Detecting Heavy Neutral SUSY Higgs Bosons Decaying to Sparticles at the High-Luminosity LHC

In supersymmetry (SUSY) models with low electroweak naturalness (natSUSY), which have been suggested to be the most likely version of SUSY to emerge from the string landscape, higgsinos are expected at the few hundred GeV scale, whilst electroweak gauginos inhabit the TeV scale. For TeV-scale heavy neutral SUSY Higgs bosons H and A, as currently required by LHC searches, the dominant decay modes of H, A are gaugino plus higgsino provided these decays are kinematically open. The light higgsinos decay to soft particles, so are largely invisible, whilst the gauginos decay to W, Z or h plus missing transverse energy (E/T). Thus, we examine the viability of H, A -> W+ E/T, Z+ E/T and h+ E/T signatures at the high luminosity LHC (HL-LHC) in light of large standard model (SM) backgrounds from (mainly) tt & macr;, VV and Vh production (where V = W, Z). We also examine whether these signal channels can be enhanced over backgrounds by requiring the presence of an additional soft lepton from the decays of the light higgsinos. We find significant regions in the vicinity of mA similar to 1-2 TeV of the mA vs. tan beta plane, which can be probed at the high luminosity LHC, using these dominant signatures by HL-LHC at 5 sigma and at the 95% confidence level (CL).

Automated summary

In SUSY models with low electroweak naturalness, higgsinos are expected at few hundred GeV scale while electroweak gauginos are at the TeV scale. For heavy neutral SUSY Higgs bosons H and A at TeV scale, the dominant decay modes are gaugino plus higgsino. We explore the possibility of H, A -> W+E/T, Z+E/T and h+E/T signatures at the HL-LHC, considering the large SM backgrounds and investigate if the presence of additional soft leptons from the decays of light higgsinos can enhance these signal channels over backgrounds. We find significant regions in the mA vs. tan beta plane around 1-2 TeV which can be probed at the HL-LHC with these dominant signatures at 5 sigma and the 95% CL.