2015/06/20 by Michele Maggiore, Maggiore, Michele
Physics and Astronomy · #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th) #gr-qc #hep-th
paper · pdf · doi:10.48550/arxiv.1506.06217
34 pages; v3: significant conceptual improvements
arxiv created 2015/09/24 · arxiv updated 2015/09/25
Recent work has shown that non-local modifications of gravity involving terms such as m2R\Box-2R (and no cosmological constant) provide a phenomenologically viable alternative to ΛCDM. We first discuss the possibility that such non-local terms emerge in the far infrared from the running of a coupling constant associated to the R2 term in higher-derivative gravity, which, depending on the UV completion of the theory, can be asymptotically free in the ultraviolet and strongly coupled in the infrared. In this scenario the mass scale m of the non-local model emerges from dimensional transmutation, similarly to Λ\rm QCD for strong interactions, leading to a technically natural value and to a novel understanding of the scale associated to dark energy. Motivated by these findings, we then explore the possibility of generating strong infrared effects in Einstein gravity, with no R2 terms, as a consequence of the higher-derivative term generated by the conformal anomaly.