Light Doubly Charged Higgs Boson via the $W{W}^{\ast }$ Channel at LHC

Abstract

The doubly charged Higgs bosons $H^{\pm \pm }$ searches at the Large Hadron Collider (LHC) have been studied extensively and strong bound is available for $H^{\pm \pm }$ dominantly decaying into a pair of same-sign di-leptons. In this paper we point out that there is a large cavity in the light $H^{\pm \pm }$ mass region left unexcluded. In particular, $H^{\pm \pm }$ can dominantly decay into $WW$ or $W{W}^{\ast }$ (For instance, in the type-II seesaw mechanism the triplet acquires a vacuum expectation value around 1 GeV.), and then it is found that $H^{\pm \pm }$ with mass even below $2m_W$ remains untouched by the current collider searches. Searching for such a $H^{\pm \pm }$ at the LHC is the topic of this paper. We perform detailed signal and background simulation, especially including the non-prompt $t\bar{t}$ background which is the dominant one nevertheless ignored before. We show that such $H^{\pm \pm }$ should be observable at the 14 TeV LHC with 10-30 fb${}^{-1}$ integrated luminosity.

Comments: 23 pages, 4 figures, typos fixed, references added, EPJC version