2010/12/20 by John Ellis, Nick E. Mavromatos · 1 voice
Physics and Astronomy · #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1016/j.physletb.2012.04.005
4 pages
arxiv created 2010/12/20 · arxiv published 2010/12/20 · arxiv updated 2015/05/20
Several recent papers discuss gravitational corrections to gauge couplings that depend quadratically on the energy. In the framework of the background-field approach, these correspond in general to adding to the effective action terms quadratic in the field strength but with higher-order space-time derivatives. We observe that such terms can be removed by appropriate local field redefinitions, and do not contribute to physical scattering-matrix elements. We illustrate this observation in the context of open string theory, where the effective action includes, among other terms, the well-known Born-Infeld form of non-linear electrodynamics. We conclude that the quadratically energy-dependent gravitational corrections are not physical in the sense of contributing to the running of a physically-measurable gauge coupling, or of unifying couplings as in string theory.