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arXiv · 1507.07841

Three-photon-annihilation contributions to positronium energies at order $m α^7$

Gregory S. Adkins·Minji Kim·Christian Parsons·Richard N. Fell
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Abstract

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 experimental results motivate the calculation of the positronium energy levels at order $m α^7$. In this work we present the result for a complete class of such contributions--those involving virtual annihilation of positronium to three photons in an intermediate state. We find an energy shift of $2.6216(11) m α^7/(n π)^3$ for the spin-triplet S state with principal quantum number n.

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Gregory S. Adkins, Minji Kim, Christian Parsons, Richard N. Fell. 2015-07-28. Three-photon-annihilation contributions to positronium energies at order $m α^7$. https://doi.org/10.1103/physrevlett.115.233401

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