Low-Energy Effective Lagrangian from Non-Minimal Supergravity with Unified Gauge Symmetry

From general supergravity theory with unified gauge symmetry, we obtain the low-energy effective Lagrangian by taking the flat limit and integrating out the superheavy fields in model-independent manner. The scalar potential possesses some excellent features. Some light fields classified by using supersymmetric fermion mass, in general, would get intermediate masses at the tree level after the supersymmetry is broken. We show that the stability of weak scale can be guaranteed under some conditions. There exist extra non-universal contributions to soft supersymmetry breaking terms which can give an impact on phenomenological study.Comment: 37 pages, Figures not include

Low-Energy Effective Lagrangian in Unified Theories with Non-Universal Supersymmetry Breaking Terms

Supersymmetric grand unified theories with non-universal soft supersymmetry breaking terms are studied. By integrating out the superheavy fields at an unification scale, we compute their low-energy effective Lagrangian. We find new contributions to the scalar potential specific to the non-universal supersymmetry breaking. $D$-term contribution to the scalar masses is one example. The gauge hierarchy achieved by a fine-tuning in the superpotential would be violated in general due to the non-universal SUSY breaking terms. We show, however, it is preserved for a certain class of the soft terms derived from a {\em hidden} ansatz. We also discuss some phenomenological implications of the non-universal supersymmetry breaking, including predictions of the radiative electroweak symmetry breaking scenario and of no-scale type models.Comment: 29 pages, LaTeX, DPSU-9402,LBL-35731,UCB-PTH-94/16,TU-45

Options for Orbifold-GUT Model Building from Five-Dimensional Supergravity

This is the first paper of a series that will examine the options for embedding supersymmetric orbifold-GUTs into five-dimensional N=2 Yang-Mills-Einstein supergravity theories (YMESGTs). In particular, we focus on the allowed couplings of charged hypermultiplets in the lowest dimensional reps of the gauge groups SU(5), SO(10) and E(6). Our results are within the classification of homogeneous quaternionic scalar manifolds. In the minimal coupling of a generation of bulk matter hypermultiplets, supergravity requires the field content of an SO(10) scenario. In the minimal coupling of $n$ bulk generations of matter and higgs hypermultiplets, supergravity requires the field content of an E(6) scenario. We also discuss the coupling of tensors and non-compact gaugings in 5D YMESGTs, which can serve as alternative ways to obtain four-dimensional Higgs sectors. Charged tensor couplings seem to be difficult to work with phenomenologically since a U(1) gauge factor is always required when they are present, and it is not clear if tensors can be put in unified multiplets with other fields, if this is desired. This seems to imply that tensor coulpings in GUT scenarios may be better suited in higher dimensional settings. The non-compact gaugings discussed here are simple, and offer a novel unification scenario in which the supergravity and vector multiplets are connected by gauge transformations. The main points are summarized in tables and the conclusion. Although the discussion is in the spirit of a "bottom-up" approach, M-theory is taken as a motivating background.Comment: V.2 Significant changes: shortened, typos corrected, main focus of paper emphasized. Submitted to Nucl. Phys.

Teleparallel Gravity and Dimensional Reductions of Noncommutative Gauge Theory

We study dimensional reductions of noncommutative electrodynamics on flat space which lead to gauge theories of gravitation. For a general class of such reductions, we show that the noncommutative gauge fields naturally yield a Weitzenbock geometry on spacetime and that the induced diffeomorphism invariant field theory can be made equivalent to a teleparallel formulation of gravity which macroscopically describes general relativity. The Planck length is determined in this setting by the Yang-Mills coupling constant and the noncommutativity scale. The effective field theory can also contain higher-curvature and non-local terms which are characteristic of string theory. Some applications to D-brane dynamics and generalizations to include the coupling of ordinary Yang-Mills theory to gravity are also described.Comment: 31 pages LaTeX; References adde

Topics in String Unification

I discuss several aspects of strings as unified theories. After recalling the difficulties of the simplest supersymmetric grand unification schemes I emphasize the distinct features of string unification. An important role in constraining the effective low energy physics from strings is played by $duality$ symmetries. The discussed topics include the unification of coupling constants (computation of $\sin ^2\theta _W$ and $\alpha _s$ at the weak scale), supersymmetry breaking through gaugino condensation, and properties of the induced SUSY-breaking soft terms. I remark that departures from universality in the soft terms are (in contrast to the minimal SUSY model) generically expected.Comment: 22 pages. Talk given at the ``Workshop on Electroweak Physics Beyond the Standard Model'', Valencia, 3-5 October 199

Charge Quantization and Neutrino Mass from Planck-scale SUSY

We show a possibility for the charge quantization of the standard model (SM) particles. If a global symmetry makes the three copies of a generation and supersymmetry (SUSY) relates the Higgs boson to a lepton, all the charges of the SM particles can be quantized through gauge-anomaly cancellation. In the minimal model realizing the possibility, the gravitino mass around the Planck-scale is needed to generate the SM couplings through (quantum) supergravity. Much below the Planck-scale, the SM is obtained as the effective theory. Interestingly, if the gaugino masses are generated through anomaly mediation, one of the neutrino masses is predicted to be around the neutrino oscillation scales. In an extension of the model, millicharged particles can exist without introducing massless hidden photons.Comment: 17 pages, v2: version appears in PL

Kahler Stabilized, Modular Invariant Heterotic String Models

We review the theory and phenomenology of effective supergravity theories based on orbifold compactifications of the weakly-coupled heterotic string. In particular, we consider theories in which the four-dimensional theory displays target space modular invariance and where the dilatonic mode undergoes Kahler stabilization. A self-contained exposition of effective Lagrangian approaches to gaugino condensation and heterotic string theory is presented, leading to the development of the models of Binetruy, Gaillard and Wu. Various aspects of the phenomenology of this class of models are considered. These include issues of supersymmetry breaking and superpartner spectra, the role of anomalous U(1) factors, issues of flavor and R-parity conservation, collider signatures, axion physics, and early universe cosmology. For the vast majority of phenomenological considerations the theories reviewed here compare quite favorably to other string-derived models in the literature. Theoretical objections to the framework and directions for further research are identified and discussed.Comment: Invited review article for International Journal of Modern Physic

Bottom-Up Approach to Moduli Dynamics in Heavy Gravitino Scenario : Superpotential, Soft Terms and Sparticle Mass Spectrum

The physics of moduli fields is examined in the scenario where the gravitino is relatively heavy with mass of order 10 TeV, which is favored in view of the severe gravitino problem. The form of the moduli superpotential is shown to be determined, if one imposes a phenomenological requirement that no physical CP phase arise in gaugino masses from conformal anomaly mediation. This bottom-up approach allows only two types of superpotential, each of which can have its origins in a fundamental underlying theory such as superstring. One superpotential is the sum of an exponential and a constant, which is identical to that obtained by Kachru et al (KKLT), and the other is the racetrack superpotential with two exponentials. The general form of soft supersymmetry breaking masses is derived, and the pattern of the superparticle mass spectrum in the minimal supersymmetric standard model is discussed with the KKLT-type superpotential. It is shown that the moduli mediation and the anomaly mediation make comparable contributions to the soft masses. At the weak scale, the gaugino masses are rather degenerate compared to the minimal supergravity, which bring characteristic features on the superparticle masses. In particular, the lightest neutralino, which often constitutes the lightest superparticle and thus a dark matter candidate, is a considerable admixture of gauginos and higgsinos. We also find a small mass hierarchy among the moduli, gravitino, and superpartners of the standard-model fields. Cosmological implications of the scenario are briefly described.Comment: 45 pages, 10 figures, typos correcte