The Peccei-Quinn field as curvaton

Abstract

A simple extension of the minimal supersymmetric standard model which naturally and simultaneously solves the strong CP and µ problems via a PecceiQuinn and a continuous R symmetry is considered. This model is supplemented with hybrid inflation and leptogenesis, but without taking the specific details of these scenarios. It is shown that the Peccei-Quinn field can successfully act as a curvaton generating the total curvature perturbation in the universe in accord with the cosmic background explorer measurements. A crucial phenomenon, which assists us to achieve this, is the 'tachyonic amplification' of the perturbation acquired by this field during inflation if the field, in its subsequent evolution, happens to be stabilized for a while near a maximum of the potential. In this case, the contribution of the field to the total energy density is also enhanced ('tachyonic effect'), which helps too. The cold dark matter in the universe consists, in this model, mainly of axions which carry an isocurvature perturbation uncorrelated with the total curvature perturbation. There are also lightest sparticles (neutralinos) which, like the baryons, originate from the inflationary reheating and, thus, acquire an isocurvature perturbation fully correlated with the curvature perturbation. So, the overall isocurvature perturbation has a mixed correlation with the adiabatic one. It is shown that the presently available bound on such an isocurvature perturbation from cosmic microwave background radiation and other data is satisfied. Also, the constraint on the non-Gaussianity of the curvature perturbation obtained from the recent Wilkinson microwave anisotropy probe data is fulfilled thanks to the 'tachyonic effect'.

Constraints on a mixed inflaton and curvaton scenario for the generation of the curvature perturbation

“…infl exceeds φ Q , we can be sure [11] that the classical evolution equation holds for this mean field until the end of inflation. For values of the mean φ in a region of fixed size somewhat bigger than H −1 infl which are smaller than about φ Q , the random walk executed [48] by this mean field due to the quantum perturbations from inflation cannot be neglected and may overshadow [47] its classical motion.…”

“…The requirement that the PQ field is essentially massless during inflation yields [11], for given values of the other parameters, an upper bound on the possible values of this field at the end of inflation. Moreover, it implies that, as inflation terminates, the PQ field emerges [11] with negligible velocity.…”

Theoretical Tools for CMB Physics

“…This occurrence, however, depends upon the specific properties of the potential. For instance in the case of a quartic potential, ρ σ ≃ 3 p σ [256,259].…”

Leptogenesis and Neutrino Masses in an Inflationary SUSY Pati-Salam Model

“…The mass spectrum of the P-P system is comprised by axion and saxion P − = (P − P)/ √ 2, axino ψ − = (ψP − ψ P )/ √ 2, a higgs, P + = (P + P)/ √ 2, and a higgsino, ψ + = (ψP + ψ P )/ √ 2, with mass of order 1 TeV and ψ denoting a Weyl spinor. The higgs and higgsinos can decay to lighter higgs and higgsinos before domination [36]. Regarding the saxion, P − , we can assume that its decay mode to axions is suppressed (w.r.t the ones to gluons, higgses and higgsinos [47,48]) and the initial amplitude of its oscillations is equal to f a ≃ 10 12 GeV.…”

“…where Ω a [Ω c ] is the axion [CDM] density parameter, φ P * ∼ 10 16 GeV [36] denotes the field value of the PQ scalar when the cosmological scales exit the horizon and θ I is the initial misalignment angle which lies [36] in the interval [−π/6, π/6]. Satisfying Eq.…”