Di-Higgs Production in SUSY models at the LHC

We study the modification to di-Higgs production via gluon fusion within the context of the Minimal Supersymmetric Standard Model(MSSM) and the Next-to-Minimal Supersymmetric Standard Model(NMSSM) in the parameter space allowed by current experimental and theoretical constraints, and also relevant to the Large Hadron Collider(LHC) experiments in the near future. The calculation is based on the analytical expression of the leading order Feynman amplitudes (which includes both quark and squark loops). We separate the di-Higgs production cross section into resonant, non-resonant, and interference parts, in order to better understand the mechanisms that are responsible for the modification to di-Higgs production rate in different regions of the allowed parameter space. We also investigate the sensitivity of High-Luminosity LHC (HL-LHC) to the di-Higgs production in these low energy supersymmetry(SUSY) models. Furthermore, we examine the complementarity between di-Higgs searches and direct searches for BSM particles and precision Higgs couplings measurements at the HL-LHC. We found that the di-Higgs production cross section can be enhanced significantly through resonant production. In the region where the resonant production cross section is small, di-Higgs receives a moderate enhancement due to the modifications in the Higgs couplings. In addition, there is a strong correlation between di-Higgs production and single Higgs production, and di-Higgs is not as sensitive as single Higgs at the HL-LHC.