$\nu$-Two Higgs Doublet Model and its Collider Phenomenology

TL;DR

The $ u$-Two Higgs Doublet Model explains small neutrino masses via a tiny VEV of an extra Higgs doublet and predicts distinctive collider signatures such as long-lived charged Higgs and neutrinos, with observable lepton number violation at colliders.

Contribution

This paper explores the collider phenomenology of the $ u$THDM, highlighting unique signatures like long-lived charged Higgs and neutrinos, and potential lepton number violation detection.

Findings

Charged Higgs can produce observable long-lived charged tracks.

Right-handed neutrinos may be long-lived, creating secondary vertices.

Lepton number violating processes could be observed at the ILC.

Abstract

Smallness of neutrino masses can be explained by introducing a tiny vacuum expectation value of an extra-Higgs doublet which couples to right-handed neutrinos ($N_R$). This situation is naturally realized in $\nu$-Two Higgs Doublet Model ($\nu$THDM), where a TeV-scale seesaw mechanism can work well. We investigate observable phenomenology of $\nu$THDM at LHC and ILC experiments. Charged Higgs boson ($H^\pm$) in $\nu$THDM is almost originated from the extra-Higgs doublet and its coupling strength to neutrinos are not small. Then this model induces rich phenomenology at the LHC, for example, when $m_{H^\pm}^{} < M_N$, observable charged tracks can be induced from long lived charged Higgs. On the other hand, when $m_{H^\pm}^{} > M_N$, right-handed neutrinos can be long-lived, and secondary vertices may be tagged at the LHC. The $\nu$THDM also predicts observable lepton number violating process at the ILC.