The Influence of the Renormalization Condition to the Equation of State of the Nuclear Matter

In the relativistic σ-ω model, the influences of the parameters b, c, d in the potential U(σ) = (1/2!)bo2 - -(1/3!)cσ3 (1/4!)dσ4 to the incompressibility, effective mass and binding energy of the nuclear matter are studied in detail.The calculation of equation of state of nuclear matter shows that the values of b, c, d depend on the renormalization condition, we also find that a soft equation of state of nuclear matter can be obtained in a suitable renormalization condition, and the experimental incompressibility coefficient can be reproduced. These results are also used to study the thermal properties of hot A-resonant nuclear matter.self-interaction of σ meson, renormalization, hot and dense hadronic matter ``     

Power Consideration for Pulsed Discharges in Potassium Seeded Argon

Minimization of energy consumed in plasma generation is critical for applications, in which a large volume of plasmas is needed. We suggest that a high electron density atmospheric pressure plasmas can be generated by pulsed discharges in potassium seeded argon at an elevated temperature with a very small power input. The ionization efficiency and power budget of pulsed discharges in such plasmas are analytically studied. The results show that ionization efficiency of argon, especially at small reduced electric field E/N （the ratio of the electric field to the gas number density）, is improved effectively in the presence of small amount of potassium additives. Power input of pulsed discharge to sustain a prescribed average level of ionization in potassium seeded argon is three orders of magnitude lower than that in pure argon. Further, unlike in pure argon, it is found that very short high-voltage pulses with very high repetition rates are unnecessary in potassium seeded argon. A pulse with lOOns of pulse duration, 5kHz of repetition rate, and 2Td （1 Td = 1 × 10^-21 Vm^2） of E/N is enough to sustain an electron density of 10^19 m^-3 in 1 arm 1500K Ar＋0.1% K mixture, with a very small power input of about 0.08 × 10^4 W/m^3.     

Role of t-channel meson exchanges in S-wave πN and KN scatterings

The low-energy S-wave πN and KN scatterings are studied by using the K-matrix approach within the meson exchange framework. The t-channel meson exchanges, especially ρ and σ exchanges, are found to play a very important role in these two processes. The t-channel ρ exchange determines the isospin structure of the scattering amplitudes, it gives attractive force in the low isospin state but repulsive force in the high isospin state. The t-channel σ exchange gives a very large contribution in these two processes, while it is negligible in meson-meson S-wave scatterings.     

Sigma Meson Production in Nuclear Reactions

The sigma meson production in p ＋ ^12C and p A- ^40Ca reactions at the incident energy Ep = 1.5 GeV is investigated within the Quantum Molecular Dynamics model. The simulation results indicate a distinctive A dependence of the sigma production, that is, the increase of A is followed by an increase of the production cross sections. We find that the σ meson production in proton-induced reactions is strongly medium-dependent, and the produced σ mesons decaying in a denser medium experience a stronger mass shift towards lower masses. This mass shift is an experimentally accessible observable in the final state pion pairs, which do not suffer from reabsorption by the surrounding nucleons. It is pointed out that the ratio of measured sigma cross sections as a function of the sigma invariant-mass from various reactions is a good probe to explore the existence of the σ meson in a dense nuclear environment.     

Effects on the Hadron Propagators due to kμkv Terms in the Vector Meson Propagator

In an approximation where the baryon current conservation is violated, the contribution of the kμkv termsin the vector meson propagator may not vanish. Their effects on the baryon and meson spectral functions and on theconsequences of self-consistency are studied in the relativistic self-consistent Hartree-Fock approximation by means ofthe σ-ω model. Two cases where the kμkv terms are and are not neglected are compared. It is found that there is amarked change in the baryon spectral function which becomes more peaked in the latter case. Such a change remainseven by a proper readjustment of parameters. The effects of self-consistency in the σ -ω model are qualitatively the samein both cases, though quantitatively there is some significant difference.     

Masses and Widths of Light Scalar Mesons in Chiral Perturbation Theory

Based on the diquark model, we assume that the light scalar mesons are q^2q^-2 states rather than qq^-. The chiral effective Lagrangian for the light scalar meson is constructed, and the mass relations are obtained： the isotriplet （a0） and the isosinglet （f0） are the heaviest and are degenerate, the isodoublets （κ） are heavier and the other isosinglet （σ） is the lightest; and 2Mκ^2 = Mα0^2＋ Mσ^2. Using experimental value for a0 and σ mass, we obtain Mκ=794 MeV, which is consistent with the experimental value. Then taking Г（a0^0 →ηπ^0） = 90 MeV and Г（f0→π^0π^0） = 20 MeV, we get the width of σ is： Г（σ0→π^＋π^-）= 150 MeV.     

Survival of charged ρ condensation at high temperature and density

The charged vector ρ mesons in the presence of external magnetic fields at finite temperature T and chemical potential μ have been investigated in the framework of the Nambu-Jona-Lasinio model.We compute the masses of charged ρ mesons numerically as a function of the magnetic field for different values of temperature and chemical potential.The self-energy of the ρ meson contains the quark-loop contribution,i.e.the leading order contribution in 1/N_C expansion.The charged ρ meson mass decreases with the magnetic field and drops to zero at a critical magnetic field eB_c,which indicates that the charged vector meson condensation,i.e.the electromagnetic superconductor can be induced above the critical magnetic field.Surprisingly,it is found that the charged ρ condensation can even survive at high temperature and density.At zero temperature,the critical magnetic field just increases slightly with the chemical potential,which indicates that charged ρ condensation might occur inside compact stars.At zero density,in the temperature range 0.2 — 0.5 GeV,the critical magnetic field for charged ρ condensation is in the range of 0.2 — 0.6 GeV~2,which indicates that a high temperature electromagnetic superconductor might be created at LHC.     

Electronic Structural Properties and Superconductivity of Diborides in the MgB2 Structure

We calculate the critical temperature Tc of a wide range of diborides which have the same crystal structure as MgB2.Their electronic structure is also calculated in the framework of the local density approximation method of density functional theory be using the pseudopotential plane wave approach.The Hopfield factors η of these materials are calculated by the frozen phonon method.Our results show that most of these diborides have low η,and hence low or no Tc;this is consistent with experimental observations.The most important result of our calculation is that AgB2 and AuB2 have higher Tc than MgB2.The high Tc of these two materials comes from the combination of the high density of states and high deformation potential of the σ bands.     

One—Proton Halo in ^31Cl with Relativistic Mean—Field Theory

We investigate proton-rich isotopes ^31,32Cl using the nonlinear relativistic mean-field model.It is shown that this model can reproduce the properties of these nuclei well.A long tail appears in the calculated proton density distribution of ^31Cl.The results of relativistic density-dependent Hartree theory show a similar trend of tail density distribution.It is strongly suggested that there is a proton halo in ^31Cl and it is indicated that there may be a proton skin in ^32Cl.The relation between the proton halo in ^31Cl and the new proton magic number is discussed.     

Analytical and Numerical Studies of Quantum Plateau State in One Alternating Heisenberg Chain

By using the coupled duster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a magnetic field, the results obtained from the coupled cluster method and density matrix renormalization group method both show that the ground state of the aiternating chain is a gapped dimerized state when the parameter a exceeds a critical point ac. The value of the critical points can be determined precisely by a detailed investigation of the behavior of the spin gap. The system therefore possesses an m = 0 plateau state in the presence of a magnetic field When a 〉 ac. In addition to the m = 0 plateau state, the results of density matrix renormaiization group indicate that there is an m = 1/4 plateau state that occurs between two critical fields in the alternating chain if a 〉 1. The mechanism for the m = 1/4 plateau state and the critical behavior of the magnetization as one approaches this plateau state are also discussed.     

Monte Carlo study of nanowire magnetic properties

In this work, we use Monte Carlo simulations to study the magnetic properties of a nanowire system based on a honeycomb lattice, in the absence as well as in the presence of both an external magnetic field and crystal field. The system is formed with NL layers having spins that can take the values σ = ±1/2 and S = ±1, 0. The blocking temperature is deduced, for each spin configuration, depending on the crystal field Δ. The effect of the exchange interaction coupling Jp between the spin configurations σ and S is studied for different values of temperature at fixed crystal field. The established ground-state phase diagram, in the plane (Jp ,Δ), shows that the only stable configurations are: (1/2, 0), (1/2, +1), and (1/2,-1). The thermal magnetization and susceptibility are investigated for the two spin configurations, in the absence as well as in the presence of a crystal field. Finally, we establish the hysteresis cycle for different temperature values, showing that there is almost no remaining magnetization in the absence of the external magnetic field, and that the studied system exhibits a super-paramagnetic behavior.     

Hyperon Haloes in A Hypernuclei in the Relativistic Continuum Hartree—Bogoliubov Theory

We investigate the existence of a single-Α hyperon halo in 3Α^15C and a two-Α hyperon halo in 4Α^16C.Ground-state properties of hyperon carbon isotopes,such as density distributions,single particle levels in the canonical basis,the binding energy,Α separation energy and radii,are calcuated and discussed by using the relativistic continuum Hartree-Bogoliubov theory.The hyperon halo phenomenon in 3Α^15C and 4Α^16C is supported by the discussion of the weakly bound state 1p3/2,extended density distribution and small separation energy of the Α hyperon.     

Short—Time Critical Behavior Affected by Weakly Long—Range Interactions

The theoretic renormalization group approach is applied to the study of short-time critical behavior of the Ginzburg-Landau model with weakly long-range interactions pσsps-p,The system initially at a high temperature is firstly quenched to the critical temperature Tc and then released to an evolution with a model A dynamics,A double expansion in ε=2σ-d and α=1-σ/2 with α of order ε of order ε is employed,where d is the spatial dimension.The asymptotic scaling laws and the initial slip exponents θ′and θ for the order parameter and the response function respectively are calculated to the second order in ε for σ close to 2.     

Effect of number density on velocity distributions in a driven quasi-two-dimensional granular gas

The motion of mono-disperse spherical steel particles in a vibration driven quasi-two-dimensional (2D) square cell is studied. The cell is horizontally vibrated to eliminate the effect of gravity compaction. The velocity distributions at different particle number densities are studied and found to obey the form exp[-β(|vy|/σy)α], in which v y and σ y are velocity and its variance in the transverse direction, and α and β are fitting parameters. The value of α is found to decrease with the number density of particles increasing. To investigate the effect of the bottom plate, the molecular dynamics simulation without considering any bottom friction is performed. The accordance between the simulation result and the experimental result shows that the influence of bottom plate friction force on the high energy tail of the velocity distribution can be neglected.     

Synchronization of Local Oscillations in a Spatial Rock-Scissors-Paper Game Model

We study a spatial rock-scissors-paper model in a square lattice and a quenched small-world network. The system exhibits a global oscillation in the quenched small-world network, but the oscillation disappears in the square lattice. We find that there is a local oscillation in the square lattice the same as in the quenched small-world 1 network. We define σ = 1/N ∑i（di-〈di〉^2 （where di is the density of a kind of species and （di） is the average value） as the variance of the oscillation amplitude in a certain local patch. It is found that σ decays in a power law with an increase of the local patch size R in the square lattice σ ∝ R^-σ, but it remains constant with an increase of the patch size in the quenched small-world network. We can speculate that in the square lattice, superposition between the local oscillations in different patches leads to global stabilization, while in the quenched small-world network, long-range interactions can synchronize the local oscillations, and their coherence results in the global oscillation.     

Upconversion Luminescence Dynamics in Er^3＋/Yb^3＋ Codoped Nanocrystalline Yttria

The upconversion luminescence and dynamics in Er^3＋ /Yb^3＋ codoped nanocrystalline yttria （7-65 nm） are studied under 980-nm pulsed laser excitation, It is found that the red emission of ^4F9/2-^4I15/2 and the green emission of ^2H11/2/^4S3/2 in nanoparticles with lower concentration of Yb^3＋ result from a two-photon excitation, In nanocrystals with higher Yb^3＋ concentration, the red emissions from a two-photon excitation, while the green emissions from a three-photon excitation, The luminescence dynamics indicates that as the particle size decreases, both the rise and the decay time constants become shorter, As the size decreases to several nanometres, the rise process nearly disappears, suggesting that the upconversion luminescence originates mainly from self-excitation of Er^3＋, instead of the energy transfer of Yb^3＋→ Er^3＋.     

Critical Behavior of Ising Model with Long Range Correlated Quenched Impurities

The theoretic renormalization-group approach is applied to the study of the critical behavior of the ddimensional Ising model with long-range correlated quenched impurities, which has a power-like correlations r^-(d-p). The asymptotic scaling law is studied in the framework of the expansion in e = 4 - d. In d ~ 4, the dynamic exponent z .is calculated up to the second order in p with ρ= O(ε^1/2). The shape function is obtained in one-loop calculation. When d = 4, the logarithmic corrections to the critical behavior are found. The finite size effect on the order parameter relaxation rate is also studied.     

Origin of the 420 nm Absorption Band and Effect of Doping Fluorine in PbWO4 Crystals

The electronic structures for three types of PbW04 (PWO) crystals, the perfect PWO, the PWO containing lead vacancy (PWO-Vpb) and fluorine doped PWO crystal (F^-：PWO), are systematically studied within the framework of density functional theory. The computational results show that the Pb 6s state situates below the valence band so that Pb^2 ions are unable to trap holes forming Pb^3 or Pb^4 to compensate for VPb^2-. The hole-trappers in PWO-Vpb are O^2- ions. Two of the longer-bond O^2- ions share a hole forming O2^3-, and four of the longer-bond oxygen ions trap two holes forming an associated color centre [O2^3--Vpb-O2^3-], which may be the origin of the 42Onto absorption band. It is also concluded that the doping of F^- would reduce the band gap and F^- ions substituting for O^2- can effectively restrict the formation of [O2^3--Vpb-O2^3-] and weaken the 42Onm absorption band and hence enhance the scintillation property of PWO.     

Study of Radiative Decays Ds1（2536） → Ds（1968） ＋γ and Ds1（2536）→ Ds^＊（2112） ＋ γ in CQM Model

There are some uncertain charazteristics of the Ds1（2536）, which deserves further discussion. Based on the assumption that the meson is constituted by c s, and belongs to T doublet （1^＋, 2^＋）, radiative decays Ds1（2536） → Ds（1968） ＋γ and Ds1（2536） → Ds^＊（2112） ＋ γ are studied in the CQM model The large branching ratios of them from our calculations not only indicate the process may be detected in the future experiments, but also can give a deep comprehension of the structure of it.     

Excitation Dependence of Dipole-Dipole Broadening in Selective Reflection Spectroscopy

We investigate the dipole-dipole broadened selective reflection spectrum with the Cs atomic density of 10~(14)-10~(15) cm~(-3).The dipole-dipole broadening is reduced and the hyperfine splitting is well resolved when the ground state atoms are excited by a detuned pump beam.The dependences of dipole-dipole broadening of Cs atoms in the 6S_(1/2)(F = 3) →6P_(3/2)(F′ = 4) hyperfine transition line on atomic density and the excitation factor are studied.It is found that the reduction of the dipole-dipole broadening is dependent on the pump beam power and is independent of the atomic density in this density range.These results are useful for understanding of the dynamical process in this range of atomic density.