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Recherche de nouvelle physique dans le canal B0s --> J/psi phi auprès de l'expérience LHCb

Abstract : Search for New Physics in the B0s --> J/psi phi decay channel at LHCb:In the B0s --> J/psi phi channel, the phase fs is predicted to be significantly small in the Standard Model. This observable is an excellent probe for New Physics because the B0s-B0sbarmixing takes place via a loop diagram where new particles is expected to intervene. These two reasons makes the fs parameter an excellent probe for New Physics processes. We developed a simplified selection for the 2010 data. It avoids any bias on the proper time distribution in order to reduce systematic uncertainty. In addition, we control the tagging performance for B0s --> J/psi phi events using the similar B0d --> J/psi K*0 and B+ --> J/psi K+ channels. With the 2010 data, we obtain 570 signal events in 36 pb−1 of integrated luminosity, a tagging power of (2.2 ± 0.4)% and a proper time resolution of 50 fs. We investigated an alternative selection which maximizes the fs sensitivity using a proper time biasing cuts. We proposed a data-driven method to correct the proper timeacceptance. We designed a fitting program to determine the fs phase. With the 2010 data, It isfound to be: phis = [−2.7,−0.5] rad at 68% of confidance. This result is compatible with the Standard Model prediction.
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https://tel.archives-ouvertes.fr/tel-00631168
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Submitted on : Tuesday, October 11, 2011 - 3:53:18 PM
Last modification on : Thursday, January 18, 2018 - 2:22:05 AM
Long-term archiving on: : Tuesday, November 13, 2012 - 4:30:34 PM

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Basem Khanji. Recherche de nouvelle physique dans le canal B0s --> J/psi phi auprès de l'expérience LHCb. Physique des Hautes Energies - Expérience [hep-ex]. Université de la Méditerranée - Aix-Marseille II, 2011. Français. ⟨tel-00631168⟩

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