Nm. Nikolov et It. Todorov, Rationality of conformally invariant local correlation functions on compactified Minkowski space, COMM MATH P, 218(2), 2001, pp. 417-436
Rationality of the Wightman functions is proven to follow from energy posit
ivity, locality and a natural condition of global conformal invariance (GCI
) in any number D of space-time dimensions. The GCI condition allows to tre
at correlation functions as generalized sections of a vector bundle over th
e compactification (M) over bar of Minkowski space M and yields a strong fo
rm of locality valid for all non-isotropic intervals if assumed true for sp
ace-like separations.