Radiative-Recoil Corrections to Hyperfine Splitting: Polarization Insertions in the Muon Factor

We consider three-loop radiative-recoil corrections to hyperfine splitting in muonium due to insertions of one-loop polarization operator in the muon factor. The contribution produced by electron polarization insertions are enhanced by the large logarithm of the electron-muon mass ratio. We obtained all single-logarithmic and nonlogarithmic radiative-recoil corrections of order ${\alpha }^3(m\mathrm{/}M)E_F$ generated by the diagrams with electron and muon polarization insertions.