Long-term LHC discovery reach for compressed Supersymmetry models using VBF processes

The identity of Dark Matter (DM) is one of the most active topics in particle physics today. Supersymmetry (SUSY) is an extension of the standard model (SM) that could describe the particle nature of DM in the form of the lightest neutralino in R-parity conserving models. We focus on SUSY models that solve the hierarchy problem with small fine tuning, and where the lightest SUSY particles ((chi) over tilde (0)(1), (chi) over tilde (+/-)(1), (chi) over tilde (0)(2)) are a triplet of higgsino-like states, such that the mass difference Delta m((chi) over tilde (0)(2), (chi) over tilde (0)(1)) is 0.5-50 GeV. We perform a feasibility study to assess the long-term discovery potential for these compressed SUSY models with higgsino-like states, using vector boson fusion (VBF) processes in the context of proton-proton collisions at root s = 13 TeV, at the CERN Large Hadron Collider. Assuming an integrated luminosity of 3000 fb(-1), we find that stringent VBF requirements, combined with large missing momentum and one or two low-pT leptons, is effective at reducing the major SM backgrounds, leading to a 5 sigma (3 sigma) discovery reach for m((chi) over tilde (0)(2)) < 180 (260) GeV, and a projected 95% confidence level exclusion region that covers m(<(chi)over tilde>(0)(2)) up to 385 GeV, parameter space that is currently unconstrained by other experiments.

Automated summary

The identity of Dark Matter (DM) is a highly discussed topic in particle physics, and Supersymmetry (SUSY) is an important extension of the standard model that can explain the nature of DM. A feasibility study was conducted at the CERN Large Hadron Collider to assess the long-term discovery potential of compressed SUSY models with higgsino-like states. The study found that using vector boson fusion (VBF) processes combined with specific requirements effectively reduces the background and provides new insights into the parameter space of DM models.