1,320 research outputs found
Broad Band Equilibration of Strangeness
We develop the "broad band equilibration" scenario for kaon productions at
GSI energies with in-medium effects.Comment: 4 pages, latex with 2 eps figure, a talk in QM200
A new state of matter at high temperature as "sticky molasses"
The main objective of this work is to explore the evolution in the structure
of the quark-antiquark bound states in going down in the chirally restored
phase from the so-called "zero binding points" to the QCD critical
temperature at which the Nambu-Goldstone and Wigner-Weyl modes meet. In
doing this, we adopt the idea recently introduced by Shuryak and Zahed for
charmed , light-quark mesons and
gluons that at , the quark-antiquark scattering length goes through
at which conformal invariance is restored, thereby transforming the
matter into a near perfect fluid behaving hydrodynamically, as found at RHIC.
We name this new state of matter as "sticky molasses". We show that the binding
of these states is accomplished by the combination of (i) the color Coulomb
interaction, (ii) the relativistic effects, and (iii) the interaction induced
by the instanton-anti-instanton molecules. The spin-spin forces turned out to
be small. While near all mesons are large-size nonrelativistic objects
bound by Coulomb attraction, near they get much more tightly bound, with
many-body collective interactions becoming important and making the
and masses approach zero (in the chiral limit). The wave function at the
origin grows strongly with binding, and the near-local four-Fermi interactions
induced by the instanton molecules play an increasingly more important role as
the temperature moves downward toward .Comment: Invited Talk at KIAS-APCTP Symposium in Astro-Hadron Physics "Compact
Stars: Quest for New States of Dense Matter", November 10-14, Seoul, Kore
Recent Developments on Kaon Condensation and Its Astrophysical Implications
We discuss three different ways to arrive at kaon condensation at n_c = 3 n_0
where n_0 is nuclear matter density: (1) Fluctuating around the n=0 vacuum in
chiral perturbation theory, (2) fluctuating around n_VM near the chiral
restoration density n_chi where the vector manifestation of hidden local
symmetry is reached and (3) fluctuating around the Fermi liquid fixed point at
n_0. They all share one common theoretical basis, "hidden local symmetry." We
argue that when the critical density n_c < n_chi is reached in a neutron star,
the electrons turn into K^- mesons, which go into an S-wave Bose condensate.
This reduces the pressure substantially and the neutron star goes into a black
hole. Next we develop the argument that the collapse of a neutron star into a
black hole takes place for a star of M = 1.5 M_sun. This means that Supernova
1987A had a black hole as result. We also show that two neutron stars in a
binary have to be within 4% of each other in mass, for neutron stars
sufficiently massive that they escape helium shell burning. For those that are
so light that they do have helium shell burning, after a small correction for
this they must be within 4% of each other in mass. Observations support the
proximity in mass inside of a neutron star binary. The result of strangeness
condensation is that there are 5 times more low-mass black-hole, neutron-star
binaries than double neutron-star binaries although the former are difficult to
observe.Comment: 42 pages, latex, 6 figure
In-Medium Effects on Charmonium Production in Heavy-Ion Collisions
Charmonium production in heavy-ion collisions is investigated within a
kinetic theory framework incorporating in-medium properties of open- and
hidden-charm states in line with recent QCD lattice calculations. A
continuously decreasing open-charm threshold across the phase boundary of
hadronic and quark-gluon matter is found to have important implications for the
equilibrium abundance of charmonium states. The survival of resonance
states above the transition temperature enables their recreation also in the
Quark-Gluon Plasma. Including effects of chemical and thermal off-equilibrium,
we compare our model results to available experimental data at CERN-SPS and
BNL-RHIC energies. In particular, earlier found discrepancies in the
ratio can be resolved.Comment: 4 pages RevTex including 4 eps-figures. v2: Minor modifications and
clarifications, typos corrected, Fig. 4 update
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Health Coverage Expansion in California: What Can Consumers Afford to Spend?
Analyzes Californians' current spending on insurance premiums and out-of-pocket expenditures to assess whether proposals to make obtaining health insurance mandatory include sufficient measures to make it affordable for low- and middle-income families
The Case for Hypercritical Accretion in M33 X-7
The spin parameter of the black hole in M33 X-7 has recently been measured to
be a*=0.77+-0.05 (Liu et al. 2008). It has been proposed that the spin of the
15.65 M_sun black hole is natal. We show that this is not a viable evolutionary
path given the observed binary orbital period of 3.45 days since the explosion
that would produce a black hole with the cited spin parameter and orbital
period would disrupt the binary. Furthermore, we show that the system has to be
evolved through the hypercritical mass transfer of about 5 M_sun from the
secondary star to the black hole.Comment: 4 page
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