Lepton-flavor violation in the MRSSMSeesaw

TL;DR

MRSSMSeesaw extends the MRSSM with three generations of right-handed neutrinos to realize a Type-I seesaw and generate light neutrino masses. It derives the mass spectra and computes LFV amplitudes for $\ell_i \rightarrow \ell_j \gamma$, $\ell_i \rightarrow \ell_j \ell_j \ell^{+}_j$, and $h \rightarrow \ell_i \ell_j$, followed by a comprehensive parameter scan with SARAH/SPheno/BSMArt. The results show LFV is dominated by non-diagonal slepton mixing $\delta_{ij}$, with $\mu \rightarrow e \gamma$ requiring $\delta_{12} \lesssim 0.075$ and Higgs LFV decays reaching $\mathcal{O}(10^{-9})$ in some channels, while right-handed neutrino effects are suppressed by $Y_\nu \sim 10^{-7}$. The study identifies viable regions under current constraints and emphasizes Higgs LFV as a promising experimental probe of MRSSMSeesaw.

Abstract

The Minimal R-symmetric Supersymmetric Standard Model with Seesaw (MRSSMSeesaw) extends the MRSSM by incorporating right-handed neutrinos to generate neutrino masses via the Type-I seesaw mechanism. This work presents a detailed analysis of lepton flavor violation (LFV) processes, including $\ell_i \rightarrow \ell_j γ$, $\ell_i \rightarrow 3\ell_j$, and Higgs decays $h \rightarrow \ell_i \ell_j$, Based on the current experimental limitations, we carry out detailed parameter scanning and numerical calculations to analyse the effects of different sensitive parameters on LFV.The numerical results show that the non-diagonal elements involving the initial and final leptons are main sensitive parameters and LFV sources.

Figures (13)

• Figure 1: (a) represents the contributions from Charginos and Sneutrino loops and (b) represents the contributions from charged Sleptons and Neutrinos loops.
• Figure 2: The Z-penguin diagrams for $\ell^{-}_{i}\to \ell^{-}_{j}\ell^{-}_{j}\ell^{+}_{j}$.
• Figure 3: The H-penguin diagrams for $\ell^{-}_{i}\to \ell^{-}_{j}\ell^{-}_{j}\ell^{+}_{j}$.
• Figure 4: Box-type diagrams for the process $\ell^{-}_{i}\to \ell^{-}_{j}\ell^{-}_{j}\ell^{+}_{j}$.(a) ,(b)represents the contributions from neutral fermions Neutralinos and charge scalars loops Sleptons and (c) represents the contributions from charged fermions Charginos and neutral scalars Sneutrinos loops.
• Figure 5: One-loop diagrams for the Higgs LFV in the MRSSMSeesaw model