Speaker
Description
I will discuss recent progress in string cosmology. Including all-order α′ corrections leads to a richer and consistent picture of the pre-Big Bang universe. In this framework, the early universe can evolve smoothly through a non-singular bounce, connecting two dual phases without encountering a singularity. When a suitable potential is added for the dilaton, this setup can also stabilize the string coupling and lead to realistic late-time cosmologies, such as matter-dominated or inflationary expansion. These theoretical improvements open up new phenomenological possibilities. During the high-curvature string phase, small changes in the sound speed of perturbations can greatly enhance the production of primordial black holes. Similarly, recent observations from NANOGrav hint at a gravitational wave background that could be naturally explained by non-minimal versions of the pre-Big Bang scenario. These results suggest non-perturbative string correction, could leave observable imprints in today’s universe.
