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 — preprints:1995:ttp95-17 [2016/03/17 11:03] (current) Line 1: Line 1: + ====== TTP95-17 HADRON RADIATION IN TAU PRODUCTION AND THE LEPTONIC Z BOSON DECAY RATE ====== + + + Secondary radiation of hadrons from a tau pair produced + in electron positron collisions may constitute an + important obstacle for precision measurements of + the production cross section and of branching ratios. + The rate for real and virtual radiation is calculated + and various distributions are presented. + For Z decays a comprehensive analysis is performed which + incorporates real and virtual radiation of + leptons. The corresponding results are also given for + primary electron and muon pairs. + Compact analytical formulae are presented for + entirely leptonic configurations. + Measurements of $Z$ partial decay rates which eliminate + all hadron and lepton radiation are about 0.3\% to 0.4\% + lower than totally inclusive measurements, a consequence of + the ${\cal O}(\alpha^2)$ negative virtual corrections which + are enhanced by the third power of a large logarithm. + + |**A.H. Hoang, J.H. K\"uhn and T. Teubner,**  | + |** Nucl. Phys. B455 3-20 1995  **  | + | {{preprints:1995:ttp95-17.pdf|PDF}} {{preprints:1995:ttp95-17.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9507255|arXiv]]   | + | |