New physics searches with Higgs-photon associated production at the Higgs factory

Abstract：

A future Higgs factory is being designed for precise measurement of Higgs characteristics and to search for new physics. In this paper we propose that the Higgs-photon associated production process, e⁺e^-→γh could be a useful channel for new physics. We express new physics model-independently in the effective Lagrangian approach, and find that the new physics effects of γh have only two degrees of freedom, much fewer than the Higgsstrahlung process. This point could be used to reduce the degeneracies of Wilson coefficients. We also calculate for the first time the 95% confidence level(CL) bounds of γh at the Higgs factory, and prove that γh is more sensitive to some dimension-6 operators than the current experimental data. In the optimistic scenario new physics effects may be observed at the CEPC or FCC-ee after the first couple of years of their run.