RMF理论框架下用粒子数守恒方法处理对关联

在相对论平均场理论框架下,利用粒子数守恒方法处理对关联,给出了具体的理论公式和数值细节;并以24Ne为例,用该方法研究了它的基态和低激发态性质. Particle-number conserving method is adopted to treat the pairing correlations in the relativistic mean-field theory. The formalism and numerical techniques are presented. As an example, the ground state properties and low-lying excited states in~(24)Ne are studied.     

O同位素的相对论平均场计算中对能隙参数的研究

在相对论平均场理论框架下, 研究了各种对能隙参数对O同位素偶偶核的适用性. 通过对原子核结合能和四极形变的系统计算表明, 在O同位素区域, 对能隙参数Λ_n和Λ_p均可取为0.5, 这样既简化了计算, 又可得到比较满意的结果.     

N－N关联和有限核相对论平均场方法

密度有关的核子－介子相互作用耦合常数是在相对论平均场近似下用核物质的相对论Ｂｒｕｅｃｋｎｅｒ－Ｈａｒｔｒｅｅ－Ｆｏｃｋ近似计算的自能参数化得到的．这种密度有关的相互作用考虑了介质中Ｎ－Ｎ关联效应，用这种密度有关的相互作用来研究有限核的基态性质，如单粒子能级，平均结合能，电荷均方根半径，与实验值较好地符合，同时还与其它模型的结果进行了比较。     

超核的相对论平均场计算

利用相对论平均场方法计算了奇异、粲和底超核的部分性质,包括各种不同味的超核的单粒子能量以及其他一些静态性质,并对结果进行了比较.对各种味的重子的势阱深度和耦合常数做了估计,得到丰富的结果.建议寻找质量数大于10?0的粲超核.同时探讨了不同重子杂质对原子核芯性质的可能影响.     

Pentaquark Θ+的介质效应

在密度相关的相对论平均场理论基础上, 假定Θ⁺通过交换有效的同位旋标量介子σ和ω与其他重子发生相互作用, 研究了强子在包含Θ⁺的奇异核物质中的性质改变. 讨论并计算了介质中的Θ⁺和核子有效质量及其对重子密度的依赖关系, 分析了Θ⁺在核物质中包含的成分大小以及核子的同位旋效应对奇异核物质性质的影响, 进一步计算了不同重子组成比例下奇异核物质的标量密度ρ_S和矢量密度ρ_B的对应曲线.     

Pentaquark~+的介质效应

在密度相关的相对论平均场理论基础上,假定~+通过交换有效的同位旋标量介子σ和ω与其他重子发生相互作用,研究了强子在包含~+的奇异核物质中的性质改变。讨论并计算了介质中的~+和核子有效质量及其对重子密度的依赖关系,分析了~+在核物质中包含的成分大小以及核子的同位旋效应对奇异核物质性质的影响,进一步计算了不同重子组成比例下奇异核物质的标量密度ρ_S和矢量密度ρ_B的对应曲线。     

相对论平均场理论中的有效超子-核子相互作用

利用相对论平均场理论,结合单超核的实验数据,研究了核介质中的Λ超子–核子有效相互作用.通过符合13ΛC超核中Λ超子1s轨道的结合能实验值,给出了5组Λ超子–核子有效相互作用参数.利用这些参数组对质量数从9到2?0?8的单Λ超核和核物质中最低Λ态的束缚能进行了系统计算,得到的结果与实验值相符.     

相对论平均场理论对Pb同位素位移的研究

运用变形的相对论平均场理论研究了Pb同位素链的基态性质. 对关联的处理采用了BCS方法, 不成对核子的处理运用了“阻塞”法. 计算的结果很好地符合了实验上Pb的平均结合能, 中子分离能, 同位素位移. 接着从原子核的微观结构出发, 比较详细地研究了Pb链同位素位移出现反常扭折这一重要性质的物理机制.     

单极巨共振的相对论平均场计算

利用最近完成的相对论平均场理论的计算程序,研究了原子核单极巨共振.计算了¹⁶O,⁴⁰Ca和²⁰⁸Pb的同位旋标量和同位旋矢量单极巨共振.得到的结果与实验符合较好.     

Stability of Strutinsky Shell Correction Energy in Relativistic Mean Field Theory

The single-particle spectrum obtained from the relativistic mean field （RMF） theory is used to extract the shell correction energy with the Strutinsky method. Considering the delicate balance between the plateau condition in the Strutinsky smoothing procedure and the convergence for the total binding energy, the proper space sizes used in solving the RMF equations are investigated in detail by taking ^208 Pb as an example. With the proper space sizes, almost the same shell correction energies are obtained by solving the RMF equations either on basis space or in coordinate space.     

Relativistic Consistent Angular-Momentum Projected Shell-Model:Relativistic Mean Field

We develop a relativistic nuclear structure model, relativistic consistent angular-momentum projected shell-model (RECAPS), which combines the relativistic mean-field theory with the angular-momentum projection method. In this new model, nuclear ground-state properties are first calculated consistently using relativistic mean-field (RMF) theory. Then angular momentum projection method is used to project out states with good angular momentum from a few important configurations. By diagonalizing the hamiltonian, the energy levels and wave functions are obtained. This model is a new attempt for the understanding of nuclear structure of normal nuclei and for the prediction of nuclear properties of nuclei far from stability. In this paper, we will describe the treatment of the relativistic mean field. A computer code, RECAPS-RMF, is developed. It solves the relativistic mean field with axial-symmetric deformation in the spherical harmonic oscillator basis. Comparisons between our calculations and existing relativistic mean-field calculations are made to test the model. These include the ground-state properties of spherical nuclei ¹⁶O and ²⁰⁸Pb, the deformed nucleus ²⁰Ne. Good agreement is obtained.     

Determining Nuclear Form factor for Detection of Dark Matter in Relativistic Mean Field Theory

In this work, we derive the nuclear form factor for the spin-independent collision between the WIMPs and nucleus in terms of the relativistic mean field (RMF) theory. Comparison with the traditional form factors which are commonly used in literature is given and it is found that our results are slightly above that of the 2PF model by 4% to 8%, but deviate from the Helm form factor by 15% to 25% for the whole recoil energy spectrum of 0 ∽ 100keV. Moreover, taking Xe and Ge as examples, we show the dependenceof the form factor on the recoil energy.     

Ground State Properties of Ds Isotopes Within the Relativistic Mean Field Theory

The ground state properties of Ds (Z=110) isotopes (N=151-195) are studied in the framework of the relativistic mean field (RMF) theory with the effective interaction NL-Z2.The pairing correlation is treated within the conventional BCS approximation.The calculated binding energies are consistent with the results from finite-range droplet model (FRDM) and Macroscopic-microscopic method (MMM).The quadrupole deformation,α-decay energy,α-decay half-live,charge radius,two-neutron separation energy and single-particle spectra are analyzed for Ds isotopes to find new characteristics of superheavy nuclei (SHN).Among the calculated results it is rather distinct that the isotopic shift appears evidently at neutron number N=184.     

Space Dependent Mean Field Approximation Modelling

It is shown that the self-consistency condition which is the basic equation for calculating the mean-field order parameter of any mean-field model Hamiltonian can be replaced by the standard Metropolis Monte Carlo scheme. The advantage of this method is its ease of implementation for both the homogeneous mean-field order parameter and the heterogeneous one. To be specific, the mean-field version of the Ising model spin system is discussed in detail and the resulting magnetization is the same as in the case of solving the respective mean-field self-consistency equation. In addition, it is shown that if a high temperature phase of such system is quenched below critical temperature then the mean field experienced by spins develops into a network of domains in analogous way as it happens with the spins in the case of the exact many-body Hamiltonian system and the coarsening processes start to take place. To show that the introduced Metropolis Monte Carlo method works also in case of the continuous variables the order parameter for the Maier-Saupe model for nematic liquid crystals has been calculated.     

A New Determination of the Lambda-Nucleon Coupling Constants in Relativistic Mean Field Theory

A new determination of the Lambda-nucleon coupling constants in relativistic mean field theory is presented by optimizing both hyperon binding energy and spin-orbit splitting. Hypernuclear single particle spectra with the new coupling constants suggest the good agreement between the calculation and available data. The spin-orbit splitting of hyperon in medium mass hypernuclei is systematically larger than that in light- or heavy-mass hypernuclei. The sensitivity of the Lambda spin-orbit splitting to the omega-Lambda-Lambda tensor coupling term is also explored.     

相对论平均场理论中的张量项对自旋-轨道劈裂的影响

在相对论平均场理论中引入同位旋标量-矢量介子ω张量项, 以²⁰⁸Pb为例,研究了张量项对原子核平均势场、介子场、自旋-轨道耦合势、单粒子能级的自旋-轨道劈裂和原子核壳层结构等的影响.结果发现张量项对核子平均势的影响主要表现在原子核的表面.随着张量耦合强度的增加, 自旋-轨道耦合势增强,单粒子能级的自旋-轨道劈裂增大,从而导致原子核单粒子能级的壳层结构发生很大变化,传统幻数所对应的主壳消失, 新的主壳出现.     

Description of ^178Hf^m2 in the Constrained Relativistic Mean Field Theory

Properties of the ground state of ^178Hf and the isomeric state ^178Hf^m2 are studied within the adiabatic and diabatie constrained relativistic mean field （RMF） approaches. The RMF calculations reproduce well the binding energy and the deformation for the ground state of ^178Hf. Using the ground state single-particle eigenvalues obtained in the present eaiculation, the lowest excitation configuration with K^π = 16^＋ is found to be v（7/2^-[514]）^-1（9/2^＋ [624]）^1 π（7/2^＋ [404]）^-1 （9/2^-[514]）^1. Its excitation energy caiculated by the RMF theory with time-odd fields taken into account is equal to 2.801 MeV, i.e., close to the ^178Hf^m2 experimentai excitation energy 2.446 MeV. The self-consistent procedure accounting for the time-odd component of the meson fields is the most important aspect of the present calculation.     

利用密度相关的相对论平均场理论对核物质与中子星的研究(英文)

研究和详细地比较了RMF理论中不同的有效相互作用强度的密度依赖性, 并且讨论了这种密度依赖性对于核物质和中子星性质的影响. 对于核物质, 不同的参数组给出的对称核物质的饱和点非常接近, 基本都在经验值的范围内. 对于中子星, 考虑超子后不同参数组给出的质量极限的范围为1.52—2.06 M☉, 半径为10.24—11.38 km.The density dependencies of various effective interaction strengths in the relativistic mean field and their influences on the properties of nuclear matter and neutron stars are studied and carefully compared. The differences of saturation properties given by various effective interactions are subtle in symmetric nuclear matter. The Oppenheimer Volkoff mass limits of neutron stars calculated from different equations of state are 1.52—2.06 M☉, and the radii are 10.24—11.38 km with hyperons included.     

A New Determination of the Lambda-Nucleon Coupling Constants in Relativistic Mean Field Theory

A new determination of the Lambda-nucleon coupling constants in relativistic mean field theory is presented by optimizing both hyperon binding energy and spin-orbit splitting.Hypernuclear single particle spectra with the new coupling constants suggest the good agreement between the calculation and available data.The spin-orbit splitting of hyperon in medium mass hypernuclei is systematically larger than that in light-or heavy-mass hypernuclei.The sensitivity of the Lambda spin-orbit splitting to the omega-Lambda-Lambda tensor coupling term is also explored.