(Quasi)elastic electron-muon large-angle scattering within the two-loop approximation: Vertex contributions

We consider quasielastic large-angle electron-muon scattering at high energies with radiative corrections up to the two-loop level. The lowest order radiative corrections arising from the one-loop virtual photon emission and a real soft emission are presented within a power accuracy. Two-loop corrections are supposed to be of three gauge-invariant classes. One of them, the so-called vertex contribution, is given in the logarithmic approximation. The relation to the renormalization group approach is discussed.