Search for doubly charged scalars in type-II seesaw mechanism through photon fusion at the LHC

Abstract

Small neutrino masses can be generated through the well-known seesaw mechanisms, among which the type-II scenario predicts a triplet scalar with doubly charged components. Except for the Drell-Yan production at the Large Hadron Collider (LHC), the doubly charged scalars ${\Delta }^{\pm \pm }$ can also be produced through photon fusion along with ultraperipheral collision of protons, the outgoing protons from which can be detected by forward detectors at the LHC, providing a promising way to explore related new physics. We study the pair production through such processes at the 14 TeV LHC, focusing on the final states of ${\mu }^{+}{\mu }^{+}{\mu }^{-}{\mu }^{-}$ and $e^{+}{e}^{+}{e}^{-}{e}^{-}$ under normal (NH) and inverted hierarchy (IH) of the neutrino mass spectra, respectively. Promising sensitivity can be reached via our proposed search strategy. With luminosity of 36.1 fb${}^{-1}$(100 fb${}^{-1}$), $m_{\Delta }\sim 430(520)$ GeV can be excluded at 95% C.L. under the NH via ${\mu }^{+}{\mu }^{+}{\mu }^{-}{\mu }^{-}$ states searching, while the mass bound can be extended to 730(880) GeV under the IH via $e^{+}{e}^{+}{e}^{-}{e}^{-}$ states. The exclusion limits on $m_{\Delta }$ can be improved up to 1 TeV and even higher with integrated luminosity accumulated to 3 ab${}^{-1}$.

Comments: 17 pages, 6 figures, 4 tables; Discussion on $\gamma$-PDF added and figures updated, references added