Second bound state of the positronium molecule and biexcitons

TL;DR

This paper reports the discovery of a new bound state of the positronium molecule with specific angular momentum and parity, which remains stable under certain mass conditions, and explores similar states in two dimensions to enhance understanding of biexciton binding.

Contribution

It introduces a previously unknown bound state of the positronium molecule with L=1 and negative parity, expanding the understanding of positronium and biexciton states.

Findings

Discovery of a new bound state with L=1 and negative parity

Stability of the state despite unequal charge masses

Existence of a similar state in two-dimensional systems

Abstract

A new, hitherto unknown bound state of the positronium molecule, with orbital angular momentum L=1 and negative parity is reported. This state is stable against autodissociation even if the masses of the positive and negative charges are not equal. The existence of a similar state in two-dimension has also been investigated. The fact that the biexcitons have a second bound state may help the better understanding of their binding mechanism.