Phenomenology Study Of Pair Production Of The Higgs Boson In NMSSM

Nowadays,Higgs physics is one of the hot research topics in high-energy physics,Because Higgs boson plays an important role in the issue of the source of mechainsm of spontaneous sym-metry breaking.In July 2012,the ATLAS and CMS collaborations reported the discovery of a 125 GeV scalar boson,then it was identified as Higgs boson in 2013.However,the study of Higgs boson does not represent an end,and further exploration is needed.There is no straightforward evidence that the particle is the Higgs boson predicted in the Standard Model.Therefore,we are looking forward to the further research on the Higgs boson,In particle physics,the Standard Model?SM?is a very successful theoretical model and considered to be a low energy effective theory.It can unify the strong interaction,weak interaction and electromagnetic interaction,and has been validated by experimental results in the decades years.The standard model has its own limitations,also can not solve all problems,such as fine-tuning problem.Physicists have proposed various new physical models beyond SM in order to solve these problems.In these new physical models,the supersymmetric model?SUSY?is one of the most widely studied mo del.In order to solve the ? problem in the MSSM,the next-to-Minimal Supersymmetric Standard Model?NMSSM?was proposed.Compared to MSSM,NMSSM introduces a singlet Higgs field?S?,which is more natural to explain the mass of Higgs boson near 125 GeV.In this article,we focus on the production of Higgs pair in the NMSSM at the LHC for an collision energy of 14 TeV.As we know,the leading order contribution of the Higgs pair production in the SM is from the loop diagrams mediated by top quark,and the LO contribution in the SUSY is also from loops.In our thesis,we suppose h₂ as SM-like Higgs boson?h?.We consider various experimental constraints,and scan over the parameter space of the NMSSM and require the fine tuning quantities bc,less than 50,then study corresponding processes pp?h₁h₁,h₂h₂,h₁h₂ respectively,and the final production rate is that one Higgs decay tob??? while the other is ?? or ?⁺?^-.We find that the cross section for the final state h₁h₁?b????⁺?^-is greatly enhanced when mh₁???62 GeV,which can reach to 5400 fb.And the production rate for the final state h₁?b?????⁺?^-?can reach to 1500 fb.The reason can be attributed to,due to the production process pp ? h₂? h₁h₁ and the enhancements of the branching ratio for h₁?b?????⁺T-?.When mh₁???62 GeV,the cross section is visibly below the SM predictions.The cross section for for the final state h₂h₂?b????⁺?^-and ?? and the production rate can deviate from the SM predictions,can maxinmally reach to 0.043fb and 1.3fb,respectively.