Preinflationary Perturbations in The Thermal Background

The solution to large-scale power deficit in the cosmic microwave background fluctuations may be relevant with the physics in the preinflationry period, and significantly depends on whether the initial conditions are set as Bunch-Davies vacuum or thermal ground state. We show the primordial cosmological perturbations based on the preinflationary model with three phases at different thermal initial conditions. The influences of different thermal initial states are studied by the detailed discussions of the adjusting role of model parameters on the power spectrum. Finally, this paper gives the solution to large-scale power deficit in the cosmic microwave background fluctuations.