First constraint on the mass of doubly-charged Higgs bosons in the same-sign diboson decay scenario at the LHC

Abstract

When the doubly-charged Higgs bosons $H^{\pm\pm}$ mainly decay into the same-sign dilepton, a lower bound on the mass is around 400 GeV by the current LHC data. On the other hand, no such bound has been reported by using the data at LEP and at the LHC for the case where the same-sign diboson decay $H^{\pm\pm}\to W^{\pm(*)} W^{\pm(*)}$ is dominant. We study limits on the mass for such a case by using the current experimental data. From the precise measurement of the total width of the Z boson at the LEP experiment, the mass below 43 GeV is excluded with the 95% C.L. It turns out that the results from four charged lepton searches at LEP do not provide any significant constraint. We show that a new lower bound is obtained in the diboson decay scenario at the LHC with the collision energy to be 7 TeV and the integrated luminosity to be 4.7 fb$^{-1}$. By using the data of the same-sign dilepton events, the lower limit is found to be 60 GeV at the 95% C.L. By the extrapolation of the data to 20 fb$^{-1}$ with the same collision energy, the lower limit is evaluated to be 85 GeV.