A Layman's guide to SUSY GUTs

The determination of the most straightforward evidence for the existence of the Superworld requires a guide for non-experts (especially experimental physicists) for them to make their own judgement on the value of such predictions. For this purpose we review the most basic results of Super-Grand unification in a simple and clear way. We focus the attention on two specific models and their predictions. These two models represent an example of a direct comparison between a traditional unified-theory and a string-inspired approach to the solution of the many open problems of the Standard Model. We emphasize that viable models must satisfy {\em all} available experimental constraints and be as simple as theoretically possible. The two well defined supergravity models, $SU(5)$ and $SU(5)\times U(1)$, can be described in terms of only a few parameters (five and three respectively) instead of the more than twenty needed in the MSSM model, \ie, the Minimal Supersymmetric extension of the Standard Model. A case of special interest is the strict no-scale $SU(5)\times U(1)$ supergravity where all predictions depend on only one parameter (plus the top-quark mass). A general consequence of these analyses is that supersymmetric particles can be at the verge of discovery, lurking around the corner at present and near future facilities. This review should help anyone distinguish between well motivated predictions and predictions based on arbitrary choices of parameters in undefined models.Comment: 25 pages, Latex, 11 figures (not included), CERN-TH.7077/93, CTP-TAMU-65/93. A complete ps file (1.31MB) with embedded figures is available by request from [email protected]

Closing the Universe by relaxing the cosmological constant

We propose a string-inspired model which correlates several aspects of particle physics and cosmology. Inspired by the flat directions and the absence of adjoint Higgs representations found in typical string models, we consider a no-scale $SU(5)\times U(1)$ supergravity model. This model entails well determined low-energy phenomenology, such as the value of the neutralino dark matter relic abundance and a negative contribution to the vacuum energy. A positive contribution to the vacuum energy is also typically present in string theory as a consequence of the running of the fundamental constants towards their fixed point values. If these two contributions cancel appropriately, one may end up with a vacuum energy which brings many cosmological observations into better agreement with theoretical expectations. The present abundance of neutralinos would then be fixed. We delineate the regions of parameter space allowed in this scenario, and study the ensuing predictions for the sparticle and Higgs-boson masses in this model.Comment: 5 pages, 2 figures (included), Latex, CTP-TAMU-06/9

New Anti-Merger Theories: A Critique

The purpose of this paper is to evaluate two new anti-merger instruments, innovation markets and unilateral effects, on the basis of economic theory and evidence. I first discuss how the economics of antitrust has developed over the years, with the intention of characterizing the intellectual inheritance of 1990s’ antitrust regulators. Within this context, I then discuss each anti-merger instrument, how it has been applied in specific cases, and how it accords with underlying economic science. On the basis of these arguments, antitrust regulators should pause and reconsider the theoretical and empirical bases of applying unilateral effects and innovation markets to merger investigations.antitrust, mergers, innovation markets, unilateral effects

Pro-growth, pro-poor : is there a tradeoff?

Is a pro-growth strategy always the best pro-poor strategy? To address this issue, the author provides an empirical evaluation of the impact of a series of pro-growth policies on inequality and headcount poverty. He relies on a large macroeconomic data set and estimate dynamic panel models that allows him to differentiate between the short- and long-run impacts of the policies under consideration on growth, inequality, and poverty. The author's findings indicate that regardless of their impact on inequality, pro-growth policies lead to lower poverty levels in the long run. However, he also finds evidence indicating that some of these policies may lead tohigher inequality and, under plausible assumptions for the distribution of income, to higher poverty levels in the short run. These findings would justify the adoption of a pro-growth policy package as the center of any poverty reduction strategy, together with pro-poor measures that complement such a package by offsetting potential short-run increases in poverty.Services&Transfers to Poor,Public Health Promotion,Poverty Impact Evaluation,Economic Conditions and Volatility,Environmental Economics&Policies,Rural Poverty Reduction,Achieving Shared Growth,Inequality,Governance Indicators,Safety Nets and Transfers