Swift charged particles in a degenerate electron gas: An estimation for the charge-sign effect in stopping.

Motivated by the recently introduced [Phys. Rev. A 94 , 042704 (2016)] and already investigated [J. Phys. B: At. Mol. Opt. Phys. 50 , 185201 (2017)] new approximate form for the stopping power in terms of scattering phase shifts, here we show analytically that within such a modeling of the observable an exact leading phase shift may contain that information which is completely enough to characterize the asymptotic charge-sign-independent Bethe term (∝ Z 1 2 ) and a charge-sign-dependent (Barkas) term (∝ Z 1 3 ) in the stopping force of a degenerate electron gas for fast projectiles with charge Z 1 . Our study is based on a spherical potential with velocity-dependent screening as in the above works. The next term in an asymptotic expansion, the Bloch term (∝ Z 1 4 ), measures the difference of the exact and first-order Born treatments with Coulomb potential. [ABSTRACT FROM AUTHOR]