Higgs-singlet scalar interactions

The effects of a coupling of the Higgs sector of the standard model to a heavy scalar singlet particle are studied in the limit of large Higgs self-coupling. It is found that the singlet does not decouple from the standard model when its mass becomes large. This is due to mixing with the Higgs particle. The leading quantum corrections to the rho-parameter, the 3W vertex and the 4W vertex are calculated and compared to the poles in the corresponding quantum corrections in massive Yang-Mills theory. In the strong coupling limit of the singlet there is no relation between the structure constants of the effective one-loop Lagrangians in both theories. This is the first explicit example of such a breakdown at the one-loop level. An expansion of multiloop integrals in powers of ratios of their masses is presented in an appendix. This formalism is then used to show the general correspondence between poles in dimensional regularization and mass divergences due a Pauli-Villars regulator. Differences with the Higgs mechanism are discussed