Related papers: Electroweak Precision Data and a Heavy Z'
It has been recently argued that realistic models with warped extra dimensions can have Kaluza-Klein particles accessible at the Large Hadron Collider if a custodial symmetry, SU(2)_V \times P_{LR}, is used to protect the T parameter and…
We present a fit to precision electroweak data in the standard model extended by an additional vector boson, Z', with suppressed couplings to the electron compared to the Z boson, with couplings to the b-quark, and with mass close to the…
Lepton and quark asymmetries at Z boson peak are a powerful means to test the couplings of the Z boson to fermions. The measurements performed at LEP and SLC colliders are reviewed, and their impact on the determination of the electroweak…
A complete analysis of the electroweak precision observables is performed within a recently proposed minimal composite Higgs model, realized as a 5-dimensional warped compactification. In particular, we compute Z->bb and the one-loop…
We consider an extended electroweak gauge group: SU(2)$_1 \times$ SU(2)$_2 \times$ U(1)$_Y$ where the first and second generation of fermions couple to SU(2)$_1$ and the third generation couples to SU(2)$_2$. Bounds based on heavy gauge…
We consider the electroweak theory with an additional neutral vector boson $Z^\prime$ at one loop. We propose a renormalization scheme which makes the decoupling of heavy $Z^\prime$ effects manifest. The proposed scheme justifies the usual…
We explore the phenomenology of an extra U(1) gauge boson which primarily couples to standard model gauge bosons. We classify all possible parity-odd couplings up to dimension 6 operators. We then study the prospects for the detection of…
Phenomenologically relevant electroweak precision pseudo-observables related to Z-boson physics are discussed in the context of the strong experimental demands of future $e^+e^-$ colliders. The recent completion of two-loop Z-boson results…
Experiment shows that the top quark is far heavier than the other elementary fermions. This finding has stimulated research on theories of electroweak and flavor symmetry breaking that include physics beyond the standard model. Efforts to…
A future $e^+e^-$ collider could run at the Z-pole to perform important electroweak (EW) precision measurements, while such a run may not be viable for a future muon collider. This however can be compensated by the measurements of other EW…
Warped extra dimensions allow a novel way of solving the hierarchy problem, with all fundamental mass parameters of the theory naturally of the order of the Planck scale. The observable value of the Higgs vacuum expectation value is…
The leading electroweak MSSM two-loop corrections to the $\rho$-parameter are calculated. They are obtained by evaluating the two-loop self-energies of the Z and the W boson at O(Gf^2 m_t^4) in the limit of heavy scalar quarks. A very…
Our contribution sets out to investigate the phenomenology of a gauge model based on an $SU_{L}(2) \times U_{R}(1)_{Q} \times U(1)_{Q'}$-symmetry group. The model can accommodate, through its symmetry-breaking pattern, a candidate to a…
Specific quasi-realistic superstring constructions often predict the existence of new TeV-scale physics which may be different in character from bottom-up motivated constructions. I describe examples of such beyond the MSSM physics, with…
The dominant electroweak two-loop corrections to the precision observables M_W and s_w^eff are calculated in the MSSM. They are obtained by evaluating the two-loop Yukawa contributions of O(alpha_t^2), O(alpha_t alpha_b), O(alpha_b^2) to…
We briefly review the limits on new interactions implied by electroweak precision data. Special attention is payed to the bounds on the Higgs boson mass. We also comment on the required cancellation among the new contributions to precisely…
If the top is very heavy, m_t >> M_Z, the dominant radiative correction effects in all electroweak precision tests can be exactly characterized in terms of two quantities, the rho-parameter and the GIM violating Z -> b bbar coupling. These…
New physics models predict the possibility of extra neutral gauge bosons ($Z'$) associated with an extra $U(1)'$ gauge symmetry. We study the couplings of the Higgs boson to the $Z$ boson and $Z'$ boson predicted by the new physics models.…
We derive the low-energy electroweak effective lagrangian for the case of additional heavy, unmixed, sequential fermions. Present data still allow for the presence of a new quark and/or lepton doublet with masses greater than $M_Z/2$,…
The 1999 precision electroweak data from LEP and SLC persist in showing some slight discrepancies from the assumed standard model, mostly regarding $b$ and $c$ quarks. We show how their mixing with exotic heavy quarks could result in a more…