NN Spin-Orbit Force in Quark Model

A chiral quark-soliton model with the gluon field and chiral fields (σ, π and ω) is employed to study the NN spin-orbit potential within a relativistic twoquark-cluster theory. The effective NN spin-orbit potential generated by the one-gluon exchange decreases with the increase of energy. It is as important as one a-meson exchange and one w-meson exchange and is close to the spin-orbit splitting in nuclei.     

The Relativistic Many-Body Perturbation Treatment of the Long Range Part of the Nuclear Force

Based on the many-body perturbation theory and cloudy bag model, the long range part of the nuclbar force is discussed. The results show that it agrees with one-pion exchange-potential in respect of both the radial dependence and the strength.     

单胶子交换正反夸克对产生模型中的自旋轨道耦合力

从单胶子交换正反夸克对产生模型出发,研究了核子间等效ρω介子交换势.计算结果表明这个模型能得到强子层次核力介子交换理论中ρ,ω介子交换势的各个部分,并且定性性质与传统的介子交换势也是相同的.     

格点核子-核子势在核物质中的相对论效应(英文)

利用最新的格点核子-核子势研究了核物质中的相对论效应。通过此格点核子-核子势场,首先我们构建一个包括π介子,σ介子以及ω介子的单玻色子交换势。势场中的介子-核子耦合常数以及截断动量通过拟合格点核力得到的核子-核子散射相移确定。随后采用非常成功的第一性原理多体计算方法Brueckner-Hartree-Fock模型,计算了核物质的基本性质。发现对称核物质的状态方程以及饱和性质在非相对论框架和相对论框架中有很明显的区别。在格点核力中,该相对论效应对核物质的结合能提供吸引的贡献。这与采用传统的核力计算得到的结果是相反的。The relativistic effect in nuclear matter is investigated with the latest lattice nucleon-nucleon (NN) potential. A one-boson-exchange potential (OBEP) including three mesons, pion, σ meson and ω meson was constructed based on the lattice NN potential. The meson-nucleon coupling constants and cutoff momentums are determined by fitting the phase shifts of NN scattering from lattice NN potential. The properties of nuclear matter with this OBEP from lattice potential are calculated by one very successful ab initio many-body method, Brueckner-Hartree-Fock model. The equations of state and saturation properties of symmetric nuclear matter present very obvious different behaviors in non-relativistic and relativistic frameworks. The relativistic effect plays attractive contributions with the components of S and D waves in lattice NN potential, which is opposite comparing to the relativistic effect from the conventional NN potential.     

Long Range Proton Couplings in Estrones

^4,6J_HH-long range couplings in an estrone-type molecule are observed and demonstrated to be helpful for the complete proton chemical shift assignment.     

Paris NN Potential and the Possible Resonance States of pp

By solving the complex Schrodinger equation with the phenomenological Paris optical potential between nucleon (N) and antinucleon(N),the near-threshold binding and resonant behaviors of the pp system are studied. As the result, a 13P0 resonance state of pp is obtained. It is found that the energy and width of the state are compatible with the BES data in which the observed enhancement in the J/ψ→γpp decay was fitted by a Breit-Wigner (B-W) formula either in the S-wave or in the P-wave. The indication of the results and the suggestion for the further theoretical investigation are discussed.     

Intermediate Range Attaction of NN Interaction from Clustering Effect in Skyrme Model

As two skyrmions overlap,a molecular-like binding may arise.This may be one of the main sources of missing intermediate range attraction in NN interaction.The attraction is found to be strong enough to form bound state of two nucleons.It seems then that one no longer needs to introduce phenomenologically scalar meson which has never been observed.     

Long Range Order for Lattice Dipoles

We consider a system of classical Heisenberg spins on a cubic lattice in dimensions three or more, interacting via the dipole-dipole interaction. We prove that at low enough temperature the system displays orientational long range order, as expected by spin wave theory. The proof is based on reflection positivity methods. In particular, we demonstrate a previously unproven conjecture on the dispersion relation of the spin waves, first proposed by Fröhlich and Spencer, which allows one to apply infrared bounds for estimating the long distance behavior of the spin-spin correlation functions.     

远程束—束作用的研究

已有的和建造中的对撞机的运行常常被束－束相互作用引起的非线性效果所限制,特别是大流强的束流,如正在研究中的ＢＥＰＣ多束团对撞方案,ＢＥＰＣⅡ上的束－束相互作用非常复杂,束团除了在南对撞点正撞外,还在环上其余１１个位置有远程相互作用,本文计算了远程束－束相互作用的频移和频散。     

On the Nonextensivity of the Long Range X-Y Model

It will be given analytical and numerical evidence supporting that the X-Y model yields an extensive, i.e., proportional to the number of degrees of freedom N, internal energy U for any value of the interaction range.     

Implicit Versus Explicit Renormalization of the NN Force: An S-Wave Toy Model

We use an S-wave toy model for the two-nucleon system to show that the implicit renormalization of a contact theory matches the explicit renormalization through a flow equation which integrates out the high momentum components. By fitting the low-momentum interaction with a new contact theory, we show that the running of the contact strengths in both original and fitted contact theories match over a wide cutoff range.     

核子–核子散射过程的研究和矢量介子交换势

在推广的手征SU(3)夸克模型下讨论了核子–核子散射过程和矢量介子交换势.给出了赝标π介子和矢量ρ和ω介子的GCM中心力的交换势和NN散射14个分波的相移.研究表明,矢量介子交换势可以替代单胶子交换势以解释核力的短程排斥.     

Evaporating Black Holes and Long Range Scaling

For an effective treatment of the evaporation process of a large black hole the problem concerning the role played by the fluctuations of the (vacuum) stress tensor close to the horizon is addressed. We present arguments which establish a principal relationship between the outwards fluctuations of the stress tensor close to the horizon and quantities describing the onset of the evaporation process. This suggest that the evaporation process may be described by a fluctuation-dissipation theorem relating the noise of the horizon to the black hole evaporation rate.     

Two-Dimensional SIR Epidemics with Long Range Infection

We extend a recent study of susceptible-infected-removed epidemic processes with long range infection (referred to as I in the following) from 1-dimensional lattices to lattices in two dimensions. As in I we use hashing to simulate very large lattices for which finite size effects can be neglected, in spite of the assumed power law p(x)～|x|^?σ?2 for the probability that a site can infect another site a distance vector x apart. As in I we present detailed results for the critical case, for the supercritical case with σ=2, and for the supercritical case with 0<σ<2. For the latter we verify the stretched exponential growth of the infected cluster with time predicted by M. Biskup. For σ=2 we find generic power laws with σ-dependent exponents in the supercritical phase, but no Kosterlitz-Thouless (KT) like critical point as in 1-d. Instead of diverging exponentially with the distance from the critical point, the correlation length increases with an inverse power, as in an ordinary critical point. Finally we study the dependence of the critical exponents on σ in the regime 0<σ<2, and compare with field theoretic predictions. In particular we discuss in detail whether the critical behavior for σ slightly less than 2 is in the short range universality class, as conjectured recently by F. Linder et al. As in I we also consider a modified version of the model where only some of the contacts are long range, the others being between nearest neighbors. If the number of the latter reaches the percolation threshold, the critical behavior is changed but the supercritical behavior stays qualitatively the same.     

Classical Motion in Force Fields with Short Range Correlations

We study the long time motion of fast particles moving through time-dependent random force fields with correlations that decay rapidly in space, but not necessarily in time. The time dependence of the averaged kinetic energy 〈p ²(t)〉/2 and mean-squared displacement 〈q ²(t)〉 is shown to exhibit a large degree of universality; it depends only on whether the force is, or is not, a gradient vector field. When it is, 〈p ²(t)〉～t ^2/5 independently of the details of the potential and of the space dimension. The stochastically accelerated particle motion is then superballistic in one dimension, with 〈q ²(t)〉～t ^12/5, and ballistic in higher dimensions, with 〈q ²(t)〉～t ². These predictions are supported by numerical results in one and two dimensions. For force fields not obtained from a potential field, the power laws are different: 〈p ²(t)〉～t ^2/3 and 〈q ²(t)〉～t ^8/3 in all dimensions d≥1.     

Taming Griffiths' Singularities in Long Range Random Ising Models

We study long range random Ising models and develop modified high temperature and strong magnetic field expansions that give decay of truncated correlation functions and uniqueness of Gibbs states, in spite of the presence of Griffiths' singularities. Received: 30 September 1996 / Accepted: 18 February 1997     

Long Range 13C Couplings in Hexamethylphosphoramide and Dimethylsulphoxide

One bond ¹³C–¹H couplings have been extensively studied and their magnitudes explained on the basis of two contributing factors, namely the percentage “s” character of the bond¹ and the carbon Z value, or effective nuclear charge². To date however, little has been reported on ¹³C couplings over more than one bond, the main reason being the previous experimental difficulties in measuring these small couplings.     

Numerical Range for Orbits Under a Central Force

We present an explicit form for the central force that describes the orbit of some roulette curve, and interpret the orbit of the roulette curve as an algebraic curve F(1, x, y) = 0 associated to the homogeneous polynomial F(t, x, y) of a matrix A. The hodograph of the orbit is obtained as the boundary generating curve of the numerical range of A.     

EchSGB远距离照明条件下的焦开关

推导了复变量双曲余弦平方-高斯光束(EchSGB)被无光阑透镜聚焦后的轴上光强分布公式,在此基础上通过数值计算和分析发现,EchSGB只有在远距离照明条件下才存在焦开关现象.焦点跃变位置随光束参数和对应高斯光束的菲涅尔数不同而变化,得到了EchSGB在平顶情形下产生焦开关的相对入射距离为11.13,表明在远距离照明和无光阑透镜精密调焦时,对于EchSGB要考虑焦开关现象的影响.     

Quantitative Measurement of Long Range Nuclear Overhauser Enhancement

Measurement of nuclear Overhauser enhancement is one of the mainstays of structural studies of molecules in solution. Measurements, particularly over long distances, are often compromised by spin diffusion. A robust and accurate method for measuring nuclear Overhauser enhancements that are largely free of spin diffusion effects is presented. The effects of using imperfect radiofrequency pulses are considered and experimental data are presented for Amphotericin B.