  We show a text-book potential for single-field inflation, namely, the
Coleman-Weinberg model can induce double inflation and formation of primordial
black holes (PBHs), because fluctuations that leave the horizon near the end of
first inflation are anomalously enhanced at the onset of second inflation when
the time-dependent mode turns to a growing mode rather than a decaying mode.
The mass of PBHs produced in this mechanism lies in several discrete ranges
depending on the model parameters. We also calculate the effects of
non-Gaussian statistics due to higher-order interactions on the abundance of
PBHs, which turns out to be small.
