Relativistic Three-Fermion Wave Equations in Reformulated QED and Relativistic Effects in Muonium Minus

Abstract

The variational method, within the Hamiltonian formalism of reformulated QED is used to determine relativistic wave equations for a system of three fermions of arbitrary mass interacting electromagnetically. The interaction kernels of the equations are, in essence, the invariant $\mathcal{M}$ matrices in lowest order. The equations are used to obtain relativistic $O(\alpha^2)$ corrections to the non-relativistic ground state energy levels of the Muonium negative ion ($\mu^+ e^- e^-$) as well as of $\mathrm{Ps}^-$ and $\mathrm{H}^-$, using approximate variational three-body wave functions. The results are compared with other calculations, where available. The relativistic correction for Mu$^-$ is found to be $-1.0773 \times 10^{-4}$ eV.