Small Cosmological Constant from Running Gravitational Coupling

Abstract

In this paper, we explore an idea of having Newton's constant change its value depending on the curvature scale involved. Such modification leads to a particular scalar-tensor gravity theory, with the Lagrangian derived from renormalization group (RG) flow arguments. Several of the well-known f(R) modified gravity models have remarkably simple description in terms of the infrared renormalization group, but not the "designer" types in general. We find that de Sitter-like accelerated expansion can be generated even in the absence of cosmological constant term, entirely due to running of the Newton's constant. In hopes of tackling the problem of cosmological constant's smallness, we explore the flows which are capable of generating exponential hierarchy between infrared and ultraviolet scales, and investigate cosmological evolution in the models thus derived.

8 pages, 6 figures; version 2 is substantially expanded

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• Black holes within Asymptotic Safety
• Asymptotically safe cosmology - a status report
• Cosmological dynamics in f(R) gravity
• On de Sitter solutions in asymptotically safe $f(R)$ theories
• Renormalization group scale-setting from the action - a road to modified gravity theories
• Higgs inflation and quantum gravity: An exact renormalisation group approach
• Stable super-inflating cosmological solutions in f(R)-gravity
• A viable logarithmic f(R) model for inflation
• Singularity formation in asymptotically safe cosmology with inhomogeneous equation of state
• Spherical vacuum and scalar collapse for the Starobinsky R^2 model
• Construction of f(R) Gravity Models