Radiative Neutralino Decay in Split Supersymmetry

TL;DR

This paper investigates the radiative decay of the second neutralino into the first neutralino and a photon within Split Supersymmetry, highlighting its potential as a clear experimental signature and its dependence on the supersymmetric scale.

Contribution

It provides the first detailed analysis of radiative neutralino decay in Split Supersymmetry, showing its significant branching ratios and dependence on the supersymmetric scale.

Findings

Branching ratio can approach unity near M2 ~ M1.

Decay signature offers a clear electromagnetic plus missing energy signal.

Decay branching ratio strongly depends on the split supersymmetric scale.

Abstract

Radiative neutralino decay $\chi^0_2 -> \chi^0_1\gamma$ is studied in a Split Supersymmetric scenario, and compared with mSUGRA and MSSM. This 1-loop process has a transition amplitude which is often quite small, but has the advantage of providing a very clear and distinct signature: electromagnetic radiation plus missing energy. In Split Supersymmetry this radiative decay is in direct competition with the tree-level three-body decay $\chi^0_2 -> \chi^0_1 f\overline f$, and we obtain large values for the branching ratio $B(\chi^0_2 -> \chi^0_1\gamma)$ which can be close to unity in the region $M_2 \sim M_1$. Furthermore, the value for the radiative neutralino decay branching ratio has a strong dependence on the split supersymmetric scale $\widetilde{m}$, which is otherwise very difficult to infer from experimental observables.