$\mathcal{O}$(1) GeV dark matter in SUSY and a very light pseudoscalar at the LHC

TL;DR

This paper explores the detection prospects of ~1 GeV singlino-dominated neutralino dark matter in the NMSSM at the 14 TeV LHC, focusing on resonant annihilation via a light pseudoscalar and novel detection strategies.

Contribution

It provides a detailed analysis of parameter space consistent with relic abundance, and introduces an innovative method for detecting collimated muons from light pseudoscalar decays at the LHC.

Findings

Large parameter space with correct relic abundance identified.

Enhanced sensitivity for pseudoscalar-associated production using muon clustering method.

Potential for significant detection at 300 fb$^{-1}$ luminosity.

Abstract

We analyze the prospects of the detection of a $\mathcal{O}(1)$ GeV neutralino dark matter, $\widetilde{\chi}^0_{1}$, in the Next-to-Minimal Supersymmetric Standard Model at the 14 TeV LHC. We perform dedicated scans of the relevant parameter space of the model and find a large number of points where the thermal relic abundance due to such a dark matter is consistent with the PLANCK measurement. We note that this dark matter is highly singlino-dominated and is always accompanied by a pseudoscalar, $A_1$, with a mass around twice its own, which is responsible for its resonant annihilation. For two benchmark points from our scan, we then carry out a detector-level signal-to-background analysis of the pair production of a heavier higgsino neutralino and a chargino. The higgsino thus produced decays into the dark matter and either the $Z$ boson or the $A_1$. For the $Z$-associated production of $\widetilde{\chi}^0_{1}$, we investigate the scope of the trilepton search channel. For the $A_1$-associated production mode, in order to identify the two collimated muons coming from the decay of the $A_1$, we employ an unconventional method of clustering them together into one jet-like object. Using this method, for certain parameter space configurations, a much larger sensitivity can be obtained at the 14 TeV LHC for the $A_1\widetilde{\chi}^0_{1}$ channel compared to the $Z\widetilde{\chi}^0_{1}$ channel, with an integrated luminosity of 300 fb$^{-1}$.