Displaced Vertex signatures of a pseudo-Goldstone sterile neutrino

TL;DR

This paper proposes a new collider signature for sterile neutrinos, produced via decays of heavier particles, which can be detected through displaced vertices at the LHC, providing a novel way to measure active-sterile mixing angles.

Contribution

It introduces a model where sterile neutrinos are produced independently of their mixing angles, enabling new experimental searches via displaced vertices.

Findings

Sterile neutrinos with 10-200 GeV mass can produce observable displaced vertices at the LHC.

The model predicts active-sterile mixing angles from a small set of parameters.

A reconstruction strategy for mixing angles from displaced vertex data is outlined.

Abstract

Low-scale models of neutrino mass generation often feature sterile neutrinos with masses in the GeV-TeV range, which can be produced at colliders through their mixing with the Standard Model neutrinos. We consider an alternative scenario in which the sterile neutrino is produced in the decay of a heavier particle, such that its production cross section does not depend on the active-sterile neutrino mixing angles. The mixing angles can be accessed through the decays of the sterile neutrino, provided that they lead to observable displaced vertices. We present an explicit realization of this scenario in which the sterile neutrino is the supersymmetric partner of a pseudo-Nambu-Goldstone boson, and is produced in the decays of higgsino-like neutralinos and charginos. The model predicts the active-sterile neutrino mixing angles in terms of a small number of parameters. We show that a sterile neutrino with a mass between a few 10 GeV and 200 GeV can lead to observable displaced vertices at the LHC, and outline a strategy for reconstructing experimentally its mixing angles.