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

Abstract

A measurement of CP asymmetry in D0→KS0KS0$$ {D}^0\to {K}{\textrm{S}}^0{K}{\textrm{S}}^0 $$ 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−$$ {D}^0\to {K}{\textrm{S}}^0{\pi}^{+}{\pi}^{-} $$ decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D0→KS0KS0$$ {D}^0\to {K}{\textrm{S}}^0{K}{\textrm{S}}^0 $$ mode is measured to beACPD0→KS0KS0=1.86±1.04±0.41%,$$ {\mathcal{A}}^{CP}\left({D}^0\to {K}{\textrm{S}}^0{K}_{\textrm{S}}^0\right)=\left(1.86\pm 1.04\pm 0.41\right)%, $$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.