Speaker
Description
Cosmic-ray (CR) antihelium can be an important observable for dark matter (DM) indirect searches due to extremely low secondary backgrounds towards low energies. In most DM models, the predicted CR antihelium flux is strongly correlated with that of CR antiprotons. Thus the upper limits on the DM annihilation cross sections from the current antiproton data can be used to place stringent limits on the maximal antihelium flux for the same model. Making use of the latest AMS-02 data on the antiproton to proton flux ratio and the coalescence model for the anti-nuclei formation, we obtain the maximal antihelium flux for typical DM annihilation final states such as $q\bar{q}$, $b\bar{b}$ and $W^+W^−$. The results are insensitive to the choices of DM density profiles and CR propagation models, but significantly dependent on the parameter of the coalescence momentum of the coalescence model. The prospects of detecting antihelium for the AMS-02 experiment is discussed. We show that with very optimistic assumptions on detection efficiency, acceptance and coalescence momentum, CR antihelium is within the reach of the AMS-02 experiment. The events which can be detected by AMS-02 are likely to have kinetic energy T≳30 GeV and dominantly arise from secondary backgrounds rather than DM interactions.
