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1. Gauge independent logarithms from inflationary gravitons

   https://doi.org/10.1007/JHEP03(2024)129  

   Glavan, D; Miao, S P; Prokopec, T; Woodard, R P (March 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Dependence on the graviton gauge enters the conventional effective field equations because they fail to account for quantum gravitational correlations with the source which excites the effective field and with the observer who measures it. Including these correlations has been shown to eliminate gauge dependence in flat space background. We generalize the technique to de Sitter background for the case of the 1-loop graviton corrections to the exchange potential of a massless, minimally coupled scalar. 

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2. Summing gravitational effects from loops of inflationary scalars

   https://doi.org/10.1088/1361-6382/ad7dc8  

   Miao, S P; Tsamis, N C; Woodard, R P (October 2024, Classical and Quantum Gravity)

   We develop a procedure for re-summing the large logarithms induced in gravity by loops of inflationary scalars. We first show how the scalar can be integrated out of the field equations in the presence of constant graviton field. We then extend this result to a fully conserved form which explains the need for a finite renormalization of the cosmological constant which was previously inferred from explicit computation. A variant of the renormalization group turns out to explain the large logarithmic corrections revealed by explicit computation in the electric field strength of gravitational radiation and in the potentials which characterize the response to a point mass. The implications for graviton loops are discussed. 

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3. Summing inflationary logarithms in nonlinear sigma models

   https://doi.org/10.1007/JHEP03(2022)069  

   Miao, S. P.; Tsamis, N. C.; Woodard, R. P. (March 2022, Journal of High Energy Physics)

   A bstract We consider two nonlinear sigma models on de Sitter background which involve the same derivative interactions as quantum gravity but without the gauge issue. The first model contains only a single field, which can be reduced to a free theory by a local field redefinition; the second contains two fields and cannot be so reduced. Loop corrections in both models produce large temporal and spatial logarithms which cause perturbation theory to break down at late times and large distances. Many of these logarithms derive from the “tail” part of the propagator and can be summed using a variant of Starobinsky’s stochastic formalism involving a curvature-dependent effective potential. The remaining logarithms derive from the ultraviolet and can be summed using a variant of the renormalization group based on a special class of curvature-dependent renormalizations. Explicit results are derived at 1-loop and 2-loop orders. 

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4. Three-loop effective potential for softly broken supersymmetry

   https://doi.org/10.1103/PhysRevD.109.015019  

   Martin, Stephen P (January 2024, Physical Review D)

   The effective potential has been previously calculated through three-loop order, in Landau gauge, for a general renormalizable theory using dimensional regularization. However, dimensional regularization is not appropriate for softly broken supersymmetric gauge theories, because it explicitly violates supersymmetry. In this paper, I obtain the three-loop effective potential using a supersymmetric regulator based on dimensional reduction. Checks follow from the vanishing of the effective potential in examples with supersymmetric vacua, and from renormalization scale invariance in examples for which supersymmetry is broken, either spontaneously or explicitly by soft terms. As byproducts, I obtain the three-loop Landau gauge anomalous dimension for the scalar component of a chiral supermultiplet, and the beta function for the field-independent vacuum energy. 

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5. Explaining large electromagnetic logarithms from loops of inflationary gravitons

   https://doi.org/10.1007/JHEP08(2023)195  

   Glavan, D; Miao, S P; Prokopec, T; Woodard, RP (August 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> Recent progress on nonlinear sigma models on de Sitter background has permitted the resummation of large inflationary logarithms by combining a variant of Starobinsky’s stochastic formalism with a variant of the renormalization group. We reconsider single graviton loop corrections to the photon wave function, and to the Coulomb potential, in light of these developments. Neither of the two 1-loop results have a stochastic explanation, however, the flow of a curvature-dependent field strength renormalization explains their factors of ln(a). We speculate that the factor of ln(Hr) in the Coulomb potential should not be considered as a leading logarithm effect. 

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