Measurement of CP asymmetry in D⁰→ KS⁰KS⁰ decays with Run 3 data

A bstract A measurement of CP asymmetry in D⁰→ KS⁰KS⁰ D 0 → K S 0 K S 0 decays is reported, based on a data sample of proton-proton collisions collected with the LHCb detector in 2024 at a centre-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 6.2 fb − 1 . The D⁰→ KS⁰π⁺π⁻ D 0 → K S 0 π + π − decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D⁰→ KS⁰KS⁰ D 0 → K S 0 K S 0 mode is measured to be ACP(D⁰→ KS⁰KS⁰)=(1.86± 1.04± 0.41)%, A CP D 0 → K S 0 K S 0 = 1.86 ± 1.04 ± 0.41 % , where the first uncertainty is statistical, and the second is systematic. This measurement represents the most precise single-experiment determination of this quantity to date.