IR finite graviton propagators in de Sitter spacetime

Abstract

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 symmetry of the classical action, but do not leave path integral measure invariant for the graviton theory in de Sitter spacetime. Due to the non-trivial Jacobian of such finite transformation the path integral measure changes and hence FFBRST transformation is capable of relating theories in two different gauges. We explicitly construct FFBRST transformation which relates theory with diverging graviton two-point function to theory with infrared (IR) finite graviton. The FFBRST transformation thus establishes that divergence in graviton two-point function may be only a gauge artifact. *

de Sitter space is unstable in quantum gravity

“…This possibility has been developed by [36], who argue that the IR divergence is in fact a gauge artifact (see also [37]). The evidence for this comes from an analysis of the graviton propagator.…”

Quantum Gauge Symmetry of Reducible Gauge Theory

“…The FFBRST is studied for maximally supersymmetric M-theories [45]. The problem of graviton propagator divergences is a also addressed [46]. The supersymmetry is also generalized by making transformation parameter finite and field dependent [47].…”

Finite field-dependent symmetry in the Thirring model

“…The key idea of generalization (extension) of BRST symmetry is to make the parameter of transformation finite and field-dependent in certain way, known as finite field-dependent BRST (FFBRST) transformation [19]. The generalization, in this way, has found enormous applications in wide area of gauge theories [20,21] as well as in gravity theory [22]. For example, the celebrated Gribov issue [23][24][25] in Yang-Mills theory has been addressed in the framework of FFBRST formulation (for details see refs.…”