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Order alpha^7 ln(1/alpha) Contribution to Positronium Hyperfine Splitting

Bernd A. Kniehl·Alexander A. Penin
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Abstract

The logarithmically enhanced alpha^7 ln(1/alpha) contribution to the hyperfine splitting of the positronium ground-state energy levels is calculated in the framework of dimensionally regularized nonrelativistic quantum electrodynamics. The correction is negative and amounts to about 1/3 of the leading logarithmic alpha^7 ln^2(1/alpha) one. The discrepancy between the experimental measurements and the theoretical prediction is reduced.

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Bernd A. Kniehl, Alexander A. Penin. 2000-10-16. Order alpha^7 ln(1/alpha) Contribution to Positronium Hyperfine Splitting. https://doi.org/10.1103/physrevlett.85.5094

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