2,523 research outputs found
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 . 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
, does not receive a correction of order from one loop, independent
of the gauge parameter.Comment: Revised and enlarged version, 14 pages, Revte
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.
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
Negative-Triangularity Configuration on EAST: Analysis of engineering limitations on superconducting, D-shaped, target-diverted plasmas
Thermonuclear fusion is so named because of the high temperature that the majority of the fuel must maintain such that nuclei can overcome the electrostatic force, fuse, and produce energy. However, the ions and electrons (plasma) are so hot that any material used to confine them would be destroyed. To achieve confinement while maintaining the 50,000,000 K temperature needed for self-sustaining fusion, magnetic confinement is needed. As of 2019, the tokamak is the leading candidate for a practical fusion reactor. In recent years, tokamak research has repeatedly shown that the edge magneto-hydrodynamic stability is critical for handling the power to the walls and the divertor plates which is now and will most likely continue to be a limiting factor in the International Thermonuclear Experimental Reactor (ITER) and the DEMOnstration Power Station (DEMO). Recent experiments at Tokamak à Configuration Variable (TCV) and DIII-D have shown that a Negative-Triangularity Configuration (NTC) has a larger power handling area on the Low-Field-Side (LFS) divertor target plate and improved edge stability. However, there have been relatively few NTC experiments performed so far and none of them have been performed on a superconducting tokamak with shaping capabilities similar to ITER. To expand upon the previous experiments on TCV and DIII-D this thesis addresses an initial test of the NTC capability of the Experimental Advanced Superconducting Tokamak (EAST) which has achieved a ¡ 6 s ohmic discharge Upper Singular Null (USN) target-diverted plasma with a lower triangularity of X! ≤ -0.09
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