The discovery of the Higgs boson, with mass known to better than the percent level, enables for the first time precision Higgs boson analyses. Toward this goal, we define an expansion formalism of the Higgs boson partial widths and branching fraction
s that facilitates such studies. This expansion yields the observables as a perturbative expansion around reference values of Standard Model input observables (quark masses, QCD coupling constant, etc.). We compute the coefficients of the expansion using state-of-the-art results. We also study the various sources of uncertainties in computing the partial widths and branching fractions more precisely. We discuss the impact of these results with efforts to discern new physics through precision Higgs boson studies.
Extra neutral gauge bosons (Z) are predicted in many extensions of the Standard Model (SM). In the minimal anomaly-free Z model (AFZ), the phenomenology is controlled by only three parameters beyond the SM ones, the Z mass and two effective coupling
constants g_Y and g_{BL}. We study the Z 5-sigma discovery potential in e+e- collisions at 1.4 and 3 TeV CLIC. Assuming LHC discovers a Z of 5 TeV mass, the expected accuracies on the Zmu+mu- couplings are presented. We discuss also the requirements on detector performance and beam polarization.
