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Proceedings of the Fourth Tegernsee International Conference on Particle Physics Beyond the Standard Model, BEYOND 2003, Castle Ringberg, Tegernsee, Germany, 9–14 June 2003
The experimental data of the past decade suggests that the quantum gravity vacuum should possess two key ingredients. The existence of three generations and their embedding in SO(10) representations. The Z2 x Z2 orbifold of the heterotic string provides examples of vacua that accommodate these properties. The utilization of string dualities to explore these models is discussed...
The standard forms of supersymmetry and supergravity are inextricably wedded to Lorentz invariance. Here a Lorentz-violating form of supergravity is proposed. The superpartners have exotic properties that are not possible in a theory with exact Lorentz symmetry and micro causality. For example, the bosonic sfermions have spin 1/2 and the fermionic gauginos have spin 1. The theory is based on a phenomenological...
Quantum-gravity effects are expected to be suppressed by the Planck mass. For experimental progress it is therefore important to identify potential signatures from Planck-scale physics that are amenable to ultrahigh-precision tests. It is argued that minuscule violations of Lorentz and CPT symmetry are candidate signals. In addition, theoretical and experimental aspects of the Standard-Model Extension,...
Astrophysical indications that the fine structure constant has undergone a small time variation during the cosmological evolution are discussed within the framework of the standard model of the electroweak and strong interactions and of grand unification. A variation of the electromagnetic coupling constant could either be generated by a corresponding time variation of the unified coupling constant...
We discuss Grand Unified Theories (GUT) in higher dimensions with orbifold compactification. Even within the the simplest 5-dimensional (5D) SU(5)set-up many attractive features appear, such as orbifold GUT symmetry breaking, natural doublet-triplet splitting and suppression of proton decay etc. We also discuss gauge coupling unification in N=1 supersymmetric 5D orbifold SU(5) model. We have found...
The Standard Model of quarks and leptons is, at first sight, nothing but a set of ad hoc rules, with no connections, and no clues to their true background. At a closer look, however, there are many inherent prophecies that point in the same direction: Compositeness in terms of three stable preons.
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