We show that if the visible universe is a membrane embedded in a higher-dimensional space, particles in uniform motion radiate gravitational waves because of spacetime lumpiness. This phenomenon is analogous to the electromagnetic diffraction radiation of a charge moving near to a metallic grating. In the gravitational case, the role of the metallic grating is played by the inhomogeneities of the extra-dimensional space, such as a hidden brane. We derive a general formula for gravitational diffraction radiation and apply it to a higher-dimensional scenario with flat compact extra dimensions. Gravitational diffraction radiation may carry away a significant portion of the particle's initial energy. This allows to set stringent limits on the scale of brane perturbations. Physical effects of gravitational diffraction radiation are briefly discussed.
V. Cardoso et al., "Gravitational Diffraction Radiation," Physical Review D - Particles, Fields, Gravitation and Cosmology, vol. 74, no. 8, American Physical Society (APS), Oct 2006.
The definitive version is available at https://doi.org/10.1103/PhysRevD.74.084011
Fundação Calouste Gulbenkian.
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© 2006 American Physical Society (APS), All rights reserved.
01 Oct 2006
V. C. acknowledges financial support from Fundação Calouste Gulbenkian through the Programa Gulbenkian de EstÃ©mulo Ã InvestigaÃ§Ã£o CientÃfica.