Abstract. We review the application of non-relativistic constituent quark models to study one, two and three non-strange baryon systems. We present results for the baryon spectra, potentials and observables of the NN, N∆, ∆∆ and NN * (1440) systems, and also for the binding energies of three non-strange baryon systems. We make emphasis on observable effects related to quark antisymmetry and its interplay with quark dynamics.
The direct reaction of
[NPCl2]
n
with the difunctional
reagent 2,2‘-dihydroxybiphenyl
(HOC6H4C6H4OH) and
K2CO3 in tetrahydrofuran gave soluble
linear phosphazene high polymers instead
of the expected cross-linked products. The reaction of
[N3P3Cl6] with 1, 2, or 3
equiv of
HOC6H4C6H4OH
and K2CO3 in acetone gave the known spiro
derivatives
[N3P3Cl4(O2C12H8)],
[N3P3Cl2(O2C12H8)2],
and [N3P3(O2C12H8)3] without
formation of bridging products, and the dichloro derivative reacted
directly with para-substituted phenols HOC6H4R and
K2CO3 in acetone to give the new compounds
[N3P3(OC6H4R)2(O2C12H8)2]
(R = Br, COC6H5, or OCH3),
without signs of replacement of the bis(aryloxy) substituents.
In an analogous
manner, poly(dichlorophosphazene)
[NPCl2]
n
reacted with
HOC6H4C6H4OH and
K2CO3 in THF without
significant cross-linking to give, depending on the mole ratio, the
soluble polymer
[NP(O2C12H8)]
n
(M
w =
450 000, T
g = 160 °C) or the partially
substituted polymers
{[NP(O2C12H8)]0.35[NPCl2]0.65}
n
.
The latter
were subsequently reacted with the para-substituted phenols
HOC6H4R and K2CO3
in THF to give the
random copolymers
{[NP(O2C12H8)]0.35[NP(OC6H4R)2]0.65}
n
[R = Br, CN, COCH3, or COC6H5).
The new
polymers are soluble (except the CN derivative, which was sparingly
soluble) white solids, with only a
few ppm of unreacted chlorine, and Mw of the order of
1 000 000 with polydispersities varying from 3 to
10. The T
g values varied with R ranging
from 73 °C (R = CN) to 54 °C (R = COMe).
By solving the Schrödinger equation for the three-quark system in the hyperspherical harmonic approach, we have studied the low energy part of the nucleon and ∆ spectra using a quark-quark interaction which reproduces the nucleon-nucleon phenomenology. The quark-quark hamiltonian considered includes, besides the usual one-gluon exchange, pion and sigma exchanges generated by the chiral symmetry breaking. The baryonic spectrum obtained is reasonable and the resulting wave function gives consistency to the ansatz used in the two baryon system.
We perform a quark model calculation of the bb and cc spectra from a screened funnel potential form suggested by unquenched lattice calculations. A connection between the lattice screening parameter and an effective gluon mass directly derived from QCD is established. Spin-spin energy splittings, leptonic widths and radiative decays are also examined providing a test for the description of the states.
We study the electromagnetic transitions of the Roper N(1440) resonance. Our
results, when combined with the previously obtained for the mass and the pionic
strong decay widths of the Roper, show that within a non-relativistic
constituent quark model scheme, a comprehensible understanding of the Roper
phenomenology can be achieved. They also seem to support the view of the Roper
as a radial excitation of the nucleon, though more experimental data are needed
to reach a definitive conclusion.Comment: 14 pages, 4 figures (7 postscript files). Some referencess adde
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