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Eight-component two-fermion equations

Ruth Haeckl·Viktor Hund·Hartmut Pilkuhn
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Abstract

An eight-component formalism is proposed for the relativistic two-fermion problem. In QED, it extends the applicability of the Dirac equation with hyperfine interaction to the positronium case. The use of exact relativistic two-body kinematics entails a CP-invariant spectrum which is symmetric in the total cms energy. It allows the extension of recent α^6 recoil corrections to the positronium case, and implies new recoil corrections to the fine and hyperfine structures and to the Bethe logarithm.

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Ruth Haeckl, Viktor Hund, Hartmut Pilkuhn. 1998-02-03. Eight-component two-fermion equations. https://doi.org/10.1103/physreva.57.3268

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