2,056 research outputs found
RMF models with -scaled hadron masses and couplings for description of heavy-ion collisions below 2A GeV
Within the relativistic mean-field framework with hadron masses and coupling
constants dependent on the mean scalar field we study properties of nuclear
matter at finite temperatures, baryon densities and isospin asymmetries
relevant for heavy-ion collisions at laboratory energies below 2 GeV.
Previously constructed (KVORcut-based and MKVOR-based) models for the
description of the cold hadron matter, which differ mainly by the density
dependence of the nucleon effective mass and symmetry energy, are extended for
finite temperatures. The baryon equation of state, which includes nucleons and
resonances is supplemented by the contribution of the pion gas
described either by the vacuum dispersion relation or with taking into account
the -wave pion-baryon interaction. Distribution of the charge between
components is found. Thermodynamical characteristics on plane are
considered. The energy-density and entropy-density isotherms are constructed
and a dynamical trajectory of the hadron system formed in heavy-ion collisions
is described. The effects of taking into account the isobars and the
-wave pion-nucleon interaction on pion differential cross sections, pion to
proton and ratios are studied. The liquid-gas first-order phase
transition is studied within the same models in isospin-symmetric and
asymmetric systems. We demonstrate that our models yield thermodynamic
characteristics of the phase transition compatible with available experimental
results. In addition, we discuss the scaled variance of baryon and electric
charge in the phase transition region. Effect of the non-zero surface tension
on spatial redistribution of the electric charge is considered for a possible
application to heavy-ion collisions at low energies.Comment: 26 pages, 17 figures; matches the submitted versio
Probability Theory Compatible with the New Conception of Modern Thermodynamics. Economics and Crisis of Debts
We show that G\"odel's negative results concerning arithmetic, which date
back to the 1930s, and the ancient "sand pile" paradox (known also as "sorites
paradox") pose the questions of the use of fuzzy sets and of the effect of a
measuring device on the experiment. The consideration of these facts led, in
thermodynamics, to a new one-parameter family of ideal gases. In turn, this
leads to a new approach to probability theory (including the new notion of
independent events). As applied to economics, this gives the correction, based
on Friedman's rule, to Irving Fisher's "Main Law of Economics" and enables us
to consider the theory of debt crisis.Comment: 48p., 14 figs., 82 refs.; more precise mathematical explanations are
added. arXiv admin note: significant text overlap with arXiv:1111.610
Solution of the Hyperon Puzzle within a Relativistic Mean-Field Model
The equation of state of cold baryonic matter is studied within a
relativistic mean-field model with hadron masses and coupling constants
depending on the scalar field. All hadron masses undergo a universal scaling,
whereas the coupling constants are scaled differently. The appearance of
hyperons in dense neutron star interiors is accounted for, however the equation
of state remains sufficiently stiff if a reduction of the meson mass is
included. Our equation of state matches well the constraints known from
analyses of the astrophysical data and the particle production in heavy-ion
collisions.Comment: 7 pages, 4 figures; replaced with the published versio
Resistivity of non-Galilean-invariant Fermi- and non-Fermi liquids
While it is well-known that the electron-electron (\emph{ee}) interaction
cannot affect the resistivity of a Galilean-invariant Fermi liquid (FL), the
reverse statement is not necessarily true: the resistivity of a
non-Galilean-invariant FL does not necessarily follow a T^2 behavior. The T^2
behavior is guaranteed only if Umklapp processes are allowed; however, if the
Fermi surface (FS) is small or the electron-electron interaction is of a very
long range, Umklapps are suppressed. In this case, a T^2 term can result only
from a combined--but distinct from quantum-interference corrections-- effect of
the electron-impurity and \emph{ee} interactions. Whether the T^2 term is
present depends on 1) dimensionality (two dimensions (2D) vs three dimensions
(3D)), 2) topology (simply- vs multiply-connected), and 3) shape (convex vs
concave) of the FS. In particular, the T^2 term is absent for any quadratic
(but not necessarily isotropic) spectrum both in 2D and 3D. The T^2 term is
also absent for a convex and simply-connected but otherwise arbitrarily
anisotropic FS in 2D. The origin of this nullification is approximate
integrability of the electron motion on a 2D FS, where the energy and momentum
conservation laws do not allow for current relaxation to leading
--second--order in T/E_F (E_F is the Fermi energy). If the T^2 term is
nullified by the conservation law, the first non-zero term behaves as T^4. The
same applies to a quantum-critical metal in the vicinity of a Pomeranchuk
instability, with a proviso that the leading (first non-zero) term in the
resistivity scales as T^{\frac{D+2}{3}} (T^{\frac{D+8}{3}}). We discuss a
number of situations when integrability is weakly broken, e.g., by inter-plane
hopping in a quasi-2D metal or by warping of the FS as in the surface states of
Bi_2Te_3 family of topological insulators.Comment: Submitted to a special issue of the Lithuanian Journal of Physics
dedicated to the memory of Y. B. Levinso
- …