6,543 research outputs found
-Meson Decays and Strong Breaking in the Three-Flavor Nambu-Jona-Lasinio Model
We study the and
decays using an extended three-flavor Nambu-Jona-Lasinio model that includes
the 't~Hooft instanton induced interaction. We find that the -meson mass,
the decay width and the
decay width are in good agreement with the experimental values when the
breaking is strong and the flavor singlet-octet mixing angle
is about zero. The effects of the breaking on the baryon
number one and two systems are also studied.Comment: 12 pages, LaTeX, 2 eps figures, Talk given at the Joint
Japan-Australia Workshop on Quarks, Hadrons and Nuclei, Adelaide, Australia,
Nov. 15-24, 199
Relation between the separable and one-boson-exchange potential for the covariant Bethe-Salpeter equation
We investigate the relation between the rank I separable potential for the
covariant Bethe-Salpeter equation and the one-boson-exchange potential. After
several trials of the parameter choices, it turns out that it is not always
possible to reproduce the phase-shifts calculated from a single term of the
one-boson-exchange potential especially of the -exchange term,
separately by the rank I separable potential. Instead, it is shown that the
separable potential is useful to parameterize the total nucleon-nucleon
interaction.Comment: 10 pages, 8 figures, to appear in J.Phys.
Enhanced mass transfer during dwarf nova outbursts by irradiation of the secondary?
One of the remaining issues in the problems of dwarf novae is whether or not
enhanced mass transfer due to irradiation of the secondary stars could occur
during outbursts. In a previous paper (Osaki and Meyer 2003), we presented a
theoretical analysis that shows no appreciable enhancement of the mass outflow
rate. This conclusion is challenged by Smak (2004) who claims that equations
used in our analysis were incorrect and that in systems with short orbital
periods substantial enhancement could occur. In this letter, we examine the
origin of such divergent conclusions. We show that Smak's solutions are
unacceptable from the standpoint of the equation of continuity and that our
analysis is an appropriate one to treat this problem.Comment: 4 pages, accepted by Astronomy &.Astrophysics Letter
Magnetic ordering and fluctuation in kagome lattice antiferromagnets, Fe and Cr jarosites
Jarosite family compounds, KFe_3(OH)_6(SO_4)_2, (abbreviate Fe jarosite), and
KCr_3(OH)_6(SO_4)_2, (Cr jarosite), are typical examples of the Heisenberg
antiferromagnet on the kagome lattice and have been investigated by means of
magnetization and NMR experiments. The susceptibility of Cr jarosite deviates
from Curie-Weiss law due to the short-range spin correlation below about 150 K
and shows the magnetic transition at 4.2 K, while Fe jarosite has the
transition at 65 K. The susceptibility data fit well with the calculated one on
the high temperature expansion for the Heisenberg antiferromagnet on the kagome
lattice. The values of exchange interaction of Cr jarosite and Fe jarosite are
derived to be J_Cr = 4.9 K and J_Fe = 23 K, respectively. The 1H-NMR spectra of
Fe jarosite suggest that the ordered spin structure is the q = 0 type with
positive chirality of the 120 degrees configuration. The transition is caused
by a weak single-ion type anisotropy. The spin-lattice relaxation rate, 1/T_1,
of Fe jarosite in the ordered phase decreases sharply with lowering the
temperature and can be well explained by the two-magnon process of spin wave
with the anisotropy.Comment: REVTeX, 14 pages with 5 figures. Submitted to Canadian Journal of
Physic
Spin 3/2 Penta-quarks in anisotropic lattice QCD
A high-precision mass measurement for the pentaquark (5Q) Theta^+ in
J^P=3/2^{\pm} channel is performed in anisotropic quenched lattice QCD using a
large number of gauge configurations as N_{conf}=1000. We employ the standard
Wilson gauge action at beta=5.75 and the O(a) improved Wilson (clover) quark
action with kappa=0.1210(0.0010)0.1240 on a 12^3 \times 96 lattice with the
renormalized anisotropy as a_s/a_t = 4. The Rarita-Schwinger formalism is
adopted for the interpolating fields. Several types of the interpolating fields
with isospin I=0 are examined such as (a) the NK^*-type, (b) the
(color-)twisted NK^*-type, (c) a diquark-type. The chiral extrapolation leads
to only massive states, i.e., m_{5Q} \simeq 2.1-2.2 GeV in J^P=3/2^- channel,
and m_{5Q} = 2.4-2.6 GeV in J^P=3/2^+ channel. The analysis with the hybrid
boundary condition(HBC) is performed to investigate whether these states are
compact 5Q resonances or not. No low-lying compact 5Q resonance states are
found below 2.1GeV.Comment: 15 pages, 6 figures, 4 table
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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