Effects of a pre-inflation radiation-dominated epoch to CMB anisotropy

Understand

We consider that the pre-inflation era is radiation-dominated, transiting smoothly to the inflationary era.

• We work out in detail the dynamics of inflaton fluctuations across the phase transition and the proper choices of initial vacuum states.
• It is found that this phase transition can suppress long-wavelength quantum fluctuations of inflaton.
• This may attribute to the large-scale CMB anisotropy a lower power than predicted in the standard $\Lambda$CDM model.