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

TL;DR

This paper investigates the production of doubly charged scalars in the type-II seesaw mechanism at the LHC via photon fusion, proposing a search strategy that could significantly extend mass exclusion limits.

Contribution

It introduces a novel photon fusion production channel for doubly charged scalars and analyzes its potential for discovering or excluding these particles at the LHC.

Findings

Mass exclusion limits up to 880 GeV for inverted hierarchy.

Potential to extend mass bounds to 1 TeV with higher luminosity.

Proposed search strategy improves sensitivity for doubly charged scalars.

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$^{-1}$), $m_{\Delta}\sim430(520)$ 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$^{-1}$.