Spin-orbit corrections of order mα6 to the fine structure of the (37,35) state in the 4He p antiprotonic helium atom

Precise numerical calculation of radiofrequency intervals between hyperfine sublevels of the (37,35) state of the antiprotonic helium-4 atom is presented. Theoretical consideration includes the QED corrections of order mα6 to the electron spin-orbit interaction. Only the leading order contribution in the electron-to-antiproton and electron-to-α particle mass ratios is considered, so the α particle and antiproton are treated nonrelativistically. The effective Hamiltonian is derived using the formalism of the nonrelativistic quantum electrodynamics.