Top-BESS model and its phenomenology

We introduce the top-BESS model which is the effective description of the strong electroweak symmetry breaking with a single new SU(2)_L+R triplet vector resonance. The model is a modification of the BESS model in the fermion sector. The triplet couples to the third generation of quarks only. This approach reflects a possible extraordinary role of the top quark in the mechanism of electroweak symmetry breaking. The low-energy limits on the model parameters found provide hope for finding sizable signals in the LHC Drell-Yan processes as well as in the s-channel production processes at the ILC. However, there are regions of the model parameter space where the interplay of the direct and indirect fermion couplings can hide the resonance peak in a scattering process even though the resonance exists and couples directly to top and bottom quarks.Comment: published in Physical Review D, minor changes in text, 21 pages, 37 figure

The vector resonance triplet with the direct coupling to the third quark generation

The effective Lagrangian with scalar and vector resonances that might result from new strong physics beyond the SM is formulated and studied. In particular, the scalar resonance representing the recently discovered 125-GeV boson is complemented with the SU(2)_{L+R} triplet of hypothetical vector resonances. Motivated by experimental and theoretical considerations, the vector resonance is allowed to couple directly to the third quark generation only. The coupling is chiral-dependent and the interaction of the right top quark can differ from that of the right bottom quark. To estimate the applicability range of the effective Lagrangian the unitarity of the gauge boson scattering amplitudes is analyzed. The experimental fits and limits on the free parameters of the vector resonance triplet are investigated.Comment: 17 pages, 10 figures, to be published in The European Physical Journal C. arXiv admin note: text overlap with arXiv:1301.212

W-Pair Production in the Process e+e−→ℓνqqˉ′e^+e^- \to \ell \nu q\bar{q}' and Measurement of the WWγWW\gamma and WWZWWZ Couplings

We performed a detailed analysis of the process $e^+e^-\to \ell \nu q\bar{q}'$ where we included all tree level Feynman diagrams that contribute to this final state. We studied the sensitivity of this process to anomalous trilinear gauge boson couplings of the $WW\gamma$ and $WWZ$ vertices using two popular parametrizations. We used a maximum likelihood analysis of a five dimensional differential cross-section based on the $W$ and $W$ decay product angular distributions. We concentrated on LEP-200 energies, taking $\sqrt{s}=175$ GeV, and energies appropriate to the proposed Next Linear Collider (NLC), a high energy $e^+e^-$ collider with center of mass energies $\sqrt{s}=500$ and 1~TeV. At 175 GeV, $g_1^Z$ can be measured to about $\pm 0.2$, $\kappa_Z$ to $\pm 0.2$ and $\kappa_\gamma$ to $\pm 0.3$, $\lambda_Z$ to $\pm 0.2$ and $\lambda_\gamma$ to $\pm 0.3$. at 95\% C.L. assuming 500~pb$^{-1}$ integrated luminosity. Although these will be improvements of existing measurements they are not sufficiently precise to test the standard model at the loop level and are unlikely to see deviations from SM expectations. At 500~GeV with 50~fb$^{-1}$ integrated luminosity, $g_1^Z$ can be measured to about $\pm 0.01$, $\kappa_Z$ and $\kappa_\gamma$ to $\pm 0.005$ and $\lambda_Z$ and $\lambda_\gamma$ to $\pm 0.003$ at 95\% C.L. while at 1 TeV with 200~fb$^{-1}$ integrated luminosity, $\kappa_V$ and $\lambda_V$ can be measured to about $\pm 0.005$ and $\pm 10^{-3}$ respectively. The 500~GeV measurements will be at the level of loop contributions to the couplings and may show hints of new physics while the 1~TeV should be sensitive to new physics at the loop level.Comment: Latex file uses revtex version 2 4 figures (uuencoded) will be added with figures command. Full postcript version with embedded figures is available at ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9503.p