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HEP: A Straightforward Explanation of the Cosmic Ray Positron Excess

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Greg Tarle, University of Michigan
When
04 November 2015 from 2:30 PM to 3:30 PM
Where
339 Davey Laboratory
Contact Name
Stephane Coutu
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Twenty years ago the HEAT balloon experiment observed an unexpected excess of positrons above 8 GeV in the cosmic radiation.   Subsequently the PAMELA satellite experiment confirmed the excess and showed continued growth to 100 GeV.  In the last few years the Alpha Matter Spectrometer on the International Space Station has obtained high precision measurements of positrons, electrons, antiprotons, protons and B/C in the cosmic radiation, showing that the anomalous rise in the positron fraction continues to hundreds of GeV.  An exciting and well-known possibility for the excess is the production of electron-positron pairs by annihilating dark matter particles in the halo of the Galaxy.   Alternate explanations have been proposed involving local astrophysical sources such as pulsars.   Using the new AMS data and available Be isotope data, I will show that the positron excess can be explained by a straightforward data-driven modification to secondary production models without any need for dark matter or other exotic production mechanisms.

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