Two-field inflation with non-minimal coupling

Abstract

Motivated by the recent 'Higgs-inflation' scenario based on a single inflaton field, we consider more generic two-field inflation with non-minimal coupling term. The generic analytic expressions are derived for cosmological observables with the product-separable as well as additive-separable potentials when the non-minimal coupling term is dominated by one of the two fields. A hybrid model with the inflaton potential V = µ 2 φ 2 [1 + cos(χ/σ)] is closely examined as a concrete example. Compared to the minimal model, the non-minimal model is shown to provide better fit to the recent cosmological observation by WMAP9 and Planck2013 with the relatively lower field values during the inflationary epoch. Most interestingly, a small value of tensor-to-scalar ratio requires a large non-minimal coupling in our scenario. The model produces non-observably small non-Gaussianity in most of parameter space while a large non-Gaussianity(∼ O(10)) is obtainable only when the inflation takes place in a limited field space along the top of the potential.

Reheating in Models with Non-minimal Coupling in metric and Palatini formalisms

“…Among the various models compatible with observations that one may consider, models with a non-minimal coupling between the Ricci scalar R and the inflaton field φ are highly motivated [31][32][33][34][35][36][37]. It is known that a generic class of cases exist where the non-minimal coupling (K(φ)R) induces the asymptotic flatness ( V (φ) K(φ) 2 ∼ const.…”

Multifield dynamics of supersymmetric Higgs inflation inSU(5)GUT

“…A. For computation of the non-Gaussianities we use another set of numerical code developed in [23,37].…”

Testing supersymmetric Higgs inflation with non-Gaussianity

“…We also use the value of the parameter £ that is fixed by the normalization of the scalar 5We checked our numerical code on simple two-field models with separable potentials, including Refs. [62][63][64][65][66], power spectrum As in the single-field limit; this leads to slight inconsistency of the parameter choice as A s also changes as other parameters (v and the initial .s-field value sinit) are varied. We shall, however, see that this is a minor issue as the change of As is less significant than that of the nonlinearity parameter / NL.…”