Unexpected cancellations in gravity theories

Z. Bern, J. J. Carrasco, D. Forde, H. Ita, and H. Johansson
Phys. Rev. D 77, 025010 – Published 11 January 2008

Abstract

Recent computations of scattering amplitudes show that N=8 supergravity is surprisingly well behaved in the ultraviolet and may even be ultraviolet finite in perturbation theory. The novel cancellations necessary for ultraviolet finiteness first appear at one loop in the guise of the “no-triangle hypothesis.” We study one-loop amplitudes in pure Einstein gravity and point out the existence of cancellations similar to those found previously in N=8 supergravity. These cancellations go beyond those found in the one-loop effective action. Using unitarity, this suggests that generic theories of quantum gravity based on the Einstein-Hilbert action may be better behaved in the ultraviolet at higher loops than suggested by naive power counting, though without additional (supersymmetric) cancellations they diverge. We comment on future studies that should be performed to support this proposal.

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  • Received 16 August 2007

DOI:https://doi.org/10.1103/PhysRevD.77.025010

©2008 American Physical Society

Authors & Affiliations

Z. Bern1, J. J. Carrasco1, D. Forde1,2, H. Ita3, and H. Johansson1

  • 1Department of Physics and Astronomy, UCLA, Los Angeles, California 90095-1547, USA
  • 2Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309, USA
  • 3Department of Physics, Swansea University, Swansea, SA2 8PP, United Kingdom

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Issue

Vol. 77, Iss. 2 — 15 January 2008

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