Application of partial wave analysis in multiphoton pair production

Electron-positron pair production is investigated in the multiphoton regime under polarized fields. Partial wave analysis can be applied to reveal the momentum spectral structure and identify the positions of valleys/peaks of the multiphoton rings by combining with <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>C</a:mi><a:mi>P</a:mi></a:math> conservation. Moreover, considering the spin states of created pairs in partial wave analysis, the particle orbital angular momentum associated with the valleys/peaks can also be identified from multiphoton rings. It is found that the approximate analytical treatments for angular distribution by using partial wave analysis are consistent with those of the numerical calculation using the Dirac-Heisenberg-Wigner formalism. The results are helpful for understanding the angular momentum information in momentum spectra, and they also have an implication for revealing the vortex structure near the valleys where the amplitude nearly vanishes. Published by the American Physical Society 2024