2005/07/31 by D. Boyanovsky, H. J. de Vega, N. Sánchez +1 · 31 citations
Physics and Astronomy · #Anisotropy #Black Holes and Theoretical Physics #CMB cold spot #Cosmic microwave background #Cosmology and Gravitation Theories #Coupling (piping) #Galaxies: Formation, Evolution, Phenomena #Geometry #Inflation (cosmology) #Inflaton #Mathematical physics #Particle physics #Physics #Quantum mechanics #Scalar (mathematics) #Scalar field #astro-ph #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.73.023008
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 73(2) (American Physical Society) · 14 pages, no figures, version to appear in Phys Rev D
arxiv created 2006/01/26 · openalex publication_date 2006/01/26 · arxiv updated 2009/12/01 · openalex created_date 2022/10/04 · openalex updated_date 2026/07/28
Slow-roll inflation is studied as an effective field theory. We find that the form of the inflaton potential consistent with Wilkinson Microwave Anisotropy Probe (WMAP) data and slow roll is V(\ensuremathφ)=NM4w(\frac\ensuremathφ√(N)MPl), where \ensuremathφ is the inflaton field, M is the inflation energy scale, and N\ensuremath∼50 is the number of e-folds since the cosmologically relevant modes crossed the Hubble radius until the end of inflation. The inflaton field scales as \ensuremathφ=√(N)MPl\ensuremathχ. The dimensionless function w(\ensuremathχ) and field \ensuremathχ are generically O(1). The WMAP value for the amplitude of scalar adiabatic fluctuations |\ensuremathΔkad(S)|2 fixes the inflation scale M\ensuremath∼0.77\ifmmode×\else\texttimes\fi1016. This form of the potential makes manifest that the slow-roll expansion is an expansion in 1/N. A Ginzburg-Landau realization of the slow-roll inflaton potential reveals that the Hubble parameter, inflaton mass and nonlinear couplings are of the seesaw form in terms of the small ratio M/MPl. For example, the quartic coupling \ensuremathλ\ensuremath∼(1)/(N)(\fracMMPl)4. The smallness of the nonlinear couplings is not a result of fine-tuning but a natural consequence of the validity of the effective field theory and slow-roll approximation. We clarify Lyth's bound relating the tensor/scalar ratio and the value of \ensuremathφ/MPl. The effective field theory is valid for V(\ensuremathφ)\ensuremath≪MPl4 for general inflaton potentials allowing amplitudes of the inflaton field \ensuremathφ well beyond MPl. Hence bounds on r based on the value of \ensuremathφ/MPl are overly restrictive. Our observations lead us to suggest that slow-roll, single field inflation may well be described by an almost critical theory, near an infrared stable Gaussian fixed point.