  We study, in the framework of open quantum systems, the entanglement dynamics
for a quantum system composed of two uniformly accelerated Unruh-Dewitt
detectors interacting with a bath of massive scalar fields in the Minkowski
vacuum. We find that the entanglement evolution for the quantum system coupled
with massive fields is always slower compared with that of the one coupled with
massless fields, and this time-delay effect brought by the field being massive
can however be counteracted by a large enough acceleration, in contrast to the
case of a static quantum system in a thermal bath, where this time delay is not
affected by the temperature. Remarkably, the maximal concurrence of the quantum
system generated during evolution may increase with acceleration for any
inter-detector separation while that for static ones in a thermal bath
decreases monotonically with temperature, and this can be considered as an
anti-Unruh effect in terms of the entanglement generated.
