Finite Values Of Temperature Research Articles

Path integral Monte Carlo benchmarks for two-dimensional quantum dots

We report numerically accurate path integral Monte Carlo results for harmonically confined two-dimensional quantum dots containing up to $N=60$ interacting electrons. The finite-temperature values are extrapolated to 0 K and zero time step in order to provide precise upper-bound energies. The ground-state energies are compared against coupled-cluster and diffusion Monte Carlo results available in the literature for $N\ensuremath{\le}20$. We also provide Pad\'e fits for the energies as a function of $N$ for different strengths of the confining potential. The fits deviate less than $0.25%$ from the path integral Monte Carlo data. Overall, our upper-bound estimates for the ground-state energies have lower values than previous diffusion Monte Carlo benchmarks due to the accurate nodal surface in our simulations. Hence, our results set a new numerical benchmark for two-dimensional (spin-unpolarized) quantum dots up to a large number of electrons.

Hadronic freeze-out in an effective relativistic mean field model

We investigate an effective relativistic equation of state at finite values of temperature and baryon chemical potential with the inclusion of the full octet of baryons, the Delta-isobars and the lightest pseudoscalar and vector meson degrees of freedom. These last particles have been introduced within a phenomenological approach by taking into account of an effective chemical potential and mass depending on the self-consistent interaction between baryons. In this framework, we study of the hadron yield ratios measured in central heavy ion collisions over a broad energy range and present the beam energy dependence of underlying dynamic quantities like the net baryon density and the energy density.

Integral representations of thermodynamic 1PI Green’s functions in the world-line formalism

The issue discussed is a thermodynamic version of the Bern–Kosower master amplitude formula, which contains all necessary one-loop Feynman diagrams. It is demonstrated how the master amplitude at finite values of temperature and chemical potential can be formulated within the framework of the world-line formalism. In particular we present an elegant method of how to introduce a chemical potential for a loop in the master formula. Various useful integral formulas for the master amplitude are then obtained. The nonanalytic property of the master formula is also derived in the zero temperature limit with the value of chemical potential kept finite.

Cosmology with adiabatic matter creation

The influence of matter creation processes on the dynamics of the early universe is investigated within a phenomenological approach. By using a balance law for the particle number in addition to the familiar relations for viscous fluid cosmologies the whole dynamics is given explicitly in terms of the particle production rate. We argue that a sufficiently high particle production rate gives rise to an inflationary behaviour with finite values of temperature and density at the beginning of the hydrodynamic period of the universe.

On the dense phases of He 3 at very low temperatures

A class of physical properties of the dense phases of He 3 are dominated at low temperatures by their nuclear spin systems. The latter determine the lower limits of these properties, and yield thereby approximately their behavior and limiting values at very low temperatures and at the absolute zero. The theory of the spin system allows one to estimate the lowest temperatures at which the various thermal properties of this class have to be determined experimentally to approach with a preset deviation their limiting values in the ground state of these dense phases. These determinations, with a common relative value of this difference, of the nuclear paramagnetic susceptibility, heat capacity, expansion coefficient, and their temperature rates of variation require decreasingly lower temperatures, with the latter finite quantities imposing temperatures one order of magnitude lower than the susceptibility. These studies suggest that in order to obtain satisfactory, experimentally inaccessible, extrapolated very low temperature behaviors and finite limits of the above class of properties, careful prior analysis of their finite temperature values will have to be performed in terms of the partial properties of the spin systems as well as those of the degrees of freedom other than spin of the dense phases of He 3.