19,228 research outputs found
Charge diffusion constant in hot and dense hadronic matter - A Hadro-molecular-dynamic calculation
We evaluate charge diffusion constant of dense and hot hadronic matter based
on the molecular dynamical method by using a hadronic collision generator which
describes nuclear collisions at energies 10 < E < 100 GeV/A and satisfies
detailed balance at low temperatures (T < 200 MeV). For the hot and dense
hadronic matter of the temperature range, 100 < T < 200 MeV and baryon number
density, 0.16 < nB < 0.32 fm^-3, charge diffusion constant D gradually
increases from 0.5 fm c to 2 fm c with temperature and is almost independent of
baryon number density. Based on the obtained diffusion constant we make simple
discussions on the diffusion of charge fluctuation in ultrarelativistic nuclear
collisions.Comment: 13 pages, 4 figure
Magnetic and Electronic Phase Diagram and Superconductivity in the Organic Superconductors k-(BEDT-TTF)2X
The magnetic susceptibility of the organic superconductors -(h8 or
d8-ET), Cu(NCS) and Cu[N(CN)]Br has been studied. A
metallic phase below 37 38 K for Cu[N(CN)]Br and
46 50 K for Cu(NCS) has an anisotropic temperature
dependence of the susceptibility and the charge transport. Partial
charge-density-wave or charge fluctuation is expected to coexist with the
metallic phase instead of the large antiferromagnetic fluctuation above
. The phase diagram and the superconductivity of -(ET)
are discussed in connection with this phase.Comment: 5 pages, 4figures, REVTeX, references are corrected, accepted for
pubication in Phys. Rev.
Relaxor ferroelectricity induced by electron correlations in a molecular dimer Mott insulator
We have investigated the dielectric response in an antiferromagnetic
dimer-Mott insulator beta'-(BEDT-TTF)2ICl2 with square lattice, compared to a
spin liquid candidate kappa-(BEDT-TTF)2Cu2(CN)3. Temperature dependence of the
dielectric constant shows a peak structure obeying Curie-Weiss law with strong
frequency dependence. We found an anisotropic ferroelectricity by pyrocurrent
measurements, which suggests the charge disproportionation in a dimer. The
ferroelectric actual charge freezing temperature is related to the
antiferromagnetic interaction, which is expected to the charge-spin coupled
degrees of freedom in the system.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Phase separation in the vicinity of the surface of -(BEDT-TTF)Cu[N(CN)]Br by fast cooling
Partial suppression of superconductivity by fast cooling has been observed in
the organic superconductor -(BEDT-TTF)Cu[N(CN)]Br by two means:
a marked sample size effect on the magnetic susceptibility and direct imaging
of insulating regions by scanning microregion infrared reflectance
spectroscopy. Macroscopic insulating regions are found in the vicinity of the
crystalline surface after fast cooling, with diameters of 50--100 m and
depths of a few m. The very large in-plane penetration depth reported to
date ( 24--100 m) can be explained by the existence of the
insulating regions.Comment: Several rhetoric alternations to avoid misleadings. 6 pages, 3
figures. to be publihsed in Phys. Rev.
Electron localization near Mott transition in organic superconductor -(BEDT-TTF)Cu[N(CN)Br
The effect of disorder on the electronic properties near the Mott transition
is studied in an organic superconductor
-(BEDT-TTF)Cu[N(CN)]Br, which is systematically irradiated
by X-ray. We observe that X-ray irradiation causes Anderson-type electron
localization due to molecular disorder. The resistivity at low temperatures
demonstrates variable range hopping conduction with Coulomb interaction. The
experimental results show clearly that the electron localization by disorder is
enhanced by the Coulomb interaction near the Mott transition.Comment: 5 pages, 4 figure
Calogero-Moser Models V: Supersymmetry and Quantum Lax Pair
It is shown that the Calogero-Moser models based on all root systems of the
finite reflection groups (both the crystallographic and non-crystallographic
cases) with the rational (with/without a harmonic confining potential),
trigonometric and hyperbolic potentials can be simply supersymmetrised in terms
of superpotentials. There is a universal formula for the supersymmetric ground
state wavefunction. Since the bosonic part of each supersymmetric model is the
usual quantum Calogero-Moser model, this gives a universal formula for its
ground state wavefunction and energy, which is determined purely algebraically.
Quantum Lax pair operators and conserved quantities for all the above
Calogero-Moser models are established.Comment: LaTeX2e, 31 pages, no figure
A calculation of the transport coefficients of hot and dense hadronic matter based on the event generator URASiMA
We evaluate thermodynamical quantities and the transport coefficients of a
dense and hot hadronic matter based on the event generator URASiMA
(Ultra-Relativistic AA collision Simulator based on Multiple Scattering
Algorithm) with periodic boundary conditions. As the simplest example of the
transport coefficients we investigate the temperature dependence and the
chemical potential dependence of the baryon diffusion constant of a dense and
hot hadronic matter.Comment: To appear in the Proceeding of the International Conference on Quark
Nuclear Physics(QNP2000), 21-25 February 2000, Adelaide, Australi
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