Dispersion relation approach to the anomalous magnetic moment in gauge theories

The reason why the dispersion relations for the anomalous magnetic moment are not valid in gauge theories is explained. New sum rules are derived based on unitary bounds of scattering amplitudes. In gauge theories these sum rules give the correct values for the anomalous magnetic moment, while, in the case of conventional renormalizable theories which contain no massive vector bosons, they are identical with the usual dispersion relations for the anomalous magnetic moment.     

Lorentz anomaly in arbitrary dimensions

It is shown that the Lorentz invariance is broken in gauge theories of chiral Weyl fermions in flat space-time via one-loop quantum corrections. Abelian gauge fields contribute to this anomaly in even dimensions larger than or equal to four and non-Abelian gauge fields do in even dimensions larger than or equal to six. The anomaly is proportional toD/2–1 power to the charge, whereD is a number of space-time dimensions.     

Local supersymmetry anomaly in two dimensions

We study the local supersymmetry anomaly by constructing an N = 1 (counted by Majorana-Weyl spinors) chiral supergravity model in two dimensions. There is the local supersymmetry anomaly as well as the gravitational anomaly. We obtain the linearized forms of these anomalies by perturbation calculation. The full non-linear forms are obtained by finding a solution to the Wess-Zumino consistency condition. These anomalies can be derived from the supersymmetric extension of the Chern-Simons invariant in three dimensions.     

Radiative decay of mesons and anomaly in 2+1 dimensions

In 2+1 space-time, we study the radiative decay of mesons with Yukawa couplings to two and four component fermions. In a four component theory, the electromagnetic current is free of parity odd radiative corrections; however an axialU(1) current is shown to develop a finite vacuum expectation value. Unlike even dimensions this anomaly is temperature dependent and does not play any role in the radiative decay. We calculate the effective action for the mesons and show that a finite kinetic term for these fields is induced at the one-loop level and vanishes as the temperature goes to infinity.     

Finiteness of the chiral anomaly graph in higher dimensions

The chiral anomaly graph in 2n dimensions is shown to be completely finite, independent of any constraints which would be imposed from vector-current conservation or Bose-symmetry. There is an n-fold ambiguity present in the graph which guarantees that all current divergences are equivalent in all (self-consistent) perturbative regulating procedures. The chiral anomaly is shown to reside in the alternating sum of current divergences. The ambiguity structure of the chiral anomaly graph in the Pauli-Villars scheme is explicitly computed as a specific example of this general result.     

Chern-Simons and WZW anomaly cancelations across dimensions

The WZW functional in D=4 can be derived directly from the Chern-Simons functional of a compactified D=5 gauge theory and the boundary fermions it supplants. A simple pedagogical model based on U(1) gauge groups illustrates how this works. A bulk-boundary system with the fermions eliminated manifestly evinces anomaly cancelations between CS and WZW terms.     

Eigenfunction approach to the persistent random walk in two dimensions

The Fourier–Bessel expansion of a function on a circular disc yields a simple series representation for the end-to-end probability distribution function w(R,φ) encountered in a planar persistent random walk, where the direction taken in a step depends on the relative orientation towards the preceding step. For all but the shortest walks, the proposed method provides a rapidly converging, numerically stable algorithm that is particularly useful for the precise study of intermediate-size chains that have not yet approached the diffusion limit.a     

The chiral anomaly and goldstone-wilczek current in even dimensions

The form of the non-abelian anomaly is described in arbitrary even dimension when the gauge group contains explicit U(1) factors. An effective action is constructed which when varied under the group reproduces the anomaly. It constitutes a generalization of the Wess-Zumino action.     

Preregularization and the path integral approach to the chiral anomaly

We explore the connection between perturbative and non-perturbative (path-integral) approaches to the axial anomaly. In particular, we show how the Jacobian associated with the fermionic measure corresponding to local axial transformations may be calculated directly from shift-of-integration-variable surface terms in four Euclidean dimensions. No regularization (explicit parametrization of UV infinities) is required in this approach, but invariance of the Jacobian under vector gauge transformations (i.e. preregularization) is required to remove a variable-of-integration ambiguity within the expression for the Jacobian of the fermionic measure.     

Axial anomaly in lattice abelian gauge theory in arbitrary dimensions

The axial anomaly of lattice abelian gauge theory on a hyper-cubic regular lattice in arbitrary even dimensions is investigated by applying the method of exterior differential calculus. The topological invariance, gauge invariance and locality of the axial anomaly determine the explicit form of the topological part. The anomaly is obtained up to a multiplicative constant for finite lattice spacing and can be interpreted as the Chern character of the abelian lattice gauge theory.     

高功率离子束在漂移管中的中性化传输

介绍了“闪光二号”加速器产生的高功率离子束在漂移管中的传输实验。对比了采用中性化措施前后的传输情况，分析了中性化措施对离子束束斑半径、束流均匀性的影响。根据实测的二极管电压模拟得到了传输一定距离后的束流波形，与实测结果符合较好。采取适当的中性化措施后，高功率离子束可以有效传输80 cm以上，束流发散得到抑制，束流均匀性得到改善。     

渐变型磁绝缘线振荡器色散关系的研究

渐变型同轴慢波结构是磁绝缘线振荡器的核心部分。从Maxwell方程和Floquet定理出发,导出了渐变型磁绝缘线振荡器TM模式色散曲线的表达式,并通过数值计算研究了不同结构参数下色散曲线的变化规律,为渐变段的设计提供了理论依据。