The anomaly in the cosmic-ray positron spectrum

Understand

A recent analysis of cosmic-ray data from a space borne experiment by the AMS collaboration supports the observation of an excess in the cosmic-ray positron spectrum by previous balloon experiments.

• The combination of the various experimental data establishes a deviation from the expected background with a significance of more than four standard deviations.
• The observed change in the spectral index cannot be explained without introducing a new source of positrons.
• When interpreted within the MSSM a consistent description of the antiproton spectrum, the diffuse gamma-ray flux and the positron fraction is obtained which is compatible with all other experimental data, including recent WMAP data.