Infrared features of gravitational scattering and radiation in the eikonal approach

Ciafaloni, Marcello (Dipartimento di Fisica, Università di Firenze Via Sansone 1, 50019 Sesto Fiorentino, Italy) ; Colferai, Dimitri (Dipartimento di Fisica, Università di Firenze and INFN, Sezione di Firenze Via Sansone 1, 50019 Sesto Fiorentino, Italy) ; Veneziano, Gabriele (Theory Department, CERN, CH-1211 Geneva 23, Switzerland and Collège de France, 11 place M. Berthelot, 75005 Paris, France)

22 March 2019

Abstract: Following a semiclassical eikonal approach—justified at transplanckian energies order by order in the deflection angle Θs4Gsb2Rb—we investigate the infrared features of gravitational scattering and radiation in four space-time dimensions, and we illustrate the factorization and cancellation of the infinite Coulomb phase for scattering and the eikonal resummation for radiation. As a consequence, both the eikonal phase 2δ(E,b) and the gravitational-wave (GW) spectrum dEGWdω are free from infrared problems in a frequency region extending from zero to (and possibly beyond) ω=1/R. The infrared-singular behavior of 4-D gravity leaves a memory in the deep infrared region (ωRωb<1) of the spectrum. At O(ωb) we confirm the presence of logarithmic enhancements of the form already pointed out by Sen and collaborators on the basis of nonleading corrections to soft-graviton theorems. These, however, do not contribute to the unpolarized and/or azimuthally averaged flux. At O(ω2b2) we find instead a positive logarithmically enhanced correction to the total flux implying an unexpected maximum of its spectrum at ωb0.5. At higher orders we find subleading enhanced contributions as well, which can be resummed, and have the interpretation of a finite rescattering Coulomb phase of emitted gravitons.

Published in: Physical Review D 99 (2019)
Published by: APS
DOI: 10.1103/PhysRevD.99.066008
arXiv: 1812.08137
License: CC-BY-4.0

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