Positronium is the simplest bound state, built of an electron and a positron. Studies of
positronium in vacuum and its decays in medium tell us about quantum electrodynamics …

Positronium (Ps) is an exotic hydrogenic atom composed of an electron bound to a positron
via the Coulomb force. Being composed of two low-mass leptons, positronium is, for all …

We report a new measurement of the positronium (Ps) 2 S 3 1→ 2 P 3 0 interval. Slow Ps
atoms, optically excited to the radiatively metastable 2 S 3 1 level, flew through a microwave …

We report a new measurement of the n= 2 Lamb shift in Muonium. Our result of 1047.2 (2.3)
stat (1.1) syst MHz comprises an order of magnitude improvement upon the previous best …

We report the results of a new measurement of the positronium 2 S 3 1→ 2 P 3 2 (ν 2)
interval. Using a modified experimental arrangement we have significantly reduced the …

This work is a collection of initial calculations and formal considerations within the Salpeter–
Sucher exact equal-time relativistic quantum electrodynamics framework. The calculations …

This work is concerned with two-spin-1/2-fermion relativistic quantum mechanics, and it is
about the construction of one-particle projectors using an inherently two-particle,“explicitly …

We report measurements of the positronium (Ps) 2 S 1 3→ 2 P 2 3 interval in which atoms
traveling in free space were irradiated with microwave radiation generated using a horn …

The fluorescence decay rate of 2 PJ 3 positronium (Ps) atoms [Γ fl] has been experimentally
determined using a Stark-mixing technique. Ground-state Ps atoms were optically excited in …

We report ortho positronium (o-Ps) thermalization observed in cryogenic silica aerogel
cooled from room temperature to 25 K. It was observed that the o-Ps thermalization rate gets …