The present paper has a twofold contribution: first, we intro-
duce a new concept of Hardy spaces on a multidimensional complexified
annular domain which is closely related to the annulus of the Klein-Di
rac
quadric important in Conformal Quantum Field Theory. Secondly, for
functions in these Hardy spaces, we provide error estimate for the p
oly-
harmonic Gauß-Jacobi cubature formulas, which have been introduced
in previous papers.
