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Mesure des couplages à 3 bosons dans l'expérience ALEPH et au LEP

Abstract : Precise measurements at LEP1 and SLD dramatically confirm the Standard Model predictions. Nevertheless, the most crucial consequence of a non-Abelian gauge theory, namely the specific form of the self-couplings of the W, Z and gamma, was poorly tested. W pair production at LEP2 was a unique opportunity to measure accurately both W boson parameters and its gauge couplings. This thesis presents a study of WW events reconstruction on one hand, and a measurement of the anomalous couplings on the other hand.

A precise measurement of the W mass (accuracy ~10-4) is a major goal of the LEP2 program. The reconstruction of W mass desintegration products, used for this measurement, is very sensitive to the simulation defaults: an essential task is to understand and minimze their effects. This work presents a detailled study of the electromagnetic showers simulation in ALEPH. From this study, a new event reconstruction is proposed, which is tested on the LEP energy measurement obtained from Z return process.

Triple gauge-boson couplings are measured from the data collected with the ALEPH detector between 1997 and 2000. Then, results are combined with the other three LEP experiments. This measurement directly confirms the non-Abelian nature of the electroweak sector. No deviation from the Standard Model is observed.
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Submitted on : Monday, June 16, 2003 - 3:37:30 PM
Last modification on : Friday, November 6, 2020 - 3:29:01 AM
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  • HAL Id : tel-00003013, version 1



Renaud Brunelière. Mesure des couplages à 3 bosons dans l'expérience ALEPH et au LEP. Physique des Hautes Energies - Expérience [hep-ex]. Université de Savoie, 2003. Français. ⟨tel-00003013⟩



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