Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">W</mml:mi><mml:mi/><mml:mo>→</mml:mo><mml:mi/><mml:mi mathvariant="italic">τ</mml:mi><mml:mi mathvariant="italic">ν</mml:mi></mml:math>Production Cross Section in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">p</mml:mi><mml:mrow><mml:mrow><mml:mover><mml:mrow><mml:mi mathvariant="italic">p</mml:mi></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover></mml:mrow></mml:mrow></mml:math>Collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mrow><mml:mi mathvariant="italic">s</mml:mi></mml:mrow></mml:msqrt><mml:mspace/><mml:mo>=</mml:mo><mml:mspace/><mml:mn>1.8</mml:mn><mml:mn/><mml:mi/><mml:mi>TeV</mml:mi></mml:math>
Abstract
We report on a measurement of $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}W+X)B(W\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\nu})$ in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ at the Fermilab Tevatron. The measurement is based on an integrated luminosity (lum) of $18{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected with the D0 detector during 1994--1995. We find that $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}W+X)B(W\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\nu})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2.22\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.10(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.10(\mathrm{lum})\mathrm{nb}$. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the $W$ boson, ${g}_{\ensuremath{\tau}}^{W}{/g}_{e}^{W}$, be unity. We find ${g}_{\ensuremath{\tau}}^{W}{/g}_{e}^{W}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.980\ifmmode\pm\else\textpm\fi{}0.031$, in agreement with lepton universality.
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