Abstract: The ratio R(S)=${\mathrm{\ensuremath{\sigma}}}_{\mathrm{tot}}$(${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}hadrons)/\ensuremath{\sigma}(${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$) is calculated to the four-loop level in perturbative QCD. The result differs from a previous calculation and is much smaller. In addition, a new result for the four-loop \ensuremath{\beta} function in QED is obtained. This result also disagrees with a previous calculation.
Publication Year: 1991
Publication Date: 1991-02-04
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 432
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