INVARIANT AMPLITUDES FOR PHOTON PROCESSES.
INVARIANT AMPLITUDES FOR PHOTON PROCESSES.
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光子过程的不变振幅。
DOI：
10.1103/physrev.173.1423
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发表时间：
1968
期刊：
影响因子：
--
通讯作者：
W. Tung
中科院分区：
文献类型：
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作者：
W. Bardeen;W. Tung
提出了一种构造光子过程独立不变振幅的方法，该振幅满足规范不变性，且不受运动学奇点和零点约束。该方法是基于使用一个简单的投影算子，自动确保规范不变性在每个阶段。发现了光生π介子、π介子康普顿散射和核子康普顿散射的不变振幅，再现了前两种情况下的已知结果，并阐明了它们的解释。对于核子康普顿散射，这个结果是新的。这些不变的振幅之间的比较，赫恩和领导人的振幅，和正规化的螺旋度振幅。Mandeltmann表示可以应用于这些无运动学奇异性和无零振幅，而无需任何特别的减法。所有已知的关于光子过程的低能定理都可以最直接地从这些不变振幅导出。
A method for constructing independent invariant amplitudes for photon processes which satisfy gauge invariance and are free from both kinematic singularities and zeros (constraints) is proposed. The method is based on the use of a simple projection operator which automatically ensures gauge invariance at every stage. The invariant amplitudes for pion photoproduction, pion Compton scattering, and nucleon Compton scattering are found. Previously known results in the first two cases are reproduced and their interpretation is clarified. For nucleon Compton scattering the result is new. Comparisons are made between these invariant amplitudes, the Hearn and Leader amplitudes, and the regularized helicity amplitudes. The Mandelstam representation may be applied to these kinematic-singularity-free and zero-free amplitudes without any ad hoc substractions. All known low-energy theorems on photon processes can be derived most directly from these invariant amplitudes.