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arXiv:2602.08541 · Physical review. D/Physical review. D.

Can mirror symmetry challenge local realism? Probing photon entanglement from positronium via Compton scattering

Junle Pei, Lina Wu

Published Oct 2, 2026• 0 citations
arXivHTMLPDF

Abstract

This study investigates photon entanglement generated from parapositronium decay by analyzing azimuthal correlations after the double Compton scattering with stationary electrons. We introduce a normalized correlation observable O 1 = cos ( 2 ϕ 1 − 2 ϕ 2 ) / C 1 to witness entanglement. In the absence of decoherence, ⟨ O 1 ⟩ = − 1 , corresponding to a maximally entangled Bell state. With decoherence parametrized by ρ , the expectation becomes − ( 1 − ρ ) , allowing direct experimental quantification of coherence loss. A prior symmetry analysis of the Compton scattering process within the quantum field theory (QFT) is provided, which establishes the mirror-symmetric nature of the single-photon angular distribution. We further examine a local hidden-variable theory (LHVT) under the angular-momentum conservation and the rotation invariance. Imposing the mirror symmetry with respect to the plane defined by the photon spin and momentum leads to a non-negative LHVT prediction for ⟨ sin 2 θ 1 sin 2 θ 2 cos ( 2 ϕ 1 − 2 ϕ 2 ) ⟩ , contradicting the negative QFT prediction value for any ρ < 1 . Thus, mirror symmetry serves as a novel criterion to exclude LHVT descriptions of the entangled state, whereas without preserving this symmetry, LHVTs can reproduce the correlations.

DOI
10.1103/t6sf-gx1v

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