Production of single W bosons in e+ e- and e- p collisions

The production of W bosons in electron-positron colliding beams below the W+W- threshold is discussed. The corresponding reactions e+ e- → l+- W-+sup((-))νsub(l) yield total cross-sections of the order of 10-37 cm2 (for l = e) and 10-38 cm2 (for l = μ). The total cross-sections as well as the angular and energy distributions of the W boson in e+e- → e+- W-+sup((-))νsub(e) are sensitive to the magnetic moment of the W. So, with this reaction, not only W bosons can be produced but also the gauge nature of the interaction can be tested. The decay Z0 → l+- W-+sup((-))νsub(l) is discussed in view of its observation in e+ e- experiments. Finally the cross-sections of e-p → νsub(e)W-X+ are computed. They are of the order of 10-38 cm2 for √s as appropriate 200 GeV. (Author)