1,720,976 research outputs found
Nonlinear gravitational waves and their polarization
No full textAbstractVacuum gravitational fields invariant for a non-Abelian Lie algebra generated by two Killing fields whose commutator is light-like are analyzed. It is shown that they represent non-linear gravitational waves obeying to two non-linear superposition laws. The energy and the polarization of this family of waves are explicitly evaluated
Scalar-tensor theories of gravity with torsion and the propagation of photons
No full textIn this paper, we study the propagation of photons in a spacetime of a scalar-tensor screwed cosmic string. We determine the Stokes parameters and compute the rotation of the polarization angle. The latter turns out to depend on the wavelength of the propagating photons and on the cosmological redshift. We then compute the circular polarization of photons showing that, to leading order in the coupling constant, it is zero for the model under consideration
Special Issue - Spacetime and Fundamental Interactions - Quantum Aspects - Vietri sul Mare, Salerno, Italy - 26-31 May 2003 - Preface
No full text
Noncommutative Schwarzschild geometry and generalized uncertainty principle
No full textWe discuss a possible link between the deformation parameter Θ μν arising in the framework of noncommutative geometry and the parameter β of the generalized uncertainty principle (GUP). We compute the shift of the Hawking temperature induced by the Θ μν-deformed Schwarzschild geometry, and then we relate it to one obtained by GUP. Results suggest a granular structure of specetime at the Planck scales. The current bounds on β allow to constraint the noncommutative parameter Θ μν
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