Abstract
Higgs field of particle physics can play the role of the inflaton in the early universe, if it is non-minimally coupled to gravity. The Higgs inflation scenario predicts a small tensor to scalar ratio: $r\simeq 0.003$. Although this value is consistent with the upper bound $r < 0.12$ given by BICEP2/Keck Array and Planck data, but it is not at their maximum likelihood point: $r\simeq 0.05$. Inflationary observables depend not only on the inflationary models, but also depend on the initial conditions of inflation. Changing initial state of inflation can improve the value of $r$. In this work, we study the Higgs inflation model under general initial conditions and show that there is a subset of these general initial conditions which leads to enhancement of $r$. Then we show that this region of parameter space is consistent with non-Gaussianity bound.
Highlights
The inflationary epoch of the early universe has became an important part of the standard big bang model of cosmology [1]
In this work we studied the Higgs inflation model under general initial conditions
The effects of the general initial conditions are constrained by the requirement that they should not spoil the inflationary background
Summary
The inflationary epoch of the early universe has became an important part of the standard big bang model of cosmology [1]. In the presence of a UV cut off, the effects of the new theory can be set on the non-trivial initial condition or the non-Bunch–Davies vacuum [20,21]. Ashoorioon et al [22,23] employed non-trivial initial conditions for the chaotic model of inflation to suppress the value of r to bring about reconciliation of the Planck data with that of the BICEP2. They excluded a large piece of parameter space by using the observational bound of the non-Gassianity.
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