Enhanced Cosmic-Ray Antinuclei Fluxes with Dark Matter Annihilation into Soft Unclustered Energy Patterns

Standard-Model (SM) hadronic parton showers initiated by secondary cosmic-ray production or dark matter (DM) annihilations robustly predict very low antinuclei yields and a strong additional suppression for heavier antinuclei. We show that an important exception can arise if DM annihilates into a confining dark sector that produces soft unclustered energy patterns (SUEPs). The hallmark of SUEPs is the emission of very large multiplicities of soft dark mesons (pi D), which can overcome the usual phase-space suppression of antinuclei formation in parton showers, provided that the dark mesons decay promptly into SM quarks, i.e., within a SM hadronization length. We study several benchmark realizations and find that for DM masses mDM O(10 TeV), dark meson masses m pi D 400 GeV, pi D dominantly decaying to tt & strns;, and a SUEP temperature TSUEP <^> 0.1m pi D, DM annihilation into SUEPs can yield tens of antideuterons and a few antihelium-3 events at AMS - 02 at kinetic energies of O(GeV/n) and a few antideuterons and antihelium-3 events in GAPS at energies below 0.5 GeV/n. A future confirmation of an antinuclei signal by the AMS - 02 or GAPS experiments could provide hints for hidden confining dynamics and would significantly constrain the relevant SUEP parameters.