Minimal Warm Inflation. (arXiv:1910.07525v1 [hep-ph])

<a href="http://arxiv.org/find/hep-ph/1/au:+Berghaus_K/0/1/0/all/0/1">Kim V. Berghaus</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Graham_P/0/1/0/all/0/1">Peter W. Graham</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Kaplan_D/0/1/0/all/0/1">David E. Kaplan</a>

Slow-roll inflation is a successful paradigm. However we find that even a

small coupling of the inflaton to other light fields can dramatically alter the

dynamics and predictions of inflation. As an example, the inflaton can

generically have an axion-like coupling to gauge bosons. Even relatively small

couplings will automatically induce a thermal bath during inflation. The

thermal friction from this bath can easily be stronger than Hubble friction,

significantly altering the usual predictions of any particular inflaton

potential. Thermal effects suppress the tensor-to-scalar ratio $r$

significantly, and predict unique non-gaussianities. This axion-like coupling

provides a minimal model of warm inflation which avoids the usual problem of

thermal backreaction on the inflaton potential. As a specific example, we find

that hybrid inflation with this axion-like coupling can easily fit the current

cosmological data.

Slow-roll inflation is a successful paradigm. However we find that even a

small coupling of the inflaton to other light fields can dramatically alter the

dynamics and predictions of inflation. As an example, the inflaton can

generically have an axion-like coupling to gauge bosons. Even relatively small

couplings will automatically induce a thermal bath during inflation. The

thermal friction from this bath can easily be stronger than Hubble friction,

significantly altering the usual predictions of any particular inflaton

potential. Thermal effects suppress the tensor-to-scalar ratio $r$

significantly, and predict unique non-gaussianities. This axion-like coupling

provides a minimal model of warm inflation which avoids the usual problem of

thermal backreaction on the inflaton potential. As a specific example, we find

that hybrid inflation with this axion-like coupling can easily fit the current

cosmological data.

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