Spinning Guest Fields during Inflation: Leftover Signatures

Abstract

We consider the possibility of extra spinning particles during inflation, focussing on the spin-2 case. Our analysis relies on the well-known fully non-linear formulation of interacting spin-2 theories. We explore the parameter space of the corresponding inflationary Lagrangian and identify regions therein exhibiting signatures within reach of upcoming CMB probes. We provide a thorough study of the early and late-time dynamics ensuring that stability conditions are met throughout the cosmic evolution. We characterise in particular the gravitational wave spectrum and three-point function finding a local-type non-Gaussianity whose amplitude may be within the sensitivity range of both the LiteBIRD and CMB-S4 experiments.

30 pages, 6 figures; v2 -- references added, minor changes, accepted for publication in JCAP

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Cited by in corpus (2)

• Large Spin-2 Signals at the Cosmological Collider
• Primordial Stochastic Gravitational Wave Background Anisotropies: in-in Formalization and Applications