Gauge Unification at the String Scale and Fermion Masses
نویسنده
چکیده
In the context of the minimal supersymmetric standard model (MSSM), we discuss the introduction of exotic matter below the string scale MX in order to achieve gauge unification at MX (a constraint of a large class of string models). The possible types of exotic matter that can realise this are investigated and its effect on the top quark mass mt is presented. The implementation of a theory of fermion masses which utilises the exotic matter is briefly discussed.
منابع مشابه
Grand Unification at Intermediate Mass Scales through Extra Dimensions
One of the drawbacks of conventional grand unification scenarios has been that the unification scale is too high to permit direct exploration. In this paper, we show that the unification scale can be significantly lowered (perhaps even to the TeV scale) through the appearance of extra spacetime dimensions. Such extra dimensions are a natural consequence of string theories with largeradius compa...
متن کاملD-branes and the Standard Model
We perform a systematic study of the Standard Model embedding in a D-brane configuration of type I string theory at the TeV scale. We end up with an attractive model and we study several phenomenological questions, such as gauge coupling unification, proton stability, fermion masses and neutrino oscillations. At the string scale, the gauge group is U(3)color × U(2)weak × U(1)1 × U(1)bulk. The c...
متن کامل3 v 3 9 J ul 1 99 7 RAL 97 - 007 SHEP 97 - 01 hep - ph / 9703293 String Unification , Spaghetti Diagrams and Infra - Red Fixed Points
The minimal supersymmetric standard model (MSSM), is perhaps the leading candidate for new physics beyond the standard model, but it encounters difficulties with string gauge unification and in addition does not shed any light on the question of fermion masses. We consider a scenario in which the MSSM is valid up to an energy scale of ∼ 10 16 GeV, but that above this scale the theory is supplem...
متن کاملαs(mZ), intermediate scales and Fermion masses in supersymmeric theories; two-loop results
One way to generate an intermediate scale being consistent with gauge coupling unification is to add new Higgs scalars above the intermediate scale. We classify such scenarios according to their degree of departure from minimal supersymmetric standard model. Thereafter, we summarize the results of a two-loop renormalization group analysis of the gauge and the Yukawa sectors of such scenarios, a...
متن کاملar X iv : h ep - p h / 05 05 25 7 v 2 1 5 Ju l 2 00 5 Minimal string - scale unification of gauge couplings
We look for the minimal particle content which is necessary to add to the standard model in order to have a complete unification of gauge couplings and gravity at the weakly coupled heterotic string scale. Using the current precision electroweak data, we find that the presence of a vector-like fermion at an intermediate scale and a non-standard hypercharge normalization are in general sufficien...
متن کامل