Results for "Jorge Davila"

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Solutions of the Yamabe Equation By Lyapunov-Schmidt ReductionDec 10 2018Given any closed Riemannian manifold $(M,g)$ we use the Lyapunov-Schmidt finite-dimensional reduction method to prove multiplicity results for positive solutions of a subcritical Yamabe type equation on $(M,g)$. If $(N,h)$ is a closed Riemannian manifold ... More
Enhanced Robot Speech Recognition Using Biomimetic Binaural Sound Source LocalizationFeb 13 2019Inspired by the behavior of humans talking in noisy environments, we propose an embodied embedded cognition approach to improve automatic speech recognition (ASR) systems for robots in challenging environments, such as with ego noise, using binaural sound ... More
Characterizations of the Connected Forcing Number of a GraphApr 04 2016Zero forcing is a dynamic graph coloring process whereby a colored vertex with a single uncolored neighbor forces that neighbor to be colored. This forcing process has been used to approximate certain linear algebraic parameters, as well as to model the ... More
Total Forcing and Zero Forcing in Claw-Free Cubic GraphsAug 16 2017A dynamic coloring of the vertices of a graph $G$ starts with an initial subset $S$ of colored vertices, with all remaining vertices being non-colored. At each discrete time interval, a colored vertex with exactly one non-colored neighbor forces this ... More
Sliding Motions on SO(3), Sliding SubgroupsMay 14 2019We propose a sliding surface for systems on the Lie group $SO(3)\times \mathbb{R}^3$ . The sliding surface is shown to be a Lie subgroup. The reduced-order dynamics along the sliding subgroup have an almost globally asymptotically stable equilibrium. ... More
A Vizing-type result for semi-total dominationMar 13 2018A set of vertices $S$ in a simple isolate-free graph $G$ is a semi-total dominating set of $G$ if it is a dominating set of $G$ and every vertex of $S$ is within distance 2 or less with another vertex of $S$. The semi-total domination number of $G$, denoted ... More
Anyons in 1+1 DimensionsMar 20 1995The possibility of excitations with fractional spin and statististics in $1+1$ dimensions is explored. The configuration space of a two-particle system is the half-line. This makes the Hamiltonian self-adjoint for a family of boundary conditions parametrized ... More
On asymptotic property CNov 18 2016Asymptotic property C was introduced by Dranishnikov to study spaces with infinite asymptotic dimension. We show that asymptotic property C is preserved by infinite products. We also show that countable restricted direct products of countable groups with ... More
Noncollinear cluster magnetism in the framework of the Hubbard modelMar 19 1999Mar 21 1999Noncollinear magnetic states in clusters are studied by using the single-band Hubbard Hamiltonian. The unrestricted Hartree-Fock (UHF) approximation is considered without imposing any symmetry constraints neither to the size or orientation of the local ... More
Matters of Gravity, the newsletter of the APS TG on gravitationFeb 09 1998Contents: *News: Topical group news, by Jim Isenberg April 1997 Joint APS/AAPT Meeting, GTG program, by Abhay Ashtekar Formation of the Gravitational-Wave International Committee, by Sam Finn The 1997 Xanthopoulos award, by Abhay Asthekar We hear that..., ... More
Dynamical invariants and diffusion of merger substructures in time-dependent gravitational potentialsMay 28 2013This paper explores a mathematical technique for deriving dynamical invariants (i.e. constants of motion) in time-dependent gravitational potentials. The method relies on the construction of a canonical transformation that removes the explicit time-dependence ... More
The Heavy Quark Free Energy in QCD and in Gauge Theories with Gravity DualsMar 03 2010Mar 19 2010We show that the Polyakov loop approaches its asymptotic value at high temperatures {\it from below} in any strongly-coupled gauge theory at large $N_c$ with a dual supergravity description. In these theories the Polyakov loop can be used to define a ... More
Connecting Polyakov Loops to the Thermodynamics of $SU(N_c)$ Gauge Theories Using the Gauge-String DualityOct 07 2009Mar 04 2010We show that in four-dimensional gauge theories dual to five-dimensional Einstein gravity coupled to a single scalar field in the bulk the derivative of the single heavy quark free energy in the deconfined phase is $dF_{Q}(T)/dT \sim -1/c_s^2(T)$, where ... More
Dense granular media as athermal glassesOct 16 2001I briefly describe how mean-field glass models can be extended to the case in which the bath and friction are non-thermal, thus promoting them to granular matter mean-field caricatures. Solving their dynamics one discovers a temperature with a thermodynamic ... More
(Super)-Gravities Beyond 4 DimensionsJun 18 2002Dec 04 2002These lectures are intended as a broad introduction to Chern Simons gravity and supergravity. The motivation for these theories lies in the desire to have a gauge invariant action -in the sense of fiber bundles- in more than three dimensions, which could ... More
Convergence of homogeneous manifoldsMay 11 2011Mar 02 2012We study in this paper three natural notions of convergence of homogeneous manifolds, namely infinitesimal, local and pointed, and their relationship with a fourth one, which only takes into account the underlying algebraic structure of the homogeneous ... More
On the moment map for the variety of Lie algebrasJun 05 2002Let V be the vector space of all skew-symmetric (non-associative) complex algebras of dimension n and L the algebraic subset of V of all Lie algebras. We consider the moment map for the action of GL(n) on the projective space P(V) and study the critical ... More
Spontaneous breaking of axial symmetry for Schroedinger's equation in the presence of a magnetic fieldSep 21 2000For appropriate parameters, the ground state for the Schroedinger and Ampere coupled equations in a cylindric domain does not have axial symmetry.
Flux-induced Nernst effect in a superconducting loopSep 03 2013Aug 26 2014When a superconducting ring encloses a magnetic flux that is not an integer multiple of half the quantum of flux, a voltage arises in the direction perpendicular to the temperature gradient. This effect is entirely due to thermal fluctuations. We study ... More
Confinement into a state with persistent current by thermal quenching of loop of Josephson junctionsApr 04 2007We study a loop of Josephson junctions that is quenched through its critical temperature. For three or more junctions, symmetry breaking states can be achieved without thermal activation, in spite of the fact that the relaxation time is practically constant ... More
A probability theory for non-equilibrium gravitational systemsJun 01 2015This paper uses dynamical invariants to describe the evolution of collisionless systems subject to time-dependent gravitational forces without resorting to maximum-entropy probabilities. We show that collisionless relaxation can be viewed as a special ... More
Approaches of near stars to the SunSep 05 2014We investigate aspects of computing the perihelion distances and impact parameters for near stars to the Sun, and, we analyze the solar motion. Keywords: perihelion distance, impact parameter, Oort cloud, solar motion
Reconstruction and stability for piecewise smooth potentials in the planeJun 09 2016Jul 15 2016We show that potentials with jump discontinuities can be recovered from the Dirichlet-to-Neumann map using Bukhgeim's method. Combining with known formulas, this enables the recovery from the scattering amplitude at a fixed energy. We also provide a priori ... More
Mass ratio determination from Halpha lines in Black-Hole X-ray transientsMar 29 2016May 10 2016We find that the mass ratio q in quiescent black hole (BH) X-ray transients is tightly correlated with the ratio of the double peak separation (DP) to the full-width-half maximum (FWHM) of the Halpha emission line, log q = -6.88 -23.2 log (DP/FWHM). The ... More
Laplacian flow of homogeneous G2-structures and its solitonsFeb 26 2016Nov 15 2016We use the bracket flow/algebraic soliton approach to study the Laplacian flow of $G_2$-structures and its solitons in the homogeneous case. We prove that any homogeneous Laplacian soliton is equivalent to a semi-algebraic soliton (i.e.\ a $G$-invariant ... More
General Navier-Stokes-like Momentum and Mass-Energy EquationsOct 22 2014Aug 29 2016A new system of general Navier-Stokes-like equations is proposed to model electromagnetic analogous to hydrodynamic. While most attempts to derive analogues of hydrodynamic to electromagnetic, and vice-versa, start with Navier-Stokes or a Euler approximation, ... More
Quantum bound to chaos and the semiclassical limitDec 05 2016We discuss the quantum bound on chaos in the context of the free propagation of a particle in an arbitrarily curved surface at low temperatures. The semiclassical calculation of the Lyapunov exponent can be performed in much the same way as the corresponding ... More
Effective bounds for quasiintegral points in orbits of rational mapsMar 15 2019We prove the existence of bounds for the number quasi-integral points in orbits of semigroups of rational maps under some conditions, exhibiting formulas for this.
Effective bounds for quasiintegral points in orbits of rational mapsMar 15 2019Apr 05 2019We prove the existence of bounds for the number quasi-integral points in orbits of semigroups of rational maps under some conditions, exhibiting formulas for this.
Propagators from characteristic surfacesJan 17 2005We study the Goursat or characteristic problem, i.e. a hyperbolic equation with given data on a surface (the half of the standard Cauchy problem), with some kind of dimensional regularization procedure to deal with the divergences that appear. We will ... More
Laplacian solitons: questions and homogeneous examplesMar 06 2017We give the first examples of closed Laplacian solitons which are shrinking, and in particular produce closed Laplacian flow solutions with a finite-time singularity. Extremally Ricci pinched G2-structures (introduced by Bryant) which are steady Laplacian ... More
Decoupling gravitational sources in general relativity: from perfect to anisotropic fluidsApr 19 2017Apr 28 2017We show the first simple, systematic and direct approach to decoupling gravitational sources in general relativity. As a direct application, a robust and simple way to generate anisotropic solutions for self-gravitating systems from perfect fluid solutions ... More
On the motion under focal attraction in a rotating mediumJan 29 2008New results are established here on the phase portraits and bifurcations of the kinematic model in a system of ODE's, first presented by H.K. Wilson in his 1971 book, and by him attributed to L. Markus (unpublished). A new, self-sufficient, study which ... More
Discontinuous Dynamical Systems: A tutorial on solutions, nonsmooth analysis, and stabilityJan 23 2009This paper considers discontinuous dynamical systems, i.e., systems whose associated vector field is a discontinuous function of the state. Discontinuous dynamical systems arise in a large number of applications, including optimal control, nonsmooth mechanics, ... More
Rings of star formation: Imprints of a close galaxy encounterDec 15 2014In this talk, I report results from galaxy merger simulations, which suggest the existence of a ring of star formation produced by close galaxy encounters. This is a generic feature of all galaxy interactions, provided that the disc spins are sufficiently ... More
Large B-Fields and Noncommutative SolitonsNov 13 2001The purpose of this talk is to review a few issues concerning noncommutativity arising from String Theory. In particular, it is shown how in Type IIB Theory, the annihilation of a D3-\bar{D3} brane pair yields a D1-string. This object, in the presence ... More
Pricing of Mexican Interest Rate Swaps in Presence of Multiple Collateral CurrenciesMar 02 2017The financial crisis of 2007/08 caused catastrophic consequences and brought a bunch of changes around the world. Interest rates that were known to follow or behave similarly of each other diverged. Furthermore, the regulation and in particular the counterparty ... More
On unitary representability of topological groupsJul 07 2006Jul 10 2006We prove that the additive group $(E^\ast,\tau_k(E))$ of an $\mathscr{L}_\infty$-Banach space $E$, with the topology $\tau_k(E)$ of uniform convergence on compact subsets of $E$, is topologically isomorphic to a subgroup of the unitary group of some Hilbert ... More
Mn I hyperfine structure in the near-infraredJun 10 1999Hyperfine interaction constants and hyperfine components of MnI lines in the near-infrared J and H bands were obtained by fitting the solar spectrum. I identified the 17744-A solar absorption line as resulting from MnI and I discarded the identifications ... More
Stochastic tidal heating by random interactions with extended substructuresJan 31 2019Gravitating systems surrounded by a dynamic sea of substructures experience fluctuations of the local tidal field which inject kinetic energy into the internal motions. This paper uses stochastic calculus techniques to describe `tidal heating' as a random ... More
Automating Truth: The Case for Crowd-Powered Scientific Investigation in EconomicsSep 07 2018Scientific investigation procedures have been evolving to follow an ever-changing cultural landscape, the sophistication of the technology available and an ever-growing knowledge base. This continuous evolution brought investigation practices through ... More
Comments on the repulsive term of Van der Waals equation of stateAug 07 2018The repulsive term of Van der Waals equation of state has been deduced and improved in this work using a probabilistic description of the configurational entropy. The aim is to find out whether its physical basis is suitable for the study of dense fluids ... More
$p$-adic derived formal geometry and derived Raynaud localization TheoremMay 08 2018The goal of the present text is to give a proof of an analogue of Raynaud localization theorem in the setting of derived geometry. More explicitly, we show that the \infcat of (good) derived $k$-analytic spaces can be realized as a localization of the ... More
Mathematical EncountersMar 24 2018Jul 29 2018This evocative essay focuses on mathematical activities witnessed by the author along 1962-64 at IMPA. The list of research problems proposed in September 1962 by Mauricio Peixoto at the Seminar on the Qualitative Theory of Differential Equations is pointed ... More
Hibernating black holes revealed by photometric mass functionsNov 09 2017We present a novel strategy to uncover the Galactic population of quiescent black holes (BHs). This is based on a new concept, the photometric mass function (PMF), which opens up the possibility of an efficient identification of dynamical BHs in large ... More
Moduli of $\ell$-adic representations of a profinite groupSep 13 2017Jun 13 2019Let $X$ be a smooth and proper scheme over an algebraically closed field. The purpose of the current text is twofold. Firstly, we construct the moduli stack parametrizing rank $n$ continuous $p$-adic representations of $\pi_1^\et(X)$ as a $\bQ_p$-analytic ... More
The Mass Spectrum of X-Ray BinariesMar 03 2005This review summarizes the observational constraints on the mass spectrum of compact objects in X-ray binaries. We currently have 20 X-ray binaries with confirmed black holes, based on dynamical information (i.e. mass in excess of 3 Msun). In two cases, ... More
A Quantum Fluctuation TheoremJul 24 2000Aug 16 2001We consider a quantum system strongly driven by forces that are periodic in time. The theorem concerns the probability $P(e)$ of observing a given energy change $e$ after a number of cycles. If the system is thermostated by a (quantum) thermal bath, $e$ ... More
Rheology, and how to stop agingDec 21 1998Recent analytical developments in glass theory are equally relevant to the understanding of anomalous rheology, with characteristic features such as the Reynolds dilatancy and the driving-power dependence of the viscosity arising naturally. A notion of ... More
Einstein solvmanifolds are standardMar 15 2007Feb 02 2010We study Einstein manifolds admitting a transitive solvable Lie group of isometries (solvmanifolds). It is conjectured that these exhaust the class of noncompact homogeneous Einstein manifolds. J. Heber has showed that under certain simple algebraic condition ... More
Characterization of the spontaneous symmetry breaking due to quenching of a one-dimensional superconducting loopJan 05 2013Apr 25 2013We study the final distribution of the winding numbers in a 1D superconducting ring that is quenched through its critical temperature in the absence of magnetic flux. The study is conducted using the stochastic time-dependent Ginzburg--Landau model, and ... More
The Fight Against the Second Law of ThermodynamicsFeb 05 1995Jan 15 1997After presenting possible motives for fighting against the second law of thermodynamics, several attempts to beat this law are analyzed. The second law wins, but an interesting interpretation of it emerges. This interpretation uses the notion of ``encoded ... More
The ADM papers and part of their modern legacy: loop quantum gravityMay 08 2015We present a summary for non-specialists of loop quantum gravity as part of the modern legacy of the series of papers by Arnowitt, Deser and Misner circa 1960.
Deriving Conclusions From Non-Monotonic Cause-Effect RelationsAug 02 2016We present an extension of Logic Programming (under stable models semantics) that, not only allows concluding whether a true atom is a cause of another atom, but also deriving new conclusions from these causal-effect relations. This is expressive enough ... More
The Asymptotics of Representations for Cyclic OpersSep 20 2016Given a Riemann surface $X = (\Sigma, J)$ we find an expression for the dominant term for the asymptotics of the holonomy of opers over that Riemann surface corresponding to rays in the Hitchin base of the form $(0,0,\cdots,t\omega_n)$. Moreover, we find ... More
Polyelectrolyte Polypeptide Scaling Laws Via Mechanical and Dielectric Relaxation MeasurementsSep 17 2016Experimental results from mechanical viscoelastic as well as dielectric relaxation times were compared to theoretical expectations utilizing polymer scaling theory. Viscoelastic relaxation of a hydrogel at 33% relative humidity fabricated from co-poly-L-(glutamic ... More
Strong diquark correlations inside the protonAug 10 2015Quantum Chromodynamics is thought to be the relativistic quantum field theory that describes the strong interaction of the Standard Model. This interaction produces mesons but it is also able to generate quark-quark (diquark) correlations inside baryons. ... More
A simple proof for the multivariate Chebyshev inequalityMay 24 2013In this paper a simple proof of the Chebyshev's inequality for random vectors obtained by Chen (arXiv:0707.0805v2, 2011) is obtained. This inequality gives a lower bound for the percentage of the population of an arbitrary random vector X with finite ... More
LIV Dimensional Regularization and Quantum Gravity effects in the Standard ModelJan 17 2005Recently, we have remarked that the main effect of Quantum Gravity(QG) will be to modify the measure of integration of loop integrals in a renormalizable Quantum Field Theory. In the Standard Model this approach leads to definite predictions, depending ... More
Noncommutative geometry of groups like $Γ_0(N)$Mar 21 2013We show that the Connes-Marcolli $GL_{2}$-system can be represented on the Big Picture, a combinatorial gadget introduced by Conway in order to understand various results about congruence subgroups pictorially. In this representation the time evolution ... More
Arithmetic structures on noncommutative tori with real multiplicationOct 04 2006Jan 03 2007We study the homogeneous coordinate rings of real multiplication noncommutative tori as defined by A. Polishchuk. Our aim is to understand how these rings give rise to an arithmetic structure on the noncommutative torus. We start by giving an explicit ... More
Towards a quantitative understanding of high $p_T$ flow harmonicsOct 31 2016In this proceedings I briefly review the recent progress achieved on the calculation of $v_n$ at high $p_T$ via the coupling of a jet energy loss model with full event-by-event viscous hydrodynamics. It is shown that that this framework can simultaneously ... More
Bertini-type theorems for formal functions in grassmanniansJun 21 2010The present note generalizes Debarre's Bertini-type results for in- verse images of Schubert varieties with the extension of formal func- tions.
Energy conserving nonholonomic integratorsSep 24 2002Mar 28 2003We address the problem of constructing numerical integrators for nonholonomic Lagrangian systems that enjoy appropriate discrete versions of the geometric properties of the continuous flow, including the preservation of energy. Building on previous work ... More
Halo Pairs in the Millennium Simulation: Love & DeceptionNov 30 2011In this work I investigate the statistical properties of a huge catalog of closely interacting pairs of dark matter haloes, extracted from the Millennium Simulation database. Only haloes that reach a minimum mass greater than 8.6 \times 10^10 Msun/h (corresponding ... More
The Cosmic Evolution of Halo Pairs: I. Global TrendsJun 16 2011Aug 29 2011Accumulating evidence suggests that galaxy interactions play an important role in shaping the properties of galaxies. For this reason, cosmological studies focused on the evolution of halo/subhalo pairs are vital. In this paper I describe a large catalogue ... More
Equivalences for noncommutative projective spacesJan 25 2010Mar 14 2011Following Artin and Zhang's formulation of noncommutative projective geometry, we classify up a family of skew polynomial quadratic algebras up to graded Morita equivalence and their corresponding noncommutative projective spaces up to birational equivalences. ... More
A Low Solar Oxygen Abundance from the First Overtone OH LinesJul 16 2004An extremely high-resolution (> 10^5) high-S/N (> 10^3) solar spectrum has been used to measure 15 very weak first overtone (Delta v = 2) infrared OH lines, resulting in a low solar abundance of A(O) ~ 8.6 when MARCS, 3D, and spatially and temporally ... More
Periodical plane puzzles with numbersJun 06 2011Consider a periodical (in two independent directions) tiling of the plane with polygons (faces). In this article we shall only give examples using squares, regular hexagons, equilateral triangles and parallelograms ("unions" of two equilateral triangles). ... More
Examples of Anosov diffeomorphismsMar 13 2002We give a simple procedure to construct explicit examples of nilmanifolds admitting an Anosov diffeomorphism, and show that a reasonable classification up to homeomorphism (or even up to commensurability) of such nilmanifolds would not be possible.
On variation of dynamical canonical heights, and Intersection numbersJul 29 2017We study families of varieties endowed with polarized canonical eigensystems of several maps, inducing canonical heights on the dominating variety as well as on the "good" fibers of the family. We show explicitely the dependence on the parameter for global ... More
Ab initio study of proper topological ferroelectricity in layered perovskite La2Ti2O7Jan 11 2011We present a first-principles investigation of ferroelectricity in layered perovskite oxide La2Ti2O7 (LTO), one of the compounds with highest Curie temperature known (1770 K). Our calculations reveal that LTO's ferroelectric transition results from the ... More
Decomposition complexity growth of finitely generated groupsFeb 22 2019Feb 25 2019Finite decomposition complexity and asymptotic dimension growth are two generalizations of M. Gromov's asymptotic dimension which can be used to prove property A for large classes of finitely generated groups of infinite asymptotic dimension. In this ... More
Cyclic metric Lie groupsJul 02 2014Jul 21 2014Cyclic metric Lie groups are Lie groups equipped with a left-invariant metric which is in some way far from being biinvariant, in a sense made explicit in terms of Tricerri and Vanhecke's homogeneous structures. The semisimple and solvable cases are studied. ... More
Comparison of methods for computing the exchange energy in laterally coupled quantum dotsSep 16 2010Mar 11 2015We calculate the exchange energy in two dimensional laterally coupled quantum dots using Heitler-London, Hund-Mullikan and variational methods. We assess the quality of these approximations in zero and finite magnetic fields comparing against numerically ... More
Supercurrent fluctuations in short filamentsSep 11 2011We evaluate the average and the standard deviation of the supercurrent in superconducting nanobridges, as functions of the temperature and the phase difference, in an equilibrium situation. We also evaluate the autocorrelation of the supercurrent as a ... More
Derivation of the Langevin equation from the principle of detailed balanceSep 03 2009Jun 03 2010For a system at given temperature, with energy known as a function of a set of variables, we obtain the thermal fluctuation of the evolution of the variables by replacing the phase-space with a lattice and invoking the principle of detailed balance. Besides ... More
Influence of Thermal Fluctuations on Uniform and Nonuniform Superconducting Rings according to the Ginzburg--Landau and the Kramer--Watts-Tobin ModelsApr 14 2009Jun 12 2010We evaluate the influence of thermal fluctuations on superconducting rings that enclose a magnetic flux, using the time-dependent Ginzburg--Landau (TDGL) or the Kramer--Watts-Tobin (KWT) model, while thermal fluctuations are accounted for by means of ... More
Noise rectification by a superconducting loop with two weak linksMay 07 2003Jul 14 2004We consider a superconducting loop with two weak links that encloses a magnetic flux. The weak links are unequal and are treated as Josephson junctions with non-sinusoidal phase dependence. We devise a model that takes into account the fluctuation of ... More
Extension of the de Broglie-Bohm theory to the Ginzburg-Landau equationSep 19 2003The de Broglie-Bohm approach permits to assign well defined trajectories to particles that obey the Schroedinger equation. We extend this approach to electron pairs in a superconductor. In the stationary regime this extension is completely natural; in ... More
Influence of the boundary conditions on the current flow pattern along a superconducting wireJan 26 2015We study the patterns at which the current flow stabilizes in a 1D superconducting wire, for various experimentally reasonable boundary conditions, for small fixed current densities and temperatures close to $T_c$. We pay special attention to the possible ... More
Effective field theory investigations of the XYZ puzzleMar 28 2016Quantum Chromodynamics, the theory of strong interactions, predicts several types of bound states. Among them are mesons ($q\bar{q}$) and baryons ($qqq$), which have been the only states observed in experiments for years. However, in the last decade, ... More
Six out of equilibrium lecturesJan 09 2009Jan 18 2009Index: 1) Trajectories, distributions and path integrals. 2) Time-reversal and Equilibrium 3) Separation of timescales 4) Large Deviations 5) Metastability and dynamical phase transitions 6) Fluctuation Theorems and Jarzynski equality
Fluctuation theorem for stochastic dynamicsSep 26 1997Feb 22 1998The fluctuation theorem of Gallavotti and Cohen holds for finite systems undergoing Langevin dynamics. In such a context all non-trivial ergodic theory issues are by-passed, and the theorem takes a particularly simple form. As a particular case, we obtain ... More
New Insights into X-ray BinariesApr 07 2009X-ray binaries are excellent laboratories to study collapsed objects. On the one hand, transient X-ray binaries contain the best examples of stellar-mass black holes while persistent X-ray binaries mostly harbour accreting neutron stars. The determination ... More
First-principles approach to lattice-mediated magnetoelectric effectsMar 06 2008We present a first-principles scheme for the computation of the magnetoelectric response of magnetic insulators. The method focuses on the lattice-mediated part of the magnetic response to an electric field, which we argue can be expected to be the dominant ... More
Transport Properties of QCD at Large $N_c$ and the Gauge/String DualityDec 24 2009Mar 06 2010Below the deconfinement phase transition large $N_c$ QCD is expected to be a very viscous hadronic fluid because both the shear and bulk viscosity to entropy density ratio, $\eta/s,\zeta/s \sim N_c^2$. In this letter I show that $\eta/s \sim N_c^2$ in ... More
Polyakov Loops in Strongly-Coupled Plasmas with Gravity DualsJan 18 2010We study the properties of the Polyakov loop in strongly-coupled gauge plasmas that are conjectured to be dual to five dimensional theories of gravity coupled to a nontrivial single scalar field. We find a gravity dual that can describe the thermodynamic ... More
Uses of Chern-Simons actionsMay 13 2008Jun 05 2008The role of Chern-Simons (CS) actions is reviewed, starting from the observation that all classical actions in Hamiltonian form can be viewed as 0+1 CS systems, in the same class with the coupling between the electromagnetic field and a point charge. ... More
Chern-Simons Gravity: From 2+1 to 2n+1 DimensionsOct 06 2000These lectures provide an elementary introduction to Chern Simons Gravity and Supergravity in $d=2n+1$ dimensions.
Supersymmetric solutions of gauged five-dimensional supergravity with general matter couplingsOct 02 2008Sep 22 2009We perform the characterization program for the supersymmetric configurations and solutions of the $\mathcal{N}=1$, $d=5$ Supergravity Theory coupled to an arbitrary number of vectors, tensors and hypermultiplets and with general non-Abelian gaugins. ... More
Minimal metrics on nilmanifoldsNov 11 2004A left invariant metric on a nilpotent Lie group is called minimal, if it minimizes the norm of the Ricci tensor among all left invariant metrics with the same scalar curvature. Such metrics are unique up to isometry and scaling and the groups admitting ... More
Pathological and Omega-transitive Representations of Free GroupsApr 25 2012Nov 13 2013Given a linear order $\Omega$ its automorphism group $\Aut(\Omega)$ forms a lattice-ordered group via pointwise order. Assuming the continuum to be a regular cardinal, we show that \emph{pathological} and \emph{$\omega$-transitive} (i.e. highly transitive) ... More
Canonical quantization of general relativity: the last 18 years in a nutshellSep 03 2002This is a summary of the lectures presented at the Xth Brazilian school on cosmology and gravitation. The style of the text is that of a lightly written descriptive summary of ideas with almost no formulas, with pointers to the literature. We hope this ... More
Una revisión a la teoría básica del CMB (A review of the basic theory of CMB)Sep 04 2014Spanish: La Cosmolog\'ia esta progresando a pasos agigantados gracias a la cantidad espectacular de datos observacionales que se obtienen tanto de los experimentos en tierra como sat\'elites. Un papel fundamental es desempe\~ndo por las observaciones ... More
Hybrid superconductor-semiconductor nanowire junctions as useful platforms to study Majorana bound statesMar 22 2017One of the most promising platforms for one-dimensional topological superconductivity is based on semiconducting nanowires with strong spin-orbit coupling (SOC), where s-wave superconductivity is induced by proximity effect and an external Zeeman field ... More
A $Sim(2)$ invariant dimensional regularizationApr 07 2017Jul 22 2018We introduce a $Sim(2)$ invariant dimensional regularization of loop integrals. Then we compute the one loop quantum corrections to the photon self energy, electron self energy and vertex in the Electrodynamics sector of the Very Special Relativity Standard ... More
Bv Gauge TheoriesFeb 07 1997Using the Non-Abelian Batalin-Vilkovisky formalism introduced recently, we present a generalization of the Yang-Mills gauge transformations , to include antisymmetric tensor fields as gauge bosons. The Freedman-Townsend transformation for the two-form ... More
Mandelstam-Leibbrandt prescriptionMar 21 2016The light cone gauge is used frequently in string theory as well as gauge theories and gravitation. Loop integrals however have to be infrared regulated to remove spurious poles. The most popular and consistent of these infrared regulators is the Mandelstam-Leibbrandt(ML) ... More
Superluminal neutrinos and the Standard ModelOct 16 2011Dec 10 2011Recently the OPERA collaboration {\cite{opera}} has reported the observation of superluminal neutrinos traveling a distance of 730 km from Grand Sasso Laboratory to CERN.These results contradict the basic tenet of the Theory of Special Relativity: No ... More