Novel SM-like Higgs decay into displaced heavy neutrino pairs in U(1)' models

TL;DR

This paper explores the potential to detect long-lived heavy neutrinos produced via Higgs decays in U(1)' extended models at the LHC, focusing on displaced vertex signatures with minimal background.

Contribution

It introduces a novel analysis of heavy neutrino signatures from Higgs decays in U(1)' models, emphasizing displaced vertices at the LHC.

Findings

Heavy neutrinos can produce detectable displaced vertices.

Displaced lepton signatures are accessible with current LHC data.

Backgrounds for these signatures are negligibly small.

Abstract

We examine the observability of heavy neutrino (nu_h) signatures of a U(1)' enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the the Large Hadron Collider (LHC). We show that heavy neutrinos can be rather long-lived particles producing distinctive displaced vertices that can be accessed in the CERN LHC detectors. We concentrate here on the gluon fusion production mechanism gg -> H_{1,2} -> nu_h nu_h, where H_1 is the discovered SM-like Higgs and H_2 is a heavier state, yielding displaced leptons following nu_h decays into weak gauge bosons. Using data collected by the end of the LHC Run 2, these signatures would prove to be accessible with negligibly small background.