Performance of a Soft Muon, Hard Jet and Moderate Missing Energy Trigger in 2018 Data

This note presents the performance of a dedicated High-Level Trigger (HLT) algorithm that requires a low transverse momentum $p_{\mathrm{T}}$ muon, a jet with transverse momentum $p_{\mathrm{T}}$ greater than 100 GeV and missing transverse momentum $p_{\mathrm{T}}^{\mathrm{miss}}$ greater than 80 GeV. The trigger algorithm targets events with ISR signatures with moderate $p_{\mathrm{T}}^{\mathrm{miss}}$ and soft muons, that are typical in SUSY models with very compressed mass spectra. The rate of the trigger is approximately 12 Hz for an instantaneous luminosity of $1.8 \times 10^{34}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$ and an average pileup of 50. The efficiency measurements are performed using $59.7~\mathrm{fb}^{-1}}$ of data recorded by the CMS detector in 2018, in orthogonal control samples collected using triggers based on pure missing transverse momentum $p_{\mathrm{T}}^{\mathrm{miss}}$ and single-muon requirements. The trigger efficiencies are parametrised in terms of the offline quantities of the three legs of the trigger: muon $p_{\mathrm{T}}$, jet $p_{\mathrm{T}}$ and $p_{\mathrm{T}}^{\mathrm{miss}}$.