2014/10/27 by Keisuke Harigaya, Masahiro Kawasaki, Tsutomu T. Yanagida · 1 citation
Earth and Planetary Sciences · Mathematics · Physics and Astronomy · #Algorithm #Black Holes and Theoretical Physics #Computer science #Cosmology and Gravitation Theories #Geophysics and Gravity Measurements #Mathematics #Philosophy #Scroll #Theology #astro-ph.CO #hep-ph #hep-th
paper · pdf · doi:10.1016/j.physletb.2014.12.053
11 pages, 6 figures
arxiv created 2014/10/27 · openalex publication_date 2015/01/05 · openalex created_date 2016/06/24 · arxiv updated 2018/05/09 · openalex updated_date 2026/08/05
We consider an initial condition problem in a nearly quadratic chaotic inflation model in supergravity. We introduce shift symmetry breaking not only in the superpotential but also in the Kahler potential. In this model the inflaton potential is nearly quadratic for inflaton field values around the Planck scale, but deviates from the quadratic one for larger field values. As a result, the prediction on the tensor-to-scalar ratio can be smaller than that of a purely quadratic model. Due to the shift symmetry breaking in the Kahler potential, the inflaton potential becomes steep for large inflaton field values, which may prevent inflation from naturally taking place in a closed universe. We estimate an upper bound on the magnitude of the shift symmetry breaking so that inflation takes place before a closed universe with a Planck length size collapses, which yields a lower bound on the tensor-to-scalar ratio, r≳0.1.