Study of Higgsstrahlung Cross Section and Higgs Mass Measurement Precisions with ZH ($Z\rightarrow \mu^+\mu^-$) events at CEPC 后印本

摘要: The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. Using Monte Carlo samples of 5 ab−1 at 250 GeV center-of-mass energy, the benchmark luminosity of CEPC Higgs runs, model independent (MI) analyses on Higgsstrahlung (ZH) cross section σZH and Higgs mass mH are performed with ZH events where the Z boson decays into a pair of muons. The relative precision of σZH could reach 0.92\% and the mH could be measured to an accuracy of 6.5 MeV. Using information from Higgs decay final states, the backgrounds could be further reduced, leading to a mass precision of 5.4 MeV. The impacts of tracker size are investigated and parameterized for these measurements. Using similar analysis technology, we analyzed the capability of CEPC in measuring the Higgs invisible decay. Using ZH (Z→μ+μ−) events at 5 ab−1, the upper limit of invisible decay cross section beyond the standard model (SM) σBSMZH,H→inv can be determined to be 2.0 fb at 95\% confidence level.