42 research outputs found
Gibbons-Hawking radiation of gravitons in the Poincare and static patches of de Sitter spacetime
We discuss the quantization of linearized gravity in the background de Sitter
spacetime using a gauge-invariant formalism to write the perturbed
gravitational field in the static patch. This field is quantized after fixing
the gauge completely. The response rate of this field to monochromatic
multipole sources is then computed in the thermal equilibrium state with the
well known Gibbons-Hawking temperature. We compare this response rate with the
one obtained in the Bunch-Davies-like vacuum state defined in the Poincar\'e
patch. These response rates are found to be the same as expected. This
agreement serves as a verification of the infrared finite graviton two-point
function in the static patch of de Sitter spacetime found previously.Comment: 10 pages, no figures. Accepted for publication in Physical Review
Gravitational waves emitted by a particle rotating around a Schwarzschild black hole : A semiclassical approach
We analyze the gravitational radiation emitted from a particle in circular motion around a Schwarzschild black hole using the framework of quantum eld theory in curved spacetime at tree level. The gravitational perturbations are written in a gauge-invariant formalism for spherically symmetric spacetimes. We discuss the results, comparing them to the radiation emitted by a particle when it is assumed to be orbiting a massive object due to a Newtonian force in at spacetime
Graviton two-point function in 3+1 static de Sitter spacetime
In [R. P. Bernar, L. C. B. Crispino and A. Higuchi, Phys. Rev. D 90 (2014) 024045.] we investigated gravitational perturbations in the background of de Sitter spacetime in arbitrary dimensions. More specifically, we used a gauge-invariant formalism to describe the perturbations inside the cosmological horizon, i.e. in the static patch of de Sitter spacetime. After a gauge-fixed quantization procedure, the two-point function in the Bunch–Davies-like vacuum state was shown to be infrared finite and invariant under time-translation. In this work, we give details of the calculations to obtain the graviton two-point function in 3 + 1 dimensions. </jats:p
Comment on "The equivalence principle in the Schwarzschild geometry" [Am. J. Phys. 62, 1037 (1994)]
Circular geodesic radiation in Schwarzschild spacetime : A semiclassical approach
Extreme curvature settings and nontrivial causal structure of curved spacetimes may have interesting theoretical and practical implications for quantum field theories. Radiation emission in black hole spacetimes is one such scenario in which the semiclassical approach, i.e. quantum fields propagating in a nondynamical background spacetime, adds a very simple conceptual point of view and allows us to compute the emitted power in a straightforward way. Within this context, we reexamine sources in circular orbit around a Schwarzschild black hole, investigating the emission of scalar, electromagnetic and gravitational radiations. The analysis of the differences and similarities between these cases provide an excellent overview of the powerful conceptual and computational tool that is quantum field theory in curved spacetime. </jats:p
Semiclassical bremsstrahlung from a charge radially falling into a Schwarzschild black hole
semiclassical investigation of the electromagnetic radiation emitted by a charged particle in a radially freely falling motion in Schwarzschild spacetime is carried out. We use quantum field theory at tree level to obtain the one-particle-emission amplitudes. We analyze and compare the energy spectrum and total energy released, which are calculated from these amplitudes, for particles with varying initial positions and for particles originating from infinity with varying kinetic energy. We also compare the results with those due to a falling charged "string" extended in the radial direction
Inequivalent quantization of the rational Calogero model with a Coulomb type interaction
We consider the inequivalent quantizations of a -body rational Calogero
model with a Coulomb type interaction. It is shown that for certain range of
the coupling constants, this system admits a one-parameter family of
self-adjoint extensions. We analyze both the bound and scattering state sectors
and find novel solutions of this model. We also find the ladder operators for
this system, with which the previously known solutions can be constructed.Comment: 15 pages, 3 figures, revtex4, typos corrected, to appear in EPJ