Breaking model degeneracies with next-generation observations

Determine how forthcoming observations from LiteBIRD, CMB-S4, and LISA can break current degeneracies among modified gravity inflationary models by exploiting measurements of the tensor tilt n_t, isocurvature modes, and precise bounds on the tensor-to-scalar ratio r.

Background

Many modified gravity scenarios produce similar scalar spectral indices and low tensor amplitudes, complicating model selection with current data. The review points to tensor properties, isocurvature, and precision B-mode measurements as key discriminators.

Establishing concrete forecasted criteria would guide both experimental design and theoretical model development.