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Phenomenological analysis of charged lepton flavour changes

Abstract : In this doctoral thesis, we investigate charged lepton flavour violating processes in effective field theory, in which possible new physics effects can be parametrized by higher dimensional gauge invariant operators built from Standard Model fields. The discovery of neutrino oscillations is a clear evidence that lepton flavour violation can occur and that neutrinos are massive. In the Standard Model extended with massive neutrinos, charged lepton flavour violating processes are strongly suppressed, and the discovery of such processes would be a clear signal of physics beyond the Standard Model. After a general introduction on the Standard Model of particle physics and beyond, this manuscript contains two introductory chapters. The first one introduce the theoretical and experimental context for the searches of charged lepton flavour violating processes, and their huge potential to constrain new physics model. We make a review of many processes and the current experiments, then we discuss the prospects for the upcoming experiments. The second chapter describe the formalism of the effective field theory approach. We discuss the principles of renormalization and loop integrals calculations with dimensional regularization. We also discuss the renormalization group equations that describe the running and the mixing of the coefficients with the energy scale. Finally, we discuss two different approaches in effective field theories. After introducing the experimental context and the effective field theory formalism, we study the μ → e conversion on nuclei in a top-down approach and charged lepton flavour violating two and three body decays of pseudoscalar mesons in a bottom-up approach. We first list all the operators and their associated coefficients that contribute to the processes. In our work, we mostly focus on dimension six operators. We compute the branching ratios for each processes as a function of the operator coefficients at the experimental scale, and use the experimental upper limit to constrain the coefficients. We also use the renormalization group equations to compute the running and the mixing of the coefficients with energy scale in both top-down and bottom-up approaches. The results discussed in this thesis are based on two publications [1, 2]
Keywords : Theoretical physics
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Submitted on : Thursday, October 17, 2019 - 5:18:07 PM
Last modification on : Friday, September 10, 2021 - 1:50:21 PM


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  • HAL Id : tel-02319188, version 1



Albert Saporta. Phenomenological analysis of charged lepton flavour changes. Physics [physics]. Université de Lyon, 2019. English. ⟨NNT : 2019LYSE1110⟩. ⟨tel-02319188⟩



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