The paper titled "Negative running prevents eternal inflation" asserts that data from Planck and BICEP2 supports the negative running of the spectral index of curvature perturbations at the 2 sigma level. This finding is significant as it suggests that negative running is sufficient to eliminate the possibility of eternal inflation. The discussion highlights that the required negative running on superhorizon scales conflicts with the conditions necessary for eternal inflation, which demands large density fluctuations that overshadow classical inflaton evolution.
PREREQUISITESAstronomers, cosmologists, and theoretical physicists interested in the implications of inflationary theory and the latest observational data from Planck and BICEP2.
Yes, the negative running that seems to be required on superhorizon scales in order to reconcile BICEP2 and Planck implies a maximum amplitude for curvature perturbations on these scales. Meanwhile, eternal inflation requires large density fluctuations that dominate over the classical evolution of the inflaton. These two ideas seem in conflict.Chronos said:It further asserts this is sufficient to preclude eternal inflation.