Pedro Cosme da Costa Vieira

Exact Spectrum of Anomalous Dimensions of Planar N=4 Supersymmetric Yang-Mills Theory

Nikolay Gromov, Vladimir Kazakov, and Pedro Vieira DESY Theory, Hamburg, Germany & II. Institut für Theoretische Physik Universität, Hamburg, Germany & St.Petersburg INP, St.Petersburg, Russia Ecole Normale Superieure, LPT, 75231 Paris CEDEX-5, France & l’Université Paris-VI, Paris, France; Max-Planck-Institut für Gravitationphysik, Albert-Einstein-Institut, 14476 Potsdam, Germany & Centro de F́ısica do Porto, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal

Spacetime and flux tube S-matrices at finite coupling for N=4 supersymmetric Yang-Mills theory.

We propose a non-perturbative formulation of planar scattering amplitudes in N=4 SYM or, equivalently, polygonal Wilson loops. The construction is based on the OPE approach and introduces a new decomposition of the Wilson loop in terms of fundamental building blocks named Pentagon transitions. These transitions satisfy a simple relation to the worldsheet S-matrix on top of the so called Gubser-Klebanov-Polyakov vacuum which allows us to bootstrap them at any value of the coupling. In this letter we present a subsector of the full solution to scattering amplitudes which we call the gluonic part. We match our results with both weak and strong coupling data available in the literature. For example, the strong coupling Y-system can be understood in this approach.

Quantum integrability for three-point functions of maximally supersymmetric Yang-Mills theory.

Quantum corrections to three-point functions of scalar single trace operators in planar N=4 Super-Yang-Mills theory are studied using integrability. At one loop, we find new algebraic structures that not only govern all two-loop corrections to the mixing of the operators but also automatically incorporate all one-loop diagrams correcting the tree-level Wick contractions. Speculations about possible extensions of our construction to all loop orders are given. We also match our results with the strong coupling predictions in the classical (Frolov-Tseytlin) limit.

Are finance, management, and marketing autonomous fields of scientific research? An analysis based on journal citations

Although there is considerable consensus that Finance, Management and Marketing are ‘science’, some debate remains with regard to whether these three areas comprise autonomous, organized and settled scientific fields of research. In this paper we aim to explore this issue by analyzing the occurrence of citations in the top-ranked journals in the areas of Finance, Management, and Marketing. We put forward a modified version of the model of science as a network, proposed by Klamer and Van Dalen (J Econ Methodol 9(2):289–315, 2002), and conclude that Finance is a ‘Relatively autonomous, organized and settled field of research’, whereas Management and (to a larger extent) Marketing are relatively non-autonomous and hybrid fields of research’. Complementary analysis based on sub-discipline rankings using the recursive methodology of Liebowitz and Palmer (J Econ Lit 22:77–88, 1984) confirms the results. In conclusions we briefly discuss the pertinence of Whitley’s (The intellectual and social organization of the sciences, 1984) theory for explaining cultural differences across these sub-disciplines based on its dimensions of scholarly practices, ‘mutual dependency’ and ‘task uncertainty’.

An economics journals’ ranking that takes into account the number of pages and co-authors

In this article, I examine whether the academics reward policy must correlate positively with the published number of articles per co-author, number of pages and journals reputation. This is accomplished by estimating a nonlinear model with a panel data from 168 economics journals covered in the ISI-Web of Knowledge database (58 825 articles). The data reinforces the conjecture that published article value is slightly increasing with the number of co-authors and is proportional to the number of pages. The data also suggests that there are four distinct groups related to journal quality that I name A, B+, B and B−.

Market equilibrium with FSS search

It is acknowledged that in the trading of homogeneous goods there is persistent price dispersion. However, it is theoretically derived that if buyers are optimizers there is no price dispersion. This negative result motivates the emergence of alternative paths in the literature that studies price dispersion. In Burdett and Judds seminal work, buyers follow the sub-optimal fixed sample size search strategy, FSS. These authors claim that under this sub-optimal strategy there are, ex ante, three points of Nash equilibrium, two of them associated with price dispersion and search. This article shows that these two points of equilibrium with price dispersion are not empirically relevant because they will not be ex post enforced, being unproductive for explaining equilibrium price dispersion using the FSS sub-optimal search strategy.

Transfer Pricing and Tax Havens for Attracting FDI

Enterprises seek profit maximization that comprises tax optimization which, within multinationals, includes the shifting of profits from the less to the most favorable countries using transfer pricing of intra-group transactions and tax havens as the “middle man”. Because FDI is an important engine of economic growth of, at least, the less developed countries and multilateral agreements impose limitations on the allocation of direct subsidies to businesses, in our research we explore the hypothesis that countries could use the relaxation of regulation on transfer pricing as a fiscal policy instrument for attracting FDI. Using a good composed of two parts, the brand and the hardware, and consumers with concave utility on the brand, we conclude that countries can use the relaxation of regulatory acceptance of transfer pricing to attract FDI when 1) the creation and development of the brand is an important part in the total cost of the good and 2) the increase in production costs of relocating the production from the most to the less developed country is not very large. Our results seem in accordance with empirical evidence.

Spacetime and Flux TubeS-Matrices at Finite Coupling forN=4Supersymmetric Yang-Mills Theory

We propose a non-perturbative formulation of planar scattering amplitudes in N=4 SYM or, equivalently, polygonal Wilson loops. The construction is based on the OPE approach and introduces a new decomposition of the Wilson loop in terms of fundamental building blocks named Pentagon transitions. These transitions satisfy a simple relation to the worldsheet S-matrix on top of the so called Gubser-Klebanov-Polyakov vacuum which allows us to bootstrap them at any value of the coupling. In this letter we present a subsector of the full solution to scattering amplitudes which we call the gluonic part. We match our results with both weak and strong coupling data available in the literature. For example, the strong coupling Y-system can be understood in this approach.

The Control of Varroa Destructor in Apis Mellifera by the Isolation of the Brood Area

Varroa destructor is a parasitic of honeybees that, beginning in the 1960´s, has become a worldwide serious economic problem. Although there are miticides capable of controlling the infestation they contaminate the honey. In this paper I question if it is possible to implement a perfectly different strategy that is to isolate the brood area from the exterior where the forager-bees stay in just in the honey area. To decrease management costs, I also question if it is possible to have a super-colony with up to 30 queen-bees isolated brood areas that share the same honey area.

Stochastic Runge–Kutta Schemes for Discretization of Hysteretic Models

The need to produce numerical solutions of stochastic differential equations (SDE) is present in problems arising in many areas. This is the case in Seismic Engineering where hysteretic models are used (see Wan et al., Soil Dyn Earthquake Eng 21:75–81, 2001 for an example of a problem involving a bridge column). The simulation of the solutions of these nonlinear equations is based on a discretization scheme. In the study of hysteretic models subjected to Gaussian white noise, we aim to compare the response obtained by using two schemes in the discretization of the SDE, in terms of the second statistical moments of the displacement, with that obtained from solving numerically the ODE system satisfied by the moments that arises after the use of adapted Monte Carlo simulation. We analyze the single degree of freedom Noori–Baber–Wen model for different values of (a) the parameters of the nonlinearity coefficient, (b) the parameters that characterize the type of hysteresis, (c) the parameters that take into account with the degradation effect of resistance, stiffness, and the pinching effect. We conclude that when the discretization step is small, the estimates of the second moment are similar in both schemes meaning that the choice between the weakly convergency schemes is irrelevant. However the solutions obtained by using the Runge–Kutta schemes are different from those obtained by approximately solving the equations of the moments. This difference is more relevant in situations where the allowed contribution of the dissipated energy is larger.