Field theory at finite temperature and \(\eta -\xi\) spacetime (Q687894)

The author investigates some properties of field theory at finite temperature formulated in terms of an auxiliary complex space introduced by him [Phys. Rev. D 42, 1988 (1990)], the \(\eta-\xi\) spacetime. This space provides a universal geometrical background for finite temperature field theories. The main motivation for the use of \(\eta-\xi\) spacetime is to carry over the Hawking black-hole radiation theory to thermal field theory in Minkowski space. It is shown that thermo field dynamics correspond to the Hamiltonian formalism of the field theory in \(\eta-\xi\) spacetime. It is proven that the vacuum Green functions on Euclidean sections in \(\eta-\xi\) spacetime are equal to the imaginary-time thermal Green functions in flat spacetime.