7,632 research outputs found
Nuclear G-Matrix Elements from Nonlocal Potentials
We study effects of nonlocality in the nuclear force on the G-matrix elements
for finite nuclei. Nuclear G-matrix elements for \O16 are calculated in the
harmonic oscillator basis from a nonlocal potential which models quark exchange
effects between two nucleons. We employ a simple form of potential that gives
the same phase shifts as a realistic local nucleon potential. The G-matrix
elements calculated from the nonlocal potential show moderate increase in
repulsion from those derived from the local potential.Comment: 11 page, LaTeX, 2 PS figures, uses epsf.st
transition in lattice QCD
We study the electromagnetic
transition in 2+1 flavor lattice QCD, which gives access to the dominant decay
mode of baryon. The magnetic dipole and the electric quadrupole
transition form factors are computed. The magnetic dipole form factor is found
to be mainly determined by the strange quark and the electric quadrupole form
factor to be negligibly small, in consistency with the quark model. We also
evaluate the helicity amplitudes and the decay rate.Comment: 8 pages, 1 figure. Added references and discussio
A look inside charmed-strange baryons from lattice QCD
The electromagnetic form factors of the spin-3/2 baryons, namely
, , and , are
calculated in full QCD on PACS-CS lattices with a pion mass of
156(9) MeV. The electric charge radii and magnetic moments from the and
multipole form factors are extracted. Results for the electric quadrupole
form factors, , are also given. Quark sector contributions are computed
individually for each observable and then combined to obtain the baryon
properties. We find that the charm quark contributions are systematically
smaller than the strange-quark contributions in the case of the charge radii
and magnetic moments. moments of the and
provide a statistically significant data to conclude that their electric charge
distributions are deformed to an oblate shape. Properties of the spin-1/2
and baryons are also computed and a thorough
comparison is given. This complete study gives valuable hints about the
heavy-quark dynamics in charmed hadrons.Comment: 14 pages, 14 figures. Includes a subsection on the systematic effect
Proposal for exotic-hadron search by fragmentation functions
It is proposed that fragmentation functions should be used to identify exotic
hadrons. As an example, fragmentation functions of the scalar meson f_0(980)
are investigated. It is pointed out that the second moments and functional
forms of the u- and s-quark fragmentation functions can distinguish the
tetraquark structure from . By the global analysis of f_0 (980)
production data in electron-positron annihilation, its fragmentation functions
and their uncertainties are determined. It is found that the current available
data are not sufficient to determine its internal structure, while precise data
in future should be able to identify exotic quark configurations.Comment: 4 pages, 4 figures, revtex, To be published in PR
Kaon-nucleon interaction in the extended chiral SU(3) quark model
The chiral SU(3) quark model is extended to include the coupling between the
quark and vector chiral fields. The one-gluon exchange (OGE) which dominantly
governs the short-range quark-quark interaction in the original chiral SU(3)
quark model is now nearly replaced by the vector-meson exchange. Using this
model, the isospin I=0 and I=1 kaon-nucleon S, P, D, F wave phase shifts are
dynamically studied by solving the resonating group method (RGM) equation.
Similar to those given by the original chiral SU(3) quark model, the calculated
results for many partial waves are consistent with the experiment, while there
is no improvement in this new approach for the P_{13} and D_{15} channels, of
which the theoretical phase shifts are too much repulsive and attractive
respectively when the laboratory momentum of the kaon meson is greater than 300
MeV.Comment: 19 pages, 16 figures. Accepted by Phys. Rev.
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