We calculate the tree-level expressions for the electroweak precision observables in the [Formula Presented] littlest Higgs model. The source for these corrections are the exchange of heavy gauge bosons and a triplet Higgs vacuum expectation value (VEV). Weak isospin violating contributions are present because there is no custodial [Formula Presented] global symmetry. The bulk of these weak isospin violating corrections arise from heavy gauge boson exchange while a smaller contribution comes from the triplet Higgs VEV. A global fit is performed to the experimental data and we find that throughout the parameter space the symmetry breaking scale is bounded by [Formula Presented] at 95% C.L. Stronger bounds on f are found for generic choices of the high energy gauge couplings. We find that even in the best case scenario one would need fine-tuning of less than a percent to get a Higgs boson mass as light as 200 GeV.
|Original language||English (US)|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Jan 1 2003|
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)