arXiv subjects

S. Salgado

Publications and source records attributed to S. Salgado.

8 recordsLinked to original sources

arXiv2024

Boson-fermion algebraic mapping in second quantization

We present an algebraic method to derive the structure at the basis of the mapping of bosonic algebras of creation and annihilation operators into fermionic algebras, and vice versa, introducing a suitable identification between bosonic and fermionic generators. The algebraic structure thus obtained corresponds to a deformed Grassmann algebra, involving anticommuting Grassmann-type variables. The role played by the latter in the implementation of gauge invariance in second quantization within our procedure is then discussed, together with the application of the mapping to the case of the bosonic and fermionic harmonic oscillator Hamiltonians.

hep-th↗

arXiv2023

Non-linear realizations and invariant action principles in higher gauge theory

We propose an extension of the formalism developed by Stelle-West and Grignani-Nardelli to the case of FDAs. We first consider the case of FDAs carrying one $p$-form extension and no non-trivial cohomology. We show that it is possible to define large gauge transformations as a direct extension of the large transformations induced by their Lie subalgebras and study the resulting non-linear realizations. Furthermore, we extend the results to the case FDAs with non-trivial cohomology by introducing large gauge transformations that carry the information about the FDA cocycle structure constants. We consider two examples of this type of gauge algebra, namely, FDA extensions of the bosonic Poincar\'{e} and Maxwell algebras, write down their dual $L_{\infty}$ algebras and study their non-linear realizations and possible invariant action principles.

hep-th↗

arXiv2021

On the $L_\infty$ formulation of Chern-Simons theories

$L_{\infty}$ algebras have been recently studied as algebraic frameworks in the formulation of gauge theories in which the gauge symmetries and the dynamics of the interacting theories are contained in a set of products acting on a graded vector space. On the other hand, FDAs are differential algebras that generalize Lie algebras by including higher-degree differential forms on their differential equations. In this article, we review the dual relation between FDAs and $L_{\infty}$ algebras. We study the formulation of standard Chern--Simons theories in terms of $L_{\infty}$ algebras and extend the results to FDA-based gauge theories. We focus on two cases, namely a flat (or zero-curvature) theory and a generalized Chern--Simons theory, both including high-degree differential forms as fundamental fields.

hep-th↗

arXiv2021

Gauge-invariant theories and higher-degree forms

A free differential algebra is generalization of a Lie algebra in which the mathematical structure is extended by including of new Maurer-Cartan equations for higher-degree differential forms. In this article, we propose a generalization of the Chern-Weil theorem for free differential algebras containing only one $p$-form extension. This is achieved through a generalization of the covariant derivative, leading to an extension of the standard formula for Chern-Simons and transgression forms. We also study the possible existence of anomalies originated on this kind of structure. Some properties and particular cases are analyzed.

hep-th↗

arXiv2018

4D spin-2 fields from 5D Chern-Simons theory

We consider a 5-dimensional Chern-Simons gauge theory for the isometry group of Anti-de-Sitter spacetime, $\operatorname{AdS}_{4+1}\simeq\operatorname{SO}(4,2)$, and invoke different dimensional reduction schemes in order to relate it to 4-dimensional spin-2 theories. The AdS gauge algebra is isomorphic to a parametrized 4-dimensional conformal algebra, and the gauge fields corresponding to the generators of non-Abelian translations and special conformal transformations reduce to two vierbein fields in $D=4$. Besides these two vierbeine, our reduction schemes leave only the Lorentz spin connection as an additional dynamical field in the 4-dimensional theories. We identify the corresponding actions as particular generalizations of Einstein-Cartan theory, conformal gravity and ghost-free bimetric gravity in first-order form.

gr-qc↗

arXiv2017

Extended gauge theory and gauged Free Differential Algebras

Recently, Antoniadis, Konitopoulos and Savvidy introduced, in the context of the so-called extended gauge theory, a procedure to construct background-free gauge invariants, using non-abelian gauge potentials described by higher degree forms. In this article it is shown that the extended invariants found by Antoniadis, Konitopoulos and Savvidy can be constructed from an algebraic structure known as Free Differential Algebra. In other words, we show that the above mentioned non abelian gauge theory, where the gauge fields are described by p-forms with p>1, can be obtained by gauging Free Differential Algebras.

hep-th↗

arXiv2016

Einstein-Hilbert action with cosmological term from Chern-Simons gravity

We propose a modification to the Lie algebra $S$-expansion method. The modification is carried out by imposing a condition on the $S$-expansion procedure, when the semigroup is given by a cyclic group of even order. The $S$-expanded algebras are called $S_{H}$-expanded algebras where $S=Z_{2n}$. The invariant tensors for $S_{H}$-expanded algebras are calculated and the dual formulation of $S_{H}$-expansion procedure is proposed. We consider the $S_{H}$-expansion of the five-dimensional $AdS$ algebra and its corresponding invariants tensors are found. Then a Chern-Simons Lagrangian invariant under the five-dimensional $AdS$ algebra $S_{H}$-expanded is constructed and its relationship to the general relativity is studied.

math-ph↗

arXiv2016

Generalized Galilean Algebras and Newtonian Gravity

The non-relativistic versions of the generalized Poincaré algebras and generalized $AdS$-Lorentz algebras are obtained. This non-relativistic algebras are called, generalized Galilean algebras type I and type II and denoted by $\mathcal{G}\mathfrak{B}_{n}$ and $\mathcal{G}\mathfrak{L}_{_{n}}$ respectively. Using a generalized Inönü--Wigner contraction procedure we find that the generalized Galilean algebras type I can be obtained from the generalized Galilean algebras type II. The $S$-expansion procedure allows us to find the $\mathcal{G}\mathfrak{B}_{_{5}}$ algebra from the Newton--Hooke algebra with central extension. The procedure developed in Ref. \cite{newton} allow us to show that the non-relativistic limit of the five dimensional Einstein--Chern--Simons gravity is given by a modified version of the Poisson equation. The modification could be compatible with the effects of Dark Matter, which leads us to think that Dark Matter can be interpreted as a non-relativistic limit of Dark Energy.

hep-th↗