Related papers: Why the Four SM Families
We point out that, in the context of the SM, $|V^2_{13}| + | V^2_{23}|$ is expected to be large, of order one. The fact that $|V^2_{13}| + |V^2_{23}| \approx 1.6 \times 10^{-3}$ motivates the introduction of a symmetry S which leads to…
In the so-called 331-models the gauge anomalies cancel only if there are three generations of fermions. This requires one of the quark generations to be in a different representation than the other two. But which generation is treated…
We extend the standard model with two extra Higgs doublets. Making use of a symmetry principle, we present flavour symmetries based on cycle groups $Z_N$ that oblige each Higgs doublet to contribute to the mass of only one generation, thus…
We do not know why there are three fermion families in the Standard Model (SM), nor can we explain the observed pattern of fermion masses and mixing angles. Standard grand unified theories based on the SU(5) and SO(10) groups fail to shed…
We study the detection of the $t^\prime$ of a fourth family during the early running of LHC with 7 TeV collision energy and 1 fb$^{-1}$ integrated luminosity. By use of a neural network we show that it is feasible to search for the $t'$…
The flavor puzzles remain among the most compelling open questions in particle physics. The striking hierarchies observed in the masses and mixing of charged fermions define the Standard Model (SM) flavor puzzle, a profound structural…
The problem of quark-lepton families is discussed in the "bottom-up" phenomenological approach to the extensions of the Standard model. It provides the possibility of the {\it Horizontal unification} of the three known families on the basis…
We show that a fourth family of quarks with $m_{t'}$ in the range of (400 - 600) GeV provides a rather simple explanation for the several indications of new physics that have been observed involving CP asymmetries of the b-quark. The…
The impact of the fourth Standard Model family on Higgs boson search at Tevatron and LHC is reviewed.
The existence of a fourth fermion generation has mostly been considered as a source of enhanced Higgs signals with respect to the 3 family Standard Model predictions. However, a fourth Standard Model family neutrino could cause the opposite…
In the frame of two Higgs doublet model we try to explain the lepton masses and mixing matrix elements assuming that neutrinos are Dirac particles. Discrete family symmetry groups, which are subgroups of U(3) up to the 1025 order are…
The latest electroweak precision data allow the existence of additional chiral generations in the standard model. We study prospects of search for the fourth standard model family fermions and quarkonia at $e^{+}e^{-}$ and $\gamma \gamma $…
In the framework of gauged flavour symmetries, new fermions in parity symmetric representations of the standard model are generically needed for the compensation of mixed anomalies. The key point is that their masses are also protected by…
A search for a fourth family at the LHC is presently a low priority, but we argue that an effective search can be conducted early with only a few inverse femtobarns of data. We discuss a method based on invariant masses of single jets for…
We present a family-non-universal extension of the Standard Model where the the first two families feature both quark-lepton and electroweak-flavour unification, via the $SU(4) \times Sp(4)_L \times Sp(4)_R$ gauge group, whereas…
We construct extensions of the standard model based on the hypothesis that the Higgs bosons also exhibit a family structure, and that the flavor weak eigenstates in the three families are distinguished by a discrete $Z_6$ chiral symmetry…
Based on a view of current flavour physics and motivated by the hierarchy problem and by the pattern of quark masses and mixings, I describe a picture of flavour physics that should give rise in a not too distant future to observable…
The Littlest Higgs Model with T-Parity (LHT) contains new sources of flavor and CP violation both in the quark and lepton sector. These have their origin in interactions of ordinary fermions with mirror fermions mediated by new heavy gauge…
Leptoquarks (LQs) are hypothetical particles that appear in various extensions of the Standard Model (SM) that can explain observed differences between SM theory predictions and experimental results. The production of these particles has…
The observability of the Higgs boson via the WW^* decay channel at the Tevatron is discussed taking into account the enhancements due to the possible existence of the extra standard model (SM) families. It seems that the existence of new SM…