Optical-model Approach For Positronium Formation In Positron Scattering From K Atom

Positronium formation is a very important channel in positroncollision with atoms especially in the low energy region. Theoptical-model approach has been used to investigate the positroniumformation process in positron collision with atoms. In present work,we have successfully obtained a momentum-space equivalent localpolarization potential to describe the positronium formationrearrangement process (the real and virtual parts describe the virtualand real positronium formation, respectively). Optical-modelapproach has been used to evaluate the positronium (n=1,2,3)formation cross sections between the positron and potassiumcollision in low energy region (0.2eV-15.0eV) and the presentresults have been compared with corresponding results ofexperimental measurements and other theoretical models. Thepresent result predicts a pronounced peak just above the threshold ofpositronium (n=2) formation and positronium (n=3) formation,respectively and shows a great discrepancy with other theoreticalresults. However, the present result exhibits good consistency withexperimental measurements, which shows that the positronium(n=3) formation is still very important.