Small Field Polynomial Inflation: Reheating, Radiative Stability and Lower Bound

Understand

We revisit the renormalizable polynomial inflection point model of inflation, focusing on the small field scenario which can be treated fully analytically.

• In particular, the running of the spectral index is predicted to be $\alpha = -1.43 \times 10^{-3} +5.56 \times 10^{-5} \left(N_{\rm CMB}-65 \right)$, which might be tested in future.
• We also analyze reheating through perturbative inflaton decays to either fermionic or bosonic final states via a trilinear coupling.
• The lower bound on the reheating temperature from successful Big Bang nucleosynthesis gives lower bounds for these couplings; on the other hand radiative stability of the inflaton potential leads to upper bounds.