title: Dipole excitation of the positronium molecule ps2.
abstract: The energy interval between the ground and the P-wave excited states of the recently discovered positronium molecule Ps2 is evaluated, including the relativistic and the leading logarithmic radiative corrections, E_{P}-E_{S}=0.181 586 7(8) a.u.. The P state, decaying usually via annihilation, is found to decay into the ground state by an electric dipole transition 19% of the time. Anticipated observation of this transition will provide insight into this exotic system.
authors.affiliation: Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2G7.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Puchalski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Czarnecki