Probing thermal fluctuations through scalar test particles

Abstract The fundamental vacuum state of quantum fields, related to Minkowski space, produces divergent fluctuations that must be suppressed in order bring reality the description physical systems. As a consequence, negative expectation values classically positive-defined quantities can appear. This has been addressed literature as subvacuum phenomenon. Here it is investigated how scalar charged test particle affected by massive field D + 1 spacetime when background evolves from empty space thermal bath, and also perfectly reflecting boundary included. It shown brought into bath gains an amount energy means positive dispersions its velocity components. magnitude this effect dependent on temperature mass. However, wall inserted, or negative, showing happens even finite environment. Furthermore, remarkable result improve fluctuations. residual effects depends switching interval time system takes evolve between two states.