Sneutrino-antisneutrino mixing at future colliders

TL;DR

This paper explores sneutrino-antisneutrino mixing in supersymmetry, proposing a background-free collider signal that can reveal neutrino mass properties and is feasible in future collider experiments.

Contribution

It introduces a novel collider signal for sneutrino-antisneutrino mixing, demonstrating its potential observability and its ability to provide insights into neutrino parameters.

Findings

Signal is free of Standard Model background.

Supersymmetric backgrounds are minimal.

Potential to extract neutrino mass and mixing information.

Abstract

Sneutrino-antisneutrino mixing occurs in a supersymmetric model where neutrinos have nonzero Majorana masses. This can lead to the sneutrino decaying into a final state with a "wrong-sign charged lepton". In an $e^- \gamma$ collider, the signal of the associated production of an electron-sneutrino and the lighter chargino and their subsequent decays can be $e^- \gamma \to e^+ {\tilde \tau}_1^- {\tilde \tau}_1^- + \mpT$ where the ${\tilde \tau}_1$s are long-lived and can produce heavily ionizing charged tracks. This signal is free of any Standard Model background, and the supersymmetric backgrounds are small. Such a signal can be experimentally observable under certain conditions which are possible to obtain in an anomaly-mediated supersymmetry breaking scenario. Information on a particular combination of the neutrino masses and mixing angles can also be extracted through the observation of this signal. Sneutrino-antisneutrino mixing at the LHC is currently under study, and asymmetry considerations seem promising there.