A REMARK ON FORMAL KMS STATES IN DEFORMATION QUANTIZATION

Within the framework of deformation quantization, we define formal KMS states on the deformed algebra of power series of functions with comp act support in phase space as C[[lambda]]-linear functionals obeying a formal variant of the usual KMS condition known in the theory of C-a lgebras. We show that for each temperature KMS states always exist and are up to a normalization equal to the trace of the argument multipli ed by a formal analogue of the usual Boltzmann factor, a certain forma l star exponential.