SingletParticle Extension of the Minimal Higgs Sector
Abstract
Assuming that the Higgs scalar is heavier than 1 TeV, lowenergy physics may still be described effectively by the standard model in the largeHiggsmass limit. It has been shown that the heavyHiggs theory is not unique but it depends on the way the limit is taken. We study this arbitrariness in terms of an extended Higgs sector. A new scalar singlet particle, the U, is coupled to the Higgs sector of the standard model, for the purpose of parametrizing the largeHiggsmass behaviour of the theory. Two extended models arise, depending on whether the U particle develops a vacuum expectation value or not. The new radiative corrections to lowenergy parameters first appear at the oneloop and twoloop levels, respectively. The U particle effects upon the rho parameter and the gauge boson mass shifts are computed. Emphasis is given to the limit where the U particle becomes as heavy as the Higgs. The new contributions demonstrate the ambiguous behaviour but they fail to restore the uniqueness of the theory in the limit. The model where U develops a vacuum expectation value is also investigated at energies higher than the vector boson mass scale. We compute the leading radiative corrections to the longitudinal vector boson scattering amplitude in the limit of high energy and even higher scalar masses. We assume a small difference between the masses of the scalars, within 10% of the lower scalar mass. Within the framework of partial wave analysis, the leading terms to the beta parameter are derived. We find a small but positive enhancement to the standard model contributions. The overall result indicates that no resonance will appear in the isospin I = 1 channel at any energy above the 1 TeV threshold.
 Publication:

Ph.D. Thesis
 Pub Date:
 1992
 Bibcode:
 1992PhDT.......148K
 Keywords:

 SINGLET PARTICLE;
 U PARTICLE;
 Physics: Elementary Particles and High Energy