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Flavon-induced connections between lepton flavour mixing and charged lepton flavour violation processes.

Pascoli, Silvia and Zhou, Ye-Ling (2016) 'Flavon-induced connections between lepton flavour mixing and charged lepton flavour violation processes.', Journal of high energy physics., 2016 (10). p. 145.


In leptonic flavour models with discrete flavour symmetries, couplings between flavons and leptons can result in special flavour structures after they gain vacuum expectation values. At the same time, they can also contribute to the other lepton-flavour-violating processes. We study the flavon-induced LFV 3-body charged lepton decays and radiative decays and we take as example the A4 discrete symmetry. In A4 models, a Z3 residual symmetry roughly holds in the charged lepton sector for the realisation of tri-bimaximal mixing at leading order. The only processes allowed by this symmetry are τ− → μ+e−e−, e+μ−μ−, and the other 3-body and all radiative decays are suppressed by small Z3-breaking effects. These processes also depend on the representation the flavon is in, whether pseudo-real (case i) or complex (case ii). We calculate the decay rates for all processes for each case and derive their strong connection with lepton flavour mixing. In case i, sum rules for the branching ratios of these processes are obtained, with typical examples Br(τ− → μ+e−e−) ≈ Br(τ− → e+μ−μ−) and Br(τ− → e−γ) ≈ Br(τ− → μ−γ). In case ii, we observe that the mixing between two Z3-covariant flavons plays an important role. All processes are suppressed by charged lepton masses and current experimental con- straints allow the electroweak scale and the flavon masses to be around hundreds of GeV. Our discussion can be generalised in other flavour models with different flavour symmetries.

Item Type:Article
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Publisher statement:© The Author(s) 2016 Open Access. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
Date accepted:17 October 2016
Date deposited:14 November 2016
Date of first online publication:26 October 2016
Date first made open access:No date available

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