Interference of Electromagnetic and Weak Interactions at High Energies and Neutral-Current μe Universality

A review is given on three types of experiments which recently detected the interference of electromagnetic and weak interactions at high energies in the reactions eD₂ → eX (SLAC, 1979), e⁺e⁻ → μ⁺μ⁻ (PETRA/PEP, 1981–83) and μ±C→μ±X (BCDMS, 1982). Asymmetry formulae are explicitely derived using the quark-parton model and the SU(2) × U(1) standard theory. With particular emphasis on the deep inelastic muon scattering experiment, the corresponding experiments are described and their results summarized. Combined fits to the 1983 asymmetry and νe data verify completely the muon-electron universality of the weak neutral current interaction giving for the vector and axial-vector coupling constants v_e = 0.02 ± 0.06, a_e = −0.54 ± 0.03 (electrons) and v_μ = −0.05 ± 0.16, a_μ = −0.51 ± 0.05 (muons).