Muonium-Antimuonium Oscillations in an extended Minimal Supersymmetric Standard Model with right-handed neutrinos

TL;DR

This paper investigates muonium-antimuonium oscillations within an extended MSSM with right-handed neutrinos, finding that contributions are generally below current experimental sensitivity but can constrain model parameters for small tanβ.

Contribution

It introduces an analysis of muonium-antimuonium oscillations in an extended MSSM with right-handed neutrinos, linking oscillation constraints to neutrino mass scales and tanβ.

Findings

Contributions to oscillation are below current experimental sensitivity for most parameters.

Small tanβ can lead to observable effects constraining neutrino mass scale.

Lower bounds on tanβ are more stringent than those from magnetic moment measurements.

Abstract

The electron and muon number violating muonium-antimuonium oscillation process in an extended Minimal Supersymmetric Standard Model is investigated. The Minimal Supersymmetric Standard Model is modified by the inclusion of three right-handed neutrino superfields. While the model allows the neutrino mass terms to mix among the different generations, the sneutrino and slepton mass terms have only intra-generation lepton number violation but not inter-generation lepton number mixing. So doing, the muonium-antimuonium conversion can then be used to constrain those model parameters which avoid further constraint from the $\mu\to e\gamma$ decay bounds. For a wide range of parameter values, the contributions to the muonium-antimuonium oscillation time scale are at least two orders of magnitude below the sensivity of current experiments. However, if the ratio of the two Higgs field VEVs, $\tan\beta$, is very small, there is a limited possibility that the contributions are large enough for the present experimental limit to provide an inequality relating $\tan\beta$ with the light neutrino mass scale $m_\nu$ which is generated by see-saw mechanism. The resultant lower bound on $\tan\beta$ as a function of $m_\nu$ is more stringent than the analogous bounds arising from the muon and electron anomalous magnetic moments as computed using this model.