Wilson-'t Hooft operators in four-dimensional gauge theories and S-duality

We study operators in four-dimensional gauge theories which are localized on a straight line, create electric and magnetic flux, and in the UV limit break the conformal invariance in the minimal possible way. We call them Wilson-'t Hooft operators, since in the purely electric case they reduce to the well-known Wilson loops, while in general they may carry 't Hooft magnetic flux. We show that to any such operator one can associate a maximally symmetric boundary condition for gauge fields on AdS^2\times S^2. We show that Wilson-'t Hooft operators are classifed by a pair of weights (electric and magnetic) for the gauge group and its magnetic dual, modulo the action of the Weyl group. If the magnetic weight does not belong to the coroot lattice of the gauge group, the corresponding operator is topologically nontrivial (carries nonvanishing 't Hooft magnetic flux). We explain how the spectrum of Wilson-'t Hooft operators transforms under the shift of the theta-angle by 2\pi. We show that, depending on the gauge group, either SL(2,Z) or one of its congruence subgroups acts in a natural way on the set of Wilson-'t Hooft operators. This can be regarded as evidence for the S-duality of N=4 super-Yang-Mills theory. We also compute the one-point function of the stress-energy tensor in the presence of a Wilson-'t Hooft operator at weak coupling.Comment: 32 pages, latex. v2: references added. v3: numerical factors corrected, other minor change

Long-Run Patterns of Demand: The Expenditure System of the CDES Indirect Utility Function - Theory and Applications

In this paper, we unify and extend the analytical and empirical application of the ”indirect addilog” expenditure system, introduced by Leser (1941), Somermeyer- Wit (1956) and Houthakker (1960). Using the Box-Cox transform, we present a parametric analysis of the Houthakker specification of the fundamental indirect utility function - called the CDES specification (constant differences of Allen elasticities of substitution) by Hanoch (1975). It is shown that the CDES demand system is less restrictive than implied by standard parameter restrictions in the literature, Hanoch (1975), Deaton & Muellbauer (1980), or else neither adequately indicated, Houthakker (1960), Silberberg & Suen (2001). Our parametric examination implies that Marshallian own-price elasticities are no longer restricted to being all larger than one in absolute value; hence CDES can now naturally exhibit both the inelastic and elastic own price elasticities of observable (Marshallian) demands. Furthermore, we argue that in computable general equilibrium models (CGE), the CDES compares favorably with other expenditure systems, e.g. the linear expenditure system (LES), since CDES and LES need the same outside information for calibration of the parameters, but CDES is not confined to constancy of marginal budget shares (linear Engel curves). Moreover, we show that the non-homothetic CDES preferences are a simple and natural extension of the homothetic CES (constant elasticities of substitution) preferences, and, accordingly, CDES can more realistically be used in specifying CGE models with a demand side of non-unitary income elasticities. A succint theoretical briefing of the CDES history with general and concise formulas is offered. We illustrate CDES estimation and the calculation of a comprehensive set of income and price elasticities by applying CDES to Danish budget survey data. With a large number budget items included, coherent numerical values for the income, own, and cross price elasticities, as shown here, seem nowhere calculated and available in the voluminous literature.CDES demand systems, non-homothetic preferences, general price elasticities, CGE modeling, budget data implementation

Multi-Threaded Actors

In this paper we introduce a new programming model of multi-threaded actors which feature the parallel processing of their messages. In this model an actor consists of a group of active objects which share a message queue. We provide a formal operational semantics, and a description of a Java-based implementation for the basic programming abstractions describing multi-threaded actors. Finally, we evaluate our proposal by means of an example application.Comment: In Proceedings ICE 2016, arXiv:1608.0313

On a novel approach for optimizing composite materials panel using surrogate models

This paper describes an optimization procedure to design thermoplastic composite panels under axial compressive load conditions. Minimum weight is the goal. The panel design is subject to buckling constraints. The presence of the bending-twisting coupling and of particular boundary conditions does not allow an analytical solution for the critical buckling load. Surrogate models are used to approximate the buckling response of the plate in a fast and reliable way. Therefore, two surrogate models are compared to study their effectiveness in composite optimization. The first one is a linear approximation based on the buckling constitutive equation. The second consists in the application of the Kriging surrogate. Constraints given from practical blending rules are also introduced in the optimization. Discrete values of ply thicknesses is a requirement. An ad-hoc discrete optimization strategy is developed, which enables to handle discrete variables

Further search for a neutral boson with a mass around 9 MeV/c2

Two dedicated experiments on internal pair conversion (IPC) of isoscalar M1 transitions were carried out in order to test a 9 MeV/c2 X-boson scenario. In the 7Li(p,e+e-)8Be reaction at 1.1 MeV proton energy to the predominantly T=0 level at 18.15 MeV, a significant deviation from IPC was observed at large pair correlation angles. In the 11B(d,n e+e-)12C reaction at 1.6 MeV, leading to the 12.71 MeV 1+ level with pure T=0 character, an anomaly was observed at 9 MeV/c2. The compatibility of the results with the scenario is discussed.Comment: 12 pages, 5 figures, 2 table