The Casimir force on a piston at finite temperature in Randall-Sundrum models

The Casimir effect for a three-parallel-plate system at finite temperature within the frame of five-dimensional Randall-Sundrum models is studied. In the case of Randall-Sundrum model involving two branes we find that the Casimir force depends on the plates distance and temperature after one outer plate has been moved to the distant place. Further we discover that the sign of the reduced force is negative as the plate and piston locate very close, but the reduced force nature becomes repulsive when the plates distance is not very tiny and finally the repulsive force vanishes with extremely large plates separation. The thermal influence causes the repulsive Casimir force greater. Within the frame of one-brane scenario the reduced Casimir force between the piston and one plate left keeps attractive no matter how high the temperature is. It is interesting that the thermal effect leads the attractive Casimir force greater instead of changing the force nature.