1,720,992 research outputs found
Progress in snyder model
No full textWe review the main features of the relativistic Snyder model and its generalizations. We discuss the quantum field theory on this background using the standard formalism of noncommutaive QFT and discuss the possibility of obtaining a finite theory
The snyder model and quantum field theory
Full text linkWe review the main features of the relativistic Snyder model and its generalizations. We discuss the quantum field theory on this background using the standard formalism of noncommutative QFT and discuss the possibility of obtaining a finite theory
Cyclotron frequency in the quantum clock geometry
No full textWe discuss the corrections to the orbital period of a particle in a constant magnetic field, driven by the model of noncommutative geometry recently associated to a quantum clock. The effects are extremely small, but in principle detectable
Dyonic black holes in nonlinear electrodynamics from Kaluza–Klein theory with a Gauss–Bonnet term
Full text linkFive-dimensional Kaluza-Klein theory with an Einstein-Gauss-Bonnet Lagrangian induces nonlinear corrections to the four-dimensional Maxwell equations, which however remain second-order. Although these corrections do not have effect on the purely electric or magnetic monopole solutions for pointlike charges, they affect the dyonic solutions, smoothing the electric field at the origin for positive values of the Gauss-Bonnet coupling constant. We investigate these solutions in flat space, and then extend them in the presence of a minimal coupling to gravity, obtaining exact charged black hole solutions that generalize the Reissner-Nordström metric
Yang Model Revisited
Full text linkA long time ago, C.N. Yang proposed a generalization of the Snyder model to the case of a curved background spacetime, based on an algebra isomorphic to o(1, 5) which includes, as subalgebras both the Snyder and the de Sitter algebras. His proposal can, therefore, be interpreted as a model of noncommutative curved spacetime, and could be useful for relating physics on very small and very large scales. We review this model and some recent progress concerning its generalizations and its interpretation in the framework of Hopf algebras. We also report some possibilities to relate it to more phenomenological aspects
Dyonic Black Holes in Kaluza-Klein Theory with a Gauss-Bonnet Action
Full text linkKaluza-Klein theory attempts a unification of gravity and electromagnetism through the hypothesis that spacetime has five dimensions, of which only four are observed. The original model gives rise to the standard Einstein-Maxwell theory after dimensional reduction. However, in five dimensions, the Einstein-Hilbert action is not unique, and one can add to it a Gauss-Bonnet term, giving rise to nonlinear corrections in the dimensionally reduced action. We consider such a model, which reduces to Einstein gravity nonminimally coupled to nonlinear electrodynamics. The black hole solutions of the four-dimensional model modify the Reissner-Nordstrom solutions of general relativity. We show that in the modified solutions, the gravitational field presents the standard singularity at r=0, while the electric field can be regular everywhere if the magnetic charge vanishes
Associative realizations of the extended Snyder model
No full textThe star product usually associated with the Snyder model of noncommutative geometry is nonassociative, and this property prevents the construction of a proper Hopf algebra. It is however possible to introduce a well-defined Hopf algebra by including the Lorentz generators and their conjugate momenta into the algebra. In this paper, we study the realizations of this extended Snyder spacetime, and obtain the coproduct and twist and the associative star product in a Weyl-ordered realization, to first order in the noncommutativity parameter. We then extend our results to the most general realizations of the extended Snyder spacetime, always up to first order
Associative realizations of κ-deformed extended Snyder model
Full text linkUsually, the realizations of the noncommutative Snyder model lead to a nonassociative star product. However, it has been shown that this problem can be avoided by adding to the spacetime coordinates new tensorial degrees of freedom. The model so obtained, called the extended Snyder model, can be subject to a κ deformation, giving rise to a unification of the Snyder and the κ-Poincaré algebras in the formalism of extended spacetime. In this paper we review this construction and consider the generic realizations of the κ-deformed extended Snyder model, calculating the associated star product, coproduct, and twist in a perturbative setting. We also introduce a representation of the Lorentz algebra in the extended space and speculate on possible interpretations of the tensorial degrees of freedom
An exactly solvable inflationary model
No full textWe discuss a model of gravity coupled to a scalar field that admits exact cosmological solutions displaying an inflationary behavior at early times and a power-law expansion at late times. We study its general solutions and the effect of the inclusion of matter
Realizations of the Yang–Poisson model on canonical phase space
No full textIn this paper, we discuss exact realizations of the Yang-Poisson model on canonical phase space. The Yang model is an example of noncommutative geometry on a background space-time of constant curvature and is notable for its duality between position and momentum manifolds. We call Yang-Poisson model its classical limit, with commutators replaced by Poisson brackets. The structure is simpler in the classical case, and exact realizations can be found
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