Precision Study On The Production Of ZZZ At The LHC

From the gradual establishment of the Standard Model in the 1960s to the discov-ery of the Higgs particle in 2012, the glorious development in these years allows us to say that the Standard Model is one of the most remarkable theoretical achievements in the history of particle physics. It successfully describes most of the interactions and the properties of the particles in the nature, and the theoretical predictions of the Standard Model are consistent with most of the high energy experiments very well. However, some shortcomings of this theory make us believe that there must be some new physics waiting for people to discover. The development of science and technology allows sci-entists to use high energy collider to verify the correctness of the theory and to search for new physics. The measurement of electroweak quartic gauge boson couplings(QGC) is of great significance to the test of the Standard Model. It will not only help us study the structure of gauge boson couplings in the Standard Model, but also improve the understanding of the electroweak spontaneous symmety breaking.The producton of triple gauge bosons at the Large Hadron Collider(LHC) has a direct relationship with quartic gauge boson couplings. Precise experiment requires precise theoretical prediction. Based on the above considerations, we study the precise calculation of ZZZ production at the LHC in this paper. This process provides a chance for the test of the ZZZZ anomalous quartic gauge coupling(aQGC), and it also serves as an important background of the supersymmetric tri-lepton production signature. We provide the next-to-leading order(NLO) QCD and electroweak(EW) corrections to this process with the subsequent leptonic decays. The calculation shows that both the cor-rections of the NLO QCD and the NLO EW are significant in precise theoretical pre-diction. We also investigate the influence of different event selection schemes on the corrections and the kinematic distributions of final state particls. We find that the large NLO QCD correction and the scale dependence of the cross sections can be suppressed by introducing a kinematic cut on the final state jet. On the other hand, the NLO EW correction is stable when event selection scheme changes.In summary, the innovations of this thesis are:●In this paper, we firstly present the NLO QCD+EW corrections to the production of ZZZ with subsequent leptonic decays at the LHC in the Standard Model. We provide the most precision theoretical predictions on this process. Our results work as the new theoretical reference for the research of QGC and the investiga-tion of new physics.● In the calculation of virtual correction, we adopt the improved LOOPTOOLS, which can improve the calculation efficiency and keep the numerical stability at the same time. The improved narrow width approximation is introduced in dealing with the leptonic decay to obtain the results including the spin correlated effect and part of the off-shell effect.