摘要
In this study,the non-trival effect of the selection of reference particles for decay angle definitions is demonstrated when constructing the partial-wave amplitude of multi-body decays using helicity formalism.This issue is often ignored in the standard use case of helicity formalism.A new technique is proposed to test the selection of the particle ordering,and it can also be used as a generalized method to calculate the rotation operators that are used for the final-state alignment between different decay chains.Moreover,numerical validations are performed to support the arguments and to verify the effectiveness of the proposed technique.
基金
This work was supported in part by National Key R&D Program of China(2017YFA0402103,2020YFA0406400)
National Natural Science Foundation of China(11775122,11822506,11975015)
Fundamental Research Funds for the Central Universities。