  We investigate configuration dynamics of a flexible polymer chain in a bath
of active particles with dynamic chirality, i.e., particles rotate with a
deterministic angular velocity $\omega$ besides self-propulsion,by Langevin
dynamics simulations in two dimensional space. Particular attentions are paid
to how the gyration radius $R_{g}$ changes with the propulsion velocity
$v_{0}$,angular velocity $\omega$ and chain length. We find that in a chiral
bath with a typical nonzero $\omega$, the chain first collapses into a small
compact cluster and swells again with increasing $v_{0}$, in quite contrast to
the case for a normal achiral bath $(\omega=0)$ wherein a flexible chain swells
with increasing $v_{0}$. More interestingly, the polymer can even form a closed
ring if the chain length is large enough,which may oscillate with the cluster
if $v_{0}$ is large. Consequently, the gyration radius $R_{g}$ shows nontrivial
non-monotonic dependences on $v_{0}$, i.e., it undergoes a minimum for
relatively short chains, and two minima with a maximum in between for longer
chains. Our analysis shows that such interesting phenomena are mainly due to
the competition between two roles played by the chiral active bath: while the
persistence motion due to particle activity tends to stretch the chain, the
circular motion of the particle may lead to an effective osmotic pressure that
tends to collapse the chain. In addition, the size of the circular motion
$R_{0}=v_{0}/\omega$ shows an important role in that the compact clusters and
closed-rings are both observed at nearly the same values of $R_{0}$ for
different $\omega$.
