Behavior of physical observables in the vicinity of the QCD critical end point

Using the SU(3) Nambu-Jona-Lasinio (NJL) model, we study the chiral phase transition at finite $T$ and $\mu_B$. Special attention is given to the QCD critical end point (CEP): the study of physical quantities, as the pressure, the entropy, the baryon number susceptibility and the specific heat near the CEP, will provide complementary information concerning the order of the phase transition. We also analyze the information provided by the study of the critical exponents around the CEP.Comment: Talk given at Quark Confinement and the Hadron Spectrum VII, Ponta Delgada, Azores, Portugal, 2-7 Sep 200

Influence of the vector interaction and an external magnetic field on the isentropes near the chiral critical end point

The location of the critical end point (CEP) and the isentropic trajectories in the QCD phase diagram are investigated. We use the (2+1) Nambu$-$Jona-Lasinio model with the Polyakov loop coupling for different scenarios, namely by imposing zero strange quark density, which is the case in the ultra relativistic heavy-ion collisions, and $\beta$-equilibrium. The influence of strong magnetic fields and of the vector interaction on the isentropic trajectories around the CEP is discussed. It is shown that the vector interaction and the magnetic field, having opposite effects on the first-order transition, affect the isentropic trajectories differently: as the vector interaction increases, the first-order transition becomes weaker and the isentropes become smoother; when a strong magnetic field is considered, the first-order transition is strengthened and the isentropes are pushed to higher temperatures. No focusing of isentropes in region towards the CEP is seen.Comment: 10 pages, 5 figures; PRD versio

1º Congresso Internacional de Geologia de Timor-Leste.

Congresso Internacional de Geologia de Timor-Lest

Phase Diagram, Scalar-Pseudoscalar Meson Behavior and Restoration of Symmetries in (2+1) Polyakov-Nambu-Jona-Lasinio Model

We explore the phase diagram and the modification of mesonic observables in a hot and dense medium using the (2+1) Polyakov-Nambu-Jona-Lasinio model. We present the phase diagram in the ($T,\,\mu_B$)-plane, with its isentropic trajectories, paying special attention to the chiral critical end point (CEP). Chiral and deconfinement transitions are examined. The modifications of mesonic observables in the medium are explored as a tool to analyze the effective restoration of chiral symmetry for different regions of the phase diagram. It is shown that the meson masses, namely that of the kaons, change abruptly near the CEP, which can be relevant for its experimental search.Comment: 25 pages, 11 figures, 2 table

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

"Shaky Foundations: Policy Lessons from America's Historic Housing Crash"

A bursting asset bubble inevitably requires central bank action, usually when it is already too late and with adverse spillover effects. In this sense, the Federal Reserve and other central banks already target asset prices; yet, by taking aim at them only on the way down--as in the current housing and credit crisis--the "Big Banks" create a self-perpetuating cycle of perverse incentives and moral hazard that often gives rise to yet another round of bubbles. The U.S. central bank's current premise is that policymakers cannot and should not target asset bubbles. However, the housing story has rendered untenable the prevailing belief that bubbles are impossible to spot ahead of time. The warning signals were ubiquitous--for example, price charts showing home values rising impossibly into the stratosphere, and Wall Street's increasing reliance on housing-backed bonds for its record-setting profits. It has become abundantly clear that there was plenty the Fed could have done to discourage speculative behavior and put a stop to predatory lending. Recent U.S. experience has bolstered the view that asset prices must come under the central bank's purview in order for the economy to retain some semblance of stability. Former Fed Chairman Paul Volcker recently called for a broader regulatory role for the central bank in light of the housing-centered credit crisis. Indeed, Treasury Secretary Henry Paulson's latest plan for tackling the crisis involves giving the Fed vast new authority to regulate investment banks, not just depository institutions. However, news analyst Pedro Nicolaci da Costa argues that attitude changes among regulators will be even more important than shifts in mandate in ensuring that regulators like the Fed do their jobs properly.

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

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

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