Nonrelativistic QED and nexttoleading hyperfine splitting in positronium
Abstract
We compute the nexttoleading O(mα^{5}) contribution to the hyperfine splitting in positronium within the framework of nonrelativistic QED (NRQED). When applied to the ground state, our calculation reproduces the known result, providing a further test of NRQED techniques. In addition to providing a very simple method of calculation of this standard result, we also obtain new expressions for excited states of positronium with negligible additional effort. Our calculation requires the complete nexttoleading matching of the lowestdimension NRQED fourFermi couplings.
 Publication:

Physical Review D
 Pub Date:
 December 1997
 DOI:
 10.1103/PhysRevD.56.8053
 arXiv:
 arXiv:hepph/9706449
 Bibcode:
 1997PhRvD..56.8053L
 Keywords:

 12.20.Ds;
 11.10.St;
 31.15.Md;
 31.30.Jv;
 Specific calculations;
 Bound and unstable states;
 BetheSalpeter equations;
 Perturbation theory;
 Relativistic and quantum electrodynamic effects in atoms and molecules;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory;
 Physics  Atomic Physics
 EPrint:
 24 pages, plain TeX, 6 figures included using epsf