(Lattice) Propagators and Extraction of Spectral Densities

In this proceeding, we explain a few steps for an alternative extraction of the spectral density of a two-point function (propagator) based on a discrete set of data points. We present a so-called Tikhonov regularization of this particular inverse problem. We test it on 2 cases: lattice 0++} glueball data and mock gluon data.Comment: 8 pages, 4 figures. Proceedings of Xth Quark Confinement and the Hadron Spectrum, October 8-12, 2012, TUM Campus Garching, Munich, German

The lattice gluon propagator in renormalizable ξ\xi gauges

We study the SU(3) gluon propagator in renormalizable $R_\xi$ gauges implemented on a symmetric lattice with a total volume of (3.25 fm)$^4$ for values of the guage fixing parameter up to $\xi=0.5$. As expected, the longitudinal gluon dressing function stays constant at its tree-level value $\xi$. Similar to the Landau gauge, the transverse $R_\xi$ gauge gluon propagator saturates at a non-vanishing value in the deep infrared for all values of $\xi$ studied. We compare with very recent continuum studies and perform a simple analysis of the found saturation with a dynamically generated effective gluon mass.Comment: 6 pages, 4 figure

Finding the right answer: an information retrieval approach supporting knowledge sharing

Knowledge Management can be defined as the effective strategies to get the right piece of knowledge to the right person in the right time. Having the main purpose of providing users with information items of their interest, recommender systems seem to be quite valuable for organizational knowledge management environments. Here we present KARe (Knowledgeable Agent for Recommendations), a multiagent recommender system that supports users sharing knowledge in a peer-to-peer environment. Central to this work is the assumption that social interaction is essential for the creation and dissemination of new knowledge. Supporting social interaction, KARe allows users to share knowledge through questions and answers. This paper describes KARe�s agent-oriented architecture and presents its recommendation algorithm

Liquid mixtures involving fluorinated alcohols: The equation of state (p, r, T, x) of (Ethanol + Trifluoroethanol) Experimental and Simulation

Liquid mixtures involving fluorinated alcohols: The equation of state (p, r, T, x) of (Ethanol + Trifluoroethanol) Experimental and Simulation Pedro Duartea, Djêide Rodriguesa, Marcelo Silvaa, Pedro Morgadoa, Luís Martinsa,b and Eduardo J. M. Filipea* aCentro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal bCentro de Química de Évora, Universidade de Évora, 7000-671 Évora, Portugal Fluorinated alcohols are substances with unique properties and high technological value in the pharmaceutical and chemical industries. Trifluoroethanol (TFE), in particular, displays a number of unusual properties as a solvent. For example, it dissolves nylon at room temperature and is effectively used as solvent in bioengineering. The presence of the three fluorines atoms gives the alcohol a high ionization constant, strong hydrogen bonding capability and stability at high temperatures. In the pharmaceutical industry, TFE finds use as the major raw material for the production of inhalation anesthetics. Mixtures of TFE and water (known as Fluorinols®) are used as working fluids for Rankine cycle heat engines for terrestrial and space applications, as a result of a unique combination of physical and thermodynamic properties such as high thermal efficiency and excellent turbine expansion characteristics. Environmentally, TFE is a CFC substitute with an acceptable short lifetime and with small ozone depletion potential. Additionally, TFE is known to induce conformational changes in proteins and it is used as a co-solvent to analyze structural features of partially folded states. The (ethanol + TFE) system displays an interesting and peculiar behaviour, combining a negative azeotrope with high positive excess volumes. In this work, liquid mixtures of (ethanol + TFE) were investigated. The densities of the mixtures were measured as a function of composition between 278K and 338K and at pressures up to 700 bar. The corresponding excess volumes as a function of temperature and pressure, the isothermal compressibilities and thermal expansivities were calculated from the experimental results. The mixtures are highly non-ideal with excess volumes ranging from 0.8 - 1.0 cm3mol-1. Finally, molecular dynamic simulations were performed to model and interpret the experimental results. The Trappe force field was used to simulate the (TFE + ethanol) mixtures and calculate the corresponding excess volumes. The simulation results are able to reproduce the correct sign and order of magnitude of the experimental VE without fitting to the experimental data. Furthermore, the simulations suggest the presence of a particular type of hydrogen bridge between ethanol and TFE, that can help to rationalize the experimental results

Gluon and Ghost Dynamics from Lattice QCD

The two point gluon and ghost correlation functions and the three gluon vertex are investigated, in the Landau gauge, using lattice simulations. For the two point functions, we discuss the approach to the continuum limit looking at the dependence on the lattice spacing and volume. The analytical structure of the propagators is also investigated by computing the corresponding spectral functions using an implementation of the Tikhonov regularisation to solve the integral equation. For the three point function we report results when the momentum of one of the gluon lines is set to zero and discuss its implications.Comment: Proceedings of Light Cone 2016, held in Lisbon, September 2016. Minor changes in text. To appear in Few B Sy