Eur. Phys. J. D 65, 405-410 (2011)
https://doi.org/10.1140/epjd/e2011-20277-x

Regular Article

Lowest lying doubly-excited P-and D-state resonances of Ps⁻ in weakly coupled plasmas

Department of Physics, Maheshtala College, Budge Budge Trunk Road, Kolkata- 700 141, West Bengal, India

^a e-mail: arindambasu@hotmail.com

Received: 11 May 2011
Received in final form: 10 July 2011
Published online: 1 December 2011

Abstract

The lowest-lying ^{1, 3}P^o and ¹D^e resonances of positronium negative ion, Ps⁻, in weakly coupled plasmas have been investigated employing the close-coupling approximation. Three different basis sets have been employed in the present study. The plasma screening condition obtained from the Debye-Hückel type potential is used to represent the interaction between the charged particles. The resonance energies and the corresponding widths of one ¹P^o, two ³P^o, and one ¹D^e resonant states associated with the n = 2 threshold of the positronium atom for various Debye lengths ranging from infinity to small values are reported. The ¹P^o resonance as well as the higher lying ³P^o resonant state transforms to a shape resonance for denser plasma conditions. The ¹D^e resonant state also changes to a shape-type resonance for very dense plasmas.