Related papers: Extended technicolor contribution to the Zbb verte…
We introduce and define operatively in a model independent way a new ``heavy" b-vertexparameter, $\eta_b$, that can be derived from the measurement of a special polarization asymmetry for production of b-quarks on Z resonance. We show that…
We consider the lepton-flavor violating(LFV) processes $l_{i}\to l_{j}\gamma$ in the framework of topcolor assisted technicolor(TC2) models. We find that the new gauge boson $Z^{\prime}$ predicted by TC2 models can give significantly…
We study the consequences of an extension of the standard model containing an invisible extra gauge group under which the SM particles are neutral. We show that effective operators, generated by loops of heavy chiral fermions charged under…
Violations of universality of couplings in a vectorlike extension of the standard model with three heavy mirror fermion families are considered. The recently observed discrepancies between experiments and the standard model in the hadronic…
Theories with large mass anomalous dimensions ($\gamma_m$) have been extensively studied because of their deep consequences for models where the scalar bosons are composite. Large $\gamma_m$ values may appear when a non-Abelian gauge theory…
We propose a new model with flavor-dependent gauged $U(1)_{B-L_1}\times U(1)_{B-L_{2}-L_{3}}$ symmetry in addition to the flavor-blind one in the standard model. The model contains three right-handed neutrinos to cancel gauge anomalies and…
We consider the physics of an extra $U(1)$ gauge boson $Z'$, which can mix with $Z$ through intermediate fermion loops. The loop contribution due to the heavy top quark significantly affects the low-energy observables, and for $m_{Z'}>m_Z$,…
We study the decay B\to X_s\gamma in a minimal extension of the standard model with extra up- and down-type quarks whose left- and right-handed components are both SU(2) singlets. Constraints on the extended Cabibbo-Kobayashi-Maskawa matrix…
We study the effect of bulk fermions on electroweak precision observables in a recently proposed model with warped extra dimensions and no custodial symmetry. We find that the top-quark mass, together with the corrections to the Zbb vertex…
In technicolor theories using an SU($N_{TC}$) gauge group, the value of $N_{TC}$ is not, {\it a priori}, determined and is typically chosen by phenomenological criteria. Here we present a novel way to determine $N_{TC}$ from the embedding…
In this paper we calculate the technicolor correction to the production of a charged top pion in association with a W boson via b\bar{b} annihilation at the CERN Large Hadron Collider in the context of the topcolor assisted technicolor…
We find that, at order alpha_s, the partial width of Z^0 to heavy flavors receives a power correction from a novel QCD mechanism, which is not suppressed by inverse powers of M_Z, but only by two unknown O(\lambdaqcd/m) constants. The…
We show that the naively expected large virtual heavy fermion effects in low energy processes may be screened if the process under consideration contains external gauge bosons constrained by gauge invariance. We illustrate this by a typical…
Conventional technicolor models with light charged technipions ($\pi ^{\pm} _T$) lead to an unacceptably large contribution to $t\ra {\pi ^+_T} b$ decay rate. Topcolor-assisted technicolor models also have additional PGBs called top-pions…
Using precision electroweak data, we put limits on non-commuting extended technicolor models. We conclude that these models are viable only if the ETC interactions are strong. Interestingly, these models predict a pattern of deviations from…
We consider the extension of the standard model with an arbitrary number of U(1) gauge fields coupled to baryon-minus-lepton number and/or hypercharge. Under the assumption that A^b_FB from the LEP1 experiment is an unlucky fluctuation, we…
For the vertex corrections to the partial decay rate $\Gamma(Z \to b\bar{b})$ involving the top quark only the leading terms of order $\alpha\alpha_s$ in the $1/M_t$ expansion are known. In this work we compute the missing next-to-leading…
We analyze the constraints on possible anomalous contributions to the $W^+W^-Z$ vertex coming from non-universal radiative corrections to the $Z \rightarrow b \bar{b}$ width. We parametrize these corrections in terms of $\epsilon_b$ and use…
We examine the rare decays $B\to X_s\tau^+\tau^-$ and $B_s\to\tau^+\tau^- \gamma$ in the framework of technicolor with scalars. The contributions from both the neutral and charged scalars predicted in this model are evaluated. We find that…
The previously developed renormalizable perturbative 1/N-expansion in higher dimensional scalar field theories is extended to gauge theories with fermions. It is based on the $1/N_f$-expansion and results in a logarithmically divergent…