Majorana CP-violating phases, RG running of neutrino mixing parameters and charged lepton flavour violating decays

2005/08/23 by S. T. Petcov, Tetsuo Shindou, T. Shindou +1 · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #CP violation #Electron #Lepton #MAJORANA #Mass matrix #Minimal Supersymmetric Standard Model #Neutrino #Neutrino Physics Research #Neutrino oscillation #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Pontecorvo–Maki–Nakagawa–Sakata matrix #Sterile neutrino #Supersymmetry #Yukawa potential #hep-ph

paper · pdf · doi:10.1016/j.nuclphysb.2005.12.028

published as Nucl.Phys.B738:219-242,2006 · 26 pages, 5 figures

arxiv created 2005/08/23 · openalex publication_date 2006/01/23 · arxiv updated 2014/11/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We consider the MSSM with see-saw mechanism of neutrino mass generation and soft SUSY breaking with flavour-universal boundary conditions at the GUT scale, in which the lepton flavour violating (LFV) decays μ→ e + γ, τ→ μ+ γ, etc.,are predicted with rates that can be within the reach of present and planned experiments. These predictions depend critically on the matrix of neutrino Yukawa couplings \bfY_ν which can be expressed in terms of the light and heavy right-handed (RH) neutrino masses, neutrino mixing matrix U_PMNS, and an orthogonal matrix \bfR. We investigate the effects of Majorana CP-violation phases in U_PMNS, and of the RG running of light neutrino masses and mixing angles from M_Z to the RH Majorana neutrino mass scale M_R, on the predictions for the rates of LFV decays μ→ e + γ, τ→ μ+ γand τ→ e + γ. Results for neutrino mass spectrum with normal hierarchy, values of the lightest ν-mass in the range 0 ≤ m₁ ≤ 0.30 eV, and quasi-degenerate heavy RH Majorana neutrinos in the cases of \bfR = \bf1 and complex matrix \bfR are presented. We find that the effects of the Majorana CP-violation phases and of the RG evolution of neutrino mixing parameters can change by few orders of magnitude the predicted rates of the LFV decays μ→ e + γand τ→ e + γ. The impact of these effects on the τ→ μ+ γdecay rate is typically smaller and only possible for m₁ > 0.10 eV. If the RG running effects are negligible, in a large region of soft SUSY breaking parameter space the ratio of the branching ratios of the μ→ e + γand τ→ e + γ(τ→ μ+ γ) decays is entirely determined in the case of \bfR ≅ \bf1 by the values of the neutrino mixing parameters at M_Z.

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• Charged lepton flavour violating radiative decays ℓ i → ℓ j + γ in see-saw models with A 4 symmetry