On the squared spin-orbit correction to the positronium fine-structure splitting

Khriplovich, I. B.; Milstein, A. I.; Yelkhovsky, A. S.

On the squared spin-orbit correction to the positronium fine-structure splitting

Authors

Khriplovich, I. B.

Milstein, A. I.

Yelkhovsky, A. S.

Description

In the recent paper by Zhang the order $α^4 R_{\infty}$ corrections to the positronium P levels were reconsidered. Those calculations confirm our corresponding results, except for the contribution due to the squared spin-orbit interaction. We present here a new derivation of our previous result for this last correction, this derivation being to our opinion both simple and convincing.
3 pages, Latex