HZZ Anomalous Coupling Coefficient Limit

The measurement of the anomalous couplings plays a key role in the discovery of new physics.In this paper,we calculate the amplitude of the Higgs-mediated processes(gg→H→ZZ→2e2μ)with anomalous HZZ coupling by using the spinor helicity amplitudes method,And the results are written into Monte Carlo for FeMtobarn(MCFM)package,in order to increase the experimental statistics,we will also take the same final state 4e/4μ into account.we numerically simulate the any two interference between SM Higgs-mediated processes,Higgs-mediated processes with anomalous HZZ couplings and its continuum background(gg→ ZZ 2e2μ)in the off-shell region and Self-interference,so we use the scattering cross section data to limit the anomalous coupling coefficient.chapter 2 is the introduction of the theoretical background,this part mainly includes three parts,one is the effective field theory,The interaction vertex is deduced by the given Lagrangian,the second is to introduce the spinor helicity amplitudes method,and the third is the general introduction of the MCFM program.Chapter 3 we mainly introduce the progress and deficiency of the CMS experiment in terms of Constraining the anomalous HZZ couplings.Chapters 4 and 5 are our main research work,which mainly includes the following aspects:1.theoretical calculation,we mainly calculates the amplitude of Higgs-mediated pro-cesses with anomalous HZZ couplings in the tree level using the spinor helicity ampli-tudes method,respectively named CP-even and CP-odd items,which are compared with the amplitude of Higgs-mediated processes under standard Model(SM).At the same time,we highlight the deferences between 2e2μfinal state process and 4e/4μ final state process although the helicity amplitude of them is similar.In order to compare with the observa-tions of the CMS experiment,the amplitude is summed and squared and then integrate the phase space and the parton distribution function(PDF)to get the cross section at hadron level.2.Numerical results,we write the above calculation results into the MCFM package,at the same time we show the new process in the MCFM package and the program of the new process,which can be used directly in the future research,then the scattering cross section under different conditions is simulated through CMS cut.We analysis the data in the on-shell and off-shell region,and we observe the interference between anomalous HZZ couplings process and continuum background process cannot be ignored.Besides,the experimental statistics will could double if we consider the contribution of 4e4μ.Con-sidering the contribution of these two aspects,we limit the anomalous couplings.After considering the interference between signal process anomalous HZZ cou-plings and continuum background process,which was not considered by the CMS ex-periment,we found that the interference can largely reduce the amplitude.So,in future experimental measurements,the interference should be taken into account.