Vortices in Ionization Collisions by Positron Impact

TL;DR

This paper investigates vortices in ionization processes caused by positron impact on hydrogen atoms, identifying vortex signatures in cross sections and analyzing their properties in momentum space, with implications for experimental measurement.

Contribution

It reveals that minima in the cross section are signatures of vortices in the continuum system and characterizes these vortices through the transition matrix analysis.

Findings

Vortices correspond to minima in the fully-differential cross section.

The study characterizes vortices via the real and imaginary parts of the transition matrix.

Results are applicable to current experimental measurement techniques.

Abstract

The presence of vortices in the ionisation of hydrogen atoms by positrons at intermediate impact energies is investigated. The present findings show that a previously reported minima in the fully-differential cross section is the signature of a vortex in the continuum positron-electron-proton system. The behaviour of the real and imaginary parts of the complex-valued transition matrix is studied in order to determine and characterize the vortex in momentum space. The obtained information is translated to fully-differential ionisation cross sections, feasible of being measured with currently available techniques.