====== TTP97-07 Eight-component two-fermion equations ======
 
 
<hidden TTP97-07  Eight-component two-fermion equations > 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 $\alpha^6$ recoil corrections to the positronium
 case, and 
 implies new recoil corrections to 
 the fine and hyperfine structures and to the Bethe logarithm.
 </hidden>
|**R. H\"ackl, V. Hund and H. Pilkuhn**  | 
|** Phys. Rev. A57 3268 1998  **  |
| {{preprints:1997:ttp97-07.pdf|PDF}} {{preprints:1997:ttp97-07.ps|PostScript}}   |
| |