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arXiv · 2605.01233

Probing Quantum Entanglement in $\tau^+\tau^-$ Pairs via the $\pi\pi$ Channel at STCF

Xiaokang Li·Chentao Bao·Hai Chen·Mingyi Liu·Dayong Wang
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Abstract

Quantum entanglement and Bell-inequality violation in $\tau^+\tau^-$ pairs provide a sensitive probe of quantum correlations in high-energy interactions. We present a feasibility study of $e^+e^- \to \tau^+\tau^-$ at the proposed Super Tau-Charm Facility based on full Monte Carlo simulation at $\sqrt{s} = 7$ GeV, focusing on the $\pi\pi$ channel ($\tau^\pm \to \pi^\pm\nu$), which offers the maximal spin-analyzing power $|\kappa| = 1$ and the simplest final-state topology for validating the quantum-tomography framework. We establish a consistency chain from the tree-level QED prediction through truth-level and detector-level reconstruction, yielding a reconstructed concurrence of $0.279 \pm 0.007$ with the good-solution approach. A complementary full-simulation study of the $\rho\rho$ channel is also briefly reported. These results demonstrate that the STCF can provide a competitive platform for precision studies of quantum correlations in $\tau$-lepton pairs.

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Xiaokang Li, Chentao Bao, Hai Chen, Mingyi Liu, Dayong Wang. 2026-05-02. Probing Quantum Entanglement in $\tau^+\tau^-$ Pairs via the $\pi\pi$ Channel at STCF. https://doi.org/10.1142/s0217751x26450028

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