Speaker
Description
The low-energy limit of string theory contains additional gravitational degrees of freedom that are not present in general relativity. Together with the metric, these are naturally embedded in the O(D,D)-symmetric framework of double field theory. First of all, I will review how the O(D,D) symmetry uniquely prescribes the interactions between the extended gravitational sector and other matter, leading to novel features beyond conventional string cosmology. I will then extend the analysis to include linear fluctuations. I will show how the generalized conservation laws modify the conditions for conservation of curvature perturbations. Finally, I will present some examples of analytic solutions for cosmological backgrounds as well as their perturbations in the superhorizon limit, maximally including a non-trivial dilaton, H-flux, a massless scalar field and radiation, and I will verify explicitly that long-wavelength fluctuations are adiabatic.
