272 research outputs found
Pion Interferometry From A Relativistic Fluid With A First Order Phase Transition In CERN-SPS 158 GeV/A Pb+Pb Collisions
We investigate pion source sizes through the Yano-Koonin-Podgoretski\u{\i}
(YKP) parametrization for the Hanbury-Brown Twiss (HBT) effect in the CERN-SPS
158 GeV/A central collisions. We calculate two-particle correlation functions
numerically based on a (3+1)-dimensional relativistic hydrodynamics with a
first order phase transition and analyze the pair momentum dependence of the
HBT radii extracted from the YKP parametrization in detail. We find that even
in the case of a first order phase transition, expansion and the surface
dominant freeze-out make the source in the hydrodynamical model opaque
significantly. Consequently, the interpretation of the temporal radius
parameter as the time duration becomes unavailable for the hydrodynamical
model.Comment: 5 pages, LaTeX with six eps figures, Contribution to 'International
Workshop XXVIII on Gross Properties of Nuclei And Nuclear Excitations'.
Hirchegg, Austria, Jan 16-22, 200
Quenched scalar meson correlator with Domain Wall Fermions
We study the singlet and non-singlet scalar-meson masses using domain wall
fermions and the quenched approximation. The singlet mass is found to be
smaller than the non-singlet mass and indicates that the lowest singlet meson
state could be lighter than 1 GeV. The two-point functions for very small quark
masses are compared with expectations from the small-volume chiral perturbation
theory and the presence of fermionic zero modes.Comment: Lattice2002(chiral), 3 page
Semi-classical analysis of non self-adjoint transfer matrices in statistical mechanics. I
We propose a way to study one-dimensional statistical mechanics models with
complex-valued action using transfer operators. The argument consists of two
steps. First, the contour of integration is deformed so that the associated
transfer operator is a perturbation of a normal one. Then the transfer operator
is studied using methods of semi-classical analysis.
In this paper we concentrate on the second step, the main technical result
being a semi-classical estimate for powers of an integral operator which is
approximately normal.Comment: 28 pp, improved the presentatio
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
Thermodynamics of two-colour QCD and the Nambu Jona-Lasinio model
We investigate two-flavour and two-colour QCD at finite temperature and
chemical potential in comparison with a corresponding Nambu and Jona-Lasinio
model. By minimizing the thermodynamic potential of the system, we confirm that
a second order phase transition occurs at a value of the chemical potential
equal to half the mass of the chiral Goldstone mode. For chemical potentials
beyond this value the scalar diquarks undergo Bose condensation and the diquark
condensate is nonzero. We evaluate the behaviour of the chiral condensate, the
diquark condensate, the baryon charge density and the masses of scalar diquark,
antidiquark and pion, as functions of the chemical potential. Very good
agreement is found with lattice QCD (N_c=2) results. We also compare with a
model based on leading-order chiral effective field theory.Comment: 24 pages, 12 figure
Time evolution in visible light emission from high-power Ar pulse-modulated induction thermal plasmas
Transient behavior of a 15-kW Ar pulse-modulated induction thermal plasma (PMITP) at a pressure of 31 kPa was observed using a high-speed video camera. The PMITP method is one of new techniques for controlling temperature and radical density in time-domain in high-power thermal plasmas. The adoption of a high-power metal-oxide-semiconductor field-effect transistor (MOSFET) inverter power supply makes it possible to sustain PMITPs with high power-conversion efficiency. The high-speed video pictures provide two-dimensional, time-dependent radiation intensity distributions from PMITPs, which are useful for understanding an unique transition behavior of PMITPs
Critical point of QCD at finite T and \mu, lattice results for physical quark masses
A critical point (E) is expected in QCD on the temperature (T) versus
baryonic chemical potential (\mu) plane. Using a recently proposed lattice
method for \mu \neq 0 we study dynamical QCD with n_f=2+1 staggered quarks of
physical masses on L_t=4 lattices. Our result for the critical point is T_E=162
\pm 2 MeV and \mu_E= 360 \pm 40 MeV. For the critical temperature at \mu=0 we
obtained T_c=164 \pm 2 MeV. This work extends our previous study [Z. Fodor and
S.D.Katz, JHEP 0203 (2002) 014] by two means. It decreases the light quark
masses (m_{u,d}) by a factor of three down to their physical values.
Furthermore, in order to approach the thermodynamical limit we increase our
largest volume by a factor of three. As expected, decreasing m_{u,d} decreased
\mu_E. Note, that the continuum extrapolation is still missingComment: 10 pages, 2 figure
Application of PDT for Uterine Cervical Cancer
We have been performing PDT using Excimer Dye Laser (EDL) or YAG-OPO laser, a type
of low power laser, both of which have a considerably higher degree of tissue penetration even
when compared to PDT using Argon Dye Laser (ADL)
Effective Model Approach to the Dense State of QCD Matter
The first-principle approach to the dense state of QCD matter, i.e. the
lattice-QCD simulation at finite baryon density, is not under theoretical
control for the moment. The effective model study based on QCD symmetries is a
practical alternative. However the model parameters that are fixed by hadronic
properties in the vacuum may have unknown dependence on the baryon chemical
potential. We propose a new prescription to constrain the effective model
parameters by the matching condition with the thermal Statistical Model. In the
transitional region where thermal quantities blow up in the Statistical Model,
deconfined quarks and gluons should smoothly take over the relevant degrees of
freedom from hadrons and resonances. We use the Polyakov-loop coupled
Nambu--Jona-Lasinio (PNJL) model as an effective description in the quark side
and show how the matching condition is satisfied by a simple ansatz on the
Polyakov loop potential. Our results favor a phase diagram with the chiral
phase transition located at slightly higher temperature than deconfinement
which stays close to the chemical freeze-out points.Comment: 8 pages, 4 figures; Talk at International Workshop on High Density
Nuclear Matter, Cape Town, South Africa, April 6-9, 201
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