Lecture

Magnetic Scattering: Pairwise Little Group and Pairwise Helicity

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Description

This lecture delves into the properties of magnetic scattering, focusing on the pairwise little group and pairwise helicity. It covers the construction of the magnetic S-matrix for 2→2 electric-magnetic scattering, helicity flip, and monopole harmonics. The instructor discusses the multi-particle representations of the Poincare group, emphasizing the importance of pairwise spinor-helicity variables. The lecture explores the implications of the pairwise little group on angular momentum and the S-matrix transformation. It concludes with a detailed analysis of the general 3-point S-matrix and the partial wave expansion for magnetic cases, including the massless limit and higher partial waves.

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