2007/02/28 by Martin E. Olsson, Martin E Olsson · 28 citations
Physics and Astronomy · #Anomaly (physics) #Axion #Cosmology and Gravitation Theories #Coupling (piping) #Dark Matter and Cosmic Phenomena #Extrapolation #Heterotic string theory #Inflation (cosmology) #Instanton #Isotropy #Particle physics theoretical and experimental studies #String (physics) #String theory #astro-ph #hep-th
paper · pdf · doi:10.1088/1475-7516/2007/04/019
published in Journal of Cosmology and Astroparticle Physics 2007(04), 019 (Institute of Physics) · 1+21 pages, 2 figures, v2: Typos corrected, v3: Typos, very minor corrections, reference added, to appear in JCAP
arxiv created 2007/04/10 · openalex publication_date 2007/04/30 · arxiv updated 2010/10/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We explore the possibility of obtaining inflation in weakly coupled heterotic string theory, where the model dependent axions are responsible for driving inflation. This model can be considered as a certain extrapolation of m 2 ϕ 2 -inflation, and is an attempt to explicitly realize the so called N -flation proposal in string theory. The instanton generated potential for the axions essentially has two parameters; a natural mass scale M and the string coupling g s . For isotropic compactifications leading to axions in the four-dimensional spectrum we find that with the observed temperature fluctuations in the CMB are correctly reproduced. We assume an initially random distribution for the vacuum expectation values (vevs) of the axions. The spectral index, n s , is generically more red than for m 2 ϕ 2 -inflation. The greater the vevs, the more red the spectral index becomes. Allowing for a wide range of vevs 55 e-foldings from the end of inflation, we find . The tensor-to-scalar ratio, r , is more sensitive to the vevs, but typically smaller than in m 2 ϕ 2 -inflation. Furthermore, in the regime where the leading order theory is valid, r is bounded by r < 0.10. The spectral index and the tensor-to-scalar ratio are correlated. For example, corresponds to .