Interference effects on Higgs mass measurement in $e^{+}{e}^{-}\to H(\gamma \gamma )Z$ at CEPC

A high luminosity Circular Electron Positron Collider (CEPC) as a Higgs Factory will be helpful to the precision measurement of the Higgs mass. The signal-background interference effect is carefully studied for the Higgs diphoton decay mode in the associated Z boson production at the future $e^{+}{e}^{-}$ colliders at energy $246\mathrm{G}\mathrm{e}\mathrm{V}$. The mass shifts go up from about $20 {\rm MeV}$to$50 {\rm MeV}$fortheexperimentalmassresolutionrangingfrom$0.8 {\rm GeV}$to$2 {\rm GeV}$.