119367954
Further study on 5q configuration states in the chiral SU(3) quark model
The structure of the 5q configuration states with strangeness S = +1 is further studied in the chiral SU(3) quark model based on our previous work. We calculate the energies of fifteen low configurations of the 5q system, four lowest configurations of J(pi) = (1)/(-)(2) with 4q partition [4]orb (0s(4)) [3 1]of, four of J(pi) (1)/(+)(2) with 4q partition [31]orb (0s(3)0p)[4](sigma f) and seven of J(pi) = (1)/(+)(2) with 4q partition [4](orb) (0s(3)0p)[31](sigma f). Some modifications are made in this further study, i.e., the orbital wave function is extended as an expansion of 4 different size harmonic oscillator forms; three various forms (quadratic, linear and error function form) of the color confinement potential are considered; the states with 4q partition [4](orb)(0s(3)0p) [31](sigma f) are added, which are unnegligible in the J(pi) = (1)/(+)(2) case and were not considered in our previous paper, further the mixing between configurations [31](orb)(0s(3)0p)[4](sigma f) and [4]orb (0s(3)0p)[31](sigma f) is also investigated. The results show that the T = 0 state is still always the lowest one for both J(pi) = (1)/(-)(2) and J(pi) = (1)/(+)(2) states, and J(pi) = (1)/(-)(2), T = 0 state is always lower than that of J(pi) = (1)/(+)(2), All of these modifications can only offer several tens to hundred MeV effect, and the theoretical value of the lowest state is still about 245 MeV higher than the experimental mass of theta(+). It seems to be difficult to get the calculated mass close to the observed one with the reasonable parameters in the framework of the chiral SU(3) quark model when the model space is chosen as a 5q cluster. (c) 2005 Elsevier B.V. All rights reserved.
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.
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.
115307247
E2/M1 ratio of the Delta gamma N transition within the chiral constituent quark model
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.
73573157
Implications of the cosmic infrared background excess for the cosmic star formation
AbstractBy phenomenologically describing the high-redshift star formation history, i.e., $$\dot \rho _ * \left( z \right) \propto \left[ {{{\left( {1 + z} \right)} \mathord{\left/
 {\vphantom {{\left( {1 + z} \right)} {4.5}}} \right.
 \kern-\nulldelimiterspace} {4.5}}} \right]^{ - \alpha }$$, and semi-analytically calculating the fractions of high-redshift Pop I/II and Pop III stars, we investigate the contributions from both high-redshfit Pop I/II and Pop III stars to the observed near-infrared (3 μm < λ < 5 μm) excess in the cosmic infrared background emission. In order to account for the observational level of the near-infrared excess, the power-law index α of the assumed star formation history is constrained to within the range of 0 ≲ α ≲ 1. Such a constraint is obtained under the condition that the viral temperature of dark matter halos belongs to the range of 500 K ⩽ Tvir ⩽ 104 K.
15555566
X-RAY AND HIGH-ENERGY FLARES FROM LATE INTERNAL SHOCKS OF GAMMA-RAY BURSTS
We study afterglow flares of gamma-ray bursts (GRBs) in the framework of the late internal shock (LIS) model based on a careful description for the dynamics of a pair of shocks generated by a collision between two homogeneous shells. First, by confronting the model with some fundamental observational features of X-ray flares, we find some constraints on the properties of the pre-collision shells that are directly determined by the central engine of GRBs. Second, high-energy emission associated with X-ray flares, which arises from synchrotron self-Compton emission of LISs, is investigated in a wide parameter space. The predicted flux of high-energy flares may reach as high as ~10–8 erg cm–2 s–1, which is likely to be detectable with the Large Area Telescope aboard the Fermi Space Telescope (formerly GLAST).
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)%.
15648290
Long-term evolution and gravitational wave radiation of neutron stars with differential rotation induced by r-modes
In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs.
119273299
The Newly Born Magnetars Powering Gamma-Ray Burst Internal-Plateau Emission: Are There Strange Stars?
The internal-plateau X-ray emission of gamma-ray bursts (GRBs) indicates that a newly born magnetar could be the central object of some GRBs. The observed luminosity and duration of the plateaus suggest that, for such a magnetar, a rapid spin with a sub- or millisecond period is sometimes able to last thousands of seconds. In this case, the conventional neutron star (NS) model for the magnetar may be challenged, since the rapid spin of nascent NSs would be remarkably decelerated within hundreds of seconds due to r-mode instability. In contrast, the r-modes can be effectively suppressed in nascent strange stars (SSs). In other words, to a certain extent, only SSs can keep nearly constant extremely rapid spin for a long period of time during the early ages of the stars. We thus propose that the sample of the GRB rapidly spinning magnetars can be used to test the SS hypothesis based on the distinct spin limits of NSs and SSs.