论文标题
自旋密度基质的参数化
Parametrizations of the Spin Density Matrix
论文作者
论文摘要
我们建议自动矩阵两个参数化，它们会自动满足非负条件，而无需对参数设置任何绑定。第一个依赖于我们证明的定理，它非常简单且易于适应某些特定的反应，例如，奇偶校验是保守的，或者是角动量保护需要选择规则。此外，如果等级小于密度矩阵的顺序，我们将展示如何通过实现先前的建议或详细说明替代方法来改善数据的拟合，我们证明了第二个定理。我们的第二个参数化是先前治疗的变体，它似乎适用于某些特定过程。此外，我们讨论了从差衰变宽度中推断密度矩阵元素的可能性。最后，我们说明了当前兴趣的各种例子，无论是在强大而弱的衰减中。其中一些可能有助于对标准模型以外的物理研究有所帮助。
We propose for the spin density matrix two parametrizations which automatically fulfil the non-negativity conditions, without setting any bound on the parameters. The first one relies on a theorem, that we prove, and it is rather simple and easily adaptable to some specific reactions, where, for example, parity is conserved or angular momentum conservation entails selection rules. Moreover, in the case when the rank is less than the order of the density matrix, we show how to improve the fits to the data, either by implementing previous suggestions, or by elaborating an alternative method, for which we prove a second theorem. Our second parametrization is a variant of previous treatments, it appears suitable for some particular processes. Moreover, we discuss about the possibility of inferring the elements of the density matrix from the differential decay width. Last, we illustrate various examples of current interest, both in strong and weak decays; some of them may be helpful in the investigation of physics beyond the standard model.
