Anomalous Magnetic Moment of the W Boson in Different Models.

We consider the anomalous magnetic moment of the W boson, kappa, from an experimental and from a theoretical point of view. In the first chapter, we consider five experiments where this parameter could in principle be measured. Our results show that the W pair-production remains the best process to measure kappa. Single W production is very sensitive to kappa, but it is plagued by very small cross-sections. Photon-electron colliders can also be valuable for measuring kappa through single W production. In the second chapter, we consider a composite model where kappa is essentially free. We found that it is impossible to rule out such a model from a single measurement of kappa. We give detailed production rates for these processes. In the second half of the thesis, we set limits on the corrections to kappa at the one loop level; first in the minimal SM and then in a two -Higgs-doublet model. The main results are that measured corrections of 0.1 would clearly indicate non-perturbative physics while the minimal SM can accommodate corrections up to 0.02. Possible extensions of the SM cannot increase this figure by much: unless one is willing to introduce several extra weakly interacting families, it remains that 75%, or more, of the corrections will arise from the minimal SM.