Showing papers by "Graham G. Ross published in 1998"
TL;DR: In this paper, the phenomenological implications of a particular class of supersymmetric models with additional space-time dimensions below the unification scale were analyzed. And they showed that the value of α 3 (M z ) is further increased from the two-loop Minimal Supersymmetric Standard Model prediction.
68 citations
TL;DR: In this article, the authors discuss the complications one has to face when trying to build up a successful D-term inflationary scenario in superstring models and show that the "vacuum shifting" phenomenon of string theories is usually very efficient even in the early Universe, thus preventing inflation from taking place.
23 citations
TL;DR: In this article, the authors discuss the complications one has to face when trying to build up a successful $D$-term inflationary scenario in superstring models and show that the ''vacuum shifting'' phenomenon of string theories is usually very efficient even in the early Universe, thus preventing inflation from taking place.
Abstract: An inflationary stage dominated by a $D$-term avoids the slow-roll problem of inflation in supergravity and may emerge in theories with a non-anomalous or anomalous U(1) gauge symmetry The most intriguing and commonly invoked possibility is that the Fayet-Iliopoulos $D$-term triggering inflation is the one emerging in superstring theories We discuss the complications one has to face when trying to build up a successful $D$-term inflationary scenario in superstring models In particular, we show that the ``vacuum shifting'' phenomenon of string theories is usually very efficient even in the early Universe, thus preventing inflation from taking place On the other hand, when $D$-term inflation is free to occur, the presence of a plethora of fields and several non-anomalous additional abelian symmetries in string theories may help in reconciling the value of the Fayet-Iliopoulos $D$-term required by the COBE normalization with the value predicted by string theories We also show that in superstring $D$-term inflation gravitinos are likely to pose no cosmological problem
22 citations
TL;DR: In this article, a new class of compactified string theories with reduced gauge symmetry that may or may not be continuously connected to the original theory is presented. But the authors use this technique to construct a class of 3 generation models with just the Standard Model gauge group after compactification.
Abstract: We show how identification of absolutely flat directions allows the construction of a new class of compactified string theories with reduced gauge symmetry that may or may not be continuously connected to the original theory. We use this technique to construct a class of 3 generation models with just the Standard Model gauge group after compactification. We discuss the low-energy symmetries necessary for a phenomenologically viable low-energy model and construct an example in which these symmetries are identified with string symmetries which remain unbroken down to the supersymmetry breaking scale. Remarkably the same symmetry responsible for stabilising the nucleon is also responsible for ensuring one and only one pair of Higgs doublets is kept light. We show how the string symmetries also lead to textures in the quark and lepton mass matrices which can explain the hierarchy of fermion masses and mixing angles.
9 citations
TL;DR: In this paper, the infra-red structure of soft supersymmetry breaking masses of the squarks and sleptons in strong unification schemes where αGUT ∼ 0.2-1.
8 citations
TL;DR: In this article, the authors analyse the phenomenological implications of a particular class of supersymmetric models with additional space-time dimensions below the unification scale and show that the value of α 3(M_z)$ is further increased from the two-loop Minimal Supersymmetric Standard Model prediction.
Abstract: We analyse the phenomenological implications of a particular class of supersymmetric models with additional space-time dimensions below the unification scale. Assuming the unification of the gauge couplings and using a two-loop calculation below the scale of the additional space-time dimensions, we show that the value of $\alpha_3(M_z)$ is further increased from the two-loop Minimal Supersymmetric Standard Model prediction. We consider whether decompactification threshold effects could bring $\alpha_3(M_z)$ into agreement with experiment and discuss the associated level of fine tuning needed.
6 citations