Cosmic antiprotons in the diffusion model. I - General properties in comparison with other models

Stimulated by latest COS-B gamma data, pointing towards the existence of a weak, radial cosmic ray flux gradient in the Galaxy, and the unsatisfactory description of the Galactic cosmic ray flux, including especially antiprotons, by both, the closed galaxy (CG) and the leaky box (LB) models, the propagation of cosmic antiprotons and protons is examined in a diffusion model (DM). For the energy- and space-dependent fluxes an analytical solution of the diffusion equation with ionization and annihilation terms is obtained. The relations to both, CG and LB models are elaborated. The results show that it is worthwhile to apply the DM to those problems so far studied only within the CG or LB models, especially whenever precise energy spectra are available.