Neutrino Non-Standard Interactions from LLE-type R-parity Violation

TL;DR

The paper analyzes neutrino NSI generated by trilinear LLE couplings in a split-family RPV SUSY framework (RPV3) with light third-generation sleptons. By classifying NSI-relevant coupling patterns and deriving the corresponding effective four-fermion interactions, it maps the LLE couplings onto NSI parameters and extensively tests the parameter space against collider, LEP, lepton-decay, LFV, neutrino-oscillation, and g-2 constraints. The study finds percent-level NSI is viable in several channels, with the largest entries reaching epsilon_ee ~ 8% and epsilon_mumu ~ 3.8%, while off-diagonal entries like epsilon_mu tau can reach ~-0.3% in certain combinations. A key result is the structural origin of the constraint patterns: tau_L mediated NSI is less constrained and can yield larger NSI than tau_R mediated cases, due to the antisymmetric LLE couplings and correlated charged-lepton processes. The work provides a robust benchmark for LLE-induced NSI in RP V3-like spectra and discusses how upcoming neutrino and collider data could help discriminate among UV completions such as the Zee model.

Abstract

We study neutrino non-standard interactions (NSI) induced by the trilinear $LLE$ couplings in $R$-parity-violating supersymmetry in a split-family spectrum where third-generation sleptons can be comparatively light. We systematically classify the relevant coupling patterns, derive the corresponding effective interactions and NSI parameters, and confront the resulting parameter space with a broad set of experimental constraints. We find that percent-level NSI can be realized in selected channels, with the largest magnitudes reaching $\varepsilon_{ee}\simeq 8\%$ and $\varepsilon_{μμ}\simeq 3.8\%$, while other entries are typically restricted to the sub-percent level (including $\varepsilon_{μτ}\simeq -0.3\%$ in the viable off-diagonal case). We also highlight the structural origin of the different constraint patterns between $\widetildeτ_R$- and $\widetildeτ_L$-mediated scenarios and comment on the relation to the Zee model.

Figures (8)

• Figure 1: NSI induced by charged-slepton exchange in the RPV3 framework for the cases considered in this work, where only the relevant $LLE$ couplings are taken to be nonzero.
• Figure 2: Diagrams contributing to $e^+e^-\to f\bar{f}^\prime$ at LEP for the RPV3 cases considered in this work, with only the relevant $LLE$ couplings taken to be nonzero.
• Figure 3: Diagrams contributing to $\mu\to e\nu\bar{\nu}$, $\tau\to e\nu\bar{\nu}$, and $\tau\to \mu\nu\bar{\nu}$ mediated by $\widetilde{\tau}_R$ in the RPV3 setup considered in this work.
• Figure 4: Diagram contributing to the LFV decay $\tau\to\mu\gamma$ in the RPV3 scenario considered in this work.
• Figure 5: One-loop neutrino mass contribution induced by the $LLE$ interactions in the RPV3 framework.