Superluminality, black holes and EFT
Abstract
Under the assumption that a UV theory does not display superluminal behavior, we ask what constraints on superluminality are satisfied in the effective field theory (EFT). We study two examples of effective theories: quantum electrodynamics (QED) coupled to gravity after the electron is integrated out, and the flatspace galileon. The first is realized in nature, the second is more speculative, but they both exhibit apparent superluminality around nontrivial backgrounds. In the QED case, we attempt, and fail, to find backgrounds for which the superluminal signal advance can be made larger than the putative resolving power of the EFT. In contrast, in the galileon case it is easy to find such backgrounds, indicating that if the UV completion of the galileon is (sub)luminal, quantum corrections must become important at distance scales of order the Vainshtein radius of the background configuration, much larger than the naive EFT strong coupling distance scale. Such corrections would be reminiscent of the nonperturbative Schwarzschild scale quantum effects that are expected to resolve the black hole information problem. Finally, a byproduct of our analysis is a calculation of how perturbative quantum effects alter charged ReissnerNordstrom black holes.
 Publication:

Journal of High Energy Physics
 Pub Date:
 February 2017
 DOI:
 10.1007/JHEP02(2017)134
 arXiv:
 arXiv:1609.00723
 Bibcode:
 2017JHEP...02..134G
 Keywords:

 Black Holes;
 Effective field theories;
 Classical Theories of Gravity;
 High Energy Physics  Theory;
 General Relativity and Quantum Cosmology
 EPrint:
 51 pages, many figures. v2 typo fixed, refs added