Charge transfer in positronium–proton collisions: comparison of classical and quantum-mechanical theories

Abstract

Charge transfer in positronium–proton collisions is calculated using the quantum-mechanical convergent close-coupling method and classical trajectory Monte-Carlo method. Previous calculations revealed that at low incident energy the cross section in both theories scales as , where nPs and EPs are the principal quantum number and the center-of-mass energy of the incident positronium atom, respectively. However, the quantum cross section is systematically lower than classical one in absolute magnitude. To investigate the origin of this quantum suppression effect, we compare the charge transfer probabilities as functions of the impact parameter. We show that the quantum suppression in the cross section is mainly due to the low-impact parameter behavior of the probabilities governed by the quantum uncertainty principle.

Antiproton collisions with excited positronium

“…[29,30]. The CTMC approach has been applied before in the case of a Ps atom interacting with a proton [18,19,24,31], and recently extended to the laser-assisted case [32]. The theory is described in brief as follows.…”

“…Thus, there is an urgent need for detailed, benchmarked theoretical data over as wide a range of initial Ps states as possible, and in the low (sub-eV) kinetic-energy range of most interest to experiment. In response to these experimental requirements, we present the results of calculations involving quantum convergent close-coupling (CCC) [17]) and Classical Trajectory Monte Carlo (CTMC) [18,19] techniques. Our work builds upon, and enhances, our previous studies [19][20][21][22][23][24], for reaction 1, as well as for Ps breakup and collisions in-volving Ps state-change: reactions 2 and 3, respectively, as Ps(n Ps , l Ps ) + p → p + e + + e − ,…”