Lifting Slepton Masses with a Non-universal, Non-anomalous U(1)'_{NAF} in Anomaly Mediated SUSY breaking

We extend the Minimum Supersymmetry Standard Model by a non-anomalous family (NAF) U(1)'_{NAF} gauge symmetry. All gauge anomalies are cancelled with no additional exotics other than the three right-handed neutrinos. The FI D-terms associated with the U(1)'_{NAF} symmetry lead to additional positive contributions to slepton squared masses. In a RG invariant way, this thus solves the tachyonic slepton mass problem in Anomaly Mediated Supersymmetry Breaking. In addition, the U (1)'_{NAF} symmetry naturally gives rise to the fermion mass hierarchy and mixing angles, and determines the mass spectrum of the sparticles.Comment: 13 pages; v2: version to appear in Phys. Lett.

TeV-Scale Horizontal Symmetry and the Slepton Mass Problem of Anomaly Mediation

We propose a new scenario for solving the tachyonic slepton mass problem of anomaly mediated supersymmetry breaking models with a non-Abelian horizontal gauge symmetry broken at the TeV scale. A specific model based on SU(3)_{H} horizontal symmetry is presented wherein the sleptons receive positive mass-squared from the asymptotically free SU(3)_{H} gauge sector. Approximate global symmetries present in the model strongly suppress flavor changing processes induced by the horizontal vector gauge bosons. The model predicts m_{h} < 120 GeV for the lightest Higgs boson mass, tan{beta} nearly equal to 4, and M_V = 1-4 TeV for the SU(3)_{H} gauge boson masses. The lightest SUSY particle is found to be the neutral Wino, which is a candidate for cold dark matter.Comment: 25 pages in LaTeX, 2 eps figure

R-symmetry, Yukawa textures and anomaly mediated supersymmetry breaking

We explore, in the MSSM context, an extension of the Anomaly Mediated Supersymmetry Breaking solution for the soft scalar masses that is possible if the underlying theory has a gauged R-symmetry. The slepton mass problem characteristic of the scenario is resolved, and a context for the explanation of the fermion mass hierarchy provided.Comment: 12 pages, Plain TeX, Uses Harvmac (big). More references added, and improved discussion of FCNC

Anomaly Mediation, Fayet-Iliopoulos D-terms and precision sparticle spectra

We consider the sparticle spectra that arise when anomaly mediation is the source of supersymmetry-breaking and the tachyonic slepton problem is solved by a Fayet-Iliopoulos D-term. We also show how this can lead to a minimal viable extension of anomaly mediation, in which the gauge symmetry associated with this D-term is broken at very high energies, leaving as its footprint in the low energy theory only the required D-terms and seesaw neutrino masses.Comment: 20 pages, 5 figures. Uses epsf. Minor corrections and added referenc

Electoral Competitiveness and Turnout in British Elections, 1964-2010

This is the author version accepted for publication in Political Science Research and Methods. The final version is forthcoming and will be available on the Publisher's website via http://journals.cambridge.org/action/displayJournal?jid=RAMAnalyzing the British Election Study from 1964 to 2010, we examine the influence of electoral context on turnout, focusing on the closeness of elections in terms of lagged seat and constituency-level winning margins. Using cross-classified multilevel models to account for individual and contextual factors and disentangle life-cycle, cohort- and election-specific effects, we find that closeness strongly affects voting behavior, particularly among new electors. Widening seat margins in British elections over the last decades have had a persistent impact on turnout. Respondents who faced less competitive environments when young are more likely to abstain in subsequent elections than those reaching voting age after close-fought races. We conclude that variations in competitiveness have had both short- and long-term effects on turnout

The Fayet-Iliopoulos D-term and its renormalisation in the MSSM

We consider the renormalisation of the Fayet-Iliopoulos D-term in a softly-broken supersymmetric gauge theory with a non-simple gauge group containing an abelian factor, and present the associated beta-function through three loops. We also include in an appendix the result for several abelian factors. We specialise to the case of the minimal supersymmetric standard model (MSSM), and investigate the behaviour of the Fayet-Iliopoulos coupling for various boundary conditions at the unification scale. We focus particularly on the case of non-standard soft supersymmetry breaking couplings, for which the Fayet-Iliopoulos coupling evolves significantly between the unification scale and the weak scale.Comment: 18 pages, Revtex, 2 figures. Expanded version including general results for gauge groups with several abelian factors. Minor typos correcte

The Fayet-Iliopoulos D-term and its renormalisation in softly-broken supersymmetric theories

We consider the renormalisation of the Fayet-Iliopoulos D-term in a softly-broken abelian supersymmetric theory, and calculate the associated beta-function through three loops. We show that there exists (at least through three loops) a renormalisation group invariant trajectory for the coefficient of the D-term, corresponding to the conformal anomaly solution for the soft masses and couplings.Comment: 30 pages, Revtex, 15 Figures. Minor changes, and inadvertent omission of author from this abstract correcte

RG-invariant Sum Rule in a Generalization of Anomaly Mediated SUSY Breaking Models

We study a generalization of anomaly-mediated supersymmetry breaking (AMSB) scenarios, under the assumption that the effects of the high-scale theory do not completely decouple and D-term type contributions can be therefore present. We investigate the effect of such possible D-term additional contributions to soft scalar masses by requiring that, for non-vanishing, renormalizable Yukawa couplings $Y^{ijk}$, the sum of squared soft supersymmetry breaking mass parameters, $M^2_{ijk} \equiv m_i^2+m_j^2+m_k^2$, is RG-invariant, in the sense that it becomes independent of the specific ultraviolet boundary conditions as it occurs in the AMSB models. These type of models can avoid the problem of tachyonic solutions for the slepton mass spectrum present in AMSB scenarios. We implement the electroweak symmetry breaking condition and explore the sparticle spectrum associated with this framework. To show the possible diversity of the sparticle spectrum, we consider two examples, one in which the D-terms induce a common soft supersymmetry breaking mass term for all sfermion masses, and another one in which a light stop can be present in the spectrum.Comment: 24 pages, latex, 12 figure

DREDed Anomaly Mediation

We offer a guide to dimensional reduction (DRED) in theories with anomaly mediated supersymmetry breaking. Evanescent operators proportional to epsilon arise in the bare Lagrangian when it is reduced from d=4 to d= (4-2 epsilon) dimensions. In the course of a detailed diagrammatic calculation, we show that inclusion of these operators is crucial. The evanescent operators conspire to drive the supersymmetry-breaking parameters along anomaly-mediation trajectories across heavy particle thresholds, guaranteeing the ultraviolet insensitivity.Comment: 24 pages. 10 figures. Uses Axodraw. Reference adde