Scattering of protons and antiprotons by hydrogen atoms

The two-, four-, five- and fourteen-state approximations of the impact parameter method have been applied to the excitation of hydrogen atoms by proton (p) and antiproton (\overlinep) impact. The effect of both channel and back couplings on the 2s and 2p excitations are investigated. The total cross sections are calculated for incident energies ranging from 1 to 2500 keV. It is found that the effect of both channel and back couplings on the antiproton-induced reactions is greater than on that induced by protons. We compare the results with those of other theoretical and experimental works.