The Research On The Heavy Quarkonium Production In Association With The Standard Model Particle

The production and decay process of the heavy quarkonium involve perturbation and nonperturbation processes,which is an ideal object for investigating perturbation and nonperturbation quantum chromodynamics and has always been one of the hot issues concerned by particle physicists.Since the first heavy quarkonium was discovered experimentally in 1974,many quarkonia have been found by experimental physicists.In order to predict and explain the production and decay process of the heavy quarkonia,theoretical physicists have made a lot of efforts and put forward theories such as CEM,CSM,and NRQCD,in which the NRQCD factorization framework has been widely accepted due to its theoretical advantages and its strong prediction and interpretation ability.However,the NRQCD also has many challenges.For example,the factorization theory has not been fully proved and the universality of the LDMEs.In explaining the relevant experiments about heavy quarkonium,the polarization of heavy charmonia χ_cJ and the production of charmonium in association with W^± boson at the LHC have not been satisfactorily explained.To further investigate the production mechanism of heavy quarkonium,we should study more about the production processes of the heavy quarkonium at the more excellent colliders.Considering that the discrimination ability of standard model particles,especially heavy particles,is mature in experiments,and the decay channels of the heavy quarkonium are also relatively clean,so the heavy quarkonia production associated with standard model particles has the potential to be found experimentally.The research on the process of the heavy quarkonium production in association with the standard model particles will not only help us further investigate the production mechanism of heavy quarkonium and strong interaction,but also help us to further test the standard model.Based on the above reasons,in this thesis,we investigate three production processes of heavy charmonium associated with the standard model particles,which are:（1）.We studied prompt J/Ψ production in association with a top quark pair at the LHC;（2）.We revisit investigated prompt J/Ψ production in association with the Higgs boson via gluon fusion at the LHC;（3）.We studied J/Ψ associated production with a bottom quark pair from the Higgs boson decay in next-to-leading order QCD.The innovations of the thesis are:We investigate the prompt J/Ψ production in association with a top quark pair to leading order in the NRQCD factorization formalism at the LHC for the first time.In addition to the contribution from direct J/Ψ production,we also include the indirect contribution from the directly produced excited states Ψ（2S）and χ_cJ.We present the numerical results for the total and differential cross sections and find that the Fock states ³S₁^（8）give the dominant contributions.The prompt J/Ψ production in association with a top quark pair signatures at the LHC are analyzed in the tetralepton channel pp→（t→ W⁺（l⁺v）b）（（?）→W^-（l^-（?））b）（J/Ψ→μ⁺μ^-）and trilepton channel pp→（t→ W⁺（qq’）b）（t→W^-（lv）b）（J/Ψ→μ⁺μ^-）.According to the numerical results,we find that ttJ/Ψ production can be potentially detected at the LHC,whose measurement is useful to test the heavy quarkonium production mechanism and help us further understand the strong interaction.We will revisit the production of prompt J/Ψ associated with the Higgs boson via gluon fusion at the LHC within the NRQCD factorization framework.The production of charmonium associated with the Higgs boson via gluon fusion has been investigated firstly in 2002 by Kniehl et al.[Phys.Rev.D 66,114002（2002）]in which they considered the contribution of the final Higgs boson radiation off the charm quark at tree level and found that this process is far too rare to be observable in any of the considered experiments.In this work,we consider the contribution of the final Higgs boson radiation off the charm quark and the Higgs boson radiation off the top quark in the loop,respectively.After considering the contribution from the final Higgs boson radiation off the top quark in the loop,which is more than 3 orders of magnitudes higher than the charm quark at the tree level,the production of prompt J/Ψ associated with the Higgs boson has great potential to be detected.If the process is really discovered in future experiments,which can help us to further understand the mechanism of the color octet and be helpful to further investigate the Yukawa coupling of the Higgs boson and fermions.We investigate the next-to-leading order QCD correction to J/Ψ associated production with a bottom quark pair from the Higgs boson decay within the nonrelativistic QCD framework.From the numerical results,we find that the decay width of process H→b+J/Ψ+（?） at leading order mainly comes from the contribution of the Fock state ³S₁^（8）and the NLO QCD corrections significantly enhance the decay width at LO accuracy by about two times.At NLO accuracy,the Fock states ³S₁^（8）and ³P_J^（8）channels give the main contribution.accounting for about 68%and 29%of the total decay width of J/Ψ associated production with a bottom quark pair at NLO accuracy from the Higgs boson decay,respectively.Considering the final states J/Ψ and bottom quark have high detection efficiency in experiments and the dominant contribution of color octet channels at NLO accuracy,the inclusive decay process H→b+J/Ψ+（?）+X has the potential to be found in future colliders with high energy/luminosity,which will help us to further investigate the production mechanism of heavy quarkonium and the properties of the Higgs boson.