[show abstract][hide abstract] ABSTRACT: A series of Higgs field quantum numbers in the anti-grand-unification model, based on the gauge group SMG3×U(1)f, is tested against the spectrum of quark and lepton masses and mixing angles. A more precise formulation of the statement that the couplings are assumed of order unity is given. It is found that the corrections coming from this more precise assumption do not contain factors of the order of the number of colors, Nc=3, as one could have feared. We also include a combinatorial correction factor, taking account of the distinct internal orderings within the chain Feynman diagrams in our statistical estimates. Strictly speaking our model predicts that the uncertainty in its predictions and thus the accuracy of our fits should be ±60%. Many of the best fitting quantum numbers give a higher accuracy fit to the masses and mixing angles, although within the expected fluctuations in a χ2. This means that our fit is as good as it can possibly be.
[show abstract][hide abstract] ABSTRACT: The fermion masses and mixing angles are fitted using only three free parameters in a nonsupersymmetric extension of the Standard Model, with new, approximately conserved chiral gauge quantum numbers broken by a set of Higgs fields. The fundamental mass scale of this anti-grand-unification model is given by the Planck mass. We also calculate neutrino mixing angles and masses, as well as CP violation from the CKM matrix. A good fit to the observed fermion masses is obtained, but our predictions of the neutrino masses are too small to lead to any observable neutrino oscillation effects claimed today, without introducing another mass scale. We also give some arguments in support of this type of model based on the observed fermion masses.
International Journal of Modern Physics A - IJMPA. 01/1998; 13:5037-5074.
[show abstract][hide abstract] ABSTRACT: We examine extensions of the standard model (SM), basing our assumptions on what has already been observed; we do not consider anything fundamentally different, such as grand unification or supersymmetry, which is not directly suggested by the SM itself. We concentrate on the possibility of additional low mass fermions (relative to the Planck mass) and search for combinations of representations which do not produce any gauge anomalies. Generalizations of the SM weak hypercharge quantization rule are used to specify the weak hypercharge, modulo 2, for any given representation of the non-Abelian part of the gauge group. Strong experimental constraints are put on our models, by using the renormalization group equations to obtain upper limits on fermion masses and to check that there is no U(1) Landau pole below the Planck scale. Our most promising model contains a fourth generation of quarks without leptons and can soon be tested experimentally.
[show abstract][hide abstract] ABSTRACT: We investigate the possibility of adding a fourth generation of quarks. We also extend the Standard Model gauge group by adding another SU(N)SU(N) component. In order to cancel the contributions of the fourth generation of quarks to the gauge anomalies we must add a generation of fermions coupling to the SU(N)SU(N) group. This model has many features similar to the Standard Model and, for example, includes a natural generalisation of the Standard Model charge quantisation rule. We discuss the phenomenology of this model and, in particular, show that the infrared quasi-fixed point values of the Yukawa coupling constants put upper limits on the new quark masses close to the present experimental lower bounds.