Tachyon inflation in the large-Nformalism

Abstract

We study tachyon inflation within the large-N formalism, which takes a prescription for the small Hubble flow slow-roll parameter ϵ1 as a function of the large number of e-folds N. This leads to a classification of models through their behaviour at large N. In addition to the perturbative N class, we introduce the polynomial and exponential classes for the ϵ1 parameter. With this formalism we reconstruct a large number of potentials used previously in the literature for tachyon inflation. We also obtain new families of potentials from the polynomial class. We characterize the realizations of tachyon inflation by computing the usual cosmological observables up to second order in the Hubble flow slow-roll parameters. This allows us to look at observable differences between tachyon and canonical single field inflation. The analysis of observables in light of the Planck 2015 data shows the viability of some of these models, mostly for certain realization of the polynomial and exponential classes.

Predictions of Spectral Parameters by Several Inflationary Universe Models in Light of the Planck Results

“…Barbosa-Cendejas et al [61] have expressed this formalism in terms of the parameter ε 1 = ε H . From Equation (3.53) we have…”

“…So called tachyon inflation is a string theory inspired model of inflation where the action has a certain form [28,61,198,199]. Although it has been shown by Kofman and Linde [200] that there are certain problems with tachyon inflation, it is considered here because it also has some nice properties.…”

“…6.33.10. The N-Formalism Applied to Tachyon Inflation N. Barbosa-Cendejas et al [61,201] have used the N-formalism and the horizon-flow parameters, and studied a tachyon inflationary model with n = 1 of the perturbative class considered in Section 5. When comparing with Equation (6.1.44) we see that the last of these equations is the same consistency relationship as that for ordinary polynomial inflation.…”

COSMOS-e’-GTachyon from string theory

“…[57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73]. The cosmological implications of the tachyon were studied in [74][75][76][77][78][79][80][81][82][83][84][85][86]. For more details see also Refs.…”

“…Inflationary paradigm [75][76][77][78][79][80][81][82][83][84][85][86]92], 2. Primordial non-Gaussianity and CMB aspects [96][97][98][99][100][101][102][103][104], 3.…”