60 citations · 208 across the 6 of their papers we have counts for
6 papers
Three-photon-annihilation contributions to positronium energies at order
Gregory S. Adkins, Minji Kim, Christian Parsons +1
Positronium spectroscopy (n=1 hyperfine splitting, n=2 fine structure, and the 1S-2S interval) has reached a precision of order 1 MHz. Vigorous ongoing efforts to improve the exper…
Positronium energy levels at order : light-by-light scattering in the two-photon-annihilation channel
Gregory S. Adkins, Christian Parsons, M. D. Salinger +2
Recent and ongoing experimental work on the positronium spectrum motivates new efforts to calculate positronium energy levels at the level of three loop corrections. We have obtain…
Positronium hyperfine splitting at order : light-by-light scattering in the two-photon-exchange channel
Gregory S. Adkins, Richard N. Fell
We have calculated the contribution to the positronium hyperfine splitting at order of the light-by-light scattering process in the exchange of two photons between the elec…
Cosmological perturbations on local systems
Gregory S. Adkins, Jordan McDonnell, Richard N. Fell
We study the effect of cosmological expansion on orbits--galactic, planetary, or atomic--subject to an inverse-square force law. We obtain the laws of motion for gravitational or e…
Two-loop corrections to the decay rate of parapositronium
Gregory S. Adkins, Nathan M. McGovern, Richard N. Fell +1
Order corrections to the decay rate of parapositronium are calculated. A QED scattering calculation of the amplitude for electron-positron annihilation into two photons at th…
Order α^2 corrections to the decay rate of orthopositronium
G. S. Adkins, R. N. Fell, J. Sapirstein
Order α^2 corrections to the decay rate of orthopositronium are calculated in the framework of nonrelativistic QED. The resulting contribution is found to be in significant disagre…