Grand Unification and Subcritical Hybrid Inflation

Understand

We consider hybrid inflation for small couplings of the inflaton to matter such that the critical value of the inflaton field exceeds the Planck mass.

• It has recently been shown that inflation then continues at subcritical inflaton field values where quantum fluctuations generate an effective inflaton mass.
• The effective inflaton potential interpolates between a quadratic potential at small field values and a plateau at large field values.
• An analysis of the allowed parameter space leads to predictions for the scalar spectral index n_s and the tensor-to-scalar ratio r similar to those of natural inflation.