Higgs-boson production and decay close to thresholds Original Research Article

At one loop in the conventional on-mass-shell renormalization scheme, the production and decay rates of the Higgs-boson H exhibit singularities proportional to (2MV−M)−1/2 as the Higgs-boson mass M approaches from below the pair-production threshold of a vector boson V with mass MV. This problem is of phenomenological interest because the values 2MW and 2MZ, corresponding to the W- and Z-boson thresholds, lie within the M range presently favoured by electroweak precision data. We demonstrate how these threshold singularities are eliminated when the definitions of mass and total decay width of the Higgs-boson are based on the complex-valued pole of its propagator. We illustrate the phenomenological implications of this modification for the partial width of the H→W+W− decay.