6/14/2023 0 Comments Xsection 7.7![]() The corresponding production cross sections for the SM Higgs boson of 125 GeV, as functions of center-of-mass energy, are plotted in Fig. The SM Higgs bosons are produced via the processes of e +e − → ZH (Higgsstrahlung), e +e − → □□̄H (WW fusion) and e +e − → e +e −H (ZZ fusion) at the CEPC, as shown in Fig. With two detectors operating over 10 years, the CEPC will accumulate about one million Higgs events, corresponding to an integrated luminosity of 5 ab −1. It will operate at a center-of-mass energy of 240–250 GeV with an instantaneous luminosity of 2 × 10 34 cm −2 s −1. ![]() The Circular Electron Positron Collider is a Higgs factory proposed by the Chinese high energy physics community. Therefore, an electron-positron Higgs factory is an essential step in understanding the nature of the Higgs boson. Almost every Higgs event can be recorded and reconstructed. Besides, it is free of the QCD backgrounds. In this way, a lepton collider can provide absolute measurements of Higgs couplings. Thus, the Higgs production cross section is available with the recoil technique. The beam energy and polarization of the initial states are precisely known and adjustable. Moreover, as the Higgs boson can only be reconstructed through its decay products at the LHC, it is impossible for the LHC to access the Higgs total width or absolute couplings in a model-independent way.Ĭompared to a hadron collider, an electron positron collider has significant advantages in precision measurements of the Higgs boson. However, this accuracy is difficult to achieve at the LHC. Thus, percent or even sub-percent level precision becomes necessary for the future Higgs measurement program. Many new physics models, however, predict the Higgs couplings deviate from the SM at the percent level. The up-to-date results indicate that it is highly Standard Model (SM) like. The Higgs boson has been studied extensively since its discovery at the LHC. With the Standard Model ZH production rate, the upper limit of could reach 1.2% at 95% confidence level. In addition, we studied the prospect of measuring the Higgs boson decaying into invisible final states at the CEPC. The impact of the TPC size on these measurements is investigated. For the standard model Higgs boson, the m H precision could be improved to 5.4 MeV by including the information from Higgs decays. The statistical precision of σ ZH ( m H) measurement could reach 0.97% (6.9 MeV) in the model-independent analysis which uses only the information from Z boson decays. With GEANT4-based full simulation and a dedicated fast simulation tool, we have evaluated the statistical precisions of the Higgstrahlung cross section σ ZH and the Higgs mass m H measurement at the CEPC in the Z → μ +μ − channel. This sample allows a percent or even sub-percent level determination of the Higgs boson couplings. The CEPC will accumulate an integrated luminosity of 5 ab −1 over ten years of operation, producing one million Higgs bosons via the Higgsstrahlung and vector boson fusion processes. It will operate at a center-of-mass energy of 240–250 GeV. The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community.
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