Heavy Higgs bosons and their low-energy impact

We investigate the impact which a heavy scalar sector has on the low-energy (E << 1TeV) structure of the standard Weinberg-Salam model. Our purpose is to determine which observables exhibit the greatest sensitivity to M/sub H/. This will be accomplished by showing that it is possible to completely characterize the low-energy sensitivity of the model to a 1-TeV Higgs sector by an effective Lagrangian. The central point of the analysis leading to the effective theory is the realization that the standard model is a regulated nonlinear sigma model coupled to an SU(2)/sub L/ x U(1) invariant Yang-Mills theory, with M/sub H/ acting as the regulator. By using the symmetry properties of the nonlinear theory and a power-counting analysis, an algorithm is developed for constructing the effective theory, order by order in the loop expansion. It is then possible to systematically classify low-energy observable according to their sensitivity to M/sub H/ and, hence, their usefulness as probes of the 1-TeV scalar sector. As a practical application of these ideas, we explicitly construct the effective Lagrangian which describes one-loop heavy Higgs effects. The maximum sensitivity of one-loop observables to M/sub H/ is shown to be logarithmic, and the M/sub H/-dependent corrections to some of these are computed. Specifically, the experiments which are discussed which are capable of isolating heavy Higgs effects include the measurement of the deviation of the ratio M/sub W//M/sub Z/ cos theta from one, the determination of the shift in the vector boson masses from q2 = 0 to their on-shell interactions on scattering processes involving vector bosons. A discussion of how the one-loop analysis is effected by the contributions of higher order calculations is presented and a critique of the effective Lagrangian approach is given