Light Pseudoscalar Higgs boson in Neutralino Decays in the Next-to-Minimal Supersymmetric Standard Model

TL;DR

This paper explores a new production channel for a light pseudoscalar Higgs boson in the NMSSM via neutralino decays, highlighting its significance in LHC SUSY searches with multiple tau leptons.

Contribution

It identifies and analyzes a novel decay pathway of neutralinos producing the light pseudoscalar Higgs in the NMSSM, emphasizing its potential observability at the LHC.

Findings

Neutralino decays can produce a light pseudoscalar Higgs with high branching ratios.

The production of $a_1$ via neutralino decays can dominate over other channels.

Final states with multiple tau leptons provide a clean signature for detection.

Abstract

We point out another important production channel of a light pseudoscalar Higgs boson $a_1$ via the decays of neutralinos, including $\widetilde{\chi}_{2,3}^0 \to \widetilde{\chi}_{1}^0 a_1$, in the framework of the NMSSM. We scan the whole parameter space using the most up-to-date version of NMHDECAY and search for regions where $B(\widetilde{\chi}_{2,3}^0 \to \widetilde{\chi}_{1}^0 a_1) > 0.5$. If the gluino and squarks are light enough for copious production of SUSY events at the LHC, there would be numerous number of $\widetilde{\chi}_{2,3}^0$ in subsequent decays of gluinos and squarks. Therefore, the production rates of $a_1$ via neutralino decays would be more important than $h \to a_1 a_1$ and others. Potentially, the final state is filled with many $\tau$ leptons, which can be reconstructed at the mass of $a_1$. This is a clean, observable, and distinguishable signature for NMSSM.