Production of light antinuclei in $pp$ collisions by dynamical coalescence and their fluxes in cosmic rays near earth

TL;DR

This paper models light antinucleus production in proton-proton collisions and estimates their fluxes near Earth, showing that background levels are below experimental sensitivities, thus aiding searches for new physics.

Contribution

It introduces a combined transport and coalescence model tuned to collider data to estimate cosmic antinucleus fluxes, providing updated flux predictions and background assessments.

Findings

Antideuteron flux estimates align with existing literature.

Upper limit on antihelium-3 flux is intermediate among current models.

Background antinucleus flux is below AMS-02 sensitivity, supporting new physics searches.

Abstract

Light antinucleus yields are calculated in a multiphase transport model (AMPT) coupled with a dynamical coalescence model. The model is tuned to reproduce the transverse momentum and rapidity distributions of antiproton in $pp$ collisions at $\rm \sqrt{s}$ = 7.7 GeV to 7 TeV. By applying a widely used cosmic ray propagation model, the antinucleus fluxes near the earth are estimated over a broad range of kinetic energies. Our result on the antideuteron flux is consistent with the calculations in the literature, while our upper limit on the antihelium-3 flux sits in-between calculations in the field that span an order of magnitude in its value. This study suggests that further accurate estimation of secondary antihelium-3 flux could be improved with more ground-based experiments and model simulations. Most importantly, our value of antinucleus background from hadronic source is far below the projected sensitivity of AMS-02 with 5 years of integration time, which supports the idea of searching for new physics by measurements of light antinuclei in upcoming decade.