137,068 research outputs found
The influence of strange quarks on QCD phase diagram and chemical freeze-out: Results from the hadron resonance gas model
We confront the lattice results on QCD phase diagram for two and three
flavors with the hadron resonance gas model. Taking into account the
truncations in the Taylor-expansion of energy density done on the
lattice at finite chemical potential , we find that the hadron resonance
gas model under the condition of constant describes very well the
lattice phase diagram. We also calculate the chemical freeze-out curve
according to the entropy density . The -values are taken from lattice QCD
simulations with two and three flavors. We find that this condition is
excellent in reproducing the experimentally estimated parameters of the
chemical freeze-out.Comment: 5 pages, 3 figures and 1 table Talk given at VIIIth international
conference on ''Strangeness in Quark Matter'' (SQM 2004), Cape Town, South
Africa, Sep. 15-20 200
Conditions driving chemical freeze-out
We propose the entropy density as the thermodynamic condition driving best
the chemical freeze-out in heavy-ion collisions. Taking its value from lattice
calculations at zero chemical potential, we find that it is excellent in
reproducing the experimentally estimated freeze-out parameters. The two
characteristic endpoints in the freeze-out diagram are reproduced as well.Comment: 8 pages, 5 eps figure
Technique for pinpointing submicron particles in the electron microprobe
Series of electron micrographs at successively lower magnifications can localize the substrate area sufficiently for a particle to be picked up by the beam of the electron microprobe. This approach could be modified to apply to fractographic studies, particularly of oxidation products stripped from fractures
Entropy for Color Superconductivity in Quark Matter
We study a model for color superconductivity with both three colors and
massless flavors including quark pairing. By using the Hamiltonian in the
color-flavor basis we can calculate the quantum entropy. From this we are able
to further investigate the phases of the color superconductor, for which we
find a rather sharp transition to color superconductivity above a chemical
potential around MeV.Comment: 10 pages, 2 eps-figure
Microprobe investigation of brittle segregates in aluminum MIG and TIG welds
Quantitative microprobe analysis of segregated particles in aluminum MIG /Metal Inert Gas/ and TIG /Tungsten Inert Gas/ welds indicated that there were about ten different kinds of particles, corresponding to ten different intermetallic compounds. Differences between MIG and TIG welds related to the individual cooling rates of these welds
Resonant relativistic corrections and the A_y problem
We study relativistic corrections to nuclear interactions caused by boosting
the two-nucleon interaction to a frame in which their total momentum does not
vanish. These corrections induce a change in the computed value of the
neutron-deuteron analyzing power A_y that is estimated using the plane-wave
impulse approximation. This allows a transparent analytical calculation that
demonstrates the significance of relativistic corrections. Faddeev calculations
are however needed to conclude on the A_y puzzle.Comment: 8 pages, 2 figures, minor addition, to appear in Phys. Rev.
An analysis of bi-directional use of frequencies for satellite communications
The bi-directional use of frequencies allocated for space communications has the potential to double the orbit/spectrum capacity available. The technical feasibility of reverse band use (RBU) at C-band (4 GHz uplinks and 6 GHz downlinks) is studied. The analysis identifies the constraints under which both forward and reverse band use satellite systems can share the same frequencies with terrestrial, line of sight transmission systems. The results of the analysis show that RBU satellite systems can be similarly sized to forward band use (FBU) satellite systems. In addition, the orbital separation requirements between RBU and FBU satellite systems are examined. The analysis shows that a carrier to interference ratio of 45 dB can be maintianed between RBU and FBU satellites separated by less than 0.5 deg., and that a carrier to interference ratio of 42 dB can be maintained in the antipodal case. Rain scatter propagation analysis shows that RBU and FBU Earth stations require separation distances fo less than 10 km at a rain rate of 13.5 mm/hr escalating to less than 100 km at a rain rate of 178 mm/hr for Earth station antennas in the 3 to 10 m range
Visual horizontal perception in relation to otolith function
Influence of otolith organs on visual horizontal perceptio
Vapor phase growth system and its use in the preparation of several III-V compound semiconductors
Vapor phase growth and properties of semiconductor material
The Effects of Quantum Entropy on the Bag Constant
The effects of quantum entropy on the bag constant are studied at low
temperatures and small chemical potentials. The inclusion of the quantum
entropy of the quarks in the equation of state provides the hadronic bag with
an additional heat which causes a decrease in the effective latent heat inside
the bag. We have considered two types of baryonic bags, and
. In both cases we have found that the bag constant without the
quantum entropy almost does not change with the temperature and the quark
chemical potential. The contribution from the quantum entropy to the equation
of state clearly decreases the value of the bag constant.Comment: 7 pages, 2 figures (two parts each
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