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Bibliographic Details
Main Authors: Zhao, Chun-Qiu, Cao, Xu, Dai, Jian-Ping
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2512.19085
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Table of Contents:
  • In the center-of-mass frame, the spin density matrix for octet baryon-antibaryon pairs produced in polarized electron-positron annihilation is unambiguously determined within the one-photon-exchange approximation. The formalism simultaneously incorporates parity ($P$) and combined parity-charge conjugation ($CP$) violation arising from the coupling of the intermediate virtual photon to the baryon pair. The finite electron mass is explicitly accounted for as a correction to these $P$ and $CP$ violating effects. Built on the spin projection operator, the derived full and compact spin density matrix provides a natural starting point for evaluating other quantities of physical interest -- particularly angular distributions of sequential decays and the quantum entanglement of hyperon pairs.