Climbing scalars in string theory and cosmology

Abstract  : In string models with "brane supersymmetry breaking" 
exponential potentials emerge at (closed string) tree level but are not accompanied by tachyons. Potentials of this type can have interesting  implications for Cosmology. In simplest examples, the logarithmic slope 
lies precisely at a  critical value where the scalar field is forced to climb up the potential when it emerges from the Big Bang. This type of behavior could also have trapped scalar fields inside potential wells. If a pre-inflationary climbing phase of this type had occurred within 6-7 e-folds of the horizon exit for the largest observable wavelengths, it would suppress power in the primordial scalar spectrum, enhancing it in the tensor spectrum and superposing oscillations on both.