Abstract: |
The reheating era in the early universe, that connects inflation and big-bang nucleosythesis, is still very weakly constrained. However, inefficient preheating can lead to a prolonged matter-dominated phase after inflation, changing the time during inflation when the Cosmic Microwave Background (CMB) modes exit the horizon. This shifts CMB predictions and thus can break the degeneracy of otherwise indistinguishable inflation models. Typically, models that allow a UV completion, include many distinct fields, often with curved field-space manifolds. Based on arXiv:2005.00528, arXiv:1810.02804, the present talk focuses on the physical mass scales that control the dynamics and observable predictions of all multi-field models with a non-zero field-space curvature: the Hessian of the potential, the turning rates of the trajectory and the field-space curvatures. We analyse how their interplay affects reheating and shifts inflationary predictions. We also demonstrate the existence of a region in parameter space, where the symmetric and asymmetric multi-field alpha-attractors, that are known by the universality of their single-field inflationary predictions, are explicitly not the same: one preheats and one does not. This leads to a different cosmic history for the two models, with one possibly exhibiting a long matter-dominated phase, and a shift in the observational predictions for ns and r. |