163,822 research outputs found

    N K Pi molecular state with I=1 and J(Pi)=3/2-

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    The structure of the molecule-like state of NKπNK\pi with spin-parity Jπ=3/2J^{\pi}={3/2}^- and isospin I=1 is studied within the chiral SU(3) quark model. First we calculate the NKNK, NπN\pi, and KπK\pi 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 (NKπ)Jπ=3/2,I=1(NK\pi)_{J^{\pi}={3/2}^-,I=1}, and the effect of the mixing to the configuration (ΔK)Jπ=3/2,I=1(\Delta K)_{J^{\pi}={3/2}^-,I=1} is also considered. The calculated energy is very close to the threshold of the NKπNK\pi 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

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    The isospin I=0 and I=1 kaon-nucleon SS, PP, DD, FF 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 ΔK\Delta K states with L=0, I=1 and I=2 are investigated. We find that the interaction between Δ\Delta and KK in the case of L=0, I=1 is attractive, which is not like the situation of the NKNK system, where the SS-wave interactions between NN and KK 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 NNNN and YNYN scattering calculations, the ΔK\Delta K 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

    A new three-parameter correlation for gamma-ray bursts with a plateau phase in the afterglow

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    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 γ\gamma-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

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    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