Bound State Theory and High Precision QED: Muonium, Positronium, Hydrogen, and Pentaquarks

The objectives and methods of the proposed research include: • Complete calculation of all three-loop radiative-recoil corrections of order á3(m/M)EF to hyperfine splitting in muonium. • Complete calculation of hard three-loop corrections to hyperfine splitting in positronium due to two-loop radiative insertions in the fermion lines in two-photon exchange nonannihilation diagrams. • Complete calculation of all three-loop nonrecoil corrections of order á3(Zá)5m to the Lamb shift in hydrogen and muonium. These are the largest still unknown contributions to the Lamb shift. Respective three-loop nonrecoil corrections to hyperfine splitting in hydrogen and muonium also will be calculated. • Further development of the hadrocharmomium interpretation of pentaquarks and quantitative description of their properties. Methods of nonrelativistic and relativistic quantum electrodynamics and chromodynamics will be applied to loosely bound two-particle systems in the proposed research. Theoretical results of the proposed research together with the theoretical results of other authors and with the results of the past and ongoing experiments would allow to determine more precise values for many fundamental physical constants: electron-muon and electron-proton mass ratios, the proton charge radius, the Rydberg constant, etc. The results will also facilitate interpretation of the nature of the recently discovered pentaquarks and allow quantitative description of their properties.