Abstract

We consider single graviton loop corrections to the effective field equation of a massless, minimally coupled scalar on de Sitter background in the simplest gauge. We find a large temporal logarithm in the approach to freeze-in at late times, but no correction to the feeze-in amplitude. We also find a large spatial logarithm (at large distances) in the scalar potential generated by a point source, which can be explained using the renormalization group with one of the higher derivative counterterms regarded as a curvature-dependent field strength renormalization. We discuss how these results set the stage for a project to purge gauge dependence by including quantum gravitational corrections to the source which disturbs the effective field and to the observer who measures it.

Highlights

  • We find a large spatial logarithm in the scalar potential generated by a point source, which can be explained using the renormalization group with one of the higher derivative counterterms regarded as a curvature-dependent field strength renormalization

  • These doubts persist in spite of the fact that similar effects derive from loops of massless, minimally coupled scalars [9, 32], which experience the same growth (1.1) as inflationary gravitons and require no gauge fixing

  • Our long term goal is to establish the reality of large loop corrections from inflationary gravitons (1.1) by purging the effective field equations of gauge dependence

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Summary

Feynman rules

Where G is Newton’s constant and Λ is the cosmological constant. We define the graviton field hμν(x) as a perturbation of the conformally rescaled metric, gμν (x) ≡ a2(η)gμν (x) ≡ a2(η) ημν + κhμν , a(η) ≡ − 1 , Hη (2.2). Our gauge fixing term is a de Sitter breaking analog of (1.2) for α = β = 1 [39, 40], LGF = − 12 aD−2ημν FμFν , Fμ = ηρσ hμρ,σ − 12 hρσ,μ +(D−2)aHhμρδ0σ In this gauge the graviton propagator is the sum of three constant tensor factors times scalar propagators, i μν ∆ρσ (x; x ) =. This form is desirable because the noncovariant tensor factors multiply differences, (i∆A − i∆B) and (i∆A − i∆C), which are only logarithmically singular at coincidence. Tracereversing on both indices gives, i μν ∆ρσ.

The primitive 4-point contribution
The primitive 3-point contribution
The linearized effective field equation
Schwinger-Keldysh formalism
The scalar mode function
The response to a point source
Conclusions
Full Text
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