A boost for the EW SUSY hunt: monojet-like search for compressed sleptons at LHC14 with 100 fb^-1

Abstract

Current Large Hadron Collider (LHC) analyses are blind to compressed supersymmetry (SUSY) models with sleptons near the lightest super partner (LSP) in mass: $m_{\tilde{l}}-m_{{\tilde{\chi }}_1^0}\equiv \Delta m\lesssim 60$ GeV. We present a search sensitive to the very compressed range $3\text{GeV}<\Delta m<24\text{GeV}$ using the channel $pp\to {\tilde{l}}^{+}{\tilde{l}}^{-}+\mathrm{jet}\to$ $l^{+}{l}^{-}{\tilde{\chi }}_1^0{\tilde{\chi }}_1^0+\mathrm{jet}$ with soft same-flavor leptons and one hard jet from initial state radiation ($p_{\mathrm{T}}^j>100$ GeV). The sleptons recoil against the jet boosting them and their decay products, making the leptons detectable and providing substantial missing transverse momentum. We use the kinematic variable $m_{T2}$ along with a different-flavor control region to reduce the large standard model backgrounds and control systematic uncertainty. We find the analysis should allow LHC14 with $100{\text{fb}}^{-1}$ to search for degenerate left-handed selectrons and smuons in the compressed region up to $m_{{\tilde{l}}_L}\lesssim 150$ GeV. In addition, it should be sensitive to $m_{{\tilde{l}}_L}\lesssim 110$ GeV for the very challenging case of auto-concealed SUSY, in which left-handed sleptons decay to the Kaluza-Klein tower of a modulino LSP which lives in $d=6$ extra dimensions. In both the compressed spectrum and auto-concealed SUSY scenarios this analysis will need more data to improve on LEP2 limits for right-handed sleptons due to their smaller cross sections.

15 pages, 3 figures, updated citations in v2

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• PYTHIA 6.4 Physics and Manual
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• Minimal Kinematic Constraints and MT2

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• Deciphering compressed electroweakino excesses with MadAnalysis 5