Multisymplectic Lagrangian and Hamiltonian Formalisms of Classical Field Theories

This review paper is devoted to presenting the standard multisymplectic formulation for describing geometrically classical field theories, both the regular and singular cases. First, the main features of the Lagrangian formalism are revisited and, second, the Hamiltonian formalism is constructed using Hamiltonian sections. In both cases, the variational principles leading to the Euler-Lagrange and the Hamilton-De Donder-Weyl equations, respectively, are stated, and these field equations are given in different but equivalent geometrical ways in each formalism. Finally, both are unified in a new formulation (which has been developed in the last years), following the original ideas of Rusk and Skinner for mechanical systems.Comment: v1: 17 pages, Talk presented in the "MAT.ES2005: 1st Joint Meeting of Mathematics RSME-SCM-SEIO-SEMA" (Valencia, Spain 2005, http://www.uv.es/mat.es2005/); v3: published versio

Sobre las interacciones fundamentales, las partículas elementales y las teorías de campos

Peer Reviewe

Sobre las interacciones fundamentales, las partículas elementales y las teorías de campos

Peer Reviewe

Multisymplectic unified formalism for Einstein-Hilbert gravity

We present a covariant multisymplectic formulation for the Einstein-Hilbert model of General Relativity. As it is described by a second-order singular Lagrangian, this is a gauge field theory with constraints. The use of the unified Lagrangian-Hamiltonian formalism is particularly interest- ing when it is applied to these kinds of theories, since it simplifies the treatment of them; in particular, the implementation of the constraint algorithm, the retrieval of the Lagrangian description, and the construction of the covariant Hamiltonian formalism. In order to apply this algorithm to the co- variant field equations, they must be written in a suitable geometrical way, which consists of using integrable distributions, represented by multivector fields of a certain type. We apply all these tools to the Einstein-Hilbert model without and with energy-matter sources. We obtain and explain the geometrical and physical meaning of the Lagrangian constraints and we construct the multimomen- tum (covariant) Hamiltonian formalisms in both cases. As a consequence of the gauge freedom and the constraint algorithm, we see how this model is equivalent to a first-order regular theory, without gauge freedom. In the case of presence of energy-matter sources, we show how some relevant geo- metrical and physical characteristics of the theory depend on the type of source. In all the cases, we obtain explicitly multivector fields which are solutions to the gravitational field equations. Finally, a brief study of symmetries and conservation laws is done in this context.Peer ReviewedPostprint (author's final draft

Order reduction, projectability and constrainsts of second-order field theories and higuer-order mechanics

The consequences of the projectability of Poincar\'e-Cartan forms in a third-order jet bundle $J^3\pi$ to a lower-order jet bundle are analyzed using the constraint algorithm for the Euler-Lagrange equations in $J^3\pi$. The results are applied to the Hilbert Lagrangian for the Einstein equations. Furthermore, the case of higher-order mechanics is also studied as a particular situation.Peer ReviewedPostprint (author's final draft

A summary on symmetries and conserved quantities of autonomous Hamiltonian systems

A complete geometric classification of symmetries of autonomous Hamiltonian systems is established; explaining how to obtain their associated conserved quantities in all cases. In particular, first we review well-known results and properties about the symmetries of the Hamiltonian and of the symplectic form and then some new kinds of non-symplectic symmetries and their conserved quantities are introduced and studied.I acknowledge the financial support from the Spanish Ministerio de Econom´ıa y Competitividad project MTM2014–54855–P, the Ministerio de Ciencia, Innovaci´on y Universidades project PGC2018-098265-BC33, and the Secretary of University and Research of the Ministry of Business and Knowledge of the Catalan Government project 2017–SGR–932. I also greatly appreciate the comments and suggestions of Prof. Mikhail S. Plyushchay. Finally, my thanks to the referees for their extensive and valuable comments that have allowed me to significantly improve the final version of the work.Postprint (author's final draft

An overview of the Hamilton–Jacobi theory: the classical and geometrical approaches and some extensions and applications

This work is devoted to review the modern geometric description of the Lagrangian and Hamiltonian formalisms of the Hamilton–Jacobi theory. The relation with the “classical” Hamiltonian approach using canonical transformations is also analyzed. Furthermore, a more general framework for the theory is also briefly explained. It is also shown how, from this generic framework, the Lagrangian and Hamiltonian cases of the theory for dynamical systems are recovered, as well as how the model can be extended to other types of physical systems, such as higher-order dynamical systems and (first-order) classical field theories in their multisymplectic formulation.I acknowledge the financial support from project PGC2018-098265-B-C33 of the Spanish Ministerio de Ciencia, Innovación y Universidades and the project 2017–SGR–932 of the Secretary of University and Research of the Ministry of Business and Knowledge of the Catalan Government.Peer ReviewedPostprint (published version

Variational Principles for multisymplectic second-order classical field theories

We state a unified geometrical version of the variational principles for second-order classical field theories. The standard Lagrangian and Hamiltonian variational principles and the corresponding field equations are recovered from this unified framework.Comment: 6 pp. Minor corrections. Clarifications and comments have been added. Two new sections ("Introduction" and "The higher-order case") have been added. Bibliography enlarge