相关论文: Could there be a Fourth Generation?
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…
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…
A fourth generation could provide, within SUSY, a solution to baryogenesis at the EW scale. It is allowed by precision measurements. Available data from Tevatron already restrict the allowed domain of parameters for the new quarks and the…
By assuming the existence of the sequential fourth generation to the minimal supersymmetric standard model (MSSM), we study the possibility of a strongly first-order electroweak phase transition. We find that there is a parameter region of…
While a chiral fourth generation of quarks is almost ruled out from the data on Higgs boson production and decay at the Large Hadron Collider, vector-like quarks are still a feasible option to extend the fermionic sector of the Standard…
We study the effect of a potential fourth fermion generation on the upper and lower Higgs boson mass bounds. This investigation is based on the numerical evaluation of a chirally invariant lattice Higgs-Yukawa model emulating the same…
We explore the possibility of a fourth generation in the gauge-coupling-unified, minimal supersymmetric (MSSM) framework. We find that a sequential fourth generation (with a heavy neutrino $\nu'$) can still fit, surviving all present…
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 present Higgs boson mass bounds in a lattice regularization allowing thus for non-perturbative investigations. In particular, we employ a lattice modified chiral invariant Higgs-Yukawa model using the overlap operator. We show results…
We analyse the impact of LHC and Tevatron Higgs data on the viability of the Standard Model with a sequential fourth generation (SM4), assuming Dirac neutrinos and a Higgs mass of 125 GeV. To this end we perform a combined fit to the signal…
Limits on the Higgs boson mass restrict CKM mixing of a possible fourth family beyond the constraints previously obtained from precision electroweak data alone. Existing experimental and theoretical bounds on the Higgs mass already…
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 examine the spectrum of supersymmetric particles predicted by grand unified theoretical (GUT) models where the electroweak symmetry breaking is accomplished radiatively. We evolve the soft supersymmetry breaking parameters according to…
We study the implications of light third generation sparticles on the production cross section and decay widths of a light CP-even Higgs boson. For simplicity, we consider scenarios in which only one of the sfermions from the third…
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 the ones in the first three generations are…
We investigate the possibility of adding a fourth generation of quarks. We also extend the Standard Model gauge group by adding another SU(N) component. In order to cancel the contributions of the fourth generation of quarks to the gauge…
We analyze the behavior of Higgs to diphoton rate and Higgs gluon-gluon production cross section in minimal extensions of the Standard Model comprising new colored vector-like fermions that do not mix with the ordinary ones. We compare…
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…
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…
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 $…