Mass Corrections to the Vector Current Correlator

Abstract

Three-loop QCD corrections to the vector current correlator are considered. The large momentum procedure is applied in order to evaluate mass corrections up to order $(m^2/q^2{)}^6$. The inclusion of the first seven terms to the ratio $R=\sigma (e^{+}{e}^{-}\to hadrons)/\sigma (e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-})$ leads to reliable predictions from the high energy region down to relatively close to threshold.

Comments: 16 pages, LaTeX, 11 postscript figures. The complete paper, including figures, is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ , or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints/