2004/11/30 by Brian R. Greene, Brian Greene, Koenraad Schalm +2 · 3 citations
Physics and Astronomy · #Anisotropy #Astronomy #Astrophysics #Black Holes and Theoretical Physics #COSMIC cancer database #Cosmic background radiation #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Decoupling (probability) #Particle physics theoretical and experimental studies #Physics #Quantum mechanics #Universe #hep-th
paper · pdf · doi:10.1088/1475-7516/2005/02/001
published as JCAP 0502 (2005) 001 · LaTeX, 26 pages, 3 figures; JCAP version, minor corrections + references added
openalex publication_date 2005/02/05 · arxiv created 2005/04/20 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
We clarify the status of trans-Planckian effects on the cosmic microwave background (CMB) anisotropy. We do so using the boundary effective action formalism of hep-th/0401164 which accounts quantitatively for the cosmological vacuum ambiguity. In this formalism we can clearly (1) delineate the validity of cosmological effective actions in an expanding universe. The corollary of the initial state ambiguity is the existence of an earliest time. The inability of an effective action to describe physics before this time demands that one sets initial conditions on the earliest time hypersurface. A calculation then shows that CMB anisotropy measurements are generically sensitive to high energy corrections to the initial conditions. (2) We compute the one-loop contribution to the stress tensor due to high energy physics corrections to an arbitrary cosmological initial state. We find that phenomenological bounds on the backreaction do not lead to strong constraints on the coefficient of the leading boundary irrelevant operator. Rather, we find that the power spectrum itself is the quantity most sensitive to initial state corrections. (3) The computation of the one-loop backreaction confirms arguments that irrelevant corrections to the Bunch–Davies initial state yield non-adiabatic vacua characterized by an energy excess at some earlier time. However, this excess only dominates over the classical background at times before the 'earliest time' at which the effective action is valid. We conclude that the cosmological effective action with boundaries is a fully self-consistent and quantitative approach to trans-Planckian corrections to the CMB.