相关论文: Fine-tuning and the doublet-triplet splitting prob…
We present a new solution to the doublet-triplet splitting problem which also works in a supersymmetric SU(5) grand unified theory and is testable at TeV-scale collider experiments. In our model, the SU(5) symmetry is broken through the…
We present GUT models based on an $SU(5)\times SU(5)$ GUT group. These models maintain the main successes of simple-group GUTs but permit simple solutions to the doublet-triplet splitting problem. Moreover, GUT breaking is triggered by…
The missing VEV solution to the doublet-triplet splitting problem in general SU(N) SUSY GUTs is found. Remarkably enough, it requires a strict equality of numbers of the fundamental colours and flavours in SU(N) and for the even-order…
We revisit the long-standing problem of supersymmetric grand unified theory (GUT), the doublet-triplet splitting problem. We discuss whether symmetry which controls the {\mu} term in the minimal supersymmetric standard model is compatible…
We construct supersymmetric theories in which the correct scale for electroweak symmetry breaking is obtained without significant fine-tuning. We calculate the fine-tuning parameter for these theories to be at the 20% level, which is…
We compute the electroweak fine-tuning in No-Scale Supergravity for a representative supersymmetric Grand Unification Theory (GUT) model, flipped $SU(5)$ with extra vector-like $flippons$, dubbed $\cal{F}$-$SU(5)$. We find that there is no…
The fine tuning in models of low energy gauge mediated supersymmetry breaking required to obtain the correct $Z$ mass is quantified. To alleviate the fine tuning problem, a model with split $(5+\bar{5})$ messenger fields is presented. This…
We propose that a modified version of string-inspired supersymmetry breaking schemes in \cite{wit2} and \cite{ross} may make affine level one SU(5) and SO(10) string models with intermediate gauge symmetry breaking scale…
We study, in a bottom-up approach, the fine-tuning problem between soft SUSY breaking parameters and the $\mu$-term for the successful electroweak symmetry breaking in the minimal supersymmetric standard model. It is shown that certain…
The little hierarchy problem encountered in the constrained minimal supersymmetric model (CMSSM) can be ameliorated in supersymmetric models based on the gauge symmetry G_{422} \equiv SU(4)_c x SU(2)_L x SU(2)_R. The standard assumption in…
We consider the doublet-triplet splitting problem in supersymmetric SU(5) grand unified theory in five dimensions where the fifth dimension is non-compact. We point out that an unnatural fine-tuning of parameters in order to obtain the…
As is well known, electroweak breaking in the MSSM requires substantial fine-tuning. We explain why this fine tuning problem is abnormally acute, and this allows to envisage possible solutions to this undesirable situation. Following these…
We find that minimizing the number of fine tuning relations in non-supersymmetric models can determine the scales at which some gauge symmetries beyond the standard model must break. We show that $SU(2)_R$ and $B-L$ gauge symmetries of the…
Various ideas support the notion that the GUT gauge group might be a semi-simple direct-product group such as $SU(5) \times SU(5)$. The doublet-triplet splitting problem can be solved with a direct product group. String theory suggests that…
We present a realistic supersymmetric SU(6) model which implements doublet-triplet splitting by the missing vev mechanism. The model makes use of only the simplest representations, requires no fine tuning of parameters and maintains…
It has been shown that the Dimopoulos-Wilczek (or missing-VEV) mechanism for doublet-triplet splitting can be implemented in $SU(5) \times SU(5)$ models, which requires no adjoint Higgs fields. This is an advantage from the point of view of…
A solution of the doublet-triplet splitting problem in the supersymmetric $SU(6)$ gauge theory is suggested. The `missing doublet' multiplet -- 175-plet of the $SU(6)$ group as well as the custodial $SU(2)_{cus}$ global symmetry play…
The anomalous gauge $U(1)_A$ symmetry which could emerge in the context of the string theories can be very useful ingredient towards builting the complete supersymmetric SO(10) model. We present an example of the $SO(10)\times U(1)_A$ model…
We present the supersymmetric $SU(5)$ models which provide a simple ``all order'' solution to the doublet-triplet splitting problem through the missing doublet mechanism. The crucial role is played by the anomalous $U(1)_A$ gauge symmetry…
We explore the phenomenological predictions of a supersymmetric standard model, with a large extra dimension and unifying gauge couplings. The modified five dimensional renormalisation group equations make it possible to obtain light,…