Weinberg power counting and the quark determinant at small chemical potential

We construct an effective action for QCD by expanding the quark determinant in powers of the chemical potential at finite temperature in the case of massless quarks. To cut the infinite series we adopt the Weinberg power counting criteria. We compute the minimal effective action (~p^4), expanding in the external momentum, which implies the use of the hard thermal loop approximation. Our main result is a gauge invariant expression for the phase theta of the functional determinant in QCD, and recovers dimensional reduction in the high-temperature limit. We compute, analytically, in the range of p << 2 pi T, including perturbative and nonperturbative contributions, the latter treated within the mean field approximation. Implications for lattice simulations are briefly discussed.Comment: 5 pages, 2 figures. v2: title changed, expanded discussion and added example (calculation of at high temperature). Published in PR

The Impacts of Pension Privatization in Latin American: A Cross-Country Comparison of Pension Reforms and the Introduction of Individual Accounts. An analysis modeled after the six guiding core principles of Social Security

Latin America was the world’s pioneering nation in the privatization of pensions. In 1981, Chile’s pension system underwent a reform making it the first country to replace a public defined-benefit pay-as-you-go pension scheme with a fully funded defined-contribution pension scheme based on individual accounts. This project assesses the impacts and results of pension privatization in Chile, Mexico and Uruguay. As indicators of a prosperous system, my analyses are made using the six core guiding principles of Social Security: i) Coverage; ii) Equal Treatment and Social Solidarity; iii) Gender Equity; iv) Adequacy of Benefits; v) Administrative Costs; vi) and, Financial Sustainability[1]. This project uses historical data from the three countries, including periods before the reform, in order to adequately compare the two systems and determine which has proven to be more efficient. The main findings of this paper are the positive impacts associated with pensions privatization with respect to the six core guiding principles of Social Security. [1] Mesa-Lago, Reassembling Social Security: A Survey of Pensions and Health Care Reforms in Latin America, 200

Pressure of massless hot scalar theory in the boundary effective theory framework

We use the boundary effective theory (BET) approach to thermal field theory in order to calculate the pressure of a system of massless scalar fields with quartic interaction. The method naturally separates the infrared physics, and is essentially non-perturbative. To lowest order, the main ingredient is the solution of the free Euler-Lagrange equation with non-trivial (time) boundary conditions. We derive a resummed pressure, which is in good agreement with recent calculations found in the literature, following a very direct and compact procedure.Comment: 10 pages, 4 figure

Effective potential in the BET formalism

We calculate the one-loop effective potential at finite temperature for a system of massless scalar fields with quartic interaction $\lambda\phi^4$ in the framework of the boundary effective theory (BET) formalism. The calculation relies on the solution of the classical equation of motion for the field, and Gaussian fluctuations around it. Our result is non-perturbative and differs from the standard one-loop effective potential for field values larger than $T/\sqrt{\lambda}$.Comment: 10 pages, 3 figure

New concepts and objectives for protein-amino acid nutrition in rabbits: a review

[EN] In the European context, the new legislation to avoid mineral contamination and the ban on antibiotics as growth promoters has led to the definition of new objectives in respect of nitrogen supply. The present study summarizes the state of nitrogen nutrition in rabbits and reviews the role of protein and amino acids in rabbit health and the new nitrogen value of protein sources based on true ileal digestibility (TID) for future recommendations. The main sources of nitrogen for microbial growth are ammonia, urea and protein (endogenous and dietary). The surplus of nitrogen flow to the caecum increases mortality rates during fattening by favouring the growth of potential pathogenic bacteria. Accordingly, feeding strategies to reduce ileal nitrogen flow have been reviewed. A large reduction of dietary protein level might have negative consequences on growth performances and mortality. In order to formulate balanced low protein diets, data on ileal and faecal amino acid digestibility of 14 raw materials is summarized. The use of this different unit for amino acid digestibility is also discussed.Financial support was provided by the Spanish Interministerial Science and Technology Commission (Projects AGL 2002-05, AGL 2005-03203 and PETRI 95-0689-OP), the Spanish Ministry of Industry (CDTI Project, 04-0136) and feed companies (NUTRECO, NANTA, COREN).Carabaño, R.; Villamide, M.; García, J.; Nicodemus, N.; Llorente, A.; Chamorro, S.; Menoyo, D.... (2009). New concepts and objectives for protein-amino acid nutrition in rabbits: a review. World Rabbit Science. 17(1):1-14. doi:10.4995/wrs.2009.66411417

Zero-mode analysis of quantum statistical physics

We present a unified formulation for quantum statistical physics based on the representation of the density matrix as a functional integral. We identify the stochastic variable of the effective statistical theory that we derive as a boundary configuration and a zero mode relevant to the discussion of infrared physics. We illustrate our formulation by computing the partition function of an interacting one-dimensional quantum mechanical system at finite temperature from the path-integral representation for the density matrix. The method of calculation provides an alternative to the usual sum over periodic trajectories: it sums over paths with coincident endpoints, and includes non-vanishing boundary terms. An appropriately modified expansion into Matsubara modes provides a natural separation of the zero-mode physics. This feature may be useful in the treatment of infrared divergences that plague the perturbative approach in thermal field theory.Comment: 9 pages, 5 figure

Langevin Simulation of Scalar Fields: Additive and Multiplicative Noises and Lattice Renormalization

We consider the Langevin lattice dynamics for a spontaneously broken lambda phi^4 scalar field theory where both additive and multiplicative noise terms are incorporated. The lattice renormalization for the corresponding stochastic Ginzburg-Landau-Langevin and the subtleties related to the multiplicative noise are investigated.Comment: 26 pages, 4 eps figures (Elsevier latex style

Semiclassical thermodynamics of scalar fields

We present a systematic semiclassical procedure to compute the partition function for scalar field theories at finite temperature. The central objects in our scheme are the solutions of the classical equations of motion in imaginary time, with spatially independent boundary conditions. Field fluctuations -- both field deviations around these classical solutions, and fluctuations of the boundary value of the fields -- are resummed in a Gaussian approximation. In our final expression for the partition function, this resummation is reduced to solving certain ordinary differential equations. Moreover, we show that it is renormalizable with the usual 1-loop counterterms.Comment: 24 pages, 5 postscript figure

Photon production from a thermalized quark gluon plasma: quantum kinetics and nonperturbative aspects

We study the production of photons from a quark gluon plasma in local thermal equilibrium by introducing a non-perturbative formulation of the real time evolution of the density matrix. The main ingredient is the real time effective action for the electromagnetic field to $\mathcal{O}(\alpha_{em})$ and to all orders in $\alpha_s$. The real time evolution is completely determined by the solution of a \emph{classical stochastic} non-local Langevin equation which provides a Dyson-like resummation of the perturbative expansion. The Langevin equation is solved in closed form by Laplace transform in terms of the thermal photon polarization. A quantum kinetic description emerges directly from this formulation. We find that photons with $k \lesssim 200 ~{Mev}$ \emph{thermalize} as plasmon quasiparticles in the plasma on time scales $t \sim 10-20 ~{fm}/c$ which is of the order of the lifetime of the QGP expected at RHIC and LHC. We then obtain the direct photon yield to lowest order in $\alpha_{em}$ and to leading logarithmic order in $\alpha_s$ in a \emph{uniform} expansion valid at all time. The yield during a QGP lifetime $t \sim 10 ~{fm}/c$ is systematically larger than that obtained with the equilibrium formulation and the spectrum features a distinct flattening for $k \gtrsim 2.5 ~{Gev}$. We discuss the window of reliability of our results, the theoretical uncertainties in \emph{any} treatment of photon emission from a QGP in LTE and the shortcomings of the customary S-matrix approach.Comment: 31 pages. To appear in Nucl. Phys. A. New section (VII) with response to and criticism of hep-ph/031222

Sensory profile of portuguese white wines using long-term memory: a novel nationwide approach

White wine sensory profiling of all 12 Protected Geographical Indications (PGIs) of mainland Portugal was achieved through completion of extended sensory questionnaires by 20 professional wine experts. No samples were assessed; the experiment was based on memory alone. Three macro-zonings were found and typicality differences were statistically validated and sensory described. PGI MINHO was found the most typical of all PGIs, with several extreme rates on Color, Aroma and Taste. SOUTHERN cluster of the four meridional PGIs presented several extreme, therefore typical, sensory assessments, mostly opposite to the profile of PGI Minho. Color tonality, alcohol and acidity were mutually related and respective variations were correlated with published findings and expressed as key factors for regional macro-zoning differentiation. Moreover, with the proposed methodology it was possible to achieve a novel nationwide sensory characterization of PGIs, overcoming ongoing macroscaling and sample representativeness limitations and envisaging new nation-sized sensory studiesinfo:eu-repo/semantics/publishedVersio