2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/148094Recent analytic calculations on the rate for the production of a pair of massive fermions in $e^+ e^-$ annihilation plus real or virtual radiation of a pair of massless fermions are discussed. The contributions for real and virtual radiation are displayed separately. The asymptotic behaviour close to threshold is given in a compact form and an application to the angular distribution of massive quarks close to threshold is presented.4 pages, latex, uses epsf.sty, invited talk given at the Europhysics Conference on High Energy Physics, Brussels Jul 27 - Aug 2 1995, presented by J.H. Kühn; complete postscript file available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-37/ttp95-37.ps or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints/High Energy Physics - Phenomenologytext