共查询到19条相似文献,搜索用时 171 毫秒
1.
魏斯考勃夫、莫斯考夫斯基和斯得舒按照单粒子模型讨论了原子核放出γ光子的跃迁机率。斯得舒详细地讨论了核子的反常磁矩在γ衰变过程中的作用。运动着的磁矩呈现与v/C成正比的电矩。其中v为运动着的磁矩的速率,C为光速。反常磁矩的作用可以在哈密顿量中加入如下的附加项: 相似文献
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本文利用重正化了的费米型V-A弱相互作用计算μ介子被质子吸收时所产生的辐射俘获现象。在计算中利用了余列多维奇等所指出的μ介子在俘获前停留在K层的单重态上的理论结果。计算的结果与李政道等忽略强相互作用的影响及忽略μ介子原子由三重态至单态的跃迁所得到的结果有很大的不同。我们得到当完全不考虑强相互作用的影响时μ介子被质子俘获时不能放出γ辐射的结论。其次我们考虑了两方面的强相互作用影响,一方面考虑了核子反常磁矩的影响,另一方面又考虑了强相互作用对V-A弱相互作用的重正化效应。计算结果指出:反常磁矩的贡献只为重正化效应的5%左右。由重正化效应所产生的辐射俘获几率只有李政道等所给出的几率的14%,放出的光子不再是100%右旋的,估计约有20%的左旋光子。 相似文献
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本文讨论了原子核独立粒子结构的力学基础问题,指出独立粒子运动的基本因素是体积效应。满壳层附近的每一个核子因为和满壳层内其他核子相互作用的结果,将使周围核物质极化,而在它自己周围形成核子云,因而这个核子的磁矩,有效电荷等将发生一定的变化。但是因为角动量和宇称守恒的关系,这个带有极化核子云的核子的角动量和宇称将不会改变。在原子核内两个核子发生碰撞的几率与原子核体积Ω成反比,三个核子发生碰撞的几率与Ω2成反比,依次类推。这样我们就证明了为什么利用耦合理论计算原子核能级是正确的。并且也证明了壳模型指出的每个核子的角动量和宇称也是正确的。但是我们不能用壳模型波函数来计算原子核的磁矩和跃迁几率。 相似文献
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已知,由于强相互作用的影响,核子的电磁作用流一般可以写为:其中u,u是核子自自旋函数,K~(p,)是核子的反常磁矩。F_(1,2)~(p,n)即表明了核子内部结构的影响。当q~2→0时,除F_1~n趋于零之外,其他均趋于1。 相似文献
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原子(离子)光电离过程中多级效应的理论研究 总被引:1,自引:0,他引:1
在相对论理论框架下,通过对氢及类氢离子光电离截面的理论研究,探讨了多极效应的变化规律和电偶极跃迁的适用范围.结果表明:光电离过程中的多极效应与入射光子的能量、电子离核的平均半径等密切相关.入射光子的能量对多极效应的影响在通常情况下更具普遍意义,当其能量较大时,光电离截面的理论计算必须考虑多极效应. 相似文献
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利用全量子理论研究了克尔介质中皮秒孤子光场与二能级原子多光子相互作用系统中粒子数反转随时间的变化特性,用MATLAB软件编程模拟并讨论了初始平均光子数、克尔介质与场模非线性相互作用强弱、孤子光场与原子耦合强度及相互作用过程中跃迁光子数目对粒子数反转的影响.数值计算结果表明:初始平均光子数越大、克尔介质与场模的非线性相互作用越强、孤子光场与原子耦合强度越小或相互作用过程中跃迁光子数目越多,粒子数反转崩坍与恢复的振荡幅度越小、平均值越大. 相似文献
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近年来,核子结构的问题引起了人们极大的兴趣。目前一般都认为核子外围为π介子云所环绕(P波为主),中心情况则不清楚,泡利(Pauli),Dancoff曾试图用强耦合介子理论来解决核子反常磁矩的问题,他们认为,核子是裸核子与外围介子云所组成的系统。把裸核子处理成一个一定分布的核源,而对介子云以场论处理。由于通常的微扰论不能应用,他们采取了一系列的变换,而把哈密顿量按耦合常数的倒数展开。随后,Pais和Serber进行了更一般的变换,其结果可利用来解决核子结构问题。Morita曾用这 相似文献
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Magnetic moments of octet baryons are parameterized to all orders of the flavor SU(3) breaking with the irreducible tensor technique in order to extract the contribution of each flavor quark to the magnetic moments of the octet baryons. The not-yet measured magnetic moment of ∑0 is predicted to be 0.649μN. Our parameterized forms for the magnetic moments are explicitly flavor-dependent, and hence each flavor component of the magnetic moments can be evaluated directly via the flavor projection operator. It is found that the strange magnetic moment of the nucleon is suppressed due to the small isoscalar anomalous magnetic moment of the nucleon. In particular, the strange magnetic form factor of the nucleon turns out to be positive, GNs(0)=0.428μN, which is consistent with recent data. 相似文献
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A thin prolate spheroidal void in an infinite conducting circular cylinder is used to model an internal flaw in a wire rope.
The rope is excited by an electric ring current which is a model for a thin solenoid or multi-turn wire loop. The anomalous
external fields are computed from the induced electric and magnetic dipole moments of the void. For this type of excitation,
the induced axial magnetic dipole moment is the dominant contributor to the scattered field. The results have application
to nondestructive testing of wire ropes. 相似文献
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The conversion electron process of the retarded electric dipole transitions of 58keV in180Hf and 67, 116, 152, 156 and 222 keV in182W have been studied by means of high resolution double focusing beta-ray spectrometers. No penetration effects were found in the conversion process of the retarded 58 keV and 67, 116 and 222 keV E1 transitions. While the retarded 152 and 156 keV transitions in182W show an anomalous internal conversion ratios compared with theoretical values. Implications of the results for current nuclear theories are discussed. 相似文献
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C. Hacker N. Wies J. Gegelia S. Scherer 《The European Physical Journal A - Hadrons and Nuclei》2006,28(1):5-9
The magnetic dipole moment of the Δ(1232) is calculated in the framework of manifestly Lorentz-invariant baryon chiral perturbation
theory in combination with the extended on-mass-shell renormalization scheme. As in the case of the nucleon, at leading order
both isoscalar and isovector anomalous magnetic moments are given in terms of two low-energy constants. In contrast to the
nucleon case, at next-to-leading order the isoscalar anomalous magnetic moment receives a (real) loop contribution. Moreover,
due to the unstable nature of the Δ(1232), at next-to-leading order the isovector anomalous magnetic moment not only receives
a real but also an imaginary loop contribution. 相似文献
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L. Greil T. R. Hemmert A. Sch?fer 《The European Physical Journal A - Hadrons and Nuclei》2012,48(5):53
We compute corrections to both the isovector anomalous magnetic moment and the isovector electromagnetic current of the nucleon
to O(p3)\ensuremath O(p^3) in the framework of covariant two-flavor Baryon Chiral Perturbation Theory. We then apply these corrections to lattice data
for the anomalous magnetic moment from the LHPC, RBC & UKQCD and QCDSF Collaborations. 相似文献
16.
A.Yu. Korchin 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):427-440
Magnetic moment and radius of the nucleon are calculated in a nonlocal extension of the chiral linear σ-model. Properties
of the nonlocal model under the vector and axial transformations are considered. The conserved electromagnetic and vector
currents, and partially conserved axial vector current are obtained. In the calculation of the nucleon electromagnetic vertex
the π- and σ-loop diagrams are included. Contribution from vector mesons is added in the vector meson dominance model with
a gauge-invariant photon-meson coupling. The nonlocality parameter associated with the πN interaction is fixed from the experimental magnetic moment of the neutron. Other parameters (nonlocality parameter for the
σN interaction and the mass of the σ-meson) are constrained by the magnetic moment of the proton. The calculated electric and
magnetic mean-square radii of the proton and neutron are in satisfactory agreement with experiment.
Received: 12 February 2001 / Accepted: 4 September 2001 相似文献
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考虑费米子的反常磁矩, 运用赝势法和热力学理论, 导出弱磁场中弱相互作用费米气体自由能的解析式, 以此为基础给出高温和低温情况下系统热力学性质, 分析反常磁矩对热力学性质的影响机理. 研究表明: 反常磁矩对热力学性质的影响与温度相关, 而且这种影响随温度的上升在低温区是增大的, 在高温区是减小的; 对于系统的化学势、内能, 反常磁矩加强了磁场的影响, 弱化了相互作用的影响; 对于系统的热容量, 反常磁矩在低温区使其减小, 在高温区使其增加. 相似文献
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We calculated the contribution of internal nucleon electric dipole moments to the Schiff moment of (199) Hg. The contribution of the proton electric dipole moment was obtained via core polarization effects that were treated in the framework of random phase approximation with effective residual forces. We derived a new upper bound |d(p)|<5.4 x 10(-24)e cm of the proton electric dipole moment. 相似文献
19.
Matthias Burkardt 《Few-Body Systems》2012,52(3-4):265-270
Parton distributions in impact parameter space, which are obtained by Fourier transforming GPDs, exhibit a significant deviation from axial symmetry when the target and/or quark are transversely polarized. Connections between this deformation and transverse single-spin asymmetries as well as with quark–gluon correlations are discussed. The sign of transverse deformation of impact parameter dependent parton distributions in a transversely polarized target can be related to the sign of the contribution from that quark flavor to the nucleon anomalous magnetic moment. Therefore, the signs of the Sivers function for u and d quarks, as well as the signs of quark–gluon correlations embodied in the polarized structure function g 2 can be understood in terms of the proton and neutron anomalous magnetic moments. 相似文献