The Experts below are selected from a list of 30 Experts worldwide ranked by ideXlab platform

Olaf Hohm - One of the best experts on this subject based on the ideXlab platform.

  • Geometry and dynamics of higher-Spin Frame fields
    Journal of High Energy Physics, 2008
    Co-Authors: Johan Engquist, Olaf Hohm
    Abstract:

    We give a systematic account of unconstrained free bosonic higher-Spin fields on D-dimensional Minkowski and (Anti-)de Sitter spaces in the Frame formalism. The generalized Spin connections are determined by solving a chain of torsion-like constraints. Via a generalization of the vielbein postulate these allow to determine higher-Spin Christoffel symbols, whose relation to the de Wit-Freedman connections is discussed. We prove that the generalized Einstein equations, despite being of higher-derivative order, give rise to the AdS Fronsdal equations in the compensator formulation. To this end we derive Damour-Deser identities for arbitrary Spin on AdS. Finally we discuss the possibility of a geometrical and local action principle, which is manifestly invariant under unconstrained higher-Spin symmetries.

Johan Engquist - One of the best experts on this subject based on the ideXlab platform.

  • Geometry and dynamics of higher-Spin Frame fields
    Journal of High Energy Physics, 2008
    Co-Authors: Johan Engquist, Olaf Hohm
    Abstract:

    We give a systematic account of unconstrained free bosonic higher-Spin fields on D-dimensional Minkowski and (Anti-)de Sitter spaces in the Frame formalism. The generalized Spin connections are determined by solving a chain of torsion-like constraints. Via a generalization of the vielbein postulate these allow to determine higher-Spin Christoffel symbols, whose relation to the de Wit-Freedman connections is discussed. We prove that the generalized Einstein equations, despite being of higher-derivative order, give rise to the AdS Fronsdal equations in the compensator formulation. To this end we derive Damour-Deser identities for arbitrary Spin on AdS. Finally we discuss the possibility of a geometrical and local action principle, which is manifestly invariant under unconstrained higher-Spin symmetries.

Diego Julio Cirilo-lombardo - One of the best experts on this subject based on the ideXlab platform.

  • The mathematical and geometrical structure of the spacetime and the concept of unification, matter and energy
    Physics of Particles and Nuclei, 2013
    Co-Authors: Diego Julio Cirilo-lombardo
    Abstract:

    Geometrical analysis of a new type of Unified Field Theoretical models follow the guidelines of previous works of the authors is presented. These new unified theoretical models are characterized by an underlying hypercomplex structure, zero non-metricity and the geometrical action is determined fundamentally by the curvature provenient of the breaking of symmetry of a group manifold in higher dimensions. This mechanism of Cartan-MacDowell-Mansouri type, permits us to construct geometrical actions of determinantal type leading a non topological physical Lagrangian due the splitting of a reductive geometry. Our goal is to take advantage of the geometrical and topological properties of this theory in order to determine the minimal group structure of the resultant spacetime Manifold able to support a fermionic structure. From this fact, the relation between antisymmetric torsion and Dirac structure of the spacetime is determined and the existence of an important contribution of the torsion to the giromagnetic factor of the fermions, shown. Also we resume and analyze previous cosmological solutions in this new UFT where, as in our work [Class. Quantum Grav. 22 (2005) 4987–5004] for the non abelian Born-Infeld model, the Hosoya and Ogura ansatz is introduced for the important cases of tratorial, totally antisymmetric and general torsion fields. In the case of spacetimes with torsion the real meaning of the Spin-Frame alignment is find and the question of the minimal coupling is discussed.

  • Unified Field Theoretical Models from Generalized Affine Geometries III
    International Journal of Theoretical Physics, 2011
    Co-Authors: Diego Julio Cirilo-lombardo
    Abstract:

    In this work the underlying structure of new type of Unified Field Theoretical model introduced in by the authors is elucidated and analyzed from the geometrical and group theoretical point of view. Our goal is to take advantage of the geometrical and topological properties of this theory in order to determine the minimal group structure of the resultant spacetime manifold able to support a fermionic structure. From this fact, the relation between antisymmetric torsion and Dirac structure of the spacetime is determined and important physical consequences enumerated. In the case of spacetime with torsion the real meaning of the Spin-Frame alignment is find and the question of the minimal coupling is discussed based in the important cases of tratorial, totally antisymmetric and general torsion fields.

L. Fatibene - One of the best experts on this subject based on the ideXlab platform.

  • Spin Frame transformations and Dirac equations.
    arXiv: Differential Geometry, 2019
    Co-Authors: R. Noris, L. Fatibene
    Abstract:

    We define Spin Frames, with the aim of extending Spin structures from the category of (pseudo-)Riemannian manifolds to the category of Spin manifolds with a fixed signature on them, though with no selected metric structure. Because of this softer requirements, transformations allowed by Spin Frames are more general than usual Spin transformations and they usually do not preserve the induced metric structures. We study how these new transformations affect connections both on the Spin bundle and on the Frame bundle and how this reflects on the Dirac equations.

Zhang Jian-hua - One of the best experts on this subject based on the ideXlab platform.