15263185
Baryon-Meson Interactions in Chiral Quark Model
Using the resonating group method (RGM), we dynamically study the baryon-meson interactions in chiral quark model. Some interesting results are obtained: (1) The Sigma K state has an attractive interaction, which consequently results in a Sigma K quasibound state. When the channel coupling of Sigma K and Lambda K is considered, a sharp resonance appears between the thresholds of these two channels. (2) The interaction of Delta K state with isospin I=1 is attractive, which can make for a Delta K quasibound state. (3) When the coupling to the Lambda K* channel is considered, the N phi is found to be a quasibound state in the extended chiral SU(3) quark model with several MeV binding energy. (4) The calculated S-, P-, D-, and F-wave KN phase shifts achieve a considerable improvement in not only the signs but also the magnitudes in comparison with other's previous quark model study.
120491051
Hyperon-Meson Vertices and Hyperon-Nucleon Interactions on Quark Model
In this paper, we introduce two parts of work: the hyperon-meson vertex structure from the one-gluon-exchange quark-antiquark pair creation model and the hyperon-nucleon interactions on a modified quark potential model. For both parts some significant results have been obtained.
123526917
Multi-strange hadronic systems in a chiral SU(3) quark mean field model
We apply the chiral SU(3) quark mean field model to investigate the finite nuclei. We find that the combined confining potential chi(c)(C) is more proper to describe finite nuclei compared with the scalar and scalar-vector potentials. The hypernuclei and multi-strange objects which include A and Xi are discussed in this model. The maximum binding energy for such kind of multi-strange objects is about 16-17 MeV and the corresponding strangeness fraction f(s) is around 1.2-1.3. (C) 2002 Elsevier Science B.V. All rights reserved.
121548156
BARYON–BARYON INTERACTION IN THE EXTENDED CHIRAL SU(3) QUARK MODEL
The hyperon-nucleon scattering processes and some dibaryon states are studied both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model by solving the resonating group method (RGM) equation. We find that the short-range interaction could be described either by the one-gluon exchange or by the vector meson exchange for baryon-baryon system.
115307247
E2/M1 ratio of the Delta gamma N transition within the chiral constituent quark model
122341351
Color screening effect in the quark potential model
By using the color confinement potential which includes the color screening effect, we studied the baryon spectra and the nucleon-nucleon interaction. The results show that the color screening effect not only improves the baryon spectrum calculation, but also can solve the long-tail problem of the color Van der Waals force. A part of the medium attraction of the nuclear force can be obtained from the color Van der Waals force.
118630729
The luminosity function of Swift long gamma-ray bursts
The formation rate of long gamma-ray bursts (GRBs) could follow the cosmic star formation rate (SFR) incorporating with cosmic metallicity evolution. Therefore, the luminosity function (LF) of GRBs can in principle be explored by modeling the redshift-luminosity distributions of Swift observed GRBs. For an assumed LF form as �z(L) / e −L p/L (L=Lp) −� (1 + z) � , we found that (1) the approximate broken-power law distribution of the luminosities of the Swift observed GRBs is probably caused by the luminosity selection of the telescope by reducing the number of the GRBs with low luminosities, (2) the evolution of the LF could approach to be very weak, i.e., � � 0, if the GRB environments are metal-poor as Z < (0:1 0:3)Z� , and (3) the slope of the LF can be derived to be within � � (1:55 1:72) by fitting the redshift distribution of the GRBs and qualitatively explaining the luminosity distribution. Finally, we also suggest an empirical detection efficiency as a function of flux for the Swift Burst Alert Telescope (BAT) in order to model the logN logP distribution of the GRBs.
119302412
HOW CAN NEWLY BORN RAPIDLY ROTATING NEUTRON STARS BECOME MAGNETARS
In a newly born (high-temperature and Keplerian rotating) neutron star, r-mode instability can lead to stellar differential rotation, which winds the seed poloidal magnetic field (∼10{sup 11} G) to generate an ultra-high (∼10{sup 17} G) toroidal field component. Subsequently, by succumbing to the Tayler instability, the toroidal field could be partially transformed into a new poloidal field. Through such dynamo processes, the newly born neutron star with sufficiently rapid rotation could become a magnetar on a timescale of ∼10{sup 2} {sup –} {sup 3} s, with a surface dipolar magnetic field of ∼10{sup 15} G. Accompanying the field amplification, the star could spin down to a period of ∼5 ms through gravitational wave radiation due to the r-mode instability and, in particular, the non-axisymmetric stellar deformation caused by the toroidal field. This scenario provides a possible explanation for why the remnant neutron stars formed in gamma-ray bursts and superluminous supernovae could be millisecond magnetars.
118552679
Cosmic histories of star formation and reionization: an analysis with a power-law approximation
With a simple power-law approximation of high-redshift (3.5) star formation history, i.e., *(z)[(1+z)/4.5]??, we investigate the reionization of intergalactic medium (IGM) and the consequent Thomson scattering optical depth for cosmic microwave background (CMB) photons. A constraint on the evolution index ? is derived from the CMB optical depth measured by the Wilkinson Microwave Anisotropy Probe (WMAP) experiment, which reads ? ? 2.18 lg ??3.89, where the free parameter ? is the number of the escaped ionizing ultraviolet photons per baryon. At the same time, the redshift zf at which the IGM is fully ionized can also be expressed as a function of ? as well as ?. By further taking into account the implication of the Gunn-Peterson trough observations to quasars for the full reionization redshift, i.e., 6zf7, we obtain 0.3?1.3 and 80?230. For a typical number of ~ 4000 of ionizing photons released per baryon of normal stars, the fraction of these photons escaping from the stars, fesc, can be constrained to within the range of (2.0?5.8)%.
197531984
Thermal evolution of rotating strange stars in color superconductivity phase
120879129
Effect of a strong magnetic field on the surface electric field of strange stars
We made a detailed study of the properties of the electron layer near the quark surface of strange stars with strong (${\sim}10^{14}{-}10^{17}$ G) magnetic fields. The electrostatic potential and the electric field at the quark surface were calculated as functions of the magnetic field intensity of bare strange stars. Using an ultrastrong ($B\geq 2.5\times10^{16}$ G) magnetic field, we found that the distribution of electrons becomes an exponential function of radial distance, which is quite different in a magnetic field-free case. We also calculated the variation in gap width between the strange core and the normal nuclear crust for strange stars, which is due to magnetic field effect.