61 research outputs found
Grozdovi obojenih s-valnih kvarkova s lomljenjem okusne simetrije
We study the properties of coloured three-particle s-wave quark clusters when flavour symmetry is broken. The relevance of such clusters for models of pentaquarks is shortly mentioned.Proučavamo svojstva obojenih tročestičnih s-valnih kvarkovskih grozdova s lomljenjem okusne simetrije. Kratko se spominje važnost tih grozdova za pentakvarkovske modele
Spectrum of the Y=2 Pentaquarks
By assuming a mass formula for the spectrum of the Y=2 pentaquarks, where the
chromo-magnetic interaction plays a main role, and identifying the lightest
state with the Theta^+(1540), we predict a spectrum in good agreement with the
few I=0 and I=1 candidates proposed in the past.Comment: 12 pages, 4 figures, LaTe
The discovery and properties of pentaquarks
The pentaquarks are exotic baryons formed of four quarks and an antiquarks.
Their existence has been discussed in the literature over the last 30 years or
more, first in connection with kaon nucleon scattering data. The subject has
been revived by the end of 2002 when experimental evidence of a narrow baryon
of strangeness = + 1, and mass 1530 MeV has been found. This is
interpreted as the lightest member of an SU(3)-flavor antidecuplet. Here we
shall mainly review the predictions of pentaquark properties as e.g. mass, spin
and parity, within constituent quark models.
Both light and heavy pentaquarks will be presented.Comment: Plenary talk, MESON2004 Conference Proceedings, Crakow, June 4-8 200
Flavored exotic multibaryons and hypernuclei in topological soliton models
The energies of baryon states with positive strangeness, or anti-charm
(-beauty) are estimated in chiral soliton approach, in the "rigid oscillator"
version of the bound state soliton model proposed by Klebanov and Westerberg.
Positive strangeness states can appear as relatively narrow nuclear levels
(Theta-hypernuclei), the states with heavy anti-flavors can be bound with
respect to strong interactions in the original Skyrme variant of the model (SK4
variant). The binding energies of anti-flavored states are estimated also in
the variant of the model with 6-th order term in chiral derivatives in the
lagrangian as solitons stabilizer (SK6 variant). The latter variant is less
attractive, and nuclear states with anti-charm or anti-beauty can be unstable
relative to strong interactions. The chances to get bound hypernuclei with
heavy antiflavors are greater within "nuclear variant" of the model with
rescaled model parameter (Skyrme constant e or e' decreased by ~30%) which is
expected to be valid for baryon numbers greater than B ~10. The rational map
approximation is used to describe multiskyrmions with baryon number up to ~30
and to calculate the quantities necessary for their quantization (moments of
inertia, sigma-term, etc.).Comment: 24 pages, 7 table
Constructing Hybrid Baryons with Flux Tubes
Hybrid baryon states are described in quark potential models as having
explicit excitation of the gluon degrees of freedom. Such states are described
in a model motivated by the strong coupling limit of Hamiltonian lattice gauge
theory, where three flux tubes meeting at a junction play the role of the glue.
The adiabatic approximation for the quark motion is used, and the flux tubes
and junction are modeled by beads which are attracted to each other and the
quarks by a linear potential, and vibrate in various string modes. Quantum
numbers and estimates of the energies of the lightest hybrid baryons are
provided.Comment: 4 pages, RevTeX. Submitted to Physical Review Letter
Pentaquark baryons in SU(3) quark model
We study the SU(3) group structure of pentaquark baryons which are made of
four quarks and one antiquark. The pentaquark baryons form {1}, {8}, {10},
{10}-bar, {27}, and {35} multiplets in SU(3) quark model. First, the flavor
wave functions of all the pentaquark baryons are constructed in SU(3) quark
model and then the flavor SU(3) symmetry relations for the interactions of the
pentaquarks with three-quark baryons and pentaquark baryons are obtained.Comment: REVTeX, 36 pages, 8 figures, references added, section for mass sum
rules is added, to appear in Phys. Rev.
Z^* Resonances: Phenomenology and Models
We explore the phenomenology of, and models for, the Z^* resonances, the
lowest of which is now well established, and called the Theta. We provide an
overview of three models which have been proposed to explain its existence
and/or its small width, and point out other relevant predictions, and potential
problems, for each. The relation to what is known about KN scattering,
including possible resonance signals in other channels, is also discussed.Comment: 29 pages, uses RevTeX4; expanded version (published form
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