Related papers: The rise and fall of the fourth quark-lepton gener…
The latest electroweak precision data are analyzed assuming the existence of the fourth generation of leptons ($N, E$) and quarks ($U, D$), which are not mixed with the known three generations. If all four new particles are heavier than $Z$…
Precise measurements of Z-boson parameters and W-boson and t-quark masses put strong constraints on non SU(2) * U(1) singlet New Physics. We demonstrate that one extra generation passes electroweak constraints even when all new particle…
It is shown that additional chiral generations are not excluded by the latest electroweak precision data if one assumes that there is no mixing with the known three generations. In the case of ``heavy extra generations'', when all four new…
We investigate the possibility of incorporating a chiral fourth generation into a GUT model. We find that in order to do so, precision fits to electroweak observables demand the introduction of light (< M_Z) supersymmetric particles. This…
We present a non-perturbative determination of the upper and lower Higgs boson mass bounds with a heavy fourth generation of quarks from numerical lattice computations in a chirally symmetric Higgs-Yukawa model. We find that the upper bound…
The possibility of additional quarks and leptons beyond the three generations already established is discussed. The make-up of this Report is (I) Introduction: the motivations for believing that the present litany of elementary fermions is…
In the light of the LHC, we revisit the implications of a fourth generation of chiral matter. We identify a specific ensemble of particle masses and mixings that are in agreement with all current experimental bounds as well as minimize the…
We investigate the impact of the fourth generation quarks on production and decays of the charged Higgs boson at CERN Large Hadron Collider (LHC) with triple $b$-tagging. The signal is the process $gg\to \bar{u_4}u_4$, followed by…
It is possible that there are additional vector-like generations where the quarks have mass terms that do not originate from weak symmetry breaking, but the leptons only get mass through weak symmetry breaking. We discuss the impact that…
We investigate the effect of introducing a sequential generation of chiral fermions in the Higgs Triplet Model with nontrivial mixing between the doublet and triplet Higgs. We use the available LHC data for Higgs boson production and decay…
The existence of extra chiral generations with all fermions heavier than $m_Z$ is strongly disfavored by the precision electroweak data. However the data still allow a few extra generations if the neutral leptons have masses close to 50…
Recent studies of precision electroweak observables have led to the conclusion that a fourth generation is highly constrained. However, we point out that a long-lived fourth generation can reopen a large portion of the parameter space. In…
In theories with TeV scale quantum gravity there is a logical possibility where the electroweak Higgs can be a fourth generation slepton. Despite maximal supersymmetry breaking such a scenario turns out to be tightly constrained, and might…
This summary of the 3rd "Beyond the 3 Generation Standard Model" workshop presents the following four statements (and their implications) for the ongoing and future searches of a fourth generation: 1) The enhancement of the Higgs…
The latest electroweak precission data allow the existence of additional chiral generations in the standard model. We study the influence of extra generations on the production of SM Higgs boson at hadron colliders. Due to the enhancement…
We use sampling techniques to find robust constraints on the masses of a possible fourth sequential fermion generation from electroweak oblique variables. We find that in the case of a light (115 GeV) Higgs from a single electroweak…
If next generations of heavy quarks and leptons exist within the standard model (SM), they can manifest themselves in Higgs boson production at the Tevatron and the LHC, before being actually observed. This generation leads to an increase…
It has been recently suggested in hep-ph/9911535 and hep-ph/0006324 that the fourth generation of leptons and quarks is not excluded by the precision Z-boson measurements, provided that the mass of the fourth neutrino is around 50 GeV and…
We continue our previous determination of the masses of the sequential fourth generation quarks in an extension of the Standard Model, and predict the mass $m_4$ ($m_L$) of the fourth generation neutrino $\nu_4$ (charged lepton $L$) by…
Precision measurements of $Z$-boson parameters and $W$-boson and $t$-quark masses put strong constraints on non $SU(2)\times U(1)$ singlet New Physics. We demonstrate that one extra generation passes electroweak constraints even when all…