Cuscuton Bounce Beyond the Linear Regime: Bispectrum and Strong Coupling Constraints

Understand

Cuscuton Gravity is characterized as a scalar field that can be added to general relativity without introducing any new dynamical degrees of freedom on a cosmological background.

• Yet, it modifies gravity such that spacetime singularities can be avoided.
• This has led to the Cuscuton bounce, a nonsingular cosmology that has been shown to be linearly stable, which is a rare feat.
• Upon introducing mechanisms known to generate a near-scale-invariant power spectrum of isocurvature perturbations in the prebounce contracting phase, we perform an extensive linear analysis of all scalar perturbations as they evolve through the Cuscuton bounce, both analytically and numerically.