Related papers: Extended technicolor contribution to the Zbb verte…
We show that the flavor-diagonal gauge boson of the extended technicolor theory contributes with opposite sign to the standard model correction for the $Zbb$ vertex. This mechanism can naturally explain the deviation of the LEP result from…
In technicolor theories a large radiative correction to the Zbb vertex generally emerges, because of the large top quark mass and SU(2)_L gauge symmetry. The correction can give us an explanation for the deviation of the experimental value…
We estimate the correction to the Zbb-bar vertex arising from the exchanges of the sideways extended technicolor (ETC) boson and the flavor-diagonal ETC boson in the multiscale walking technicolor model. The obtained result is too large to…
We study the effect of the diagonal extended technicolor(ETC) gauge boson on the oblique correction parameters. It is shown that in the $T$ parameter is unacceptably large when the $Zbb$ vertex correction and $S$ parameter are consistent…
Extended technicolor theories generate potentially large corrections to the $\Zbb$ vertex. These can be observed in current experiments at LEP.
In extended technicolor (ETC) theories, while the sideways ETC boson exchange decreases the width $\Gamma_b \equiv \Gamma (Z\rightarrow b \bar{b})$, the flavor-diagonal ETC boson exchange tends to increase it, and the ETC-corrected $R_b…
As described previously, a new massive gauge boson (X) coupling only to the third family produces a tantalizing pattern of deviations away from the standard model. These include increasing Gamma_b/Gamma_h and decreasing the alpha_s(M_Z)…
The full solution of technicolor (TC) Schwinger-Dyson equations should include radiative corrections induced by extended technicolor (ETC) (or other) interactions. We verify that when TC is embedded into a larger theory including also QCD,…
The extended technicolor theory is a candidate of the physics beyond the standard model. To explain the mass hierarchy of the quarks and leptons, the extended technicolor gauge symmetry must hierarchically break to the technicolor gauge…
New strong gauge interactions remain a viable source for the electroweak symmetry breaking. However, addressing the generation of fermion masses remains a challenge. A basic observable which provides stringent constraints on the flavor…
We consider the radiative decay $b\rightarrow s \gamma$, and the correction to the $Zb\overline{b}$ vertex in technicolor models with scalars. In these models, the scalar develops a vacuum expectation value when the technifermions condense,…
Several aspects of the flavor-diagonal extended technicolor (ETC) gauge boson are reviewed. Among them are an increase of $R_b$ that could explain the LEP $R_b$ excess, a sizable, positive correction to the $\tau$ asymmetry parameter…
Recent study on the charged top-pion correction to R_b shows that it is negative and large, so that the precision experimental value of R_b gives rise to a severe constraint on the topcolor-assisted technicolor models such that the top-pion…
We study radiative corrections on $Zb{\bar b}$ vertex generated by the ETC gauge bosons, ``diagonal'' as well as sideways. Although the oblique corrections due to the ETC bosons are small in comparison with the oblique correction due to the…
An extension of the Standard Model is presented that leads to the possible existence of new gauge bosons with masses in the range of a few TeV. Due to the fact that their couplings to Standard Model fermions are strongly suppressed, it is…
It is notorious that, contrary to all other precision electroweak data, the forward-backward asymmetry for b quarks $A_{FB}^b$ measured in Z decays at LEP1 is nearly three standard deviations away from the predicted value in the Standard…
LEP precision measurements of the $Zb\bar{b}$ vertex coupling are sufficiently accurate to see the non-oblique corrections from the heavy gauge boson responsible for the large top mass in standard extended tecnicolour models. If the ETC…
The rates of the rare flavor-changing processes, $b \rightarrow s \gamma$ and $B_s \rightarrow \mu^+ \mu^-$ are estimated in extended technicolor models with and without a GIM mechanism. We find the $b \rightarrow s \gamma$ rate in ETC…
We study the Yukawa corrections to the gamma gamma --> b\bar{b} corss section in the topcolor assisted technicolor models at the photon-photon colliders. We find that, for the favorable parameters, the relative corrections from pseudo…
Extended technicolor theories generate potentially large corrections to the $\Zbb$ vertex which can be observed in current experiments at LEP.