Wino Cold Dark Matter from Anomaly-Mediated SUSY Breaking

TL;DR

This paper explores Wino-like neutralinos as dark matter candidates produced via moduli decay in anomaly-mediated SUSY breaking, predicting detectable signals in direct detection experiments and cosmic positron observations.

Contribution

It proposes a scenario where Wino LSPs from moduli decay account for dark matter, linking anomaly-mediated SUSY breaking to observable dark matter signals.

Findings

Wino relic density can match observed dark matter density through moduli decay.

Detection rates in Ge detectors could reach 0.1-0.01 events/kg/day.

Significant positron signals from Wino annihilation are predicted for AMS detection.

Abstract

The cosmological moduli problem is discussed in the framework of sequestered sector/anomaly-mediated supersymmetry (SUSY) breaking. In this scheme, the gravitino mass (corresponding to the moduli masses) is naturally 10 - 100 TeV, and hence the lifetime of the moduli fields can be shorter than $\sim 1 sec$. As a result, the cosmological moduli fields should decay before big-bang nucleosynthesis starts. Furthermore, in the anomaly-mediated scenario, the lightest superparticle (LSP) is the Wino-like neutralino. Although the large annihilation cross section means the thermal relic density of the Wino LSP is too small to be the dominant component of cold dark matter (CDM), moduli decays can produce Winos in sufficient abundance to constitute CDM. If Winos are indeed the dark matter, it will be highly advantageous from the point of view of detection. If the halo density is dominated by the Wino-like LSP, the detection rate of Wino CDM in Ge detectors can be as large as $0.1 - 0.01$ event/kg/day, which is within the reach of the future CDM detection with Ge detector. Furthermore, there is a significant positron signal from pair annihilation of Winos in our galaxy which should give a spectacular signal at AMS.