Collider signatures of a light NMSSM pseudoscalar in neutralino decays in the light of LHC results

TL;DR

This paper explores the potential for detecting a very light pseudoscalar Higgs in the NMSSM through neutralino decays at the LHC, identifying specific signatures and selection criteria that could reveal such particles.

Contribution

It introduces a novel analysis of light pseudoscalar signatures in NMSSM neutralino decays, including optimized selection cuts and benchmark scenarios for LHC detection.

Findings

Certain NMSSM parameter points can produce detectable signals at the LHC.

The proposed selection cuts effectively distinguish signal from background.

Some benchmark points show promising prospects for discovery at 8 TeV LHC.

Abstract

We investigate signatures induced by a very light pseudoscalar Higgs in neutralino decays in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and determine their observability at the LHC. We concentrate on scenarios which feature two light scalar Higgs bosons (one of them is SM-like with a mass of 125 GeV and a singlet-like lighter one) with a very light (singlet-like) pseudoscalar Higgs in the mass range 2m_tau < m_a1 < 2m_b. We consider neutralino-chargino pair production and the subsequent decay X_{2,3}-> X_1 a1, which leads to topologies involving multi-leptons and missing transverse energy. We determine a set of selection cuts that can effectively isolate the signal from backgrounds of the Standard Model or the Minimal Supersymmetric Standard Model. We also exemplify the procedure with a set of benchmark points, for which we compute the expected number of events and signal strength for LHC with 8 TeV center of mass energy. We show that this signal can already be probed for some points in the NMSSM parameter space.