One-loop Electroweak and QCD corrections to vector boson scattering into top pairs and application to ILC

We calculate the electroweak and QCD corrections to W-W+ -> tt and ZZ -> tt. We also consider the interplay of these corrections with the effect of anomalous interactions that affect the massive weak bosons and the top. The results at the VV level fusion are convoluted with the help of the effective vector boson approximation to give predictions for a high energy e+e- collider.Comment: 19 pages, 27 figure

Anomalous Quartic WWγγWW\gamma\gamma and ZZγγZZ\gamma\gamma Couplings in eγe\gamma Collision With Initial Beams and Final State Polarizations

The constraints on the anomalous quartic $WW\gamma\gamma$ and $ZZ\gamma\gamma$ gauge boson couplings are investigated through the processes $e\gamma\to W^{-}\gamma\nu_{e}$ and $e\gamma\to Z\gamma e$. Considering the longitudinal and transverse polarization states of the final W or Z boson and incoming beam polarizations we find 95% confidence level limits on the anomalous coupling parameters $a_{0}$ and $a_{c}$ with an integrated luminosity of 500 $fb^{-1}$ and $\sqrt{s}$=0.5, 1 TeV energies. Assuming the $W^{+}W^{-}\gamma\gamma$ couplings are independent of the $ZZ\gamma\gamma$ couplings we show that the longitudinal polarization state of the final gauge boson improves the sensitivity to anomalous couplings by a factor of 2-3 depending on energy and coupling. An extra enhancement in sensitivity by a factor of 1.3 comes from a set of initial beam polarizations

Study of V_LV_L to t tbar at the ILC Including O(alpha_s) QCD Corrections

In the event that the Higgs mass is large or that the electroweak interactions are strongly interacting at high energy, top quark couplings to longitudinal components of the weak gauge bosons could offer important clues to the underlying dynamics. It has been suggested that precision measurements of W_L W_L to t tbar and Z_L Z_L to t tbar might provide hints of new physics. In this paper we present results of O(alpha_s) QCD corrections to V_LV_L to t tbar scattering at the ILC. We find that corrections to cross sections can be as large as 30% and must be accounted for in any precision measurement of VV to t tbar.Comment: 8 pages, 8 figures, Minor changes in wording. uses Revtex

Strong Coupling Electroweak Symmetry Breaking

The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models

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

Higgs signals and hard photons at the Next Linear Collider: the ZZZZ-fusion channel in the Standard Model

In this paper, we extend the analyses carried out in a previous article for $WW$-fusion to the case of Higgs production via $ZZ$-fusion within the Standard Model at the Next Linear Collider, in presence of electromagnetic radiation due real photon emission. Calculations are carried out at tree-level and rates of the leading order (LO) processes e^+e^-\rightarrow e^+e^- H \ar e^+e^- b\bar b and e^+e^-\rightarrow e^+e^- H \ar e^+e^- WW \ar e^+e^- \mathrm{jjjj} are compared to those of the next-to-leading order (NLO) reactions e^+e^-\rightarrow e^+e^- H (\gamma)\ar e^+e^- b\bar b \gamma and e^+e^-\rightarrow e^+e^- H (\gamma)\ar e^+e^- WW (\gamma) \ar e^+e^- \mathrm{jjjj}\gamma, in the case of energetic and isolated photons.Comment: 12 pages, LaTeX, 5 PostScript figures embedded using epsfig and bitmapped at 100dpi, complete paper including high definition figures available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9611.ps or at http://www.hep.phy.cam.ac.uk/theory/papers

Anomalous quartic WWgammagamma and WWZgamma couplings through WWZ production in gamma gamma colliders

We find 95% confidence level limits on the anomalous coupling parameters $a_0$, $a_c$ and $a_n$ with an integrated luminosity of $500fb^{-1}$ and $\sqrt s =0.5, 1$ and 1.5 TeV energies. We take into account incoming beam polarizations and also the final state polarizations of the gauge bosons in the cross-section calculations to improve the bounds. We show that polarization leads to a significant amount of improvement in the sensitivity limits.Comment: 16 pages, 6 figures, 3 table

Testing the Higgs Mechanism in the Lepton Sector with multi-TeV e+e- Collisions

Multi-TeV e+e- collisions provide with a large enough sample of Higgs bosons to enable measurements of its suppressed decays. Results of a detailed study of the determination of the muon Yukawa coupling at 3 TeV, based on full detector simulation and event reconstruction, are presented. The muon Yukawa coupling can be determined with a relative accuracy of 0.04 to 0.08 for Higgs bosons masses from 120 GeV to 150 GeV, with an integrated luminosity of 5 inverse-ab. The result is not affected by overlapping two-photon background.Comment: 6 pages, 2 figures, submitted to J Phys G.: Nucl. Phy

Indirect Probes of New Physics

We summarize the indirect effects of new physics in a variety of processes. We consider precision electroweak measurements, the $g-2$ of the muon, rare decays, meson mixing, CP violation, lepton number violating interactions, double beta decay, and the electric dipole moments of atoms, molecules, and the neutron. We include discussions of both model independent and dependent analyses where applicable.Comment: 100 pgs + 27 figures (not included here). Complete postscript file available on SLAC-SPIRES web pages. To appear in {\it Electroweak Symmetry Breaking and Beyond the Standard Model}, ed. T. Barklow, S. Dawson, H. Haber, and S. Siegris