Cosmic-Ray Propagation Models Elucidate the Prospects for Antinuclei Detection

TL;DR

This paper uses advanced cosmic-ray propagation models fitted to high-precision data to estimate the astrophysical and dark matter contributions to antinuclei fluxes, informing the search for new physics through cosmic-ray observations.

Contribution

It introduces a state-of-the-art propagation model constrained by recent data to better predict antinuclei fluxes from astrophysical and dark matter sources.

Findings

Astrophysical sources can produce ~1 antideuteron and 0.1 antihelium-3 events over 15 years.

Dark matter models could generate higher antinuclei levels with distinct energy signatures.

Detection of antihelium-4 would require new dark matter theories or production mechanisms.

Abstract

Tentative observations of cosmic-ray antihelium by the AMS-02 collaboration have re-energized the quest to use antinuclei to search for physics beyond the standard model. However, our transition to a data-driven era requires more accurate models of the expected astrophysical antinuclei fluxes. We use a state-of-the-art cosmic-ray propagation model, fit to high-precision antiproton and cosmic-ray nuclei (B, Be, Li) data, to constrain the antinuclei flux from both astrophysical and dark matter annihilation models. We show that astrophysical sources are capable of producing $\mathcal{O}(1)$ antideuteron events and $\mathcal{O}(0.1)$ antihelium-3 events over 15~years of AMS-02 observations. Standard dark matter models could potentially produce higher levels of these antinuclei, but showing a different energy-dependence. Given the uncertainties in these models, dark matter annihilation is still the most promising candidate to explain preliminary AMS-02 results. Meanwhile, any robust detection of antihelium-4 events would require more novel dark matter model building or a new astrophisical production mechanism.