Quarks and Leptons Beyond the Third Generation

  title={Quarks and Leptons Beyond the Third Generation},
  author={Paul Howard Frampton and Phạm Quang Hưng and Marc A. Sher},
  journal={Physics Reports},
Abstract The possibility of additional quarks and leptons beyond the three generations already established is discussed. The make-up of this Report is (1)  Introduction : the motivations for believing that the present litany of elementary fermions is not complete; (2)  quantum numbers : possible assignments for additional fermions; (3)  masses and mixing angles : mass limits from precision electroweak data, vacuum stability and perturbative gauge unification; empirical constraints on mixing… Expand
We consider extensions of the standard model with fourth generation fermions (SM4) in which extra symmetries are introduced such that the transitions between the fourth generation fermions and theExpand
Implications of gauge-mediated supersymmetry breaking with vector-like quarks and a ~125 GeV Higgs boson
We investigate the implications of models that achieve a Standard Model-like Higgs boson of mass near 125 GeV by introducing additional TeV-scale supermultiplets in the vector-like 10+\bar{10}Expand
Brane world unification of quark and lepton masses and its implication for the masses of the neutrinos
Abstract A TeV-scale scenario is constructed in an attempt to understand the relationship between quark and lepton masses. This scenario combines a model of early (TeV) unification of quarks andExpand
Neutrino masses and a fourth generation of fermions
Abstract We study neutrino mass generation in models with four chiral families of leptons and quarks and four right handed neutrinos. Generically, in these models there are three differentExpand
Flavor-changing interactions with singlet quarks and their implications for the LHC
We investigate the flavor-changing interactions in an extension of the standard model with singlet quarks and singlet Higgs, which are induced by the mixing between the ordinary quarks and theExpand
Beautiful mirrors and precision electroweak data
The Standard Model (SM) with a light Higgs boson provides a very good description of the precision electroweak observable data coming from the LEP, SLD and Tevatron experiments. Most of theExpand
Collider signals of a composite Higgs in the Standard Model with four generations
Abstract Recent fits of electroweak precision data to the Standard Model (SM) with a 4th sequential family (SM4) point to a possible “three-prong composite solution”: (1) the Higgs mass is at theExpand
Sealing the fate of a fourth generation of fermions
The search for the effects of heavy fermions in the extension of the Standard Model with a fourth generation is part of the experimental program of the Tevatron and LHC experiments. Besides beingExpand
Long lived fourth generation and the Higgs
A chiral fourth generation is a simple and well motivated extension of the standard model, and has important consequences for Higgs phenomenology. Here we consider a scenario where the fourthExpand
Beautiful mirrors, unification of couplings, and collider phenomenology
The standard model provides an excellent description of the observables measured at high energy lepton and hadron colliders. However, measurements of the forward-backward asymmetry of the bottomExpand


Structure of exotic generations.
Theoretical and phenomenological aspects of nonstandard multiplets of anomaly-free fermions (exotic generations) are examined and it is shown that it is possible that some of the known members of the incomplete third generation may actually be part of a triplet family, rather than a standard doublet family. Expand
Top quark and Higgs boson masses: Interplay between infrared and ultraviolet physics
Abstract We review recent efforts to explore the information on masses of heavy matter particles, notably of the top quark and the Higgs boson, as encoded at the quantum level in the renormalizationExpand
New neutral gauge bosons and new heavy fermions in the light of the new LEP data
Abstract We derive limits on a class of new physics effects that are naturally present in grand unified theories based on extended gauge groups, and in particular in E 6 and SO (10) models. WeExpand
Production and decay properties of ultra-heavy quarks
Abstract The widths of ultra-heavy quarks that can be decay into W, Z or Higgs bosons are discussed. If the lifetimes become much shorter than the typical strong interaction time scale Λ −1 QCD ∼ 10Expand
Higgs potential bounds on extra quark-lepton generations
We consider the bounds for the values of higgs mass $M_H$ and of the mass of the extra quarks and leptons $M_{extra}$ derived from the stability of vacuum and from the absence of Landau pole in HiggsExpand
Heavy families: Masses and mixings
Abstract We use the infrared fixed-point structure of the SU(3) × SU(2) × U(1) renormalization group equations to derive predictions for the masses and mixings of heavy families in perturbativelyExpand
Cosmological bounds on the lifetime of a fourth generation charged lepton
Abstract If a fourth generation of leptons exists, both the neutrino and the charged lepton must have masses in excess of 45 GeV. It is certainly possible that the neutrino will be the heavier of theExpand
Is the t Quark Responsible for the Mass of W and Z Bosons
Based on the dynamical model having a large anomalous dimension γm≃2, we propose that the t quark condensate is responsible for the mass of W and Z bosons within the framework of theExpand
Electroweak symmetry breaking by fourth-generation condensates and the neutrino spectrum.
  • Hill, Luty, Paschos
  • Physics, Medicine
  • Physical review. D, Particles and fields
  • 1991
A dynamical generalization of the seesaw mechanism is proposed based upon the BCS theory in which a neutrino condensate gives rise to right-handed-neutrino Majorana masses and all associated spin-zero bosons are composite. Expand
Implications of the electroweak precision data: A 1996 update
Abstract The most reliable prediction for the Higgs-boson mass, M H , is obtained in a fit to the leptonic Z-resonance observables Γ 1 and S W −2 combined with the W-boson mass, M W , and top-quarkExpand