Measurement of the Low-Energy Antideuteron Inelastic Cross Section

Area of Science:

• High Energy Physics
• Nuclear Physics
• Astroparticle Physics

Background:

• Antimatter production and propagation are crucial for understanding cosmic rays and dark matter.
• Antideuterons are sensitive probes of these phenomena, but their interaction cross sections are poorly constrained.
• Previous measurements have lacked precision at low momenta.

Purpose of the Study:

• To measure the inelastic cross section for antideuteron-nucleus interactions at low momenta (0.3–4 GeV/c).
• To provide crucial data for refining models of antimatter propagation in the interstellar medium.
• To aid in the interpretation of indirect dark matter search signals.

Main Methods:

• Utilized proton-nucleus (p-Pb) collisions at the CERN Large Hadron Collider (LHC) with the ALICE detector.
• Employed the detector material as an absorber for antideuterons and antiprotons.
• Compared experimental antiparticle-to-particle ratios with geant4 simulations.

Main Results:

• Reported the first measurement of antideuteron-nucleus inelastic cross sections averaged over ALICE detector materials (⟨A⟩=17.4 and 31.8).
• Observed a potential excess (up to a factor 2.1) compared to Glauber model predictions in the lowest momentum interval (0.3–0.47 GeV/c).
• Established a benchmark using well-constrained antiproton cross sections.

Conclusions:

• The measured cross sections provide essential data for understanding antimatter propagation and antinuclei production from cosmic ray interactions.
• The observed excess at low momenta warrants further investigation and may impact dark matter search interpretations.
• This measurement opens new avenues for studying fundamental interactions involving antimatter.