Narrow Results

Ten three-body processes in e⁺e⁻ collisions for heavy particle productions such as Higgs, t-quark, W^± and Z⁰ are calculated by two independent computer codes for automatic calculation of Feynman amplitude. The results are in excellent agreement within statistical error of numerical integration (about 0.5%). This demonstrates that these systems are quite powerful for theoretical study for future e⁺e⁻, e^±γ and γγ colliders. Numerical values of cross sections are summarized in tables and a figure.

We propose some empirical formulas relating the masses of the heaviest particles in the standard model (the W, Z, H bosons and the t quark) to the charge of the positron e and the Higgs condensate v. The relations for the masses of gauge bosons m_W = (1+e)v/4 and are in good agreement with experimental values. By requiring the electroweak standard model to be free from quadratic divergences at the one-loop level, we find: and , or the very simple ratio (m_t/m_H)² = e.

The eγ collider is better suited to study single production of the gauge bosons. In this paper, we first consider the contributions of the three-site Higgsless (3SHL) model and the left–right twin Higgs (LRTH) model to the standard model (SM) processes eγ→eZ and eγ→ν_eW, and then study single production of the new neutral and charged gauge bosons predicted by these two models via eγ collision in the future high energy e⁺e^- linear collider experiments. We find that the correction effects of 3SHL model on the processes eγ→eZ and eγ→ν_eW might be detected in the future, while this is not the case for the LRTH model. The process eγ→eZ' can give rise to different signatures in the 3SHL and LRTH models and thus can be used to distinguish these two kinds of new physics models at the high energy e⁺e^- linear colliders.

In a particle theory model whose most readily discovered new particle is the $\sim 1$ TeV bilepton resonance in same-sign leptons, currently being sought at CERN’s LHC, there exist three quarks ${𝒟}$, ${𝒮}$, ${𝒯}$ which will be bound by QCD into baryons and mesons. We consider the decays of these additional baryons and mesons whose detailed experimental study will be beyond the reach of the 14 TeV CERN collider and accessible only at an O(100 TeV) collider.

Constraints are obtained on the mass of additional, family-nonuniversal W′ bosons, suggested by the Sp(6)_L⊗U(1)_Y model, from high-energy collider data. A lower bound is obtained on W′ mass, M_W′ ≳ 626 GeV. We studied the Drell–Yan production and corresponding decay signatures of the W′ bosons at the CERN Large Hadron Collider (LHC) and discussed how to distinguish the model by examining the couplings of W′ to fermions through its leptonic decay modes.

We summarize an extensive Tevatron (1984–2011) electroweak physics program that involves a variety of W and Z boson precision measurements. The relevance of these studies using single and associated gauge boson production to our understanding of the electroweak sector, quantum chromodynamics and searches for new physics is emphasized. We discuss the importance of the W boson mass measurement, the W/Z boson distributions and asymmetries, and diboson studies. We highlight the recent Tevatron measurements and prospects for the final Tevatron measurements.

We study the muon anomalous magnetic moment in an electroweak model based on the gauge symmetry SU(4)_L ⊗ U(1)_N, which has right-handed neutrinos in its spectrum, and no flavor changing neutral currents at tree level. We discuss relevant collider and electroweak constraints on the model, and derive the most stringent upper bounds on the scale of symmetry breaking based on the corrections to the muon magnetic moment. We conclude that a scale of symmetry breaking of around 2 TeV might explain the muon magnetic moment anomaly. In case the anomaly is otherwise resolved, using the current and projected sensitive of g-2 experiments, we rule out scales of symmetry breaking smaller than 3.5 TeV (5.5 TeV) at 1σ level.

Extra neutral gauge bosons suggested by models beyond the standard model can indirectly show up in e⁺e^- collisions through off-resonance deviations of various physical observables from the corresponding standard model values. We considered leptonic observables and studied the dependence of the deviations on the polarizations of the positron and electron beams. We showed that, for a given model, the magnitude of the deviation of a given observable can attain its maximum value if the polarizations of the positron and electron beams are properly chosen. We determined, for a given model, a single set of beam polarization so that if this set is employed in measuring all considered observables, it produces the highest extra gauge boson discovery limits.

We categorize new physics signatures that manifest themselves as a “dip” structure at colliders. One potential way to realize a dip is to require interactions to be zero when all particles are mass on-shell, but not if one or more are mass off-shell. For three particle interactions, we have found three interesting cases: one massive gauge boson with two identical scalars; one massless gauge boson with two different scalars; one massive gauge boson with two identical massless gauge bosons. For each case, we identify the relevant effective operators to explore its dip signature at the LHC. Unfortunately, the unstable particle with a vanishing mass-on-shell interaction has a complex mass which is coincident with the complex pole in its propagator. As a result, a contact-like amplitude without a dip is produced. Some interesting collider signatures for “fermion-phobic” vector bosons are also discussed.

In light of the ongoing effort on reducing the theoretical uncertainties and an upcoming experiment concerning muon magnetic moment, we perform a detailed study of an 3-4-1 electroweak gauge extension of the standard model that contains exotic charged leptons in its spectrum. We discuss flavor changing neutral current, collider and electroweak bounds on the model and derive $\mathrm{1\sigma }$ limits using current and projected limits on the muon magnetic moment. In summary, we exclude the masses of new gauge bosons that couple to muons and heavy charged leptons up to 700 GeV. Moreover, we find a projected lower bound on the scale of symmetry breaking to be 2 TeV.

A new classification of the fundamental particles based upon the use of only three additive quantum numbers (charge, particle number, generation quantum number) compared with the nine additive quantum numbers of the Standard Model (charge, lepton number, muon lepton number, tau lepton number, baryon number, strangeness, charm, bottomness, topness) is presented. This classification provides a new basis for the weak isospin symmetry characteristic of both leptons and quarks.