Conformal Field Theories: From Old to New

In a short review of recent work, we discuss the general problem of constructing the actions of new conformal field theories from old conformal field theories. Such a construction follows when the old conformal field theory admits new conformal stress tensors in its chiral algebra, and it turns out that the new conformal field theory is generically a new spin-two gauge theory. As an example we discuss the new spin-two gauged sigma models which arise in this fashion from the general conformal non-linear sigma model.Comment: 7 pages, LaTeX, to appear in a memorial issue of Theoretical and Mathematical Physics in memory of F.A. Lune

Unification of the General Non-Linear Sigma Model and the Virasoro Master Equation

The Virasoro master equation describes a large set of conformal field theories known as the affine-Virasoro constructions, in the operator algebra (affine Lie algebra) of the WZW model, while the Einstein equations of the general non-linear sigma model describe another large set of conformal field theories. This talk summarizes recent work which unifies these two sets of conformal field theories, together with a presumable large class of new conformal field theories. The basic idea is to consider spin-two operators of the form $L_{ij} \partial x^i \partial x^j$ in the background of a general sigma model. The requirement that these operators satisfy the Virasoro algebra leads to a set of equations called the unified Einstein-Virasoro master equation, in which the spin-two spacetime field $L_{ij}$ couples to the usual spacetime fields of the sigma model. The one-loop form of this unified system is presented, and some of its algebraic and geometric properties are discussed.Comment: 18 pages, Latex. Talk presented by MBH at the NATO Workshop `New Developments in Quantum Field Theory', June 14-20, 1997, Zakopane, Polan

Unified Einstein-Virasoro Master Equation in the General Non-Linear Sigma Model

The Virasoro master equation (VME) describes the general affine-Virasoro construction T=L^{ab}J_aJ_b+iD^a \dif J_a in the operator algebra of the WZW model, where $L^{ab}$ is the inverse inertia tensor and $D^a$ is the improvement vector. In this paper, we generalize this construction to find the general (one-loop) Virasoro construction in the operator algebra of the general non-linear sigma model. The result is a unified Einstein-Virasoro master equation which couples the spacetime spin-two field $L^{ab}$ to the background fields of the sigma model. For a particular solution $L_G^{ab}$, the unified system reduces to the canonical stress tensors and conventional Einstein equations of the sigma model, and the system reduces to the general affine-Virasoro construction and the VME when the sigma model is taken to be the WZW action. More generally, the unified system describes a space of conformal field theories which is presumably much larger than the sum of the general affine-Virasoro construction and the sigma model with its canonical stress tensors. We also discuss a number of algebraic and geometrical properties of the system, including its relation to an unsolved problem in the theory of $G$-structures on manifolds with torsion.Comment: LaTeX, 55 pages, one postscript figure, uses epsfig.sty. contains a few minor corrections; version to be published in Int. J. Mod. Phys.

Economic consequences of intifada: a sequel

We give an assessment of the loss in the nominal gross domestic product (GDP) and nominal gross national income (GNI) due to twenty- seven months of intifada. It is based on the modest growth scenario given by the International Monetary Fund (IMF) and the World Bank (WB) in their first assessment of the economic developments in 2006 in Palestine. It turns out that the assessed loss is equivalent to the GDP of 1997 and the GNI in 1999: one year on two (and a quarter). Moreover, we show that our 2004 estimates of macro figures of 2002, based on a static computable general equilibrium model, are closer to the 2007 consensus estimates by IMF and WB than the 2003 estimates of IMF, based on an income-expenditure model. We argue that the shortening of the time horizon and the quantity adjustment following the dramatic shock explain why our model performs better.Palestine;macro-economic indicators;computable general equilibrium model

Economic consequences of intifada

In 2003 the World Bank (WB) and the International Monetary Fund (IMF) published estimates of macro-economic indicators for 2002 of the economy of Palestine. WB used a micro-founded recursive dynamic computable general equilibrium (CGE) model, calibrated on the 1998 Social Accounting Matrix (SAM) of Palestine, to which shocks were applied, whereas IMF based its estimates on a macro-founded income-expenditure model relying on more recent data. It turned out that there were substantial differences: the estimate by WB of the real Gross National Income (at 1998 prices) was 25% less than the corresponding figure calculated by IMF. This huge difference is not only relevant for a full understanding of the economic consequences of the intifada, but also for the size of the international community intervention. In this paper we propose our own evaluation with the help of a static CGE model, based on the 1998 SAM and the so-called intifada shock derived from data of WB, that we constructed for the analysis of some forms of emergency assistance in a previous article. It turns out that our estimates, based on an entirely different methodology, are remarkably close to those of IMF.Palestine;macro-economic indicators;computable general equilibrium model

Introducing the indirect addilog system in a computable general equilibrium model: a case study for Palestine

A popular functional form for modeling the consumption block of a computable general equilibrium model (CGE) is the Linear Expenditure System (LES) for which the Engel curves are straight lines. To allow for more general shapes two other systems have been proposed in recent literature: An Implicitly Directly Additive Demand System (AIDADS, a generalization of LES) and the Specialized Constant Differences of Elasticities (CDE) system. To calibrate the parameters outside information on all income elasticities and all own price elasticities is needed, whereas LES only requires information on income elasticities and the Frisch parameter. In this paper we consider a special case of CDE, the Indirect Addilog System (IAS) that allows for non-straight Engel curves, whereas its outside data requirement is the same as for LES. The only disadvantage is that all cross price elasticities of a particular price are the same. In many developing countries there is hardly any information on price responses so that the AIDADS and CDE cannot be used. We propose the use of IAS rather than LES. In the empirical part we use IAS in a CGE model for Palestine and show that predictions of macro-economic indicators are remarkably close to those of IMF.Palestine;CGE model;indirect addilog system;consumption block;functional forms

Critical behavior at Mott-Anderson transition: a TMT-DMFT perspective

We present a detailed analysis of the critical behavior close to the Mott-Anderson transition. Our findings are based on a combination of numerical and analytical results obtained within the framework of Typical-Medium Theory (TMT-DMFT) - the simplest extension of dynamical mean field theory (DMFT) capable of incorporating Anderson localization effects. By making use of previous scaling studies of Anderson impurity models close to the metal-insulator transition, we solve this problem analytically and reveal the dependence of the critical behavior on the particle-hole symmetry. Our main result is that, for sufficiently strong disorder, the Mott-Anderson transition is characterized by a precisely defined two-fluid behavior, in which only a fraction of the electrons undergo a "site selective" Mott localization; the rest become Anderson-localized quasiparticles.Comment: 4+ pages, 4 figures, v2: minor changes, accepted for publication in Phys. Rev. Let

A gobal fit to the anomalous magnetic moment, b->s gamma and Higgs limits in the constrained MSSM

New data on the anomalous magnetic moment a_mu of the muon together with the b->s gamma decay rate are considered within the supergravity inspired constrained minimal supersymmetric model. We perform a global statistical chi^2 analysis of these data and show that the allowed region of parameter space is bounded from below by the Higgs limit, which depends on the trilinear coupling and from above by the anomalous magnetic moment a_mu. The newest b->s gamma data deviate 1.7 sigma from recent SM calculations and prefer a similar parameter region as the 2.6 sigma deviation from a_mu.Comment: 12 pages, 7 figs. Refs. update

The orbifold-string theories of permutation-type: II. Cycle dynamics and target space-time dimensions

We continue our discussion of the general bosonic prototype of the new orbifold-string theories of permutation type. Supplementing the extended physical-state conditions of the previous paper, we construct here the extended Virasoro generators with cycle central charge $\hat{c}_j(\sigma)=26f_j(\sigma)$, where $f_j(\sigma)$ is the length of cycle $j$ in twisted sector $\sigma$. We also find an equivalent, reduced formulation of each physical-state problem at reduced cycle central charge $c_j(\sigma)=26$. These tools are used to begin the study of the target space-time dimension $\hat{D}_j(\sigma)$ of cycle $j$ in sector $\sigma$, which is naturally defined as the number of zero modes (momenta) of each cycle. The general model-dependent formulae derived here will be used extensively in succeeding papers, but are evaluated in this paper only for the simplest case of the "pure" permutation orbifolds.Comment: 32 page