Prospects of detecting dark matter through cosmic-ray antihelium with the antiproton constraints

TL;DR

This paper assesses the potential for detecting dark matter via cosmic-ray antihelium, using AMS-02 data and hadronic models, concluding that detection is challenging but possibly within reach under optimistic assumptions.

Contribution

It combines cosmic-ray data and hadronic modeling to predict antihelium flux from dark matter, analyzing uncertainties and detection prospects with AMS-02.

Findings

Antihelium flux predictions are highly insensitive to dark matter density and propagation models.

Detection of antihelium by AMS-02 is possible under optimistic assumptions.

Most detectable antihelium events are likely from secondary backgrounds rather than dark matter.

Abstract

Cosmic-ray (CR) antihelium is an important observable for dark matter (DM) indirect searches due to extremely low secondary backgrounds towards low energies. In a given DM model, the predicted CR antihelium flux is expected to be strongly correlated with that of CR antiprotons. In this work, we use the AMS-02 $\bar p/p$ data to constrain the DM annihilation cross section, and the ALICE data on the $^3\overline{\text{He}}$ and $\overline{\text{T}}$ productions to determine the parameters in the coalescence model for anti-nucleus formation. The hadronic cross sections are estimated using Monte-Carlo event generators including $\texttt{EPOS-LHC}$ and $\texttt{DPMJET}$. Based on these constraints, we make predictions for the maximal antihelium flux for typical DM annihilation final states, and perform a detailed analysis on the uncertainties due to the DM density profiles and CR propagation models. We find that the results are highly insensitive to both of them, but still significantly depends on the hadronization models in event generators. The prospects of detecting antihelium for the AMS-02 experiment is discussed. We show that with very optimistic assumptions, CR $^3\overline{\text{He}}$ is within the reach of the AMS-02 experiment. The $^3\overline{\text{He}}$ events which can be detected by AMS-02 are likely to have kinetic energy $T \gtrsim 30$~GeV, which is consistent with the preliminary AMS-02 search results. The events which can be observed by AMS-02 are likely to arise dominantly from secondary backgrounds rather than DM interactions.