122891080
THE GENERALIZED CHAPLYGIN GAS MODEL WITH INTERACTION
A two-fluid generalized Chaplygin gas (GCG) model including two different cases is considered in this paper. Concretely, the evolution of the GCG model with interaction is discussed and the statefinder diagnostic for the GCG models is performed, respectively. By analysis, we show that the effective state parameter of dark energy can cross the so-called phantom divide ω = -1, the behavior of GCG will be like ΛCDM in the future and therefore our Universe will not end up with the Big Rip in the future. In addition, we find that the statefinder diagnostic can differentiate the GCG model with or without interaction. Also, trajectories of both the GCG model mixed with cold dark matter (CDM) and the pure GCG model in the parameter plane are illustrated to be significantly different.
122969926
K− Nucleus Elastic Scattering and Momentum-Dependent Optical Potentials
The K− nucleus differential elastic scattering cross section for 12C and 40Ca at is calculated with three momentum-dependent optical potential models, which are density-dependent, relativistic mean field, and hybrid model, respectively. It is found that the forms of momentum-dependent optical potential models proposed by us are reasonable and gain success in the calculations and the momentum-dependent hybrid model is the best model for the K− nucleus elastic scattering.
120641266
$K^-$-Nuclear Bound States in Relativistic Mean-Field Theory
122405140
Effects of Delta Degrees of Freedom on Quark Condensate in Hot and Dense Matter
The relativistic mean-field theory is applied to study the quark condensate systematically in nuclear matter at zero and finite temperature in terms of the relative importance of delta degrees of freedom. Calculations have included the high-order contributions to quark condensate in nuclear medium due to the baryon-baryon interactions. Numerical results are presented for the nuclear density up to five times larger than the normal density and temperature up to 120 MeV. It is found that the delta resonance in nuclear matter can cause substantial decreases to in-medium quark condensate.
124229961
A light-cone QCD inspired effective Hamiltonian model for pseudoscalar and scalar mesons
Considering the one-gluon exchange interaction and phenomenological quark confinement potential, an improved light-cone effective Hamiltonian for mesons and the corresponding radial mass eigen equations in angular momentum representation is obtained. Solving the J = 0 eigen equations numerically and using a set of adjustable parameters, the obtained solutions for ground states and radial excited states can simultaneously describe both pseudoscalar and scalar flavour-off-diagonal mesons. Some radial excited states are also predicted and wait for experimental test. More results for the vector and axial vector mesons are expected.
18809945
Quark mass and phase transition for strange matter
We have derived the popularly used mass parametrization formula for light quarks and modified the corresponding formula for strange quarks with the mass-densitydependent model. A simple expression for the critical density of phase transition of strange quark matter at zero temperature is thus found and its value is estimated to be over 6 times the normal nuclear density.
13168124
DETECTION OF A TERTIARY BROWN DWARF COMPANION IN THE sdB-TYPE ECLIPSING BINARY HS 0705+6700
HS 0705+6700 is a short-period (P = 2.3 hr), close binary containing a hot sdB-type primary and a fully convective secondary. We have monitored this eclipsing binary for more than two years and as a result, 32 times of light minimum were obtained. Based on our new eclipse times together with these compiled from the literature, it is discovered that the observed-calculated curve of HS 0705+6700 shows a cyclic variation with a period of 7.15 years and a semiamplitude of 92.4 s. The periodic change was analyzed for the light-travel time effect that may be due to the presence of a tertiary companion. The mass of the third body is determined to be M3 sin i' = 0.0377(+/- 0.0043) M(circle dot) when a total mass of 0.617 M(circle dot) for HS 0705+6700 is adopted. For orbital inclinations i' >= 32.degrees 8, the mass of the tertiary component would be below the stable hydrogen-burning limit of M(3) similar to 0.072M(circle dot), and thus it would be a brown dwarf. The third body is orbiting the sdB-type binary at a distance shorter than 3.6 AU. HS 0705+6700 was formed through the evolution of a common envelope after the primary becomes a red giant. The detection of a substellar companion in HS 0705+6700 system at this distance from the binary could give some constraints on stellar evolution in such systems and the interactions between red giants and their companions.
119496386
Inflation in Kaluza-Klein theory: Relation between the fine structure constant and the cosmological constant
In this paper we investigate a model of an inflationary universe in Kaluza-Klein theory, which is a four-dimensional de Sitter space plus a one-dimensional compactified internal space. We find that the energy scale for inflation can be predicted from the fine-structure constant in a self-consistent solution of the semi-classical Einstein equations including the Casimir effect. From the observed value of the fine-structure constant, we obtain an energy scale for inflation of $\epsilon=1.84\times 10^{16}g_*^{1/4}$ Gev, where $g_*$ is a dimensionless number depending on the spin and number of matter fields existing in the universe. This value is consistent with the values often discussed for inflation and grand unification. The wave function for this model predicts a high probability for forming such universes, independent of the value of the cosmological constant. The tunneling probability favors the creation of inflationary universes with a compactified dimension, over those with all macroscopic dimensions.
122935177
STRANGENESS PRODUCTION IN RELATIVISTIC NUCLEAR COLLISIONS
Quark matter produced in relativistic nuclear collisions is thermally equilibrated. A phenomenological model is used to calculate the yield of strange quark pairs at AGS, SPS and RHIC, which is comparable to the results from the experiments. In addition, analysis with this model indicates that there is a signal of phase transition where the cms energy is approximately 7.5 GeV.
118380628
Binary interactions on the calibrations of star formation rate
Using the Yunnan evolutionary population synthesis (EPS) models with and without binary interactions, we present the luminosity of H alpha recombination line (L-H alpha), the luminosity of [O II]lambda 3727 forbidden line doublet (L-[O II]), the ultraviolet (UV) fluxes at 1500 and 2800 angstrom (L-i,L-UV) and far-infrared flux (L-FIR) for burst, S0, Sa-Sd and Irr galaxies, and present the calibrations of star formation rate (SFR) in terms of these diagnostics. By comparison, we find that binary interactions lower the SFR versus L-H alpha and SFR versus L-[O II] conversion factors by similar to 0.2 dex. The main reason is that binary interactions raise the UV flux (shortwards of the Lyman limit) of the stellar population (SP) in the age range 6.7 < log t/yr < 8.4 and thus more ionizing photons are present in the nebula. Moreover, binary interactions do not significantly vary the calibrations of SFR in terms of L-i,L-UV. This is because binary interactions raise the flux at 1500 angstrom of the SP in the range 8.75 < log t/yr < 9.2 and the maximal difference is about 1 dex. In addition, binary interactions have little effect on the flux at 2800 angstrom. At last, the calibration of SFR from L-FIR is almost unaffected by binary interactions. This is caused by the fact that binary interactions almost do not affect the bolometric magnitudes of SPs. We also discuss the effects of initial mass function (IMF), gas-recycle assumption and EPS models [including GISSEL98 (Galaxy Isochrone Synthesis Spectral Evolution Library), BC03, STARBURST99, POPSTAR and PEGASE models] on these SFR calibrations. Comparing the results obtained by using the Salpeter (hereafter S55) IMF with those by using the Miller & Scalo (hereafterMS79) IMF, we find that the SFR versus L-H alpha and SFR versus L-[O II] conversion factors obtained by using the S55 IMF are greater by 0.4 and 0.2 dex than those by using the MS79 IMF for the Yunnan models with and without binary interactions, respectively. The SFR versus L-i,L-UV and SFR versus L-FIR conversion factors by using the S55 IMF are larger by an amount of 0.2 dex than the corresponding ones by using the MS79 IMF. The inclusion of gas-recycle assumption only lowers these SFR calibrations at faint SFR. Moreover, comparing the results when using different EPS models, we find that the differences in the SFR versus L-H alpha and SFR versus L-[O II] conversion factors reach similar to 0.7 and 0.9 dex, the difference in the SFR versus L-FIR conversion factor reaches 0.4 and 0.8 dex, and the differences in the SFR versus L-i,L-UV conversion factors reach 0.3 and 0.2 dex when using the S55 and non-S55 IMFs (including Chabrier, Kroupa-Aarseth-Hurley, Kroupa-Tout-Gilmore and Miller-Scalo IMFs, partly caused by the difference in the IMF), respectively. At last, we give the conversion coefficients between SFR and these diagnostics for all models.
118305953
Accretion, growth of supermassive black holes, and feedback in galaxy mergers
Super-Eddington accretion is very efficient in growing the mass of a black hole: in a fraction of the Eddington time its mass can grow to an arbitrary large value if the feedback effect is not taken into account. However, since super-Eddington accretion has a very low radiation efficiency, people have argued against it as a major process for the growth of the black holes in quasars since observations have constrained the average accretion efficiency of the black holes in quasars to be >rsim0.1. In this paper, we show that the observational constraint does not need to be violated if the black holes in quasars have undergone a two-phase growing process: with a short super-Eddington accretion process they get their masses inflated by a very large factor until the feedback process becomes important, then with a prolonged sub-Eddington accretion process they have their masses increased by a factor of >rsim 2. The overall average efficiency of this two-phase process is then >rsim 0.1, and the existence of black holes of masses ∼109 M⊙ by redshift 6 is easily explained. An observational test of the existence of the super-Eddington accretion phase is briefly discussed.