Modified Supersymmetric Dark Sectors

TL;DR

This paper explores how modified supersymmetric dark sectors, especially with the inclusion of the QCD axion and axino, can produce detectable displaced decays at the LHC, offering new avenues for dark matter and SUSY searches.

Contribution

It introduces a scenario where the axino from a modified dark sector can be detected via displaced neutralino decays at the LHC, expanding SUSY phenomenology.

Findings

Displaced neutralino decays to axinos can occur within the ATLAS detector.

The axino signature can mimic other long-lived neutralino scenarios.

Cosmological viability of the scenario is briefly discussed.

Abstract

SUSY models with a modified dark sector require constraints to be reinterpreted, which may allow for scenarios with low tuning. A modified dark sector can also change the phenomenology greatly. The addition of the QCD axion to the Minimal Supersymmetric Standard Model (MSSM) solves the strong CP problem and also modifies the dark sector with new dark matter candidates. While SUSY axion phenomenology is usually restricted to searches for the axion itself or searches for the ordinary SUSY particles, this work focuses on scenarios where the axion's superpartner, the axino may be detectable at the Large Hadron Collider (LHC) in the decays of neutralinos displaced from the primary vertex. In particular this work focuses on the KSVZ axino. The decay length of neutralinos in this scenario easily fits the ATLAS detector for SUSY spectra expected to be testable at the 14 TeV LHC. This signature of displaced decays to axinos is compared to other well motivated scenarios containing a long lived neutralino which decays inside the detector. These alternative scenarios can in some cases very closely mimic the expected axino signature, and the degree to which they are distinguishable is discussed. The cosmological viability of such a scenario is also considered briefly.