  We consider inhomogeneous preheating in a multi-field trapping model. The
curvature perturbation is generated by inhomogeneous preheating which induces
multi-field trapping at the enhanced symmetric point (ESP), and results in
fluctuation in the number of e-foldings. Instead of considering simple
reheating after preheating, we consider a scenario of shoulder inflation
induced by the trapping. The fluctuation in the number of e-foldings is
generated during this weak inflationary period, when the additional light
scalar field is trapped at the local maximum of its potential. The situation
may look similar to locked or thermal inflation or even to hybrid inflation,
but we will show that the present mechanism of generating the curvature
perturbation is very different from these others. Unlike the conventional
trapped inflationary scenario, we do not make the assumption that an ESP
appears at some unstable point on the inflaton potential. This assumption is
crucial in the original scenario, but it is not important in the multi-field
model. We also discuss inhomogeneous preheating at late-time oscillation, in
which the magnitude of the curvature fluctuation can be enhanced to accommodate
low inflationary scale.
