Natural inflation, strong dynamics, and the role of generalized anomalies

Understand

We revisit models of natural inflation and show that the single-field effective theory described by the potential $V(a)\sim \cos\frac{a}{f}$ breaks down as the inflaton $a$ makes large-field excursions, even for values of $f$ smaller than the Planck scale.

• In order to remedy the problem, we modify the potential in order to account for the heavy degrees of freedom (hadrons) that become intertwined with the light inflaton as the latter rolls down its potential.
• By embedding the low energy degrees of freedom into an ultraviolet complete gauge theory, we argue that the intertwining between the two scales can be explained as the result of a generalized mixed 't Hooft anomaly between the discrete chiral symmetry and background fractional fluxes in the baryon number, color, and flavor directions.
• Further, we study the multi-field inflation and show that it entertains rich dynamics.