Rare meson decays into very light neutralinos

TL;DR

This paper analyzes the potential for rare meson decays to reveal very light neutralinos within the MSSM, providing explicit decay formulas and exploring flavor violation effects, with implications for collider searches.

Contribution

It offers the first complete calculation of loop-induced meson decays into light neutralinos and examines the impact of flavor violation on decay rates and experimental bounds.

Findings

Supersymmetric decay rates are highly suppressed under minimal flavor violation.

No bounds on neutralino mass can be derived from current meson decay data.

Allowing non-minimal flavor violation can enhance decay rates and constrain MSSM parameters.

Abstract

We investigate the bounds on the mass of the lightest neutralino from rare meson decays within the MSSM with and without minimal flavor violation. We present explicit formulae for the two-body decays of mesons into light neutralinos and perform the first complete calculation of the loop-induced decays of kaons to pions and light neutralinos and B mesons to kaons and light neutralinos. We find that the supersymmetric branching ratios are strongly suppressed within the MSSM with minimal flavor violation, and that no bounds on the neutralino mass can be inferred from experimental data, i.e. a massless neutralino is allowed. The branching ratios for kaon and B meson decays into light neutralinos may, however, be enhanced when one allows for non-minimal flavor violation. We find new constraints on the MSSM parameter space for such scenarios and discuss prospects for future kaon and B meson experiments. Finally, we comment on the search for light neutralinos in monojet signatures at the Tevatron and at the LHC.