Microphysical nature of inflation

Determine the microphysical underpinnings of cosmic inflation by identifying the underlying degrees of freedom, equations of motion, and action that realize the inflationary epoch and generate the observed primordial perturbations.

Background

The paper argues that, despite the empirical success of ΛCDM, cosmology faces permanent underdetermination regarding the microphysics of its exotic components. For inflation, cosmological observables probe only a narrow window of the inflaton potential roughly 50–60 e-folds before the end of inflation, yielding just a handful of well-measured parameters (e.g., amplitude, spectral index, limited constraints on tensors and non-Gaussianity).

Given these limited probes, many distinct inflationary models remain observationally indistinguishable, and it is straightforward to generate large numbers of microphysical theories compatible with current and anticipated constraints. The authors contend that this creates a severe, possibly permanent, underdetermination of the microphysical theory of inflation by available cosmological data.