Entanglement-sensitive observables in e+e- → τ+τ- at STCF: a detector-level feasibility study
Abstract
Quantum entanglement in τ+τ- production provides a direct probe of non-classical spin correlations in a relativistic quantum system, with the τ decay products serving as spin analyzers. We investigate the detector-level feasibility of such measurements in e+e-→τ+τ- at the Super Tau-Charm Facility (STCF) at √s=7 GeV, using the ρρ and πρ decay channels. Signal and dominant background processes are simulated with the full STCF detector and reconstruction framework. Dedicated reconstruction and event-selection procedures yield overall signal efficiencies of approximately 4.5% and 4.8%, with corresponding purities of about 87.6% and 93.2% for the ρρ and πρ channels, respectively. From the reconstructed decay kinematics, the τ+τ- spin-density matrix is inferred and the concurrence C[ρ] together with the Bell-sensitive quantity m12[C] are evaluated in a selected fiducial region. For the benchmark requirement |cosθ|<0.2 and an integrated luminosity of 1 ab−1, the projected relative precision on C[ρ] is about 2.2% in both channels, while that on m12[C] is approximately 1.4% for ρρ and 1.5% for πρ, including statistical and detector-resolution uncertainties. The reconstructed m12[C] shows a larger separation from its reference threshold in the ρρ channel, making this topology particularly sensitive to Bell-type spin correlations. These results demonstrate the detector-level feasibility of probing quantum entanglement and non-classical spin correlations in hadronic τ decays at STCF.
Related
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BibTeX
@misc{bao2026entanglementsensitive,
title = {{Entanglement-sensitive observables in $e^+e^- \to τ^+τ^-$ at STCF: a detector-level feasibility study}},
author = {Chentao Bao and Xi Tao and Hai Chen and Lailin Xu and Xiaorong Zhou and Mingyi Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03024},
eprint = {2610.03024},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03024},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Entanglement-sensitive observables in e^+e^- → τ^+τ^- at STCF: a detector-level feasibility study
AU - Chentao Bao
AU - Xi Tao
AU - Hai Chen
AU - Lailin Xu
AU - Xiaorong Zhou
AU - Mingyi Liu
PY - 2026
DA - 2026/10/02
PB - arXiv
DO - 10.48550/arxiv.2610.03024
UR - https://arxiv.org/abs/2610.03024
AB - Quantum entanglement in τ^+τ^- production provides a direct probe of non-classical spin correlations in a relativistic quantum system, with the τ decay products serving as spin analyzers. We investigate the detector-level feasibility of such measurements in e^+e^-→τ^+τ^- at the Super Tau-Charm Facility (STCF) at √s=7 GeV, using the ρρ and πρ decay channels. Signal and dominant background processes are simulated with the full STCF detector and reconstruction framework. Dedicated reconstruction and event-selection procedures yield overall signal efficiencies of approximately 4.5% and 4.8%, with corresponding purities of about 87.6% and 93.2% for the ρρ and πρ channels, respectively. From the reconstructed decay kinematics, the τ^+τ^- spin-density matrix is inferred and the concurrence C[ρ] together with the Bell-sensitive quantity m_12[C] are evaluated in a selected fiducial region. For the benchmark requirement |cosθ|<0.2 and an integrated luminosity of 1 ab^−1, the projected relative precision on C[ρ] is about 2.2% in both channels, while that on m_12[C] is approximately 1.4% for ρρ and 1.5% for πρ, including statistical and detector-resolution uncertainties. The reconstructed m_12[C] shows a larger separation from its reference threshold in the ρρ channel, making this topology particularly sensitive to Bell-type spin correlations. These results demonstrate the detector-level feasibility of probing quantum entanglement and non-classical spin correlations in hadronic τ decays at STCF.
ER -