Search for $\delta^{\pm\pm}$ with new decay patterns at the LHC
  A study of searching for doubly charged Higgs $(\delta^{\pm \pm})$ is performed in two-Higgs-doublet extension of the conventional type-II seesaw model. We find that a fantastic mixing effect between singly charged Higgs of Higgs doublet and of triplet is arisen from the scalar potential. The mixing leads to following intriguing phenomena: (a) the mass splittings in triplet particles are magnified, (b) QCD processes dominate the production of $\delta^{\pm \pm}$, and (c) new predominant decay channels of $\delta^{\pm \pm}$ are $\delta^{\pm \pm} \to W^{\pm^{[*]}} H^{\pm^{(*)}}_{1(2)}$, but not $\delta^{\pm} \to (\ell^\pm \ell^\pm, W^\pm W^\pm)$ which are usually discussed in the literature. With luminosity of 40 fb$^{-1}$ and collision energy of 13 TeV, we demonstrate that $\delta^{\pm \pm}$ with mass below $330$ GeV could be observed at the $5\sigma$ level. Moreover, when the luminosity approaches to 300 fb$^{-1}$, the observed mass of $\delta^{\pm \pm}$ could reach up to 450 GeV. 
Chuan-Hung Chen, Takaaki Nomura
hep-ph hep-ex