We measure the branching fraction for the Cabibbo-suppressed decay $D^0\to K_S^0{K}_S^0{\pi }^{+}{\pi }^{-}$ and search for $CP$ violation via a measurement of the $CP$ asymmetry $A_{CP}$ as well as the $T$-odd triple-product asymmetry $a_{CP}^T$. We use $922{\mathrm{fb}}^{-1}$ of data recorded by the Belle experiment, which ran at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The branching fraction is measured relative to the Cabibbo-favored normalization channel $D^0\to K_S^0{\pi }^{+}{\pi }^{-}$; the result is $\mathcal{B}(D^0\to K_S^0{K}_S^0{\pi }^{+}{\pi }^{-})=[4.79\pm 0.08(\mathrm{stat})\pm 0.10(\mathrm{syst})\pm 0.31(\mathrm{norm})]\times {10}^{-4}$, where the first uncertainty is statistical, the second is systematic, and the third is from uncertainty in the normalization channel. We also measure $A_{CP}=[-2.51\pm 1.44(\mathrm{stat}{)}_{-0.10}^{+0.11}(\mathrm{syst})]\%$, and $a_{CP}^T=[-1.95\pm 1.42(\mathrm{stat}{)}_{-0.12}^{+0.14}(\mathrm{syst})]\%$. These results show no evidence of $CP$ violation.

• Received 16 July 2022
• Accepted 30 January 2023

DOI:https://doi.org/10.1103/PhysRevD.107.052001

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society