Massive Fields as Systematics for Single Field Inflation
Abstract
During inflation, massive fields can contribute to the power spectrum of curvature perturbation via a dimension-5 operator. This contribution can be considered as a bias for the program of using ns and r to select inflation models. Even the dimension-5 operator is suppressed by = Mp, there is still a significant shift on the ns-r diagram if the massive fields have m H. On the other hand, if the heavy degree of freedom appears only at the same energy scale as the suppression scale of the dimension-5 operator, then significant shift on the ns-r diagram takes place at m= 70H, which is around the inflationary time-translation symmetry breaking scale. Hence, the systematics from massive fields pose a greater challenge for future high precision experiments for inflationary model selection. This result can be thought of as the impact of UV sensitivity to inflationary observables.