Chiral Phase Transitions in QCD at Finite Temperature: Hard-Thermal-Loop Resummed Dyson-Schwinger Equation in the Real Time Formalism

Chiral phase transition in thermal QCD is studied by using the Dyson-Schwinger (DS) equation in the real time hard thermal loop approximation. Our results on the critical temperature and the critical coupling are significantly different from those in the preceding analyses in the ladder DS equation, showing the importance of properly taking into account the essential thermal effects, namely the Landau damping and the unstable nature of thermal quasiparticles.Comment: 4 pages including 2 figures (ps file), to appear in the proceedings of the 4th International Conference on Physics and Astrophysics of Quark-Gluon Plasma (ICPAQGP-2001), 26-30 November 2001, Jaipur, Indi

Gauge Independence of Limiting Cases of One-Loop Electron Dispersion Relation in High-Temperature QED

Assuming high temperature and taking subleading temperature dependence into account, gauge dependence of one-loop electron dispersion relation is investigated in massless QED at zero chemical potential. The analysis is carried out using a general linear covariant gauge. The equation governing the gauge dependence of the dispersion relation is obtained and used to prove that the dispersion relation is gauge independent in the limiting case of momenta much larger than $eT$. It is also shown that the effective mass is not influenced by the leading temperature dependence of the gauge dependent part of the effective self-energy. As a result the effective mass, which is of order $eT$, does not receive a correction of order $e^2T$ from one loop, independent of the gauge parameter.Comment: Revised and enlarged version, 14 pages, Revte

Allometric scaling of dietary linoleic acid on changes in tissue arachidonic acid using human equivalent diets in mice

The ability to extrapolate nutritional intervention data from experimental rodent models to humans requires standardization of dietary design. The inability to translate the level of nutrients from animal models to humans has contributed to contradictory findings between species. It is hypothesized that dietary linoleic acid (LA) promotes chronic and acute diseases by enriching tissues with arachidonic acid (AA), its downstream metabolite. However, levels of LA in rodent diets are notoriously erratic making interspecies comparisons unreliable. Therefore, the ability to extrapolate the biological effects of dietary LA from experimental rodents to humans necessitates an allometric scaling model that is rooted within a human equivalent context. To determine the physiological effect of dietary LA on tissue AA, a mathematical model for extrapolating nutrients based on energy was designed to mimic human equivalent doses. C57BL/6J mice were divided into 9 groups fed a background diet equivalent to that of the US diet (including LA, ALA, AA, EPA, DHA) with supplemental doses of LA (up to 2.3x) or AA (up to 5x). Changes in the phospholipid fatty acid compositions were monitored in plasma and erythrocytes and compared to data from humans supplemented with equivalent doses of LA or AA. Increasing dietary LA had little effect on tissue AA, while supplementing diets with AA significantly increased tissue AA levels, recapitulating results from human trials. Thus, interspecies comparisons for dietary LA between rodents and humans can be achieved when rodents are provided human equivalent doses based on differences in metabolic activity as defined by energy consumption

Thermalisation of Longitudinal Gluons

In the usual real-time finite-temperature gauge theory both the physical and the unphysical degrees of freedom are thermalised. We discuss the alternative approach where only the physical transverse components of the gauge field have bare thermal propagators, whereas the unphysical degrees of freedom are not heated. We show how pinch singularities are avoided: sometimes this requires resummation. If only the hard thermal loop is included in the resummation, the spatially-longitudinal component of the gauge field, which contains an extra collective plasmon mode, becomes fully thermalised, though the Faddeev-Popov ghost and the remaining unphysical component of the gauge field remain frozen.Comment: 10 pages, 1 figure appended as pictex-file, DAMTP 93-06, TUW-93-0

Light-front Schwinger Model at Finite Temperature

We study the light-front Schwinger model at finite temperature following the recent proposal in \cite{alves}. We show that the calculations are carried out efficiently by working with the full propagator for the fermion, which also avoids subtleties that arise with light-front regularizations. We demonstrate this with the calculation of the zero temperature anomaly. We show that temperature dependent corrections to the anomaly vanish, consistent with the results from the calculations in the conventional quantization. The gauge self-energy is seen to have the expected non-analytic behavior at finite temperature, but does not quite coincide with the conventional results. However, the two structures are exactly the same on-shell. We show that temperature does not modify the bound state equations and that the fermion condensate has the same behavior at finite temperature as that obtained in the conventional quantization.Comment: 10 pages, one figure, version to be published in Phys. Rev.