Future lepton colliders such as the Circular Electron Positron Collider (CEPC) and FCC (Future Circular Collider)-ee would run as high-luminosity Z -boson factories, which offer a unique opportunity to study long-lived particles which couple to Z bosons. In order to exemplify this particular advantage, in this work, we consider one benchmark physics scenario where the long-lived lightest neutralinos pair ( χ ? 1 0 χ ? 1 0 ) is produced from Z decays in the context of the R-parity-violating supersymmetry. Our analysis indicates that when assuming BR ( Z → χ ? 1 0 χ ? 1 0 ) = 10 ? 3 and m χ ? 1 0 ～ 40 ? ? GeV , the model parameter λ 112 ′ / m f ? 2 can be discovered down to as low as ～ 1.5 × 10 ? 14 ( 3.9 × 10 ? 14 ) ? ? GeV ? 2 at the FCC-ee (CEPC) with center-of-mass energy s = 91.2 ? ? GeV and 150 ? ( 16 ) ? ? ab ? 1 integrated luminosity. These limits exceed the projected sensitivity reaches of the ATLAS experiment at the high-luminosity Large Hadron Collider (LHC) and the proposed LHC experiments with far detectors (AL3X, CODEX-b, FASER, and MATHUSLA).
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