Speaker
Description
Global fits of primary and secondary cosmic-ray (CR) fluxes measured by AMS-02
have great potential to study CR propagation models and search for exotic
sources of antimatter such as annihilating dark matter (DM). Previous studies
of AMS-02 antiprotons revealed a possible hint for a DM signal which, however,
could be affected by systematic uncertainties. To test the robustness of such a
DM signal, in this work we systematically study two important sources of
uncertainties: the antiproton production cross sections needed to calculate the
source spectra of secondary antiprotons and the potential correlations in the
experimental data, so far not provided by the AMS-02 collaboration. To
investigate the impact of cross-section uncertainties we perform global fits of
CR spectra including a covariance matrix determined from nuclear cross-section
measurements. As an alternative approach, we perform a joint fit to both the CR
and cross-section data. The two methods agree and show that cross-section
uncertainties have a small effect on the CR fits and on the significance of a
potential DM signal, which we find to be at the level of 3 sigma. Correlations
in the data can have a much larger impact. To illustrate this effect, we
determine possible benchmark models for the correlations in a data-driven
method. The inclusion of correlations strongly improves the constraints on the
propagation model and, furthermore, enhances the significance of the DM signal
up to above 5 sigma. Our analysis demonstrates the importance of providing the
covariance of the experimental data, which is needed to fully exploit their
potential.
