Differentiating G-inflation from String Gas Cosmology using the Effective Field Theory Approach

摘要: A characteristic signature of String Gas Cosmology is primordial power spectra for scalar and tensor modes which are almost scale-invariant but with a red tilt blue modes. This feature, however, can also be realized in the so-called G-inflation model, Horndeski operators introduced leads to by softly breaking Null Energy Condition. In this article we search potential observational differences between these two cosmologies performing detailed perturbation analyses based on Effective Field Theory approach. Our results show that, although both models produce tilted perturbations, they behave differently three aspects. Firstly, predicts specific consistency relation index ns that ones nt, hard reproduced G-inflation. Secondly, typically non-Gaussianities highly suppressed observable scales, while gives rise observationally large because kinetic terms action become important during inflation. However, after finely tuning model parameters it possible obtain spectrum negligible degeneracy models. broken third observable, namely scale dependence nonlinearity parameter, vanishes has case Cosmology. Therefore, conclude principle distinguishable from single field inflationary cosmology, even allowing modifications such as