Measurement of the time-integrated πΆβ’π asymmetry in π· 0 β πΎ$^{0}_{S}$πΎ$^{0}_{S}$ decays using opposite-side flavor tagging at Belle and Belle II
We measure the time-integrated πΆβ’π asymmetry in π· 0 β πΎ$^{0}_{S}$πΎ$^{0}_{S}$ decays reconstructed in π + β’π β β $c\bar{c}$ events collected by the Belle and Belle II experiments. The corresponding data samples have integrated luminosities of 980 and 428 fb β1 , respectively. To infer the flavor of the π· 0 meson, we exploit the correlation between the flavor of the reconstructed decay and the electric charges of particles reconstructed in the rest of the π + β’π β β $c\bar{c}$ event. This results in a sample which is independent from any other previously used at Belle or Belle II. The result, π΄ πΆβ’π β‘(π· 0 β πΎ$^{0}_{S}$πΎ$^{0}_{S}$)=(1.3Β±2.0Β±0.2)%, where the first uncertainty is statistical and the second systematic, is consistent with previous determinations and with πΆβ’π symmetry.