsJan 02 2011Jan 11 2011We study fermionic T-duality symmetries of integrable Green-Schwarz sigma-models on Anti-de-Sitter backgrounds with Ramond-Ramond fluxes, constructed as Z_4 supercosets of superconformal algebras. We find three algebraic conditions that guarantee self-duality ... More

An analytic solution for the minimal bathtub toy model: challenges in the star-formation history of high-z galaxiesFeb 10 2014We study the minimal ``bathtub" toy model as an analytic tool for capturing key processes of galaxy evolution and identifying robust successes and challenges in reproducing observations at high redshift. The source and sink terms of the continuity equations ... More

Merger Rates of Dark-Matter HaloesFeb 04 2008May 22 2008We derive analytic merger rates for dark-matter haloes within the framework of the Extended Press-Schechter (EPS) formalism. These rates become self-consistent within EPS once we realize that the typical merger in the limit of a small time-step involves ... More

Feedback and the fudamental line of low-luminosity LSB/dwarf galaxiesOct 20 2002Dec 12 2003We study in simple terms the role of feedback in establishing the scaling relations of low-surface-brightness and dwarf galaxies with stellar masses in the range 6x10^5 <M*< 3x10^10 Msun. These galaxies, as measured from SDSS and in the Local Group, show ... More

Towards a Resolution of the Galactic Spin Crisis: Mergers, Feedback, and Spin SegregationJan 11 2002We model in simple terms the angular-momentum problems of galaxy formation in CDM cosmologies, and identify the key elements of a scenario that may solve them. The buildup of angular momentum is modeled via dynamical friction and tidal stripping in a ... More

Asymmetry of Outer SpaceOct 28 2009Mar 23 2011We study the asymmetry of the Lipschitz metric d on Outer space. We introduce an (asymmetric) Finsler norm that induces d. There is an Out(F_n)-invariant potential \Psi on Outer space such that when the Lipschitz norm is corrected by the derivative of ... More

Duality after Supersymmetry BreakingJun 10 1998Starting with two supersymmetric dual theories, we imagine adding a chiral perturbation that breaks supersymmetry dynamically. At low energy we then get two theories with soft supersymmetry-breaking terms that are generated dynamically. With a canonical ... More

Tensor products and support varieties for some noncocommutative Hopf algebrasNov 30 2016We explore questions of projectivity and tensor products of modules for finite dimensional Hopf algebras. We construct many classes of examples in which tensor powers of nonprojective modules are projective and tensor products of modules in one order ... More

WIMPless Dark Matter from Non-Abelian Hidden Sectors with Anomaly-Mediated Supersymmetry BreakingFeb 01 2011In anomaly-mediated supersymmetry breaking (AMSB) models, superpartner masses are proportional to couplings squared. Their hidden sectors therefore naturally contain WIMPless dark matter, particles whose thermal relic abundance is guaranteed to be of ... More

Smooth Lie group actions are parametrized diffeological subgroupsDec 01 2010We show that every effective smooth action of a Lie group G on a manifold M is a diffeomorphism from G onto its image in Diff(M), where the image is equipped with the subset diffeology of the functional diffeology.

Normalizers and centralizers of cyclic subgroups generated by lone axis fully irreducible outer automorphismsMar 23 2016Jul 03 2016We let $\varphi$ be an ageometric fully irreducible outer automorphism so that its Handel-Mosher axis bundle consists of a single unique axis. We show that the centralizer $Cen(\langle\varphi\rangle)$ of the cyclic subgroup generated by $\varphi$ equals ... More

Duality in the Presence of Supersymmetry BreakingJan 22 1998Sep 01 1998We study Seiberg duality for N=1 supersymmetric QCD with soft supersymmetry-breaking terms. We generate the soft terms through gauge mediation by coupling two theories related by Seiberg duality to the same supersymmetry-breaking sector. In this way, ... More

Support Vector Machines for Current Status DataMay 05 2015Current status data is a data format where the time to event is restricted to knowledge of whether or not the failure time exceeds a random monitoring time. We develop a support vector machine learning method for current status data that estimates the ... More

Compressing Communication in Distributed ProtocolsMay 31 2015Aug 04 2015We show how to compress communication in distributed protocols in which parties do not have private inputs. More specifically, we present a generic method for converting any protocol in which parties do not have private inputs, into another protocol where ... More

Flavored Gauge-MediationMar 01 2011Feb 23 2012The messengers of Gauge-Mediation Models can couple to standard-model matter fields through renormalizable superpotential couplings. These matter-messenger couplings generate generation-dependent sfermion masses and are therefore usually forbidden by ... More

Tensor functors between Morita duals of fusion categoriesJul 10 2014Oct 04 2016Given a fusion category $\mathcal{C}$ and an indecomposable $\mathcal{C}$-module category $\mathcal{M}$, the fusion category $\mathcal{C}^*_\mathcal{M}$ of $\mathcal{C}$-module endofunctors of $\mathcal{M}$ is called the (Morita) dual fusion category ... More

Cohomology of finite tensor categories: duality and Drinfeld centersJul 23 2018Feb 15 2019This work concerns the finite generation conjecture for finite tensor categories (Etingof and Ostrik '04), which proposes that for such a category C, the self-extension algebra of the unit Ext*_C(1,1) is a finitely generated algebra and that, for each ... More

Mapping tori of small dilatation irreducible train-track mapsSep 25 2012Nov 23 2012We prove that for every P there is a bound B depending only on P so that the mapping torus of every P--small irreducible train-track map can be obtained by surgery from one of B mapping tori. We show that given an integer P>0 there is a bound $M$ depending ... More

Holographic optical trappingJun 13 2005Holographic optical tweezers use computer-generated holograms to create arbitrary three-dimensional configurations of single-beam optical traps useful for capturing, moving and transforming mesoscopic objects. Through a combination of beam-splitting, ... More

Magnetically Confined Wind Shocks in X-rays - a ReviewSep 22 2015A subset (~ 10%) of massive stars present strong, globally ordered (mostly dipolar) magnetic fields. The trapping and channeling of their stellar winds in closed magnetic loops leads to magnetically confined wind shocks (MCWS), with pre-shock flow speeds ... More

A dense geodesic ray in the $Out(F_r)$-quotient of reduced Outer SpaceAug 23 2015Jun 03 2016In 1981 Masur proved the existence of a dense geodesic in the moduli space for a Teichm\"uller space. We prove an analogue theorem for reduced Outer Space endowed with the Lipschitz metric. We also prove two results possibly of independent interest: we ... More

Solvability of a class of braided fusion categoriesMay 10 2012We show that a weakly integral braided fusion category C such that every simple object of C has Frobenius-Perron dimension at most 2 is solvable. In addition, we prove that such a fusion category is group-theoretical in the extreme case where the universal ... More

On fusion categories with few irreducible degreesMar 11 2011Nov 04 2011We prove some results on the structure of certain classes of integral fusion categories and semisimple Hopf algebras under restrictions on the set of its irreducible degrees.

Support varieties for finite tensor categories: Complexity and tensor productsMay 16 2019We advance support variety theory for finite tensor categories. We prove that the dimension of the support variety of an object is equal to the rate of growth of a minimal projective resolution as measured by Frobenius-Perron dimension. We ask when the ... More