Abstract

Heavy scalar fields can undergo an instability during inflation as a result of their kinetic coupling with the inflaton. This effect is known as the geometrical destabilization of inflation, as it is caused by the curvature of the internal manifold parametrized by the fields. The instability can drive the system away from its original path in field space into a new inflationary attractor, a scenario that we call “sidetracked inflation”. This talk will aim at describing the physics of this second phase and its observable consequences. I will show that the behavior of cosmological fluctuations can be understood by means of a single-field effective theory in which perturbations propagate with either a modified dispersion relation, a reduced speed of sound, or a speed of sound that is imaginary. The latter case is especially interesting as it leads to novel observational signatures, and in particular to unusual shapes in the non-Gaussianities