Matemática
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Exact phase space functional for two-body systems
(2010-11-21)The determination of the two-body density functional from its one-body density is achieved for Moshinsky's harmonium model, using a phase-space formulation, thereby resolving its phase dilemma. The corresponding sign rules ... -
Quantum gauge models without classical Higgs mechanism
(2010-09-15)We examine the status of massive gauge theories, such as those usually obtained by spontaneous symmetry breakdown, from the viewpoint of causal (Epstein-Glaser) renormalization. The BRST formulation of gauge invariance in ... -
Reconstruction of manifolds in noncommutative geometry
(2008-01-31)We show that the algebra A of a commutative unital spectral triple (A,H,D) satisfying several additional conditions, slightly stronger than those proposed by Connes, is the algebra of smooth functions on a compact spin manifold. -
Fourier analysis on the affine group, quantization and noncompact Connes geometries
(2008-04)We find the Stratonovich-Weyl quantizer for the nonunimodular affine group of the line. A noncommutative product of functions on the half-plane, underlying a noncompact spectral triple in the sense of Connes, is obtained ... -
A two-step estimation procedure for locally stationary ARMA processes with tempered stable innovations
(2023-03)The class of locally stationary processes assumes a time-varying (tv) spectral representation and finite second moment. Different areas have observed phenomena with heavy tail distributions or infinite variance. Using ... -
Teaching basic statistics to blind students
(2017)Understanding statistics has become extremely important not only for researchers but also for the general public in order to understand publications that include statistical analysis. Having in mind promoting ... -
Orbifolds are not commutative geometries
(2008)In this note we show that the crucial orientation condition for commutative geometries fails for the natural commutative spectral triple of an orbifold M/G. -
Dixmier traces on noncompact isospectral deformations
(2006)We extend the isospectral deformations of Connes, Landi and Dubois-Violette to the case of Riemannian spin manifolds carrying a proper action of the noncompact abelian group R^l. Under deformation by a torus action, a ... -
Combinatorics of renormalization as matrix calculus
(2006)We give a simple presentation of the combinatorics of renormalization in perturbative quantum field theory in terms of triangular matrices. The prescription, that may be of calculational value, is derived from first ... -
Indirect inference for locally stationary ARMA processes with stable innovations
(2020)The class of locally stationary processes assumes that there is a time-varying spectral representation, that is, the existence of finite second moment. We propose the α-stable locally stationary process by modifying the ... -
The local index formula for SU_q(2)
(2005)We discuss the local index formula of Connes-Moscovici for the isospectral noncommutative geometry that we have recently constructed on quantum SU(2). We work out the cosphere bundle and the dimension spectrum as well as ... -
The Dirac operator on SU_q(2)
(2005)We construct a 3^+ summable spectral triple (A(SU_q(2)),H,D) over the quantum group SU_q(2) which is equivariant with respect to a left and a right action of U_q(su(2)). The geometry is isospectral to the classical case ... -
Asociación entre la introducción de la vacuna contra el COVID-19 y el Índice Mensual de Actividad Económica en Costa Rica
(2023)Este trabajo es un esfuerzo por lograr asociar el comportamiento de la economía de Costa Rica afectada por las restricciones impuestas por la pandemia COVID-19 y la introducción de la vacuna contra el virus causante ... -
Examples of noncommutative geometrical spaces
(2004-01)We develop some examples of spectral triples in noncommutative geometry, on the theme of the noncommutative torus but with several variations. -
Moyal planes are spectral triples
(2004-04)Axioms for nonunital spectral triples, extending those introduced in the unital case by Connes, are proposed. As a guide, and for the sake of their importance in noncommutative quantum field theory, the spaces R^2N endowed ... -
The interface of noncommutative geometry and physics
(2004-01)As a mathematical theory per se, noncommutative geometry (NCG) is by now well established. From the beginning, its progress has been crucially influenced by quantum physics: we briefly review this development in recent ... -
Hopf algebras in noncommutative geometry
(2003)We give an introductory survey to the use of Hopf algebras in several problems of noncommutative geometry. The main example, the Hopf algebra of rooted trees, is a graded, connected Hopf algebra arising from a universal ... -
Quantum symmetry groups of noncommutative spheres
(2001-08)We show that the noncommutative spheres of Connes and Landi are quantum homogeneous spaces for certain compact quantum groups. We give a general construction of homogeneous spaces which support noncommutative spin geometries. -
Quantum electrodynamics in external fields from the spin representation
(1994-07)Systematic use of the infinite-dimensional spin representation simplifies and rigorizes several questions in quantum field theory. This representation permutes "Gaussian" elements in the fermion Fock space, and is necessarily ... -
The metaplectic representation and boson fields
(1991-12)We construct explicitly the infinite-dimensional metaplectic representation and show how its use simplifies and rigorizes several questions in bosonic Quantum Field Theory. The representation permutes Gaussian elements in ...
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