THERMAL FIELD-DYNAMICS AND BIALGEBRAS

In thermal field dynamics, thermal states are obtained from restrictio ns of vacuum states on a doubled field algebra. It is shown that the s uitably doubled Fock representations of the Heisenberg algebra do not need to be introduced by hand but can be canonically handed down from deformations of the extended Heisenberg bialgebra. No artificial redef initions of fields are necessary to obtain the thermal representations and the case of arbitrary dimension is considered from the beginning. Our results support a possibly fundamental role of bialgebra structur es in defining a general framework for thermal field dynamics. (C) 199 7 American Institute of Physics.