A5022860121- Black Holes and Theoretical Physics
- Cosmology and Gravitation Theories
- Noncommutative and Quantum Gravity Theories
- Quantum Chromodynamics and Particle Interactions
- Quantum Mechanics and Applications
- Quantum Electrodynamics and Casimir Effect
- Particle physics theoretical and experimental studies
- Topological Materials and Phenomena
- Physics of Superconductivity and Magnetism
- Quantum many-body systems
- Quantum and electron transport phenomena
- Advanced Differential Geometry Research
- Geometric Analysis and Curvature Flows
- Quantum Information and Cryptography
- Advanced Topics in Algebra
- Theoretical and Computational Physics
- Nonlinear Waves and Solitons
- Homotopy and Cohomology in Algebraic Topology
- Algebraic and Geometric Analysis
- Quantum Computing Algorithms and Architecture
- Spectral Theory in Mathematical Physics
- Algebraic structures and combinatorial models
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Operator Algebra Research
- Quantum chaos and dynamical systems
Universidad de Zaragoza
2016-2025
University of Illinois Urbana-Champaign
2015
Max Planck Institute of Quantum Optics
2011
Universidad de Sevilla
2010
The Open University
2010
Western University
2005
Universidade Federal de Juiz de Fora
2005
Universidade Federal do Rio de Janeiro
1995
Harvard University
1989
Sorbonne Université
1981
The exploration of the universe has recently entered a new era thanks to multi-messenger paradigm, characterized by continuous increase in quantity and quality experimental data that is obtained detection various cosmic messengers (photons, neutrinos, rays gravitational waves) from numerous origins. They give us information about their sources properties intergalactic medium. Moreover, astronomy opens up possibility search for phenomenological signatures quantum gravity. On one hand, most...
Abstract The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions various possible theories gravity put to test, where a clear signal properties is still missing. dawn multi-messenger high-energy astrophysics tremendously beneficial, as it allows us study particles with much higher energies travelling longer distances than in terrestrial experiments, but more progress needed on several fronts. A thorough appraisal current...
We analyze the perturbative implications of most general high derivative approach to quantum gravity based on a diffeomorphism-invariant local action. In particular, we consider superrenormalizable case with large number metric derivatives in The structure ultraviolet divergences is analyzed some detail. show that they are independent gauge-fixing condition and choice field reparametrization. cosmological counterterm shown vanish under certain parameter conditions. elaborate unitarity...
A bstract One of the remarkable differences between renormalizable quantum gravity with four-derivative action and its superrenormalizable polynomial generalizations is that latter admit a more sophisticated particle mass spectrum. Already in simplest case, theory has six-derivative Lagrangian, admitting either real or complex spectrum masses. In case spectrum, there are graviton, massive unphysical ghosts, normal particles masses exceeding ones ghosts. It also possible to have pairs...
The infrared behaviour of quantum field theories confined in bounded domains is strongly dependent on the shape and structure space boundaries. most significant physical effect arises vacuum energy. Casimir energy can be attractive or repulsive depending nature boundary. We calculate for a massless scalar between two homogeneous parallel plates with general type boundary conditions four parameters. analysis provides powerful method to identify which generate forces plates. In interface both...
We analyze the global theory of boundary conditions for a constrained quantum system with classical configuration space compact Riemannian manifold M regular Γ=∂M. The ℳ self-adjoint extensions covariant Laplacian on is shown to have interesting geometrical and topological properties which are related different closures M. In this sense, change topology connected nontrivial structure ℳ. itself can be identified unitary group [Formula: see text] Hilbert data text]. This description,...
We analyze the unitarity properties of higher derivative quantum field theories which are free ghosts and ultraviolet singularities. point out that in spite absence most these not unitary. This result confirms difficulties finding a consistent theory gravity.
A sample of some relevant developments that have taken place during the last twenty years in classical and quantum tomography are displayed. We will present a general conceptual framework provides simple unifying mathematical picture for all them and, as an effective use it, three subjects been chosen offer wide panorama scope tomography: along lines submanifolds, coherent state abstract algebraic setting systems.
The one-loop structure of the trace anomaly is investigated using different regularizations and renormalization schemes: dimensional, proper time Pauli-Villars. universality this analyzed from a very general perspective. Euler Weyl terms anomalous stress tensor are absolutely universal. pure derivative $ \square R$-term shown to be universal only if regularization breaks conformal symmetry softly. If breaking by method hard coefficient term might become arbitrary which points out presence an...
We show that regularization of gauge theories by higher covariant derivatives and invariant Pauli-Villars regulators is a consistent method if the vector fields are considered in regulating pathological original Slavnov proposal Landau not correct because appearance massless modes which do decouple when ultraviolet regulator removed. In such case does correspond to pure theory but interaction with ghost fields. This explains problems pointed out Martin Ruiz gauge. However, minor modification...
The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions various possible theories gravity put to test. dawn multi-messenger high-energy astrophysics tremendously beneficial, as it allows us study particles with much higher energies travelling longer distances than in terrestrial experiments, but more progress is needed on several fronts. A thorough appraisal current strategies experimental frameworks, regarding...
Analytical arguments suggest that the Casimir energy in 2+1 dimensions for gauge theories exponentially decays with distance between boundaries. The phenomenon has also been observed by non-perturbative numerical simulations. dependence of this exponential decay on different boundary conditions could help to better understand infrared behavior these and particular their mass spectrum. A similar is expected 3+1 dimensions. Motivated feature we analyze massive scalar fields dimensional...
The consistency of quantum field theories defined on domains with external borders imposes very restrictive constraints the type boundary conditions that fields can satisfy. We analyse global geometrical and topological properties space all possible for scalar theories. variation Casimir energy under change reveals existence singularities generically associated which either involve topology changes underlying physical or edge states unbounded below classical energy. effect be understood in...
We point out that the evolution of a quantum system can be considered as parallel transport unitary operators in Hilbert spaces along time with respect to generalized connection. The different representations are shown correspond choices cross sections principal fiber bundle where connection is defined. This interpre- tation allows us solve problem formulation particle four-dimensional gauge field.
The quantum planar rotor is chosen as a model to test different approximate techniques, emphasizing the analogies between this simple system and non-Abelian gauge field theories (instantons, $\ensuremath{\theta}$ vacuum, etc.). In particular, variational perturbative methods, path-integral Monte Carlo simulations are applied. It pointed out that maximal destructive interference instantons takes place in $\ensuremath{\theta}$-vacuum realization of interacting with...
We introduce several possible generalizations of tomography to curved surfaces. analyze different types elliptic, hyperbolic, and hybrid tomograms. In all cases it is consistently define the inverse tomographic map. find two ways introducing sections. The first method operates by deformations standard Radon transform. second proceeds shifting a given quadric pattern. most general transformation can be defined in terms marginals over surfaces generated complete families hyperplanes or...
The theory of self-adjoint extensions first- and second-order elliptic differential operators on manifolds with boundary is studied via its most representative instances: Dirac Laplace operators. developed by exploiting the geometrical structures attached to them and, using an adapted Cayley transform each case, space [Formula: see text] such shown have a canonical group composition law structure. obtained results are compared von Neumann's theorem characterizing densely defined symmetric...
The meaning of local observables is poorly understood in gauge theories, not to speak quantum gravity. As a step towards better understanding we study asymptotic (infrared) transformations physics. Our are smeared by test functions, at first vanishing infinity. In this context show that the equations motion can be seen as constraints, which generate group, group space and time dependent transformations. This one main points paper. Infrared nontrivial effects captured allowing functions do...