  The small field inflation (SFI) of Coleman-Weinberg (CW) type suffers from
precise tuning of the initial inflaton field value to be away from the true
vacuum one. We propose a dynamical trapping mechanism to solve this problem: an
ultra-supercooling caused by an almost scale-invariant CW potential traps the
inflaton at the false vacuum, far away from the true vacuum dominantly created
by the quantum scale anomaly, and allows the inflaton to dynamically start the
slow-roll down due to a classical explicit-scale breaking effect. To be
concrete, we employ a successful CW-SFI model and show that the proposed
mechanism works consistently with the observed bounds on the inflation
parameters. The proposed new mechanism thus provides new insights for
developing small field inflation models.
