IR Effects in De Sitter Space, Screening of Cosmological Constant and Inflation

Abstract

It is known that infrared (IR) quantum fluctuations in de Sitter space could break the de Sitter symmetry and generate time dependent observable effects. In this seminar, the speaker and his research group consider a dilation-gravity theory. They find that gravitational IR effects lead to a time dependent shift on the VEV of the dilation and result in a screening (temporal) of the cosmological constant/ Hubble parameter. In the Einstein frame, the effect is exponentiated and can give rises to a much more notable amount of screening. Taking the dilation as inflation, they obtain an inflationary expansion of the slow roll kind. This inflation is driven by the IR quantum effects of de Sitter gravity and does not rely on the use of a slow roll potential. As a result, the model is free from the eta problem which baffles the standard slow roll inflation models.