  I study ultralight particle creation which becomes from the Yukawa
interaction between the inflaton and the thermal bath during fresh inflation.
Particle creation is important in the first stages of fresh inflation, when the
nonequilibrium thermal effects are important. I find that the number density of
the ultralight created particles is more important as the scale factor growth
rate is more large (i.e., for $p$ large -- $a \sim t^p$). Ultralight boson
fields created during fresh inflation could be an alternative mechanism to
cosmological constant to explain the discrepancy between the observed $\Omega_m
\simeq 0.2$ and $\Omega_{tot} \simeq 1$, predicted by inflationary models.
