Abstract :
The single- W production mechanism is synonymous to the e+e− annihilation into eνe and a W boson with the outgoing electron lost in a small cone around the beam direction. It requires a renormalization scheme that preserves gauge invariance and fermion masses cannot be neglected in the calculation. A recently proposed generalization of the so-called Fermion-Loop scheme is applied to the evaluation of observables at LEP 2 energies. The total contribution to single- W processes can be split, in a gauge invariant manner, into a s -channel component and a t -channel one. The latter is dominated by a regime of low momentum transfer of the outgoing electron and any high-energy renormalization scheme, as the GF -one, fails to give the correct description of the scale. The Fermion-Loop scheme automatically converts, among other things, all couplings of the theory into couplings that are running at the appropriate scale. Therefore, in addition to represent the only scheme fully justified on a field-theoretical basis, the Fermion-Loop is the best starting point to include radiative corrections into single- W production. Numerical results are presented, showing a decrease in the predictions that can be sizeable. There is no naive and overall rescaling of αQED in any pragmatic scheme, as the Fixed-Width one, that can reproduce the Fermion-Loop results, at the requested accuracy, for all configurations and for all kinematical cuts.
