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Bell nonlocality and entanglement in χcJ decays into a baryon pair

Peng-Cheng Hong1,2,*, Rong-Gang Ping2,3,†, and Wei-Min Song1,‡

  • *Contact author: hongpc@ihep.ac.cn
  • †Contact author: pingrg@ihep.ac.cn
  • ‡Contact author: weiminsong@jlu.edu.cn
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Phys. Rev. D 113, 076009 – Published 9 April, 2026

DOI: https://doi.org/10.1103/8bx4-gfc4

Abstract

We present a systematic analysis of Bell nonlocality and entanglement in χcJ(J=0,1,2) decays into a baryon pair (BB¯), with particular emphasis on their production via the process e+e−→ψ(2S)→γχcJ at BESIII. From the baryon-antibaryon spin density matrix, we construct measurable Bell observables and concurrence, revealing a striking hierarchy of quantum correlations: χc0 decays exhibit maximal violation and entanglement; χc1 decays violate Bell inequalities for θ1∈(0,π) with angle-modulated strength; we find that the BB¯ pair in χc2 decays is in a separable state, and no indication of Bell inequality violation is observed. We provide complete analytical results for J=0, 1 and quantitative, uncertainty-aware estimations for J=2 based on experimental inputs from BESIII. These results establish the χcJ system produced via this radiative transition as a novel and promising platform for testing quantum entanglement and Bell nonlocality in high-energy collisions.

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Phys. Rev. D 113, 076009– Published 9 April, 2026
  • Received 3 January 2026
  • Accepted 13 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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