含物质纯重力场部分贡献的静态和稳态重力场研究

给出了包含重力场贡献在内具有宇宙因子项最普遍形式的重力场方程为Rμν-gμνR/2+λgμν=8πG(T(Ⅰ)μν+T(Ⅱ)μν)/c4，这里λ为Einstein宇宙常数，Ｔ（Ⅰ）μν，Ｔ（Ⅱ）μν分别代表物质纯物质部分和纯重力场部分的能量-动量张量.物质纯重力场部分的能量-动量张量表述为T(Ⅱ)μν=(DμρＤρν-gμνＤαβＤαβ/4)/4πG，式中Dμν的定义为Ｄμν＝ωμ／xν-ων／xμ，ωμ≡-c2gμ0/g00.并用重力场贡献在内最普遍形式的重力场方程分别研究了几个大家所熟悉的静态和稳态重力场，像带有Einstein宇宙因子λ项球对称纯物质球外部静态度规、静态荷电球外部度规、匀速转动星体外部度规及理想纯物质星体内部静态平衡等,并进行了讨论. 关键词： 能量动量张量 重力场方程 静态重力场 稳态重力场     

具有广义协变的包含重力场贡献的重力场方程

利用半度规λ^(α)_μ表象的数学工具定义一个对广义坐标具有协变形式的重力场矢势函数ω^(α)_μ≡-cλ^(α)_μ，给出一个具有广义协变的包含重力场贡献的重力场方程R_μν-g_μνR/2+Λg_μν=8πG(T^(Ⅰ)_μν+T^(Ⅱ)_μν) 关键词： 重力场方程 协变形式 能量-动量张量 量子化     

关于引力场的能量问题

本文讨论引力场中局部区域的能量问题。这里提出了一个新的引力场总能量-动量赝张量密度,它所表示的引力场局部空间区域中的能量对纯空间坐标变换是不变量,因而引力场的局部区域能量具有确定的物理意义。关于Schwarzschild场的能量和动量,新的赝张量给出的结果要比现有广义相对论文献中的其他形式的赝张量所给出的结果较为合理。文中还讨论了在引力理论中质量与能量的关系问题。 关键词：     

一般含时线性势的量子解及有关问题

对于一般形式的含时线性势, 通过假设波函数形式的方法得到了Schr?dinger方程的精确和完备解. 同时指出, 用两个波函数φ(t)〉和ψ(t)〉定义的坐标和动量的矩阵元〈φ(t)xψ(t)〉和〈φ(t)pψ(t)〉满足经典形式的运动方程. 按照量子力学的系综理论, 这样的经典形式的运动方程实际上是流体方程. 进一步研究发现, 对于任意形式的线性系统有类似的结论. 关键词： 线性势 Schr?dinger方程 Heisenberg对应原理 经典运动方程     

Ne-HF体系的相互作用势及散射截面的密耦计算

利用非线性最小二乘法拟合在CCSD(T)/aug-cc-pVQZ理论水平下计算的相互作用能,得到了基态Ne-HF体系相互作用势的解析表达式.基于拟合的CCSD(T)势,通过密耦计算得到了入射能量分别为60,75,100和150meV 时,Ne-HF散射的微分截面和分波截面,详细讨论了散射截面随能量的变化趋势以及态-态激发截面对总非弹性散射截面的影响. 关键词： 相互作用势 散射截面 密耦计算 Ne-HF体系     

电子碰撞原子(e,2e)反应的复极化势

研究包括连续通道等非处理通道的复极化势对(e,2e)碰撞过程三重微分截面的影响,即将耦合通道光学势方法得到的复极化势附加到畸变波玻恩近似方法的畸变势中,在靶态的HF近似下,计算了Ar原子和Ne原子在非共面对称几何条件下(e,2e)反应的三重微分截面.对于较高的入射能量,在实验的误差范围内,计算结果与电子动量谱的实验数据符合较好,复极化势的影响很小;对于较低的入射能量,复极化势的作用明显增大. 关键词： 复极化势 (e;2e)反应 三重微分截面 电子动量谱     

重离子碰撞中的对称势翻转

利用同位旋和动量相关的输运模型IBUU，以Sn,Sn同位素在低能与高能碰撞为例，在两种不同的对称势作用下，研究了重离子碰撞中的对称势翻转现象.我们发现从低能到高能在同位旋相分化、发射核子的中-质比、发射核子的双n/p比，中-质微分横向流观测量中均存在对称势翻转现象.对称势翻转效应的研究有利于确定对称能的密度依赖性. 关键词： 重离子碰撞 对称势翻转 对称能     

La2-xSrxCuO4单晶膜的热电势与电阻率

测量了高质量的单晶膜La2-xSrxCuO4(x=010,020,025)的电阻率和热电势.La19Sr01CuO4电阻率呈现S型行为,表明存在一个赝能隙,在赝能隙态可以用公式ρ=ρ0+βexp(-ΔT)很好地拟合.热电势的测量表明,在超导转变前样品的残余热电势值非常小,这是膜的高质量引起的,三个样品在200K以上都出现一个宽峰,对其进行了一些理论模型分析,并与电子型超导体热电势结果作了比较. 关键词： 薄膜 输运性质 热电势     

Bessel光束的矢量分析及其能流密度的特征

通过比较自由空间Besssel光束标量解E(r,t)满足的方程和光场矢量E(r,t)与矢量势A(r,t)之间的关系表达式,利用Bessel的特点,合理构造了矢量势A(r,t)的具体形式,推导出电场量E(r,t)的磁场量B(r,t)各分量满足的具体形式。通过数值计算,给出电场E(r,t)在不同参数θ,φ下与径向坐标ρ之间的关系图线(图1,图2),发现由方程(6)描述的标量解仅是矢量场E(r,t)(方程15描述)在小θ下的近似。通过对能量传输特性的讨论,说明“超光速”的提法是不恰当的。     

低能He-H2(D2,T2)碰撞分波截面计算

采用Tang Toennes势模型 ,当入射氦原子能量是E =0 .0 5eV时 ,计算了He -H2 (D2 ,T2 )弹性分波截面和非弹性激发分波截面随量子数的变化。     

A background-dependent approach to the theory of gravitation II. Relativistic gravitational equations

On the basis of the results of Paper I and guided by a Machian view of nature, we find new gravitational equations which are background dependent. Such equations describe a purely geometrical theory of gravitation, and their dependence on the background structure is through the total energy-momentum tensor on the past sheet of the light cone of each space-time pointx [θ^μν x, say], i.e., through the integral on the past sheet of the light cone ofx of the parallel transport of the energy-momentum tensor from the space-time point in which it is defined tox along the geodesic connecting the two space-time points. Following Gürsey, we assume that the source of the De Sitter metric is not the cosmological term, but, rather, the energy-momentum tensor of a “uniform distribution of mass scintillations” [T ^μν x, say].T ^μν x, indeed, turns out to be equal to the metric tensor times a constant factor. As a consequence, in any local inhomogeneity A of a space-time whose background structure is determined by the Perfect Cosmological Principle,θ ^μν turns out to be approximately equal to the metric tensor times a constant factor, providedT=g _αβ T ^αβ is sufficiently small and the structure of the past sheet of the light cones of the space-time points belonging to Λ is not too much perturbed by the local gravitational field. As a consequence, in Λ the new equations approximately reduce to Einstein's equations. If one considers a “superuniverse model” in which our universe is considered as a local inhomogeneity in a De Sitter background, then from the above result there follows a fortiori the agreement of the new gravitational equations with the classical tests of gravitation. Furthermore, the dependence on the background structure is such that the new equations (i) incorporate the idea that the frame has to be fixeddirectly in connection with cosmological observations, and (ii) are singular in the absence of matter in the whole space-time. Moreover, (iii) the coupling constant turns out to be dimensionless in natural units (c=1=?), and (iv) a local inertial frame in a De Sitter background is determined by the condition that with respect to it the background structure is homogeneous in space and in time and is Lorentz invariant.     

Gravitational Energy-Momentum and Conservation of Energy-Momentum in General Relativity

Based on a general variational principle, Einstein-Hilbert action and sound facts from geometry, it is shown that the long existing pseudotensor, non-localizability problem of gravitational energy-momentum is a result of mistaking different geometrical, physical objects as one and the same. It is also pointed out that in a curved spacetime, the sum vector of matter energy-momentum over a finite hyper-surface can not be defined. In curvilinear coordinate systems conservation of matter energy-momentum is not the continuity equations for its components. Conservation of matter energy-momentum is the vanishing of the covariant divergence of its density-flux tensor field. Introducing gravitational energy-momentum to save the law of conservation of energy-momentum is unnecessary and improper. After reasonably defining “change of a particle’s energy-momentum”, we show that gravitational field does not exchange energy-momentum with particles. And it does not exchange energy-momentum with matter fields either. Therefore, the gravitational field does not carry energy-momentum, it is not a force field and gravity is not a natural force.     

Energy of Gravitational Field of Static Spherically Symmetric Neutron Stars

By using the Einstein-Tolman expression of the energy-momentum pseudo-tensor, the energy density of the gravitational field of the static spherically symmetric neutron stars is calculated in the Cartesian coordinate system.It is exciting that the energy density of gravitational field is positive and rational The xmmerical results of the energy density of gravitational field of neutron stars are calculated. For neutron stars with M=2M, the ratio of the energy density of gravitational field to the energy density of pure matters would be up to 0.54 at the surface.     

Energy of Gravitational Field of Static Spherically Symmetric Neutron Stars

By using the Einstein-Tolman expression of the energy-momentum pseudo-tensor, the energy density ofthe gravitational field of the static spherically symmetric neutron stars is calculated in the Cartesian coordinate system.It is exciting that the energy density of gravitational field is positive and rational. The numerical results ot the energydensity of gravitational field of neutron stars are calculated. For neutron stars with M = 2M , the ratio of the energydensity of gravitational field to the energy density of pure matters would be up to 0.54 at the surface.     

A Non-geometric Relativistic Theory of Gravitation

A non-geometric relativistic theory of gravitation is developed by defining a semi-metric to replace the metric tensor as gravitational vector potential. The theory show that the energy-momentum tensor of the gravitational field belong to the gravitational source, gravitational radiation is contained in Einstein’s field equations that including the contribution of gravitational field, the real physical singularity in the gravitational field can be eliminated, and the dark matter in the universe is interpreted as the matter of pure gravitational field.     

Gauge Gravitational Field in a Fractal Space-Time

Considering the fractal structure of space-time, the scale relativity theory in the topological dimension D_T=2 is built. In such a conjecture, the geodesics of this space-time imply the hydrodynamic model of the quantum mechanics. Subsequently, the gauge gravitational field on a fractal space-time is given. Then, the gauge group, the gauge-covariant derivative, the strength tensor of the gauge field, the gauge-invariant Lagrangean, the field equations of the gauge potentials and the gauge energy-momentum tensor are determined. Finally, using this model, a Reissner-Nordström type metric is obtained.     

Some Properties of the Bel and Bel-Robinson Tensors

The properties of the Bel and Bel-Robinson tensors seem to indicate that they are closely related to the gravitational energy-momentum. We present some new properties of these tensors which might throw some light onto this relationship. First, for any spacetime we find a decomposition of the Bel tensor in terms of the Bel-Robinson tensor and two other tensors, which we call the pure matter super-energy tensor and the matter-gravity coupling super-energy tensor. We show that the pure matter super-energy tensor of any Einstein-Maxwell field is simply the square of the usual energy-momentum tensor. This, together with the fact that the Bel-Robinson tensor has dimensions of energy density square, leads us to the definition of square root for the Bel-Robinson tensor: a two-covariant symmetric traceless tensor with dimensions of energy density and such that its square gives the Bel-Robinson tensor. We prove that this square root exists if and only if the spacetime is of Petrov type O, N or D, and its general expression is explicitly presented. The properties of this new tensor are examined and some interesting explicit examples are analyzed. Of particular interest are an invariant function that appears in the spherically symmetric metrics and an expression for the energy carried out by pure plane gravitational waves. We also examine the decomposition of the whole Bel tensor for Vaidya's radiating metric and Kerr-Newman's solution. Finally, we generalize the definition of square root to a factorization of the Bel-Robinson tensor and get the general solution for all Petrov types.