2010/06/14 by Timothy J. Hollowood, G.M. Shore, Graham M. Shore · 3 citations
Physics and Astronomy · #Amplitude #Astrophysical Phenomena and Observations #Black Holes and Theoretical Physics #Classical mechanics #Geometry #Gravitation #Gravitational field #Photon #Photon structure function #Physics #Quantum Electrodynamics and Casimir Effect #Quantum electrodynamics #Quantum mechanics #Quark #Singularity #Spacetime #Tidal force #Unitarity #Vacuum polarization #Virtual particle #hep-th
paper · pdf · doi:10.1016/j.physletb.2010.07.006
published as Phys.Lett.B691:279-284,2010 · 13 pages, 1 figure, minor corrections
arxiv created 2010/06/14 · openalex publication_date 2010/07/11 · arxiv updated 2014/11/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The effect of gravitational tidal forces on photon propagation in curved spacetime is investigated. It is found that the imaginary part of the local refractive index Im n(u;w) may be negative as well as positive, corresponding to a local amplification as well as attenuation of the amplitude of the renormalized photon field. This is interpreted in terms of the effect of tidal forces on the virtual e+e- cloud surrounding the bare photon field---a positive/negative Im n(u;w) corresponds to an increased dressing/undressing of the bare photon. Below threshold decays of the photon to e+e- pairs can occur. Photon undressing in the vicinity of a black hole singularity is described as an example. These results are shown to be consistent with unitarity and the optical theorem in curved spacetime, which is derived here both in a local form and integrated over the photon trajectory.