Dilaton, Screening of the Cosmological Constant and IR-Driven Inflation
  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 paper, we consider a dilaton-gravity theory. We find that gravitational IR
effects lead to a time dependent shift on the vev of the dilaton and results 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 dilaton as inflaton, we 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, our model is free from the eta problem which
baffles the standard slow roll inflation models.
