13,131 research outputs found
Lattice QCD and Hydro/Cascade Model of Heavy Ion Collisions
We report here on a recent lattice study of the QCD transition region at
finite temperature and zero chemical potential using domain wall fermions
(DWF). We also present a parameterization of the QCD equation of state obtained
from lattice QCD that is suitable for use in hydrodynamics studies of heavy ion
collisions. Finally, we show preliminary results from a multi-stage
hydrodynamics/hadron cascade model of a heavy ion collision, in an attempt to
understand how well the experimental data (e.g. particle spectra, elliptic
flow, and HBT radii) can constrain the inputs (e.g. initial temperature,
freezeout temperature, shear viscosity, equation of state) of the theoretical
model.Comment: 10 pages, 12 figures. Proceedings for the 26th Winter Workshop on
Nuclear Dynamics, Ocho Rios, Jamaica, Jan 2-9, 201
Atomic displacements and lattice distortion in the magnetic-field-induced charge ordered state of SmRuP
Structural properties of SmRuP in the anomalous magnetic ordered
phase between K and K in magnetic fields has
been studied by x-ray diffraction. Atomic displacements of Ru and P, reflecting
the field-induced charge order of the electrons, have been deduced by
analyzing the intensities of the forbidden Bragg peaks, assuming a cubic space
group . Also, by utilizing high-resolution x-ray diffraction
experiment, we observed a splitting of fundamental Bragg peaks, clarifying that
the unit cell in the magnetic ordered phase is rhombohedral elongated along the
axis. Responses of the rhombohedral domains to the magnetic
field, which reflects the direction of the magnetic moment, is studied in
detail.Comment: 11 pages, 11 figures, accepted for publication in PR
Spin Fluid Dynamics Observed by Magnetic Fountain Effect and Mechano-Spin Effect in the Ferromagnetic Superfluid He A Phase
Systematic observations of the magnetically generated fountain pressure in
the superfluid He A have been carried out in a newly built apparatus
designed to reduce the effect of thermal gradients. In the same apparatus,
mechanical pumping and filtering of polarized nuclear spins were realized by
the pneumatic pumping action of an electrostatically actuated membrane. In both
experiments, the measured induced pressure was observed to decay at all
temperatures where the A phase appeared in magnetic fields up to 13 T and
liquid pressures between 1 and 29 bar. The inferred spin relaxation rate tended
to increase as the low temperature phase boundary with the A phase
(T) was approached. The increase in spin relaxation rate near T
can be explained by the presence of a minority spin condensate in the A
phase as predicted by Monien and Tewordt and by the application of the
Leggett-Takagi theory of spin relaxation in superfluid He.Comment: 12 pages, 15 figures, to appear in Physical Review
New Dissipation Relaxation Phenomenon in Oscillating Solid He-4
We describe the first observations on the time-dependent dissipation when the
drive level of a torsional oscillator containing solid He-4 is abruptly
changed. The relaxation of dissipation in solid He-4 shows rich dynamical
behavior including exponential and logarithmic time-dependent decays,
hysteresis, and memory effects.Comment: 4 pages, 4 figure
Oscillation Frequency Dependence of Non-Classical Rotation Inertia of Solid He
The non-classical rotational inertia fraction of the identical cylindrical
solid He below 300 mK is studied at 496 and 1173 Hz by a double resonance
torsional oscillator. Below 35 mK, the fraction is the same at sufficiently low
rim velocities. Above 35 mK, the fraction is greater for the higher than the
lower mode. The dissipation peak of the lower mode occurs at a temperature
4 mK lower than that of the higher mode. The drive dependence of the two
modes shows that the reduction of the fraction is characterized by critical
velocity, \textit{not} amplitude nor acceleration.Comment: 4 pages, 4 figure
Coherent center domains from local Polyakov loops
We analyze properties of local Polyakov loops using quenched as well as
dynamical SU(3) gauge configurations for a wide range of temperatures. It is
demonstrated that for both, the confined and the deconfined regime, the local
Polyakov loop prefers phase values near the center elements 1, exp(i 2 pi/3),
exp(-i 2 pi/3). We divide the lattice sites into three sectors according to
these phases and show that the sectors give rise to the formation of clusters.
For a suitable definition of these clusters we find that in the quenched case
deconfinement manifests itself as the onset of percolation of the clusters. A
possible continuum limit of the center clusters is discussed
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