2018/06/14 by Lei-Hua Liu, Tomislav Prokopec, Alexei A. Starobinsky
Physics and Astronomy · #Asymptotic safety in quantum gravity #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Gravitation #Mathematical physics #Particle physics theoretical and experimental studies #Physics #Planck #Quantum #Quantum gravity #Quantum mechanics #Scalar (mathematics) #Spectral index #Spectral line #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.98.043505
published as Phys. Rev. D 98, 043505 (2018) · 29 pages, 6 figures
arxiv created 2018/06/14 · openalex created_date 2018/06/21 · openalex publication_date 2018/08/06 · arxiv updated 2018/08/15 · openalex updated_date 2026/08/05
We consider an inflationary model motivated by quantum effects of gravitational and matter fields near the Planck scale. Our Lagrangian is a resummed version of the effective Lagrangian recently obtained by Demmel, Saueressig, and Zanusso [A proper fixed functional for four-dimensional quantum Einstein gravity, J. High Energy Phys. 08 (2015) 113.] in the context of gravity as an asymptotically safe theory. It represents a refined Starobinsky model, Leff=MP2R/2+(a/2)R2/[1+bln(R/\ensuremathμ2)], where R is the Ricci scalar, a and b are constants, and \ensuremathμ is an energy scale. By implementing the COBE normalization and the Planck constraint on the scalar spectrum, we show that increasing b leads to an increased value of both the scalar spectral index ns and the tensor-to-scalar ratio r. Requiring ns to be consistent with the Planck Collaboration upper limit, we find that r can be as large as r\ensuremath≃0.01, the value possibly measurable by Stage IV CMB ground experiments and certainly from future dedicated space missions. The predicted running of the scalar spectral index \ensuremathα=dns/dln(k) is still of the order \ensuremath-5\ifmmode×\else\texttimes\fi10^\ensuremath-4 (as in the Starobinsky model), about 1 order of magnitude smaller than the current observational bound.