Title: Searching for Weak Singlet Charged Scalar at Future Lepton Colliders
Speaker: Dr. Zhang Jue
Abstract: Weak singlet charged scalar exists in many new physics models that try to explain phenomena beyond the Standard Model. In this talk I will discuss the possibility of a light SU(2) weak singlet charged scalar with mass around 100 GeV, whose existence is still allowed by current experimental data. To describe the interactions with the Standard Model particles, we adopt the effective field theory approach by considering gauge invariant operators up to dimension-5. Dominant decay modes of the singlet charged scalar are then obtained, and a subtlety involving field redefinition and gauge fixing due to a dimension-5 operator is also clarified. Incorporating the existing LEP charged Higgs and slepton search results, we find that the singlet charged scalar with mass above 65 GeV is still allowed. To assess the searching prospects at future lepton colliders, we consider three scenarios, CEPC, ILC-350 and ILC-500, and obtain the corresponding discovery/exclusion limits on the weak singlet charged scalar.