Closing in on the Wino LSP via trilepton searches at the LHC

TL;DR

This paper explores how to optimize trilepton searches at the LHC to better detect wino-like neutralino dark matter, proposing alternative channels and cut strategies to improve sensitivity.

Contribution

It introduces a modified analysis approach including additional production channels and optimized cuts to enhance detection prospects for wino-like DM at the LHC.

Findings

Enhanced sensitivity for wino-like DM detection at 14 TeV LHC

Combined channels can reach above 4σ significance for 100 GeV DM

Discarding certain cuts improves signal detection efficiency

Abstract

The neutralino dark matter (DM) predicted by the Minimal Supersymmetric Standard Model (MSSM) has been probed in several search modes at the Large Hadron Collider (LHC), one of the leading ones among which is the trilepton plus missing transverse momentum channel. The experimental analysis of this mode has, however, been designed to probe mainly a bino-like DM, originating in the decays of a pair of next-to-lightest neutralino and lightest chargino, both of which are assumed to be wino-like. In this study, we analyse how this trilepton channel can be tuned for probing also the wino-like DM. We note that, while the mentioned standard production mode generally leads to a relatively poor sensitivity for the wino-like DM, there are regions in the MSSM parameter space where the net yield in the trilepton final state can be substantially enhanced at the LHC with $\sqrt{s}=14$ TeV. This is achieved by taking into account also an alternative channel, pair-production of the wino-like DM itself in association with the heavier chargino, and optimisation of the kinematical cuts currently employed by the LHC collaborations. In particular, we find that the cut on the transverse mass of the third lepton highly suppresses both the signal channels and should therefore be discarded in this DM scenario. We perform a detailed detector-level study of some selected parameter space points that are consistent with the most important experimental constraints, including the recent ones from the direct and indirect DM detection facilities. Our analysis demonstrates the high complementarity of the two channels, with their combined significance reaching above 4$\sigma$ for a wino-like DM mass around 100 GeV, with an integrated luminosity as low as 100 fb$^{-1}$.