Search

Correlations and fluctuations of physical quantities are known to play an important role in phase transitions and critical phenomena. In recent years some experimental attempts were made in the scope of the Beam Energy Scan program to locate a possible critical point in the QCD phase diagram. In this work we use the Nambu--Jona-Lasinio model to investigate the off-diagonal quark susceptibility, which is related to the quark--anti-quark scaled correlation at the mean field level. We show that this correlation has a significant peak near the critical point and, therefore, may be a useful quantity to measure in experiment. We further study the effects of a repulsive vector coupling, which reduces the strength of the scaled correlation near the critical point., Comment: 17 pages, 10 figures

Malaria remains endemic in tropical areas, especially in Africa. For the evaluation of new tools and to further ourunderstanding of host-parasite interactions, knowing the environmental risk of transmission-even at a very local scale-isessential. The aim of this study was to assess how malaria transmission is influenced and can be predicted by local climaticand environmental factors. As the entomological part of a cohort study of 650 newborn babies in nine villages in the ToriBossito district of Southern Benin between June 2007 and February 2010, human landing catches were performed to assessthe density of malaria vectors and transmission intensity. Climatic factors as well as household characteristics were recordedthroughout the study. Statistical correlations between Anopheles density and environmental and climatic factors weretested using a three-level Poisson mixed regression model. The results showed both temporal variations in vector density(related to season and rainfall), and spatial variations at the level of both village and house. These spatial variations could belargely explained by factors associated with the house's immediate surroundings, namely soil type, vegetation index andthe proximity of a watercourse. Based on these results, a predictive regression model was developed using a leave-one-outmethod, to predict the spatiotemporal variability of malaria transmission in the nine villages. This study points up theimportance of local environmental factors in malaria transmission and describes a model to predict the transmission risk ofindividual children, based on environmental and behavioral characteristics., Comment: PLoS ONE, Public Library of Science, 2012

In the recently years it has been argued that spectators in heavy ion collisions are responsible for creating a strong magnetic field that could play an important role in the QCD phase transition. In this work we use the SU(2) Nambu--Jona-Lasinio (NJL) model in order to study the chiral transition in quark matter subject to a strong magnetic field. We show some results involving the breaking of chiral symmetry and its restoration at finite temperature and density., Comment: Contribution for the Conference Proceedings of the Compact Stars in the QCD Phase Diagram III (CSQCD III) conference, December 12-15, 2012, Guaruj\'a, Brazil. http://www.astro.iag.usp.br/~foton/CSQCD3

We consider the simplest versions of the Nambu--Jona-Lasinio (NJL) model and the Linear Sigma Model (LSM), in the Mean Field Approximation (MFA), in order to analyze hot and dense two flavor quark matter subject to strong magnetic fields. We pay especial attention to the case of a finite chemical potential, which has not yet been fully explored. Our results, for the NJL model, are in qualitative agreement with other recent applications showing that, for stronger fields, the first order segment of the transition line increases with the magnetic strength while the coexistence chemical potential value, at low temperatures, decreases. In the present work, one of the most important results is related to the analysis of how these features affect the phase coexistence region in the $T-\rho_B$ plane. We find that the coexistence boundary oscillates around the B=0 value for magnetic fields of the order $eB \lesssim 9.5\, m_\pi^2$ which can be understood by investigating the filling of Landau levels at vanishing temperature. So far, most investigations have been concerned with the effects of the magnetic field over the $T-\mu$ plane only while other thermodynamical quantities such as the adiabats, the quark number susceptibility, the interaction measure and the latent heat have been neglected. Here, we take a step towards filling this gap by investigating the influence of a magnetic field over these quantities. Finally, we argue that a naive application of the MFA does not seem to be appropriate to treat the LSM in the presence of magnetic fields., Comment: New results for the Linear Sigma Model with alternative parametrization. Recent references added