70 research outputs found

    Moduli stabilization and SUSY breaking in heterotic orbifold string models

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    In this paper we discuss the issues of supersymmetry breaking and moduli stabilization within the context of E_8 x E_8 heterotic orbifold constructions and, in particular, we focus on the class of "mini-landscape" models. In the supersymmetric limit, these models admit an effective low energy field theory with a spectrum of states and dimensionless gauge and Yukawa couplings very much like that of the MSSM. These theories contain a non-Abelian hidden gauge sector which generates a non-perturbative superpotential leading to supersymmetry breaking and moduli stabilization. We demonstrate this effect in a simple model which contains many of the features of the more general construction. In addition, we argue that once supersymmetry is broken in a restricted sector of the theory, then all moduli are stabilized by supergravity effects. Finally, we obtain the low energy superparticle spectrum resulting from this simple model.Comment: LaTeX, v2: 57+1 pages, 4 figures, 8 Tables, added references; this version i) discusses volume moduli stabilization with exponentials of both sign (as sometimes mandated by modular invariance); ii) includes the anomalous U(1)_A D-term & the leading Coleman-Weinberg 1-loop correction into the MSSM soft masses to prevent tachyonic results

    Reconciling Grand Unification with Strings by Anisotropic Compactifications

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    We analyze gauge coupling unification in the context of heterotic strings on anisotropic orbifolds. This construction is very much analogous to effective 5 dimensional orbifold GUT field theories. Our analysis assumes three fundamental scales, the string scale, \mstring, a compactification scale, \mc, and a mass scale for some of the vector-like exotics, \mex; the other exotics are assumed to get mass at \mstring. In the particular models analyzed, we show that gauge coupling unification is not possible with \mex = \mc and in fact we require \mex \ll \mc \sim 3 \times 10^{16} GeV. We find that about 10% of the parameter space has a proton lifetime (from dimension 6 gauge exchange) 1033yrτ(pπ0e+)1036yr10^{33} {\rm yr} \lesssim\tau(p\to \pi^0e^+) \lesssim 10^{36} {\rm yr}. The other 80% of the parameter space gives proton lifetimes below Super-K bounds. The next generation of proton decay experiments should be sensitive to the remaining parameter space.Comment: 36 pages and 5 figures, contains some new references and additional paragraph in conclusio