旋转运动磁单极势与辐射能

近来许多工作给出磁单极势与场强的解,其中不少为静止磁单极的球对称解[1].最近的一些工作,讨论了匀加速直线运动磁单极的推迟势与场强[2],此外还给出任意变速运动磁单极势与场强的解[3].本文讨论作旋转运动磁单极的势、场强和辐射能的表示式.磁单极场的势与场强的表示式不同干电荷的场,但具有严格对偶相等的表现形式.至于辐射能,最大的辐射强度将分布在与磁单极旋转平面相垂直的z轴方向,而平行于旋转平面的方向辐射强度为最小. 我们知道,对于一个电荷和一个磁荷共存的体系,真空中的Maxwell方程可写成上式用四维电磁场张量可改写为式中民占…     

螺线管和自旋磁性之间的一个差别

讨论一个通有电流的圆环与磁单极的相互作用和自旋磁性与磁单极的相互作用．计算表明两种能量是不一致的．     

磁单极理论的进展

这是关于磁单极理论最近某些工作的简短 综述.所取得的进展归因于某种观念的引进。 这种观念将时空分为若干个区域,从而消去奇 性 .这个观念是十分简单的,并将首先加以 讨论. (A)如何消除奇性 磁单极就是磁荷.虽然磁单极的概念必然 在经典物理中,在电学和磁学的早期就讨论过, 但是现代的讨论还要追溯到1931年,在狄拉克 的一篇重要文章[1]中,他指出量子力学中的磁 单极显示出某些附加的而且微妙的特征.特别 是,与强度为g的磁单极一起存在时、电荷和磁 荷必须在量子力学中被量子化.我们将用几分 钟的时间对这个结果给出一个新的推导。 如果…     

统一场论中的磁单极

本文的主要目的是介绍磁单极理论的基本结果。 我们首先介绍Dirac磁单极的基本思想。然后,进一步评述统一场论中的拓扑磁单极,并说明磁单极在早期宇宙中是怎种产生的。最后,我们讨论磁单极问题上最惊人的现象——磁单极对核子衰变的催衰化作用及其温度依赖关系。     

统一场论中的磁单极

本文的主要目的是介绍磁单极理论的基本结果。 我们首先介绍Dirac磁单极的基本思想。然后,进一步评述统一场论中的拓扑磁单极,并说明磁单极在早期宇宙中是怎种产生的。最后,我们讨论磁单极问题上最惊人的现象——磁单极对核子衰变的催衰化作用及其温度依赖关系。     

电磁学与电动力学中的磁单极-I

本文及后继三篇文章在电磁学和电动力学框架内分别介绍磁单极的若干奇特性质.针对由一个磁单极和一个点电荷构成的体系,首先证明这个体系的电磁场角动量具有极简洁的表达式并讨论可能的电荷量子化,然后显式地演示体系角动量的转化与守恒.     

关于非亚贝尔规范群的对偶荷(单磁荷)问题(Ⅱ)

本文把我们在前一工作中所发展的使规范势与球面上的联络相对应的方法推广于讨论有O(5)对称的SU(2)磁单极势,得到了有双弦奇异性及单弦奇异性的磁单极势的表达式.最后通过一个坐标-规范联合交换,得出了无奇异弦的,有O(5)对称的SU(2)磁单极规范势.     

磁荷对中子星质量半径比的约束

讨论了荷电(磁)质点的量子力学波方程及其解. 由磁场中解的奇异性讨论了磁单极的存在; 由Rubakov-Callan模型推知中子星可能含有大量磁单极. 然后采用中子星的结构方程, 讨论了磁荷对中子星质量半径比的约束, 分别得到了磁荷对中子星质量半径比上限的影响 和磁荷对中子星质量半径比下限的影响的数学表达式. 关键词： 磁单极 中子星 质量半径比     

电磁学与电动力学中的磁单极—V

作为本系列5篇文章的最后一篇,作者在电磁学和电动力学框架内用尽量科普的方式对比前4篇文章介绍一个磁单极很不奇特的性质.本文主要研究用小电流圈定义的磁偶极子和用正负磁单极对定义的磁偶极子的差别.文章仔细讨论一个在2012年曾在业界引起很多争议的由一个点电荷和一个磁偶极子构成的体系的可能的现象,并展示对这个体系,由正负磁单极对构成的磁偶极子比由电流圈构成的磁偶极子要简单和平庸许多.     

双孤子非线性干涉中的狄拉克磁单极势

本文深入研究了孤子干涉过程中的相位演化特性及其背后的拓扑矢势.基于一维非线性薛定谔方程的双孤子解,发现波函数密度零点广泛存在于拓展的复平面内,并且每一个密度零点对应狄拉克磁单极的矢势场.矢势场是由周期排布的具有相反磁荷的狄拉克磁单极对组成.通过观察磁单极子的运动,可以方便地理解干涉过程中的相位演化特征.特别发现,一对正负磁单极对在实轴上的碰撞恰好对应波函数相位在节点处的π跃变.此外,还对比讨论了线性波包干涉动力学中的狄拉克磁单极.结果表明狄拉克磁单极势广泛存在于波场的干涉现象之中,并且磁单极在拓展的复平面内分布特征可用于区分线性干涉和非线性干涉过程背后的拓扑性质.     

Higher dimensional global monopole in Brans-Dicke theory

The gravitational field of a higher dimensional global monopole in the context of Brans-Dicke theory of gravity is investigated. The space time metric and the scalar field generated by a global monopole are obtained using the weak field approximation. Finally, the geodesic of a test particle due to the gravitational field of the monopole is studied.     

整体单极子黑洞引力场中的加速效应

给出了含有整体单极子的黑洞的引力场中试验粒子加速度的表达式, 讨论了整体单极子对加速效应的贡献. 结果表明, 由于整体单极子的存在, 产生了斥力效应; 当速度趋近于光速时, 中性粒子在引力场中受到了斥力作用. 这是牛顿力学中所没有的.     

Gravitational energy-momentum density in teleparallel gravity

In the context of a gauge theory for the translation group, a conserved energy-momentum gauge current for the gravitational field is obtained. It is a true spacetime and gauge tensor, and transforms covariantly under global Lorentz transformations. By rewriting the gauge gravitational field equation in a purely spacetime form, it becomes the teleparallel equivalent of Einstein's equation, and the gauge current reduces to the Moller's canonical energy-momentum density of the gravitational field.     

A self-gravitating Dirac–Born–Infeld global monopole

We generalize the field theory of the global monopole to the Dirac–Born–Infeld (DBI) field and investigate the gravitational property of a DBI global monopole in four-dimensional spherically symmetric spacetime. The coupled equations for the metric and the DBI scalar field are solved asymptotically and numerically. It is found that, just as for a canonical global monopole, the gravitational effect of the DBI global monopole is equivalent to that of a deficit solid angle in the metric plus a negative mass at the origin. However, compared with a canonical global monopole, for the same false vacuum and symmetry-breaking scale, a DBI global monopole has a relatively smaller core and a larger absolute value of effective mass. Thus, it can yield a larger deflect angle when the light is passing by. Especially, when the scale of the warp factor is small enough, the effective mass of a DBI global monopole does not depend apparently on the value of the false vacuum, which is qualitatively different from that of a canonical global monopole.     

Global gravitational anomalies

A general formula for global gauge and gravitational anomalies is derived. It is used to show that the anomaly free supergravity and superstring theories in ten dimensions are all free of global anomalies that might have ruined their consistency. However, it is shown that global anomalies lead to some restrictions on allowed compactifications of these theories. For example, in the case of O(32) superstring theory, it is shown that a global anomaly related to ₇(O(32)) leads to a Dirac-like quantization condition for the field strength of the antisymmetric tensor field.Related to global anomalies is the question of the number of fermion zero modes in an instanton field. It is argued that the relevant gravitational instantons are exotic spheres. It is shown that the number of fermion zero modes in an instanton field is always even in ten dimensional supergravity.Supported in part by NSF Grant No. PHY80-19754     

Local and global gravity

Our long experience with Newtonian potentials has inured us to the view that gravity only produces local effects. In this paper we challenge this quite deeply ingrained notion and explicitly identify some intrinsically global gravitational effects. In particular we show that the global cosmological Hubble flow can actually modify the motions of stars and gas within individual galaxies, and even do so in a way which can apparently eliminate the need for galactic dark matter. Also we show that a classical light wave acquires an observable, global, pathdependent phase in traversing a gravitational field. Both of these effects serve to underscore the intrinsic difference between nonrelativistic and relativistic gravity.     

Effect of null aether field on weak deflection angle of black holes

We study light rays in the static and spherically symmetric gravitational field of the null aether theory (NAT). To this end, we employ the Gauss-Bonnet theorem to compute the deflection angle formed by a NAT black hole in the weak limit approximation. Using the optical metrics of the NAT black hole, we first obtain the Gaussian curvature and then calculate the leading terms of the deflection angle. Our calculations indicate how gravitational lensing is affected by the NAT field. We also illustrate that the bending of light stems from global and topological effects.     

Orbital Precession Effect in the Reissner-Nordström Field with a Global Monopole

Using an elegant mathematical method advanced by us, we calculate the orbital precession effect in the gravitational field of the centre mass with electric charge and a global monopole. Analysing the results, we obtain that the orbital precession effect increases on account of the global symmetry breaking, but the orbital precession effect aroused by the electric charge of the field source reduces the orbital precession effect aroused by the mass of the field source. Generalizing the effect in the Schwarzschild field, we obtain interesting results by discussing the parameters of the celestial body, which provide a feasible experimental verification of the general relativity.     

The weight of extended bodies in a gravitational field with flat spacetime

Einstein's gravitational field equations in empty space outside a massive plane with infinite extension give a class of solutions describing a field with flat spacetime giving neutral, freely moving particles an acceleration. This points to the necessity of defining the concept gravitational field not simply by the nonvanishing of the Riemann curvature tensor, but by the nonvanishing of certain elements of the Christoffel symbols, called the physical elements, or the nonvanishing of the Riemann curvature tensor. The tidal component of a gravitational field is associated with a nonvanishing Riemann tensor, while the nontidal components are associated with nonvanishing physical elements of the Christoffel symbols. Spacetime in a nontidal gravitational field is flat. Such a field may be separated into a homogeneous and a rotational component. In order to exhibit the physical significance of these components in relation to their transformation properties, coordinate transformations inside a given reference frame are discussed. The mentioned solutions of Einstein's field equations lead to a metric identical to that obtained as a result of a transformation from an inertial frame to a uniformly accelerated frame. The validity of the strong principle of equivalence in extended regions for nontidal gravitational fields is made clear. An exact calculation of the weight of an extended body in a uniform gravitational field, from a global point of view, gives the result that its weight is independent of the position of the scale on the body.