Abstract.
From a data sample of \(9.98 {\mathrm{ pb^{-1}}}\) integrated luminosity, collected by DELPHI at a centre-of-mass energy of 172 GeV, 118 events were selected as W-pair candidates. From these, the branching fraction \({\mathrm Br}({\mathrm W} \rightarrow{\mathrm q}\bar{\mathrm q})\) was measured to be \(0.660^{+0.036}_{-0.037} (\mathrm{stat.}) \pm 0.009 (\mathrm{syst.})\) and the cross-section for the doubly resonant process \(\mat hrm{e^+ e^- \rightarrow W^+ W^-}\) to be \(11.58^{+1.44}_{-1.35} (\mathrm{stat.}) \pm 0.32 (\mathrm{syst.})\) pb. The mass of the W boson, obtained from direct reconstruction of the invariant mass of the fermion pairs in the decays \(\mathrm{ WW \rightarrow \ell\nu q \bar{q}}\) and \(\mathrm{ WW \rightarrow q\bar{q}q\bar{q}}\), was determined to be \(m_{\mathrm W} = \: 80.22 \: \pm \: 0.41 (\mathrm{stat.}) \: \pm 0.04 (\mathrm{syst.}) \: \p m 0.05 (\mathrm{int.}) \: \pm 0.03 (\mathrm{LEP})\: \mathrm{GeV}/c^2\), where “int.” denotes the uncertainty from interconnection effects like colour reconnection and Bose-Einstein interference. Combined with the W mass obtained from the cross-sections measured by DELPHI at threshold, a value of \(m_{\mathrm W} = \: 80.33 \: \pm \: 0.30 (\mathrm{stat.}) \: \pm 0.05 ({\mathrm{syst.}}) \: \pm \: 0.03 (\mathrm{int.}) \: \pm \: 0.03 (\mathrm{LEP}) \: \mathrm{GeV}/c^2\) was found.
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Received: 12 December 1997 / Published online: 10 March 1998
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DELPHI Collaboration., Abreu et al., P. Measurement of the W-pair cross-section and of the W mass in \({\mathrm{e^+ e^-}}\) interactions at 172 GeV. Eur. Phys. J. C 2, 581–595 (1998). https://doi.org/10.1007/s100529800857
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DOI: https://doi.org/10.1007/s100529800857