Eur. Phys. J. C (2016) 76: 189
https://doi.org/10.1140/epjc/s10052-016-4008-x

Regular Article - Theoretical Physics

IR finite graviton propagators in de Sitter spacetime

¹ Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB, T1K 3M4, Canada
² Department of Physics, Banaras Hindu University, Varanasi, 221005, India

^* e-mail: bhabani.mandal@gmail.com

Received: 14 June 2015
Accepted: 8 March 2016
Published online: 7 April 2016

Abstract

The graviton propagator diverges in certain gauges in de Sitter spacetime. We address this problem in this work by generalizing the infinitesimal BRST transformations in de Sitter spacetime to finite field-dependent BRST (FFBRST) transformations. These FFBRST transformations are a symmetry of the classical action, but they do not leave the path integral measure invariant for the graviton theory in de Sitter spacetime. Due to the non-trivial Jacobian of such a finite transformation the path integral measure changes and hence the FFBRST transformation is capable of relating theories in two different gauges. We explicitly construct the FFBRST transformation which relates the theory with a diverging graviton two-point function to a theory with an infrared finite graviton. The FFBRST transformation thus establishes that the divergence in a graviton two-point function may be only a gauge artifact.