2021-10-20 15:00  P5A-1

[Journal Club] Dark Matter Annihilation Can Produce a Detectable Antihelium Flux or The inhomogeneous BBN?

Dart-yin Soh

Recent observations by the Alpha Magnetic Spectrometer (AMS-02) have tentatively detected a handful of cosmic-ray antihelium events. Such events have long been considered as smoking-gun evidence for new physics, because astrophysical antihelium production is expected to be negligible. However, the dark- matter-induced antihelium flux is also expected to fall below current sensitivities, particularly in light of existing antiproton constraints. Here, we demonstrate that a previously neglected standard model process— the production of antihelium through the displaced-vertex decay of Λ ̄ b-baryons—can significantly boost the dark matter induced antihelium flux. This process can entirely dominate the production of high-energy antihelium nuclei, increasing the rate of detectable AMS-02 events by 2 orders of magnitude.

(I may also mention the inhomogeneous BBN producing anti-matter regions to explain this anti-helium excess. )

arXiv:2006.16251