Constrained inflaton due to a complex scalar

Romy H S Budhi,Shoichi Kashiwase,Daijiro Suematsu

doi:10.1088/1475-7516/2015/09/039

Romy H S Budhi, Shoichi Kashiwase + Show 1 more

Open Access

https://doi.org/10.1088/1475-7516/2015/09/039

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Abstract

We reexamine inflation due to a constrained inflaton in the model of a complex scalar. Inflaton evolves along a spiral-like valley of special scalar potential in the scalar field space just like single field inflation. Sub-Planckian inflaton can induce sufficient e-foldings because of a long slow-roll path. In a special limit, the scalar spectral index and the tensor-to-scalar ratio has equivalent expressions to the inflation with monomial potential φn. The favorable values for them could be obtained by varying parameters in the potential. This model could be embedded in a certain radiative neutrino mass model

Highlights

Inflationary expansion of the Universe is believed to have existed before the radiation dominated era in the early Universe [1, 2]
Recent results of the CMB observations seem to have ruled out many of them already [2]. This has been done by comparing both values of the scalar spectral index and the tensor-to-scalar ratio obtained from the CMB observations and predicted values for them by each model
We have considered an inflation scenario based on a complex singlet scalar

Summary

Introduction

Inflationary expansion of the Universe is believed to have existed before the radiation dominated era in the early Universe [1, 2]. If we take a large inflaton scenario in the slow-roll inflation framework, trans-Planckian values are required for realization of sufficient e-foldings. We cannot answer the question why higher non-renormalizable terms do not contribute to the inflaton potential If we include such terms in inflaton potential, slow-roll conditions cannot be satisfied. The higher order corrections to the potential realizing the spiralized inflation are found to affect significantly the predicted tensor-to-scalar ratio without changing the spectral index substantially [14]. The required number for e-foldings is found to be realized in this model, the predicted tensor-to-scalar ratio by the model is too large compared with a central value of the up-dated observational results [2, 16].

A sub-Planckian inflaton model

Mp2l χe dχ χ

Spectral index

Relation with particle physics

Summary