1,987 research outputs found
Higher order correlations for fluctuations in the presence of fields
The higher order moments of the fluctuations for the thermodynamical systems
in the presence of fields are investigated in the framework of a theoretical
method. The metod uses a generalized statistical ensemble consonant with the
adequate expression for the generalized internal energy. The applications refer
to the case of a system in magnetoquasistatic field. In the case of linear
magnetic media one finds that for the description of the magnetic induction
fluctuations the Gaussian approximation is good enough. For nonlinear media the
coresponding fluctuations are non-Gaussian, they having a non-null asymmetry.
Aditionally the respective fluctuations have characteristics of leptokurtic,
mesokurtic and platykurtic type, depending of the value of the magnetic field
strength comparatively with a scaling factor of the magnetization curve.Comment: 10 pages, REVTe
Fluctuations in the presence of fields -Phenomenological Gaussian approximation and a new class of thermodynamic inequalities-
The work approaches the study of the fluctuations for the thermodynamic
systems in the presence of the fields. The approach is of phenomenological
nature and developed in a Gaussian approximation. The study is exemplified on
the cases of a magnetizable continuum in a magnetoquasistatic field, as well as
for the so called discrete systems. In the last case one finds that the
fluctuations estimators depends both on the intrinsic properties of the system
and on the characteristics of the environment. Following some earlier ideas of
one of the authors we present a new class of thermodynamic inequalities for the
systems investigated in this paper. In the case of two variables the mentioned
inequalities are nothing but non-quantum analogues of the well known quantum
Heisenberg (''uncertainty'') relations. Also the obtained fluctuations
estimators support the idea that the Boltzmann's constant k has the
signification of a generic indicator of stochasticity for thermodynamic
systems.
Pacs number(s): 05.20.-y, 05.40.-a, 05.70.-a, 41.20.GzComment: preprint, 24 page
The deconfined phase near Tc and its decay into hadrons
We sketch an effective theory for the deconfined state of QCD near Tc. This
relates the behavior of the expectation value of the Polyakov loop, and its
two-point functions, to the pressure. Defining the ``mass'' of three and two
gluon states from the imaginary and real parts of the Polyakov loop, while this
ratio is 3:2 in perturbation theory, at Tc it is 3:1. We also discuss the decay
of the deconfined state into hadrons.Comment: 4 pages, no figures, Contribution to the Proceedings of "Quark Matter
2002", Nantes, France, 18-24 Jul 200
Calculation of the expansion rate of the three-volume measure in high-energy heavy-ion collisions
In ultrarelativistic heavy-ion collisions the local three-volume measure is
expanding in the longitudinal and transverse directions. This is similar to the
Hubble-expansion of the universe, except that the former is not locally
isotropic. As an example the expansion rate is calculated assuming that the
energy-momentum tensor in the central region is that of an ideal fluid,
undergoing Bjorken flow in longitudinal direction, and with initial conditions
as expected for BNL-RHIC energy. While the longitudinal expansion of
three-volume is independent of the energy density of the fluid, in case of 3+1
dimensional expansion the form of the hydrodynamical solution (rarefaction wave
or deflagration shock) affects the three-volume expansion rate on the
hadronization hypersurface. As a consequence the average expansion rate on that
surface depends on the transverse size of the system. This may reflect in an
impact-parameter dependence of the formation probability of light nuclei and of
the freeze-out temperature of the strong interactions in the system.Comment: 10 Pages REVTEX, 4 Figures; Title slightly modified, 2 new figure
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