New Calculation of Secondary Antiprotons in Cosmic Rays

Abstract

A dramatic increase in the accuracy and statistics of space-borne cosmic ray (CR) measurements has yielded several breakthroughs over the last several years. The most puzzling is the rise in the positron fraction above 10 GeV over the predictions of the propagation models assuming pure secondary production. Antiprotons are produced in CR interactions with interstellar gas and are,therefore, called secondary. These are the same interactions that produce charged and neutral mesons which decay to secondary electrons and positrons andγ-rays. However, in contrast to CR electrons and positrons that can be produced copiously in pulsars, there is no known astrophysical source of primary ̄p. Therefore, ̄pdata and their correct interpretation hold the key to the resolution of many astrophysical puzzles. We calculated ̄pproduction inp p-,pA-, and AA-interactions using EPOS-LHC and QGSJET-II-04, two of the most advanced Monte Carlo generators tuned to accelerator data including those from the LHC. The new cross sections are being incorporated into the GALPROP code to allow an accurate calculation of the spectrum of secondary ̄pin CRs.