164,341 research outputs found
N K Pi molecular state with I=1 and J(Pi)=3/2-
The structure of the molecule-like state of with spin-parity
and isospin I=1 is studied within the chiral SU(3) quark
model. First we calculate the , , and phase shifts in the
framework of the resonating group method (RGM), and a qualitative agreement
with the experimental data is obtained. Then we perform a rough estimation for
the energy of , and the effect of the mixing to
the configuration is also considered. The
calculated energy is very close to the threshold of the system. A
detailed investigation is worth doing in the further study.Comment: 11 pages, 3 figures; accepted for publication in Phys. Rev.
N K and Delta K states in the chiral SU(3) quark model
The isospin I=0 and I=1 kaon-nucleon , , , wave phase shifts are
studied in the chiral SU(3) quark model by solving the resonating group method
(RGM) equation. The calculated phase shifts for different partial waves are in
agreement with the experimental data. Furthermore, the structures of the
states with L=0, I=1 and I=2 are investigated. We find that the
interaction between and in the case of L=0, I=1 is attractive,
which is not like the situation of the system, where the -wave
interactions between and for both I=0 and I=1 are repulsive. Our
numerical results also show that when the model parameters are taken to be the
same as in our previous and scattering calculations, the
state with L=0 and I=1 is a weakly bound state with about 2 MeV binding energy,
while the one with I=2 is unbound in the present one-channel calculation.Comment: 14 pages, 6 figures. PRC70,064004(2004
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Predicting Software Defects Based on Cognitive Error Theories
As the primary cause of software defects, human error is the key to understanding and perhaps to predicting and preventing software defects. However, little research has been done to forecast software defects based on defects' cognitive nature. This paper proposes an idea for predicting software defects by applying the current scientific understanding of human error mechanisms. This new prediction method is based on the main causal mechanism underlying software defects: an error-prone scenario triggers a sequence of human error modes. Preliminary evidence for supporting this idea is presented
A new three-parameter correlation for gamma-ray bursts with a plateau phase in the afterglow
Gamma ray bursts (GRBs) have great advantages for their huge burst energies,
luminosities and high redshifts in probing the Universe. A few interesting
luminosity correlations of GRBs have been used to test cosmology models.
Especially, for a subsample of long GRBs with known redshifts and a plateau
phase in the afterglow, a correlation between the end time of the plateau phase
(in the GRB rest frame) and the corresponding X-ray luminosity has been found.
In this paper, we re-analyze the subsample and found that a significantly
tighter correlation exists when we add a third parameter, i.e. the isotropic
-ray energy release, into the consideration. Additionally, both long
and intermediate duration GRBs are consistent with the same three-parameter
correlation equation. It is argued that the new three-parameter correlation is
consistent with the hypothesis that the subsample of GRBs with a plateau phase
in the afterglow be associated with the birth of rapidly rotating magnetars,
and that the plateau be due to the continuous energy-injection from the
magnetar. It is suggested that the newly born millisecond magnetars associated
with GRBs might provide a good standard candle in the Universe.Comment: 11 pages, 3 figures, 1 table; A&A, in pres
Sigma_c Dbar and Lambda_c Dbar states in a chiral quark model
The S-wave Sigma_c Dbar and Lambda_c Dbar states with isospin I=1/2 and spin
S=1/2 are dynamically investigated within the framework of a chiral constituent
quark model by solving a resonating group method (RGM) equation. The results
show that the interaction between Sigma_c and Dbar is attractive, which
consequently results in a Sigma_c Dbar bound state with the binding energy of
about 5-42 MeV, unlike the case of Lambda_c Dbar state, which has a repulsive
interaction and thus is unbound. The channel coupling effect of Sigma_c Dbar
and Lambda_c Dbar is found to be negligible due to the fact that the gap
between the Sigma_c Dbar and Lambda_c Dbar thresholds is relatively large and
the Sigma_c Dbar and Lambda_c Dbar transition interaction is weak.Comment: 7 pages,2 figures. arXiv admin note: text overlap with
arXiv:nucl-th/0606056 by other author
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