# Recherche du boson de Higgs dans le canal $WH$ et étude de la production $Wb\bar{b}$ dans les collisions $p\bar{p}$ à 1.96 TeV dans l'expérience $D0$ auprès du Tevatron de Fermilab

Abstract : The introduction of the Higgs boson in the standard model provides a mechanism to explain the origin of the masses of the elementary particles. The Higgs boson has
not yet been discovered but a lower limit on its mass has been set of 114.4 GeV at 95% confidence level by LEP experiments. The search of the Higgs boson is been pursued at the Tevatron, proton­antiproton collider, in the associated production channel $WH$ with a Higgs mass lower than 135 GeV where the Higgs decay in $b\bar{b}$. The detector $D0$ is used to record the signals. For this analysis, the calorimeter and the tracker are the main sub­detector. The signals from the calorimeter have been studied through a calibration and a study on the noise level in order to improve the reconstruction of the objects. The missing transverse energy, the electrons and the jets are well identified objects so they can be used in our analysis $W (\to e\nu)+$ jets. As $D0$ has a new tracker and solenoid system, informations from this system allows us to tag jets when they are originating from a $b$­quark. The analysis of events $W (\to e\nu$)+2 b­tag jets has been made on 174 pb$^{-1}$. An upper limit on the cross section production of the processus $W (\to e\nu)b\bar{b}$ has been derived at 20.3 pb at 95% confidence level. This processus is the main irreductible background of a $WH \to e\nub\bar{b}$. In the second part of the analysis, the search of the Higgs boson has been done for different mass values between 105 GeV and 135 GeV. Upper Limits on cross section production times branching ratio have been set. For a Higgs mass of 115 GeV, the upper limit is set of 12.4 pb at 95% confidence limit.
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Physique des Hautes Energies - Expérience [hep-ex]. Université Pierre et Marie Curie - Paris VI, 2004. Français

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• HAL Id : tel-00106136, version 1

### Citation

Stéphanie Beauceron. Recherche du boson de Higgs dans le canal $WH$ et étude de la production $Wb\bar{b}$ dans les collisions $p\bar{p}$ à 1.96 TeV dans l'expérience $D0$ auprès du Tevatron de Fermilab. Physique des Hautes Energies - Expérience [hep-ex]. Université Pierre et Marie Curie - Paris VI, 2004. Français. 〈tel-00106136〉

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