Abstract
We propose a class of models of supersymmetric hilltop inflation (also called ``new inflation'') where the initial conditions of the inflaton close to the hilltop are generated through ``matter field preinflation''. This is achieved via a coupling term between the inflaton and matter fields (i.e. Standard Model fields or a right-handed neutrino). The same coupling also opens up a decay channel for the inflaton into Standard Model fields, which allows efficient reheating of the universe. We discuss the multifield dynamics of the inflaton and matter fields during inflation using the δN formalism and show under which conditions the model effectively reduces to single-field hilltop inflation during the last 60 e-folds. We also study perturbative reheating through the matter-inflaton coupling for a specific example where the matter field is identified with a right-handed (s)neutrino, and demonstrate that in this case the model can generate the observed baryon asymmetry through nonthermal leptogenesis.
Highlights
The non-Gaussianity parameter has been constrained to fNL = 2.7 ± 5.8 at 68% C.L., which is consistent with single-field slow-roll inflation
We have proposed a new class of models of hilltop inflation where the initial conditions of the inflaton close to the hilltop are generated from “matter field preinflation”
This is achieved via a coupling term between the inflaton and a matter field (cf. second term in eq (2.5)), in addition to the usual term for supersymmetric hilltop inflation
Summary
Models of hilltop inflation are usually presented in form of a potential for a real scalar field φ,. Xn can be any gauge invariant contraction of matter superfields, e.g. the right-handed neutrino superfield which contains the right-handed neutrino fermion and the scalar right-handed sneutrino, or some lepton-Higgs (LHu, LHdE) or quark-Higgs (QHuU , QHdD ) direction.2 Such a coupling has the following advantages, in addition to being able to fix the shape of the superpotential by symmetries (i.e. to solve challenge 1 in a supersymmetric framework):. With the scalar component X of Xbeing non-zero in an early epoch, a mass term for φ is generated which drives it to small field values This yields a stage of preinflation (along the lines of so-called “tribrid inflation” models [15,16,17]) and solves challenge 2 by a rather minimalistic extension of the model, using only matter fields for preinflation, where by matter fields we mean Standard Model fields and right-handed neutrinos as well as their superpartners. When Xis a right-handed neutrino superfield, the latter decay would proceed via the neutrino Yukawa couplings, and can even generate the baryon asymmetry of the universe via the non-thermal leptogenesis mechanism [18]
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