Searching for weak singlet charged scalar at the Large Hadron Collider

A weak singlet charged scalar exists in many new physics models beyond the Standard Model. In this work, we show that a light singlet charged scalar with mass above 65 GeV is still allowed by the LEP and LHC data. The interactions of the singlet charged scalar with the Standard Model particles are described by operators up to dimension 5. Dominant decay modes of the singlet charged scalar are obtained, and a subtlety involving field redefinition and gauge fixing due to a dimension-5 operator is also clarified. We demonstrate that it is promising to observe the singlet charged scalar at the LHC.