This thesis tests the possibility of detecting effects due to the Higgs exchange diagram in high energy µ⁺µ^-, e⁺e^-, and τ ⁺τ^- collisions producing a pair of W bosons. This could serve as an indirect proof of the existence of the Higgs boson in case it is not discovered directly at the LHC or after all data from Tevatron Run II are processed and analyzed. The processes l ⁺l^- → W ⁺WU (with l = µ, e, τ) are analyzed, analytically and by means of MadEvent simulations, to determine the center of mass energy where the effects from Higgs exchange are of the order of the total cross section or amount to 10% of the total cross section. The scaling of the center of mass energy where Higgs exchange becomes relevant with the mass of the incoming leptons is also studied.

I specifically concentrate on the W⁺ W^- → l^±ν _ljj final state after realistic experimental cuts are imposed to identify the center of mass energy for which the Higgs exchange diagram becomes important, and which could be probed experimentally at future lepton colliders. Finally, the effects of realistic experimental cuts on the total cross section including the Higgs exchange diagram versus the total cross section without the Higgs exchange diagram are considered as a function of the center of mass energy.