Neutralino Oscillations at the LHC

TL;DR

This paper explores neutralino oscillations in R-symmetric supersymmetric models, predicting distinctive displaced vertex signatures at the LHC due to tiny mass splittings caused by anomaly-mediated Majorana gaugino masses.

Contribution

It introduces the concept of neutralino oscillations in R-symmetric models and analyzes their potential observable signatures at the LHC, including displaced vertices.

Findings

Oscillations can produce observable displaced vertices at the LHC.

Tiny mass splittings enable neutralino oscillations in R-symmetric models.

Displaced vertex distributions can directly reveal oscillation phenomena.

Abstract

We study a supersymmetric phenomenon that can give spectacular signals at the LHC: oscillations of neutralinos. Such oscillations can be naturally realised in R-symmetric models, where additional fields are introduced as Dirac mass partners of gauginos and Higgsinos. Majorana masses for gauginos, necessarily generated from anomaly mediation, can create tiny mass splittings between degenerate mass eigenstates, causing states produced at the LHC to oscillate between neutralinos and their Dirac partner fields. Scenarios where such states decay with displaced vertices can lead to striking signatures at the LHC, where the oscillation can be visible directly in the distribution of displaced vertex lengths. We elaborate on the theory and LHC phenomenology of this feature within a specific scenario of a Higgsino decaying with a displaced vertex into a gravitino and a Z boson.