Long-lived light mediators from Higgs boson decay at HL-LHC and FCC-hh, and a proposal of dedicated long-lived particle detectors for FCC-hh

We study the pair production of the long-lived mediator particles from the decay of the standard model Higgs boson and their subsequent decay into standard model particles. We compute the projected sensitivity, both model independently and with a minimal model, of using the muon spectrometer of the CMS detector at the HL-LHC experiment for ggF, VBF, and VH production modes of the Higgs boson and various decay modes of the mediator particle, along with dedicated detectors for long-lived particle searches like CODEX-b and MATHUSLA. Subsequently, we study the improvement with the FCC-hh detector at the 100 TeV collider experiment for such long-lived mediators, again focusing on the muon spectrometer. We propose dedicated long-lived particle detector designs for the 100 TeV collider experiment, detector for long-lived particles at high energy of 100 TeV, and study their sensitivities.

Automated summary

This study focuses on the pair production and decay of long-lived mediator particles from the decay of the standard model Higgs boson. The projected sensitivity of using different production modes and decay modes for these particles is calculated. The improvement in sensitivity with the FCC-hh detector at the 100 TeV collider experiment is also studied, with a specific focus on the muon spectrometer. Dedicated long-lived particle detector designs for the 100 TeV collider experiment are proposed and their sensitivities are studied.