Related papers: Extended technicolor contribution to the Zbb verte…
We argue that extended technicolor augmented with topcolor requires that all mixing between the third and the first two quark generations resides in the mixing matrix of left-handed down quarks. Then, the anti-B_d--B_d mixing that occurs in…
Applying the method of light-cone sum rules with photon distribution amplitudes, we compute the subleading-power correction to the radiative leptonic $B \to \gamma \ell \nu$ decay, at next-to-leading order in QCD for the twist-two…
The effects of an extra $Z'$ gauge boson with family nonuniversal fermion couplings on the rare top quark decay $t --> c $gamma$ are first examined in a model independent way and then in the minimal 331 model. It is found that the…
The bottom quark forward-backward asymmetry ($A_{FB}^b$) data at LEP exhibits a long-standing discrepancy with the standard model prediction. We propose a novel method to probe the $Zb\bar{b}$ interactions through $gg\to Zh$ production at…
In general, attempts to extend the standard model will include extra gauge structure. We parameterize string and technicolor models for a Z' boson with primitive lepton flavor violating interactions. Calculations for its muon conversion…
Recent experimental results on color coherence phenomena from e+e-, ep, and ppbar collisions are presented. The data are compared to analytic perturbative QCD calculations based on the modified leading logarithm approximation and the local…
If the Standard Model is embedded in a left-right symmetric gauge theory at the TeV scale, the pair production of light W-bosons in e^+e^- collisions, e^+e^- -> W^+W^-, will be affected by mixings in the gauge and neutrino sectors, and by…
We consider the rare decay channels of the $Z$ boson: $Z \to \text{two}\ \textrm{jets} + \gamma$ and $Z \to \text{two}\ \textrm{jets} +2\, \gamma$. To obtain the widths and distributions for these processes, we compute the effect of NLO QCD…
We use the LEP/SLD data to place constraints on Topcolor Assisted Technicolor Models. We find that due to a large negative shift in R_b induced by charged top-pion exchange, it is difficult to make the models compatible with experiment.
We introduce a toy model implementing the proposal of using a custodial symmetry to protect the Zbb coupling from large corrections. This "doublet-extended standard model" adds a weak doublet of fermions (including a heavy partner of the…
We recently showed that a new gauge boson $\gamma_B$ coupling only to baryon number is phenomenologically allowed, even if $m_B<m_Z$ and $\alpha_B \approx 0.2$. In our previous work we assumed that kinetic mixing between the baryon number…
We study the exclusive flavor chancing neutral current process Lambda(b)-->Lambda neutrino antineutrino in the leptophobic Z-prime model, where charged leptons do not couple to the extra Z-prime boson. The branching ratio, as well as, the…
Partial compositeness is a key ingredient of models where the electroweak symmetry is broken by a composite Higgs state. Recently, a UV completion of partial compositeness was proposed, featuring a new strongly coupled gauge interaction as…
The framed standard model (FSM), constructed initially for explaining the existence of three fermion generations and the hierarchical mass and mixing patterns of quarks and leptons, suggests also a "hidden sector" of particles including…
We performed a detailed analysis of the process $e^+e^-\to \ell \nu q\bar{q}'$ to determine its sensitivity to anomalous trilinear gauge boson couplings of the $WW\gamma$ and $WWZ$ vertices and how the sensitivity varies with energy and…
The discrepancies between the measurements of rare (semi-)leptonic $B$ decays and the corresponding Standard Model predictions point convincingly towards the existence of new physics for which a heavy neutral gauge boson ($Z^\prime$) is a…
We consider a new massive vector-boson Z' that couples to leptons through the L_mu - L_tau current, and to quarks through an arbitrary set of couplings. We show that such a model can be obtained from a renormalizable field theory involving…
The QCD-induced $W^\pm \gamma$ production channels in association with two jets are computed at next-to-leading order QCD accuracy. The W bosons decay leptonicly and full off-shell and finite width effects as well as spin correlations are…
We discuss and estimate the contributions of the new particles predicted by topcolor assisted technicolor(TC2) models to the muon anomalous magnetic moment $a_{\mu}$. Our results show that the contributions of Pseudo Goldstone bosons are…
The Standard Model fit prefers values of the Higgs boson mass that are below the 114 GeV direct lower limit from LEP II. The discrepancy is acute if the 3.2 sigma disagreement for the effective weak interaction mixing angle from the two…