Massive gauge-flation

Abstract

Gauge-flation model at zeroth order in cosmological perturbation theory offers an interesting scenario for realizing inflation within a particle physics context, allowing us to investigate interesting possible connections between inflation and the subsequent evolution of the Universe. Difficulties, however, arise at the perturbative level, thus motivating a modification of the original model. In order to agree with the latest Planck observations, we modify the model such that the new dynamics can produce a relation between the spectral index ns and the tensor-to-scalar ratio r allowed by the data. By including an identical mass term for each of the fields of the system, we find interesting dynamics leading to slow-roll inflation of the right length. The presence of the mass term has the potential to modify the ns vs. r relation so as to agree with the data. As a first step, we study the model at zeroth order in cosmological perturbation theory, finding the conditions required for slow-roll inflation and the number of e-foldings of inflation. Numerical solutions are used to explore the impact of the mass term. We conclude that the massive version of Gauge-flation offers a viable inflationary model.

Production and backreaction of spin-2 particles of SU(2) gauge field during inflation

“…while the latter are given by 2 [7,8] [15] Higgsed 0 1 L Gf [12,16] L Cn [14] Spectator-Higgsed 1 1 L Gf − L Cn − Table 1. Inflationary models involving an SU (2) gauge field in the literature and their relation to L A , α s and α H .…”

“…On the other hand, J A should be at most on the order of the slow-roll suppressed terms, i.e., J A H 2 ψ ≡ B A 1, which is more restrictive. Before we leave this section, let us comment on the Higgsed models, e.g., Higgsed gauge-flation and Higgsed chromo-natural models [12,14,16]. Both scalar and tensor perturbations are amplified by the Higgs VEV in this set up, with the scalar ones being more strongly amplified; thus, the Higgs VEV, quantified by ξ Z 0 , reduces the tensor-toscalar ratio [14,16].…”

“…In addition to the original models 1 , there are several more inflationary models with the SU (2) VEV which share the above features [11][12][13][14][15][16]. Despite differences in details of the models, their tensor sector can be presented in a unified manner.…”

Gravitational leptogenesis, reheating, and models of neutrino mass

“…Unfortunately, it has been recently shown that this mechanism does not generate a sufficient lepton asymmetry without spoiling inflation [28]. Other, more promising examples are inflationary scenarios that contain SU(2) gauge fields with classical vacuum expectation values, such as gauge-flation [29][30][31] and its variants [32,33], chromo-natural inflation (CNI) [34][35][36][37] and its variants [38][39][40], and models that include spectator chromo-natural-like sectors [41][42][43][44]. Gravitational leptogenesis has been studied within the context of these SU(2) models [45][46][47]; however, these works focused on the UV modes and suffer from similar criticisms regarding regularization and renormalization as the original proposal.…”

Instabilities in Horndeski-Yang-Mills inflation

“…[33][34][35] as extensions of the original Chromo-natural model. Within the framework of gaugeflation, it remains to be explored whether more general Lagrangians can be compatible with observations, e.g., its massive variant [36].…”