Abstract
We study reheating in α-attractor models of inflation in which the inflaton couples to other scalars or fermions. We show that the parameter space contains viable regions in which the inflaton couplings to radiation can be determined from the properties of CMB temperature fluctuations, in particular the spectral index. This may be the only way to measure these fundamental microphysical parameters, which shaped the universe by setting the initial temperature of the hot big bang and contain important information about the embedding of a given model of inflation into a more fundamental theory of physics. The method can be applied to other models of single field inflation.
Highlights
Of these temperature fluctuations has confirmed several predictions of cosmic inflation [5]
We show that the parameter space contains viable regions in which the inflaton couplings to radiation can be determined from the properties of CMB temperature fluctuations, in particular the spectral index. This may be the only way to measure these fundamental microphysical parameters, which shaped the universe by setting the initial temperature of the hot big bang and contain important information about the embedding of a given model of inflation into a more fundamental theory of physics
The good agreement of the observed light element abundances with the predictions from big bang nucleosynthesis (BBN) indicates that the universe was filled with a dense medium of relativistic particles in thermal equilibrium, which we in the following refer to as “radiation”, and puts a lower bound of roughly 10 MeV on the temperature in the early universe [6]
Summary
Tre should not be understood as a temperature in the microphysical sense of phase space distribution functions, but as a convenient effective parameter to associate the onset of the radiation dominated era with an energy scale. It corresponds to a physical temperature if the equilibration is very rapid. There are corrections from gravity that may not be negligible for φ/Mpl > 1 We assume that these effects are negligible during reheating, which usually occurs at small (sub-Planckian) field values φ in the scenarios that we consider. We may treat the inflaton couplings to radiation near φ 0 (which drive reheating) and the parameters in V(φ) at the field values φk where the observable φ-mode k crosses the horizon during inflation as independent fit parameters. To simplify the notation, we in the following do not distinguish between V and V and between φ and φ
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