330 research outputs found
Electromagnetic and Axial Current Form Factors and Spectroscopy of Three-Flavor Holographic Baryons
We present an analysis of the three-flavor holographic model of QCD
associated to a brane configuration, with symmetry breaking induced by
a worldsheet instanton associated to a closed loop connecting
. We calculate the electromagnetic and axial couplings
of all octet and decuplet baryons, as well as several negative parity
excitations, with and without symmetry breaking effects, and demonstrate
qualitative and quantitative agreement with many available experimental
measurements, with marked improvement over the analogous two-flavor models.Comment: 23 page
Nonabelian Berry Phases in Baryons
We show how generic nonabelian gauge fields can be induced in baryons when a
hierarchy of fast degrees of freedom is integrated out. We identify them with
nonabelian Berry potentials and discuss their role in transmuting quantum
numbers in bag and soliton models of baryons. The resulting baryonic spectra
for both light and heavy quark systems are generic and resemble closely the
excitation spectrum of diatomic molecules. The symmetry restoration in the
system, i.e., the electronic rotational invariance in diatomic molecules, the
heavy-quark symmetry in heavy baryons etc. is interpreted in terms of the
vanishing of nonabelian Berry potentials that otherwise govern the hyperfine
splitting.Comment: Latex 35 pages (2 figures not added, will be faxed if requested),
NTG-92-2
H-dibaryon matter in the Skyrme model on a hypersphere
We study the properties of H-dibaryon matter through the SO(3) Skyrmion
solution on a three-dimensional hypersphere . As the density increases,
the swelling of H-dibaryon is found. Above a critical density, the system
becomes uniform in terms of the baryon density. In this uniform phase, the
critical order parameter is largely reduced, which can be interpreted as the
chiral symmetry restoration. From the comparison with the
solution, the SO(3) soliton is found to be the true ground state for high
density system with fm in the B=2 sector with .Comment: 10 pages LaTeX, 7 epsf figures, epsf.sty, to be published in Physics
Letters B Comparison with SO(2)xSO(2) configuration is adde
Rethinking the Properties of the Quark-Gluon Plasma at
We argue that although at asymptotically high temperatures the QGP in bulk
behaves as a gas of weakly interacting quasiparticles (modulo long-range
magnetism), at temperatures up to few times the critical temperature it
displays different properties. If the running of the QCD coupling constant
continues in the Coulomb phase till the screening length scale, it reaches the
strong coupling treshold . As a result, the Coulomb phase
supports weakly bound Coulombic s-wave , light quark and even
states.
The existence of shallow bound states dramatically increases the
quasiparticle rescattering at low energies, reducing the viscosity and thereby
explaining why heavy ion collisions at RHIC exhibit robust collective
phenomena. In conformal gauge theories at finite temperature the Coulomb
binding persists further in the strong coupling regime, as found for SUSY YM in the Maldacena regime.Comment: v2 version have one more figure and one more reference, v3 is the
same as v2 except a double-page format (the v2 had corrupted last lines on
the page
Thermal Dileptons from a Nonperturbative Quark-Gluon Phase
Assuming that gluon condensates are important even above the deconfining
phase transition, we develop a model for the dilepton yield from a quark gluon
plasma. Using a simple fire ball description of a heavy ion collision, and
various estimates of the strengths of the gluon condensates, we compare our
predicted dilepton yields with those observed in the CERES and HELIOS
experiments at CERN. The simple model gives an adequate description of the
data, and in particular it explains the observed considerable enhancement of
the yield in the low mass region.Comment: 7 pages, 6 figures, reference adde
Dilepton and Photon Emission Rates from a Hadronic Gas III
We extend our early analyses of the dilepton and photon emission rates from a
hadronic gas to account for strange mesons using a density expansion. The
emission rates are reduced to vacuum correlation functions using three-flavor
chiral reduction formulas, and the latters are assessed in terms of empirical
data. Using a fire-ball, we compare our results to the low and intermediate
mass dilepton data available from CERN. Our results suggest that a baryon free
hadronic gas does not account for the excess of low mass dielectrons observed
at CERES but do well in accounting for the intermediate dimuons at HELIOS. The
same observations apply to the recent low and high dielectron rates from
CERES.Comment: 12 pages LaTeX, 11 eps figure
The Skyrme model predictions for the mass spectrum and the - mass splittings
The -plet mass spectrum and the - mass splittings are computed in the framework of the minimal SU(3)
extended Skyrme model. As functions of the Skyrme charge and the SU(3)
symmetry breaking parameters the predictions are presented in tabular form. The
predicted mass splitting - is the smallest among
all SU(3) baryonic multiplets.Comment: 4 pages, 2 tables, version to appear in Phys. Rev.
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