Modelling strong interactions and longitudinally polarized vector boson scattering

We study scattering of the electroweak gauge bosons in 5D warped models. Within two different models we determine the precise manner in which the Higgs boson and the vector resonances ensure the unitarity of longitudinal vector boson scattering. We identify three separate scales that determine the dynamics of the scattering process in all cases. For a quite general background geometry of 5D, these scales can be linked to a simple functional of the warp factor. The models smoothly interpolate between a `composite' Higgs limit and a Higgsless limit. By holographic arguments, these models provide an effective description of vector boson scattering in 4D models with a strongly coupled electroweak breaking sector.Comment: 30 pages, no figure

About the holographic pseudo-Goldstone boson

Pseudo-Goldstone bosons in 4D strongly coupled theories have a dual description in terms of 5D gauge theories in warped backgrounds. We introduce systematic methods of computing the pseudo-Goldstone potential for an arbitrary warp factor in 5D. When applied to electroweak symmetry breaking, our approach clarifies the relation of physical observables to geometrical quantities in five dimensions.Comment: 16 page

Political Reforms and Public Policies: Evidence from Agricultural Protection.

This paper studies the effect of political regime transitions on public policy using a dataset on global agricultural distortions over 50 years (including data from 74 developing and developed countries over the period 1955-2005). We employ both difference-in-differences regressions and semi-parametric matching methods, exploiting the time series and cross-sectional variation in the data. Our semi-parametric estimates show that parametric methods might underestimate the effect of democracy on public policy. In addition, we find that the effect is asymmetric: agricultural protection increases after a country’s transition to democracy of about 9% points, but there is no effect when the political regime shifts from democracy to autocracy. Overall, the evidence supports the redistributive nature of democratic institutions toward the majority and, therefore, it is consistent with the median voter model of political behaviour.

Altruism, sharing, and reciprocity in children as related to friendship status.

The friendship status of a recipient was taken into consideration with respect to the sharing patterns of third grade children. Subjects were found to share significantly more candies initially with a friend than a desired friend or nonfriend peer* A variety of psychological phenomenon determined the second sharing after the receipt of a large, small, or equal amount of candy from the previous recipent. Children increased their sharing to a desired friend after friendly overtures from him (her) and retaliated small donations by an established friend with decreased sharing. In still more neutral conditions, the children followed a norm of equality that was introduced into the experimental situation. Subsequent sharing with a needy child was related neither to feeling good nor to feeling guilty. Also subjects did not respond differently in the experimental conditions because of sex. Finally highly popular children followed more reciprocal patterns of sharing than other children, and were more susceptible to modeling influences of their peers

Community dynamics mining

In this paper we propose a model to analyze community dynamics. Recently, several methods and tools have been proposed to extract communities from static graphs. However, since communities are not static, but change over time, it is necessary to provide methods to determine and observe the community transitions and to extract the factors that cause the development. We regard a community as an object that exists over time and propose to observe community transitions along the time axis. For this we partition the time axis under observation by time windows. In each time window, a set of interactions between community participants is aggregated. These static networks are analyzed for subcommunities by applying community detection mechanisms. Through this we detect communities in each interval and can observe if communities persist over time or undergo a transition. We present community transitions and the observable indicators for the respective development. We furthermore present a software environment that incorporates several community detection and analysis methods to analyze community transitions. It supports a dynamic temporal community analysis and provides several forms of visualizations and analysis settings thus providing an interactive tool to observe community dynamics

Constraints for the existence of flat and stable non-supersymmetric vacua in supergravity

We further develop on the study of the conditions for the existence of locally stable non-supersymmetric vacua with vanishing cosmological constant in supergravity models involving only chiral superfields. Starting from the two necessary conditions for flatness and stability derived in a previous paper (which involve the Kahler metric and its Riemann tensor contracted with the supersymmetry breaking auxiliary fields) we show that the implications of these constraints can be worked out exactly not only for factorizable scalar manifolds, but also for symmetric coset manifolds. In both cases, the conditions imply a strong restriction on the Kahler geometry and constrain the vector of auxiliary fields defining the Goldstino direction to lie in a certain cone. We then apply these results to the various homogeneous coset manifolds spanned by the moduli and untwisted matter fields arising in string compactifications, and discuss their implications. Finally, we also discuss what can be said for completely arbitrary scalar manifolds, and derive in this more general case some explicit but weaker restrictions on the Kahler geometry.Comment: 22 pages, Latex, no figure

Holography, Pade Approximants and Deconstruction

We investigate the relation between holographic calculations in 5D and the Migdal approach to correlation functions in large N theories. The latter employs Pade approximation to extrapolate short distance correlation functions to large distances. We make the Migdal/5D relation more precise by quantifying the correspondence between Pade approximation and the background and boundary conditions in 5D. We also establish a connection between the Migdal approach and the models of deconstructed dimensions.Comment: 28 page

Does market structure influence price transmission in the agro-food sector?

There exists a large literature on price transmission in agro-food sectors. However, a great majority of empirical studies focus on the existence of asymmetry and, by and large, do not investigate the reason for its presence or absence. This is in sharp contrast to the theoretical literature that provides a number of explanations of why we should expect (a)symmetry. In response, this paper investigates the reasons for asymmetric price transmission in the agro-food chain, using meta-analysis of exist- ing studies. Our focus is on the organizational and institutional characteristics of the agro-food supply chain. Our findings suggest that asymmetric price transmis- sion in farm – retail relationships is more likely to occur in sectors/countries with more fragmented farm structure, higher governmental support and more restrictive regulations on price controls in the retail sector. On the other hand, more restric- tive regulations on entry barriers in the retail sector and the relative importance of the sector tend to promote symmetric farm – retail price transmission. The latter is also more likely in the presence of a strong processing indust

Warped Domain Wall Fermions

We consider Kaplan's domain wall fermions in the presence of an Anti-de Sitter (AdS) background in the extra dimension. Just as in the flat space case, in a completely vector-like gauge theory defined after discretizing this extra dimension, the spectrum contains a very light charged fermion whose chiral components are localized at the ends of the extra dimensional interval. The component on the IR boundary of the AdS space can be given a large mass by coupling it to a neutral fermion via the Higgs mechanism. In this theory, gauge invariance can be restored either by taking the limit of infinite proper length of the extra dimension or by reducing the AdS curvature radius towards zero. In the latter case, the Kaluza-Klein modes stay heavy and the resulting classical theory approaches a chiral gauge theory, as we verify numerically. Potential difficulties for this approach could arise from the coupling of the longitudinal mode of the light gauge boson, which has to be treated non-perturbatively