Revisiting the AMS-02 antiproton excess: The role of correlated errors

TL;DR

This paper reevaluates the AMS-02 antiproton excess by incorporating correlated systematic errors, revealing that the significance of the excess diminishes significantly, thus questioning its robustness as evidence for primary antiprotons.

Contribution

It introduces a detailed analysis of correlated errors in cosmic-ray antiproton measurements, using Glauber-Gribov theory to improve error modeling and reassess the excess significance.

Findings

Correlated errors significantly reduce the antiproton excess significance.

The analysis becomes more sensitive to diffusion models at low rigidities.

The excess significance drops below 1σ when considering correlated errors.

Abstract

Cosmic-ray antiprotons are a remarkable diagnostic tool for the study of astroparticle physics' processes in our Galaxy. While the bulk of measured antiprotons is consistent with a secondary origin, several studies have found evidence for a subdominant primary component in the AMS-02 data. In this proceedings article, we revisit the excess considering systematic errors that could affect the signal. Of particular importance are unknown correlations in the AMS-02 systematic errors, the dominant of which are associated with the cross sections for cosmic-ray absorption in the detector. We compute their correlations in a careful reevaluation of nuclear scattering data, utilizing the Glauber-Gribov theory to introduce a welcomed redundancy that we explore in a global fit. The inclusion of correlated errors has a dramatic effect on the significance of the signal. In particular, the analysis becomes more sensitive to the diffusion model at low rigidities. For a minimal extension beyond single-power-law diffusion, the global significance drops below 1$\sigma$ severely questioning the robustness of the finding.