Tailoring Non-Compact Spin Chains

We study three-point correlation functions of local operators in planar $\mathcal{N}=4$ SYM at weak coupling using integrability. We consider correlation functions involving two scalar BPS operators and an operator with spin, in the so called SL(2) sector. At tree level we derive the corresponding structure constant for any such operator. We also conjecture its one loop correction. To check our proposals we analyze the conformal partial wave decomposition of known four-point correlation functions of BPS operators. In perturbation theory, we extract from this decomposition sums of structure constants involving all primaries of a given spin and twist. On the other hand, in our integrable setup these sum rules are computed by summing over all solutions to the Bethe equations. A perfect match is found between the two approaches.Comment: 2 figure

Top ranking economics journals impact variability and a ranking update to the year 2002

In this paper I address four questions concerning the quality of scientific economic papers. First, I validate the ex-ante procedure of computing the average impact of economic papers by comparing its results with the expost values. Second, I calibrate an estimator of papers normalised impact. Third, I compute the ranking variability of journals using a bootstrap procedure. Fourth, I test the statistical hypothesis that journals’ ranking did not changed over the time interval between 1980 and 2000. I concluded that this hypothesis is rejected only for the ‘Quarterly Journal of Economics’ and ‘Econometrica’, which saw their citation impact improved.

Market equilibrium with search and computational costs

Although it is an empirical regularity that in the trade of homogeneous goods there is persistent price dispersion and buyers search for low-priced items, theoretically we find that in market equilibrium, when buyers are optimisers (the neo-classical framework), these regularities do not occur. Summing this undesirable theoretical result to the fact that the computation of optimal strategies is demanding, the relevance of using optimisation models in rationalising human behaviour is put in question. Even so, Lucas (1981) claims that optimisation models should not be abandoned because only these are “able to isolate those aspects of behaviour that remain invariant to policy shifts from those that do not”. In this work, following Lucas’ claim, we introduce economic agents as having computational limitations in the neo-classical optimisation model, which is new in the literature. As a result of this alteration to the model, in market equilibrium, we observe both price dispersion and search when buyers have information and computational limitations.Computational limitations, Optimisation, Search, Market equilibrium

Multi Product Market Equilibrium with Sequential Search

In this paper I investigate whether, in market equilibrium, one observes price dispersion and search when buyers intend to acquire several products whose price is unknown and exists a positive search cost. Although that seems fruitful, I prove that in market equilibrium it is not observed neither price dispersion nor search and shops act as if they where monopolists. Nevertheless, there is one property of the theory that is in accordance with empirical data, namely the continuous increase in the number and dimension of larger shops.Search, Price Dispersion, Market Equilibrium, Multi-products

Animals domestication and agriculture as outcomes of collusion

Although it is known that there are circumstances where the competitive situation does not promote social welfare maximization, collusion is usually associated with firms’ strategies that decrease welfare. In this paper, using the theoretical framework of the industrial organization, I demonstrate in a model with two sectors that the economic revolution induced by the animal domestication and the agriculture is an outcome from the strengthen in collusion between human beings in the course of historical time and not vice-versa.Collusion, welfare progress, domestication, agriculture emergence

The importance in the papers' impact of the number of pages and of co-authors - an empirical estimation with data from top ranking economic journals

On a regular basis the scientific output of academic people has to be evaluated, e.g. to decide tenure. A very important item in this evaluation is the published papers’ quality that tends to be approximated by its impact in the literature. As the measure of this impact requires a long-term analysis, thus it is used as its estimator the journal average impact where each paper is published. But some papers have a single author while others have several and some papers have one or two pages while others have more than fifty. In this work I validate the conjecture that these two variables have a significant and positive effect in papers’ future impact, i.e. in papers quality. Nonetheless, I quantify that this two variables jointly considered merely explain 2.8% of papers’ impact variability.Scientific Skill, Co-authorship, Papers’ impact

Human Capital and Corruption: A microeconomic model of the bribes market with democratic contestability

To overcome market failures society creates common laws that stimulate or penalize individual actions, the enforcement of which depends on the actions of public authorities who may be susceptible to corruption. We model this behaviour for an autocracy versus a democracy, using a microeconomic framework. We assume that in an autocracy rulers have a monopoly over the bribes market, whereas in a democracy conflicting groups compete in the bribes market. The models constructed produce results that are compatible with the well-known stylized facts, namely that (1) in a democracy the level of corruption is lower than in an autocracy, although still positive, that (2) in environments where the level of human capital is higher, regimes are closer to democracies and the level of corruption is lower, and that (3) the level of corruption is higher in more regulated economies.