Electronic stopping power of electron gases for slow antiparticles

The stopping power of slow antiparticles penetrating electron gases are evaluated within a scattering theory approach to the energy-loss problem. The required effective scattering potential is obtained from a self-consistent density-functional calculation. A relationship of the stopping power S proportional to \Z\(b) (b is in the range of 0.7-0.9) at low velocities is found, in contrast to the Z(2) dependence predicted by the linear-response theory. The diffuse distribution of partial wave contributions of screening electrons in the case of antiparticles is quite different from that for normal particles and is thought to be the main reason for the monotonic increment of the stopping power as a function of \Z\.