Results for "Diego Rubiera-Garcia"

total 10638took 0.18s
Accelerated observers and the notion of singular spacetimeOct 24 2017Jan 18 2018Geodesic completeness is typically regarded as a basic criterion to determine whether a given spacetime is regular or singular. However, the principle of general covariance does not privilege any family of observers over the others and, therefore, observers ... More
Minimum main sequence mass in quadratic Palatini $f(\mathcal{R})$ gravityJun 11 2019General Relativity yields an analytical prediction of a minimum required mass of roughly $\sim 0.08-0.09 M_{\odot}$ for a star to stably burn sufficient hydrogen to fully compensate photospheric losses and, therefore, to belong to the main sequence. Those ... More
Gauss-Bonnet black holes supported by a nonlinear electromagnetic fieldMar 14 2015We study $D$-dimensional charged static spherically symmetric black hole solutions in Gauss-Bonnet theory coupled to nonlinear electrodynamics defined as arbitrary functions of the field invariant and constrained by several physical conditions. These ... More
New scalar compact objects in Ricci-based gravity theoriesJun 11 2019Taking advantage of a previously developed method, which allows to map solutions of General Relativity into a broad family of theories of gravity based on the Ricci tensor (Ricci-based gravities), we find new exact analytical scalar field solutions by ... More
Novel couplings between nonmetricity and matterJan 03 2019We present a novel theory of gravity, namely, an extension of symmetric teleparallel gravity. This is done by introducing a new class of theories where the nonmetricity $Q$ is coupled nonminimally to the matter Lagrangian. This nonminimal coupling entails ... More
On gravitational waves in Born-Infeld inspired non-singular cosmologiesJul 27 2017Jul 03 2018We study the evolution of gravitational waves for non-singular cosmological solutions within the framework of Born-Infeld inspired gravity theories, with special emphasis on the Eddington-inspired Born-Infeld theory. We review the existence of two types ... More
Nonsingular charged black holes à la PalatiniJul 18 2012We argue that the quantum nature of matter and gravity should lead to a discretization of the allowed states of the matter confined in the interior of black holes. To support and illustrate this idea, we consider a quadratic extension of General Relativity ... More
Non-topological solitons in field theories with kinetic self-couplingMay 01 2007Aug 07 2007We investigate some fundamental features of a class of non-linear relativistic lagrangian field theories with kinetic self-coupling. We focus our attention upon theories admitting static, spherically symmetric solutions in three space dimensions which ... More
Geons as wormholes of modified gravityJan 02 2016Wormholes may arise as solutions of extensions of General Relativity without violation of the energy conditions. Working in a Palatini approach we consider classical geometries supporting such wormholes. It is shown that the resulting space-times represent ... More
Soliton solutions in relativistic field theories and gravitationDec 11 2007Mar 26 2011We report on some recent results on a class of relativistic lagrangian field theories supporting non-topological soliton solutions and their applications in the contexts of Gravitation and Cosmology. We analyze one and many-components scalar fields and ... More
Generalized gauge field theories with non-topological soliton solutionsAug 04 2007We perform a systematic analysis of the conditions under which \textit{generalized} gauge field theories of compact semisimple Lie groups exhibit electrostatic spherically symmetric non-topological soliton solutions in three space dimensions. By the term ... More
Positive Ricci curvature on simply-connected manifolds with cohomogeneity-two torus actionsSep 20 2016May 13 2019A gap in the proof of the main result in reference [1] in our original submission propagated into the constructions presented in the first version of our manuscript. In this version we give an alternative proof for the existence of Riemannian metrics ... More
What is a singular black hole beyond General Relativity?Feb 04 2017Exploring the characterization of singular black hole spacetimes, we study the relation between energy density, curvature invariants, and geodesic completeness using a quadratic $f(R)$ gravity theory coupled to an anisotropic fluid. Working in a metric-affine ... More
Wormholes as a cure for black hole singularitiesJan 02 2016Using exactly solvable models, it is shown that black hole singularities in different electrically charged configurations can be cured. Our solutions describe black hole space-times with a wormhole giving structure to the otherwise point-like singularity. ... More
Einstein-Cartan-Dirac gravity with $U(1)$ symmetry breakingFeb 06 2019Einstein-Cartan theory is an extension of the standard formulation of General Relativity where torsion (the antisymmetric part of the affine connection) is non-vanishing. Just as the space-time metric is sourced by the stress-energy tensor of the matter ... More
Cosmological future singularities in interacting dark energy modelsJul 21 2016Dec 05 2016The existence of interactions between dark matter and dark energy has been widely studied, since they can fit well the observational data and may provide new physics through such an interaction. In this work we analyze these models and investigate their ... More
Q-singularitiesJul 21 2016The existence of interactions among dark matter and dark energy have been widely studied in the literature, since such models fit well the observational data and may provide new physics through such an interaction. Here we analyze this kind of models, ... More
Lyapunov decay in quantum irreversibilityDec 14 2015The Loschmidt echo -- also known as fidelity -- is a very useful tool to study irreversibility in quantum mechanics due to perturbations or imperfections. Many different regimes, as a function of time and strength of the perturbation, have been identified. ... More
Photon-mediated qubit interactions in 1D discrete and continous modelsFeb 19 2015In this work we study numerically and analytically the interaction of two qubits in a one-dimensional waveguide, as mediated by the photons that propagate through the guide. We develop strategies to assert the Markovianity of the problem, the effective ... More
Explaining Deep Classification of Time-Series Data with Learned PrototypesApr 18 2019The emergence of deep learning networks raises a need for algorithms to explain their decisions so that users and domain experts can be confident using algorithmic recommendations for high-risk decisions. In this paper we leverage the information-rich ... More
Structure and dynamics in low density regions: galaxy-galaxy correlations inside cosmic voidsDec 13 2018We compute the galaxy-galaxy correlation function of low-luminosity SDSS-DR7 galaxies $(-20 < M_{\rm r} - 5\log_{10}(h) < -18)$ inside cosmic voids identified in a volume limited sample of galaxies at $z=0.085$. To identify voids, we use bright galaxies ... More
Compact Groups analysis using weak gravitational lensingFeb 01 2017We present a weak lensing analysis of a sample of SDSS Compact Groups (CGs). Using the measured radial density contrast profile, we derive the average masses under the assumption of spherical symmetry, obtaining a velocity dispersion for the Singular ... More
On the binary origin of FS CMa stars: young massive clusters as test bedsOct 17 2016Oct 21 2016FS CMa stars are low-luminosity objects showing the B[e] phenomenon whose evolutionary origin is yet to be unraveled. Various binary-related hypotheses have been recently proposed, two of them involving the spiral-in evolution of the binary orbit. The ... More
Palatini wormholes and energy conditions from the prism of General RelativityJul 05 2016Nov 09 2017Wormholes are hypothetical shortcuts in spacetime that in General Relativity unavoidably violate all of the pointwise energy conditions. In this paper, we consider several wormhole spacetimes that, as opposed to the standard \emph{designer} procedure ... More
Born-Infeld inspired modifications of gravityApr 11 2017May 17 2017General Relativity has shown an outstanding observational success in the scales where it has been directly tested. However, modifications have been intensively explored in the regimes where it seems either incomplete or signals its own limit of validity. ... More
A correspondence between modified gravity and General Relativity with scalar fieldsOct 09 2018Jan 22 2019We describe a novel procedure to map the field equations of nonlinear Ricci-based metric-affine theories of gravity, coupled to scalar matter described by a given Lagrangian, into the field equations of General Relativity coupled to a different scalar ... More
Coupling matter in modified $Q$-gravityJun 27 2018We present a novel theory of gravity by considering an extension of symmetric teleparallel gravity. This is done by introducing, in the framework of the metric-affine formalism, a new class of theories where the nonmetricity $Q$ is nonminimally coupled ... More
Early-time cosmic dynamics in $f(R)$ and $f(|\hatΩ|)$ extensions of Born-Infeld gravityNov 23 2014We consider two types of modifications of Born-Infeld gravity in the Palatini formulation and explore their dynamics in the early universe. One of these families considers $f(R)$ corrections to the Born-Infeld Lagrangian, which can be seen as modifications ... More
Mapping nonlinear gravity into General Relativity with nonlinear electrodynamicsJul 17 2018Oct 26 2018We show that families of nonlinear gravity theories formulated in a metric-affine approach and coupled to a nonlinear theory of electrodynamics can be mapped into General Relativity (GR) coupled to another nonlinear theory of electrodynamics. This allows ... More
Uncertainties in Atmospheric Muon-Neutrino Fluxes Arising from Cosmic-Ray PrimariesDec 09 2016We present an updated calculation of the uncertainties on the atmospheric muon-neutrino flux arising from cosmic-ray primaries. For the first time, we include recent measurements of the cosmic-ray primaries collected since 2005. We apply a statistical ... More
The sparkling Universe: Clustering of voids and void clumpsMar 30 2017We analyse the clustering of cosmic voids using a numerical simulation and the main galaxy sample from the Sloan Digital Sky Survey. We take into account the classification of voids into two types that resemble different evolutionary modes: those with ... More
Void DynamicsOct 29 2014Cosmic voids are becoming key players in testing the physics of our Universe. Here we concentrate on the abundances and the dynamics of voids as these are among the best candidates to provide information on cosmological parameters. Cai, Padilla \& Li ... More
Charged black holes in Palatini $f(R)$ theoriesJan 10 2013In $f(R)$ extensions of General Relativity the Palatini approach provides ghost-free theories with second-order field equations and allows to obtain charged black hole solutions which depart from the standard Reissner-Nordstr\"om solution.
Palatini $f(R)$ Black Holes in Nonlinear ElectrodynamicsOct 04 2011The electrically charged Born-Infeld black holes in the Palatini formalism for $f(R)$ theories are analyzed. Specifically we study those supported by a theory $f(R)=R\pm R^2/R_P$, where $R_P$ is Planck's curvature. These black holes only differ from their ... More
Nonsingular Black Holes in $f(R)$ TheoriesSep 08 2015We study the structure of a family of static, spherically symmetric space-times generated by an anisotropic fluid and governed by a particular type of $f(R)$ theory. We find that for a range of parameters with physical interest, such solutions represent ... More
Brane-world and loop cosmology from a gravity-matter coupling perspectiveMay 28 2014We show that the effective brane-world and the loop quantum cosmology background expansion histories can be reproduced from a modified gravity perspective in terms of an $f(R)$ gravity action plus a $g(R)$ term non-minimally coupled with the matter Lagrangian. ... More
Semiclassical geons at particle acceleratorsJun 27 2013Jan 31 2014We point out that in certain four-dimensional extensions of general relativity constructed within the Palatini formalism stable self-gravitating objects with a discrete mass and charge spectrum may exist. The incorporation of nonlinearities in the electromagnetic ... More
Deforming solitons in generalized Abelian Higgs modelsNov 09 2011Apr 09 2012This work deals with several aspects of the extension to Abelian Higgs models of the deformation method originally developed for scalar field models. We present several examples allowing to transform self-dual solutions of different generalized Abelian ... More
Nonsingular black holes in quadratic Palatini gravityDec 02 2011Jul 25 2012We find that if general relativity is modified at the Planck scale by a Ricci-squared term, electrically charged black holes may be nonsingular. These objects concentrate their mass in a microscopic sphere of radius $r_{core}\approx N_q^{1/2}l_P/3$, where ... More
The quantum, the geon, and the crystalJul 28 2015Effective geometries arising from a hypothetical discrete structure of space-time can play an important role in the understanding of the gravitational physics beyond General Relativity. To discuss this question, we make use of lessons from crystalline ... More
Non-Riemannian geometry: towards new avenues for the physics of modified gravityJun 06 2015Less explored than their metric (Riemannian) counterparts, metric-affine (or Palatini) theories bring an unexpected phenomenology for gravitational physics beyond General Relativity. Lessons of crystalline structures, where the presence of defects in ... More
BPS solitons in a Dirac-Born-Infeld actionJan 31 2014We present several classes of solitons in ($1+1$)-dimensional models where the standard canonical kinetic term is replaced by a Dirac-Born-Infeld (DBI) one. These are static solutions with finite energy and different properties, namely, they can have ... More
Nonsingular Black Holes in Palatini Extensions of General RelativityJan 11 2013We discuss static, spherically symmetric solutions with an electric field in a quadratic extension of general relativity formulated in the Palatini approach (assuming that metric and connection are independent fields). Unlike the usual metric formulation ... More
Importance of torsion and invariant volumes in Palatini theories of gravityJun 18 2013Oct 26 2013We study the field equations of extensions of General Relativity formulated within a metric-affine formalism setting torsion to zero (Palatini approach). We find that different (second-order) dynamical equations arise depending on whether torsion is set ... More
Black hole solutions in functional extensions of Born-Infeld gravityAug 17 2016Sep 08 2016We consider electrovacuum black hole spacetimes in classical extensions of Eddington-inspired Born-Infeld gravity. By rewriting Born-Infeld action as the square root of the determinant of a matrix $\hat{\Omega}$, we consider the family of models $f (|\hat{\Omega}|)$, ... More
Thermodynamic analysis of black hole solutions in gravitating nonlinear electrodynamicsApr 11 2012Sep 28 2013We perform a general study of the thermodynamic properties of static electrically charged black hole solutions of nonlinear electrodynamics minimally coupled to gravitation in three space dimensions. The Lagrangian densities governing the dynamics of ... More
Reissner-Nordström black holes in extended Palatini theoriesJul 25 2012We study static, spherically symmetric solutions with an electric field in an extension of general relativity (GR) containing a Ricci-squared term and formulated in the Palatini formalism. We find that all the solutions present a central core whose area ... More
Generalized sine-Gordon solitonsJun 20 2011Jul 26 2011In this paper we construct analytical self-dual soliton solutions in (1+1) dimensions for two families of models which can be seen as generalizations of the sine-Gordon system but where the kinetic term is non-canonical. For that purpose we use a projection ... More
A Production Oriented Approach for Vandalism Detection in Wikidata - The Buffaloberry Vandalism Detector at WSDM Cup 2017Dec 19 2017Wikidata is a free and open knowledge base from the Wikimedia Foundation, that not only acts as a central storage of structured data for other projects of the organization, but also for a growing array of information systems, including search engines. ... More
On-surface route for producing planar nanographenes with azulene moietiesDec 15 2017Large aromatic carbon nanostructures are cornerstone materials due to their increasingly active role in functional devices, but their synthesis in solution encounters size and shape limitations. New on-surface strategies facilitate the synthesis of large ... More
Voids and Superstructures: correlations and induced large-scale velocity flowsMay 18 2017The expanding complex pattern of filaments, walls and voids build the evolving cosmic web with material flowing from underdense onto high density regions. Here we explore the dynamical behaviour of voids and galaxies in void shells relative to neighboring ... More
Classical resolution of black hole singularities via wormholesApr 27 2015Mar 05 2016In certain extensions of General Relativity, wormholes generated by spherically symmetric electric fields can resolve black hole singularities without necessarily removing curvature divergences. This is shown by studying geodesic completeness, the behavior ... More
Quadratic Palatini gravity and stable black hole remnantsNov 25 2013We present a four-dimensional Planck-scale corrected quadratic extension of General Relativity (GR) where no a priori relation between metric and connection is imposed (Palatini formalism). Static spherically symmetric electrovacuum solutions are obtained ... More
Black holes in extended gravity theories in Palatini formalismJan 14 2013We consider several physical scenarios where black holes within classical gravity theories including $R^2$ and Ricci-squared corrections and formulated \`a la Palatini can be analytically studied.
Unveiling the Dynamics of the UniverseJul 11 2016Jul 27 2016We explore the dynamics and evolution of the Universe at early and late times, focusing on both dark energy and extended gravity models and their astrophysical and cosmological consequences. Modified theories of gravity not only provide an alternative ... More
Melvin Universe in Born-Infeld gravityApr 08 2015We consider a magnetic flux pointing in the $z$ direction of an axially symmetric space-time (Melvin Universe) in a Born-Infeld-type extension of General Relativity (GR) formulated in the Palatini approach. Large magnetic fields could have been produced ... More
Geonic black holes and remnants in Eddington-inspired Born-Infeld gravityNov 04 2013Apr 28 2014We show that electrically charged solutions within the Eddington-inspired Born-Infeld theory of gravity replace the central singularity by a wormhole supported by the electric field. As a result, the total energy associated with the electric field is ... More
Crystal clear lessons on the microstructure of space-time and modified gravityDec 15 2014Jun 12 2015We argue that a microscopic structure for space-time such as that expected in a quantum foam scenario, in which microscopic wormholes and other topological structures should play a relevant role, might lead to an effective metric-affine geometry at larger ... More
Born-Infeld gravity and its functional extensionsJun 04 2014Aug 04 2014We investigate the dynamics of a family of functional extensions of the (Eddington-inspired) Born-Infeld gravity theory, constructed with the inverse of the metric and the Ricci tensor. We provide a generic formal solution for the connection and an Einstein-like ... More
Semiclassical geons as solitonic black hole remnantsJun 11 2013We find that the end state of black hole evaporation could be represented by non-singular and without event horizon stable solitonic remnants with masses of the order the Planck scale and up to 16 units of charge. Though these objects are locally indistinguishable ... More
Geodesic completeness in a wormhole spacetime with horizonsAug 13 2015The geometry of a spacetime containing a wormhole generated by a spherically symmetric electric field is investigated in detail. These solutions arise in high-energy extensions of General Relativity formulated within the Palatini approach and coupled ... More
Black holes in five-dimensional Palatini $f(R)$ gravity and implications for the AdS/CFT correspondenceMay 01 2014We show that theories having second-order field equations in the context of higher-dimensional modified gravity are not restricted to the family of Lovelock Lagrangians, but can also be obtained if no a priori assumption on the relation between the metric ... More
Compact vortex in a generalized Born-Infeld modelMar 25 2011Nov 17 2011We study vortexlike solutions in a generalized Born-Infeld model. The model is driven by two distinct parameters, one which deals with the Born-Infeld term, and the other, which controls the presence of high-order power term in the covariant derivative ... More
Black hole formation from a null fluid in extended Palatini gravitySep 15 2012We study the formation and perturbation of black holes by null fluxes of neutral matter in a quadratic extension of General Relativity formulated a la Palatini. Working in a spherically symmetric space-time, we obtain an exact analytical solution for ... More
Microscopic wormholes and the geometry of entanglementFeb 20 2014Jun 02 2014It has recently been suggested that Einstein-Rosen (ER) bridges can be interpreted as maximally entangled states of two black holes that form a complex Einstein-Podolsky-Rosen (EPR) pair. This relationship has been dubbed as the ER = EPR correlation. ... More
Impact of curvature divergences on physical observers in a wormhole space-time with horizonsFeb 04 2016The impact of curvature divergences on physical observers in a black hole space-time which, nonetheless, is geodesically complete is investigated. This space-time is an exact solution of certain extensions of General Relativity coupled to Maxwell's electrodynamics ... More
Geometric aspects of charged black holes in Palatini theoriesJun 06 2015Charged black holes in gravity theories in the Palatini formalism present a number of unique properties. Their innermost structure is topologically nontrivial, representing a wormhole supported by a sourceless electric flux. For certain values of their ... More
Nonsingular BTZ-type solutions of $2+1$ Born-Infeld gravitySep 19 2016We study Born-Infeld gravity coupled to a static, nonrotating electric field in $2+1$ dimensions and find exact analytical solutions. Two families of such solutions represent geodesically complete, and hence nonsingular, spacetimes. Another family represents ... More
Mapping Ricci-based theories of gravity into general relativityJan 31 2018We show that the space of solutions of a wide family of Ricci-based metric-affine theories of gravity can be put into correspondence with the space of solutions of general relativity (GR). This allows us to use well-established methods and results from ... More
Bottom up synthesis of multifunctional nanoporous grapheneApr 25 2018Nanosize pores can turn semimetallic graphene into a semiconductor and from being impermeable into the most efficient molecular sieve membrane. However, scaling the pores down to the nanometer, while fulfilling the tight structural constraints imposed ... More
21-cm synthesis observations of VIRGOHI 21 - a possible dark galaxy in the Virgo ClusterJun 11 2007Many observations indicate that dark matter dominates the extra-galactic Universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously we have suggested that VIRGOHI 21, a 21-cm source we found in the ... More
Nonlinear Schrödinger equation on graphs: recent results and open problemsApr 03 2013Apr 08 2013In the present paper an introduction to the new subject of nonlinear dispersive hamiltonian equations on graphs is given. The focus is on recently established properties of solutions in the case of nonlinear Schr\"odinger equation. Special consideration ... More
Working with 2s and 3sApr 09 2007We establish an equivalent condition to the validity of the Collatz conjecture, using elementary methods. We derive some conclusions and show several examples of our results. We also offer a variety of exercises, problems and conjectures.
An Arithmetic MetricJun 03 2009What is the distance between 11 (a prime number) and 12 (a highly composite number)? If your answer is 1, then ask yourself "is this reasonable?" In this work, we will introduce a distance between natural numbers based on their arithmetic properties, ... More
Polynomial Sequences Associated with the Moments of Hypergeometric WeightsNov 19 2015Apr 29 2016We present some families of polynomials related to the moments of weight functions of hypergeometric type. We also consider different types of generating functions, and give several examples.
Fisher information of orthogonal polynomials IAug 20 2007Following the lead of J. Dehesa and his collaborators, we compute the Fisher information of the Meixner-Pollaczek, Meixner, Krawtchouk and Charlier polynomials.
Polynomial solutions of nonlinear integral equationsMar 12 2008We analyze the polynomial solutions of a nonlinear integral equation, generalizing the work of C. Bender and E. Ben-Naim. We show that, in some cases, an orthogonal solution exists and we give its general form in terms of kernel polynomials.
Asymptotic analysis of the Hermite polynomials from their differential-difference equationJan 04 2006We analyze the Hermite polynomials $H_{n}(x)$ and their zeros asymptotically, as $n\to\infty.$ We obtain asymptotic approximations from the differential-difference equation which they satisfy, using the ray method. We give numerical examples showing the ... More
Asymptotic analysis of the Askey-scheme I: from Krawtchouk to CharlierJan 05 2005We analyze the Charlier polynomials C(n,x)and their zeros asymptotically for large n. We obtain asymptotic approximations, using the limit relation between the Krawtchouk and Charlier polynomials, involving some special functions. We give numerical examples ... More
Some functional inequalities on polynomial volume growth Lie groupsSep 16 2010Jan 21 2011We study in this article some Sobolev-type inequalities on polynomial volume growth Lie groups. We show in particular that improved Sobolev inequalities can be extended without the use of the Littlewood-Paley decomposition to this general framework.
An extension of the classical derivativeMar 22 2006Mar 24 2006We extend the usual definition of the derivative in a way that Calculus I students can easily comprehend and which allows calculations at branch points.
Some remarks on the Wu-Sprung potential. Preliminary reportOct 17 2005Some observations on the Wu-Sprung potential.
How to build a gravity generatorJun 25 2012Aug 04 2013This article explores a simple way to construct an electric device capable to generate an artificial gravitational field by exploiting a resonance phenomenon.
Three amalgams with remarkable normal subgroup structuresJun 15 2005We construct three groups $\Lambda_1$, $\Lambda_2$, $\Lambda_3$, which can all be decomposed as amalgamated products $F_9 \ast_{F_{81}} F_{9}$ and have very few normal subgroups of finite or infinite index. Concretely, $\Lambda_1$ is a simple group, $\Lambda_2$ ... More
On infinite groups generated by two quaternionsFeb 24 2005Oct 06 2006Let $x$, $y$ be two integral quaternions of norm $p$ and $l$, respectively, where $p$, $l$ are distinct odd prime numbers. We investigate the structure of $<x,y>$, the multiplicative group generated by $x$ and $y$. Under a certain condition which excludes ... More
Counting $(1,β)$-BM relations and classifying $(2,2)$-BM groupsJul 11 2006In the first part, we prove that the number of $(1,\beta)$-BM relations is $3 \cdot 5 \cdot \ldots \cdot (2\beta + 1)$, which was conjectured by Kimberley. In the second part, we construct two isomorphisms between certain $(2,2)$-BM groups. This completes ... More
Holographic dark energy and late cosmic accelerationOct 02 2006It has been persuasively argued that the number of the effective degrees of freedom of a macroscopic system is proportional to its area rather than to its volume. This entails interesting consequences for cosmology. Here we present a model based on this ... More
Nonperturbative Ground State of the Stochastic Stabilization of 2D Quantum GravityOct 14 1993May 23 1994I construct the ground state, up to first nonperturbative order, of the stochastic stabilization of the zero dimensional matrix model which defines 2D Quantum Gravity. It is given by the linear combination of a perturbative wave function and a nonperturbative ... More
Reduction of internal degrees of freedom in the large N limit in matrix modelsJun 02 1997Nov 05 1998In this paper the large $N$ limit of one hermitian matrix models coupled to an external matrix is considered. It is shown that in the large N limit the number of degrees of freedom are reduced to be order N even though it is order $N^{2}$ for finite N. ... More
Dualité et principe local-global sur des corps locaux de dimension 2May 04 2016Let $k$ be an algebraically closed field, a finite field or a $p$-adic field. Let $K_0=k((x,y))$ be the field of Laurent series in two variables over $k$. We define Tate-Shafarevich groups of a commutative group scheme over $K_0$ via cohomology classes ... More
Towards the Use of Deep Reinforcement Learning with Global Policy For Query-based Extractive SummarisationNov 10 2017Nov 14 2017Supervised approaches for text summarisation suffer from the problem of mismatch between the target labels/scores of individual sentences and the evaluation score of the final summary. Reinforcement learning can solve this problem by providing a learning ... More
Harnack's inequality for solutions to the linearized Monge-Ampere equation under minimal geometric assumptionsOct 24 2011Mar 16 2012We prove a Harnack inequality for solutions to $L_A u = 0$ where the elliptic matrix $A$ is adapted to a convex function satisfying minimal geometric conditions. An application to Sobolev inequalities is included.
Lagrangian submanifolds from tropical hypersurfacesApr 04 2018We prove that a smooth tropical hypersurface in $\mathbb{R}^3$ can be lifted to a smooth embedded Lagrangian submanifold in $(\mathbb{C}^*)^3$. This completes the proof of the result announced in the article "Lagrangian pairs pants" arXiv:1802.02993. ... More
Lagrangian pairs of pantsFeb 08 2018We construct a Lagrangian submanifold, inside the cotangent bundle of a real torus, which we call a Lagrangian pair of pants. It is given as the graph of the differential of a smooth function defined on the real blow up of a Lagrangian coamoeba. Lagrangian ... More
Cohomogeneity one Einstein-Sasaki 5-manifoldsJun 14 2006Mar 19 2007We consider hypersurfaces in Einstein-Sasaki 5-manifolds which are tangent to the characteristic vector field. We introduce evolution equations that can be used to reconstruct the 5-dimensional metric from such a hypersurface, analogous to the (nearly) ... More
Vanishing theorems and Brauer-Hasse-Noether exact sequences for the cohomology of higher-dimensional fieldsMar 23 2018Jun 07 2018Let $k$ be a finite field, a $p$-adic field or a number field. Let $K$ be a finite extension of the Laurent series field in $m$ variables $k((x_1,...,x_m))$ or, more generally, a finite extension of the field of rational functions $k((x_1,...,x_m))(y_1,...,y_n)$. ... More
Théorèmes de dualité pour les corps de fonctions sur des corps locaux supérieurs et applications arithmétiquesMay 08 2014Jun 01 2014Let $K$ be the function field of a smooth projective curve $X$ over a higher-dimensional local field $k$. We define Tate-Shafarevich groups of a commutative group scheme via cohomology classes locally trivial at each completion of $K$ coming from a closed ... More
Some observations on a Kapteyn seriesOct 03 2005We study the Kapteyn series $% %TCIMACRO{\dsum \limits_{n=1}^{\infty}}% %BeginExpansion {\displaystyle\sum\limits_{n=1}^{\infty}} %EndExpansion t^{n}\mathrm{J}_{n}(nz) $. We find a series representation in powers of $z$ and analyze its radius of convergence. ... More
LHCb anomalies from a natural perspectiveNov 10 2016Mar 29 2017Tension between the Standard Model (SM) and data concerning $b \rightarrow s$ processes has become apparent. Most notoriously, concerning the $R_K$ ratio, which probes lepton non-universality in $b$ decays, and measurements involving the decays $B \rightarrow ... More
Integral representation of the Ising modelOct 17 2005The partition function of the 2D Ising model coupled to an external magnetic field is studied. We show that the sum over the spin variables can be reduced to an integration over a finite number of variables. This integration must be performed numerically. ... More