Long-lived Heavy Neutrinos from Higgs Decays

TL;DR

This paper explores the production and detection of long-lived right-handed neutrinos from Higgs decays in a gauged B-L model, highlighting their potential signatures at colliders and the sensitivity to active-sterile mixing.

Contribution

It introduces a novel analysis of displaced leptonic signatures from Higgs-mediated right-handed neutrino production in a B-L model, assessing collider sensitivities.

Findings

LHC can probe active-sterile mixing down to 10^{-7} with 100 fb^{-1}

Future colliders and detectors like MATHUSLA can improve sensitivity by an order of magnitude

Displaced vertex signatures provide a promising avenue for neutrino mass and mixing measurements

Abstract

We investigate the pair-production of right-handed neutrinos via the Standard Model (SM) Higgs boson in a gauged $B-L$ model. The right-handed neutrinos with a mass of few tens of GeV generating viable light neutrino masses via the seesaw mechanism naturally exhibit displaced vertices and distinctive signatures at the LHC and proposed lepton colliders. The production rate of the right-handed neutrinos depends on the mixing between the SM Higgs and the exotic Higgs associated with the $B-L$ breaking, whereas their decay length depends on the active-sterile neutrino mixing. We focus on the displaced leptonic final states arising from such a process, and analyze the sensitivity reach of the LHC and proposed lepton colliders in probing the active-sterile neutrino mixing. We show that mixing to muons as small as $V_{\mu N} \approx 10^{-7}$ can be probed at the LHC with 100 fb$^{-1}$ and at proposed lepton colliders with 5000 fb$^{-1}$. The future high luminosity run at LHC and the proposed MATHUSLA detector may further improve this reach by an order of magnitude.