On the inflationary massive field with a curved field manifold

Abstract

Massive fields during inflation provide an interesting opportunity to test new physics at very high energy scales. Meanwhile in fundamental realizations, the inflationary field space typically has a curved geometry, which may leave detectable imprints in primordial observables. In this paper we study an extension of quasi-single field inflation where the inflaton and the massive field belong to a curved field manifold. Because of the nontrivial field space curvature, the massive field here can get significant mass corrections of order the Hubble scale, thus the quasi-single field predictions on primordial non-Gaussianity are affected. We derive the same result in an equivalent approach by using the background effective field theory of inflation, where a dimension-6 operator is identified to play an important role and its cutoff scale is associated with the curvature scale of the field space. In addition, due to the slow-roll evolution of the inflaton, this type of mass correction has intrinsic time-dependence. Consequently, the running mass modifies the scaling behaviour in the squeezed limit of the scalar bispectrum, while the resulting running index measures the curvature of the internal field space. Therefore the minimal setup of a massive field within curved field space during inflation may naturally lead to new observational signatures of the field space geometry.

Phase Information in Cosmological Collider Signals

“…The slow-roll correction can also make the masses of the intermediate states time dependent, and thereby generates signals with scale-dependent frequencies and scale-dependent magnitudes [33,45]. The phases in such scenarios can in principle be calculated as well.…”

Precision Calculation of Inflation Correlators at One Loop

“…[W −iμ,iν (z)] * = W +iμ,iν (z) for μ, ν ∈ R and z ∈ R + . (27) We utilize it to reduce the computational load for the (ab) = (+−) diagram. The CC signal for the diagram is given by…”

Opening the reheating box in multifield inflation

“…In fact, to be more precise, NG is also compatible with single-field models provided the fields have non-canonical terms but non-canonical and multifield NG may be of different type and therefore can be, at least in principle, distinguished (see, e.g., Refs. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] for specific signatures of multifield inflation in the NG signal). On the other hand, the presence of non-adiabatic modes in the data would establish, beyond any doubt, that the dynamics during inflation involves several degrees of freedom.…”