Probing Doubly Charged Higgs Bosons at the LHC through Photon Initiated Processes

We show that the photon-photon fusion process contributes significantly to the pair production of doubly charged Higgs bosons at the LHC at a level comparable to the Drell-Yan production. We reinterpret the ATLAS lower limit of 570 GeV (420 GeV) on the mass of $\Delta_{L}^{\pm\pm}$ ($\Delta_{R}^{\pm\pm}$) arising from $SU(2)_L$ triplet (singlet) scalar by including the photon initiated process and derive a new lower limit of 748 GeV (570 GeV), assuming that $\Delta^{\pm \pm}$ decays into $e^\pm e^\pm$ 100% of the time. We have also shown that the 5$\sigma$ discovery reach for ${\Delta_{L}^{\pm\pm}}$ (${\Delta_{R}^{\pm\pm}}$) is 846 GeV (783 GeV) with 100 fb$^{-1}$ luminosity at 13 TeV LHC. We derive a somewhat more stringent limit on the mass when the doubly charged scalar arises from higher dimensional representations of $SU(2)_L$.