ANALYTICITY PROPERTIES AND THERMAL EFFECTS FOR GENERAL QUANTUM-FIELD THEORY ON DESITTER SPACE-TIME

We propose a general framework for quantum field theory on the de Sitt er space-time (i.e. for local field theories whose truncated Wightman functions are not required to vanish). By requiring that the fields sa tisfy a weak spectral condition, formulated in terms of the analytic c ontinuation properties of their Wightman functions, we show that a geo desical observer will detect in the corresponding ''vacuum'' a blackbo dy radiation at temperature T = 1/2 pi R. We also prove the analogues of the PCT, Reeh-Schlieder and Bisognano-Wichmann theorems.