The role of soft modes in de-Sitter and inflation
By Ricardo Ferreira (ICCUB)
Friday 17 Feb
Place: Aula 507 (Faculty of Physics)
During the accelerated expansion of the universe scalar and tensor modes are stretched outside the Hubble horizon. Although these modes are locally indistinguishable from a coordinate transformation they break the symmetries of de-Sitter. In this talk I will present the asymptotic charges associated with these soft modes and show how do they affect local vacua. In particular I will show that the different vacua in the inflated patch become orthogonal to each other when t_dS -> M_p^2/H^3 (the equivalent of the Page time for de-Sitter), signaling the breakdown of the perturbative description, as previously suggested in the literature.
Finally, I will comment on more recent work where the connection between the charge, Bogolyubov transformations and coordinate transformations is made. That allows to go beyond perturbation theory and derive probability distributions for the power spectrum of scalar perturbations.