Decays mediated by flavor-changing neutral currents are suppressed in the standard model (SM) and provide an indirect route to search for new physics because beyond-the-SM particles may enter via loop diagrams. The ๐ต 0 → ๐พ 0๐ 0 decays comprise an important example, which allow us to probe CP violation either directly in the decays (๐CP), or indirectly due to interference between decays with and without ๐ต 0–๐ตฬ
0 mixing (๐ฎCP). The CKM and color suppression of the tree-level ๐ → ๐ข๐ ๐ขฬ
transition implies that ๐ต 0 → ๐พ 0๐ 0 decays are dominated by the top-quark mediated ๐ → ๐ ๐๐ฬ
loop diagram, which carries a weak phase arg(๐๐ก๐๐๐ก๐ ∗ ); ๐๐๐ denote the CKM matrix elements. Neglecting subleading contributions to the decay amplitude, ๐ฎCP is expected to be equal to sin 2๐ฝ and ๐CP ≈ 0. Possible new physics contributions to the amplitude can introduce deviations from the expected values. Furthermore, ๐ต 0 → ๐พ 0๐ 0 decays are the key in testing an isospin sum rule that relates all four ๐ต → ๐พ๐ decays. We report measurements of branching fraction and direct CP-violating asymmetry ๐CP in the charmless decay ๐ต 0 → ๐พ๐ 0๐ 0 performed using 189.8 fb −1 of e +e − collision data recorded at the Υ(4๐) resonance by the Belle II experiment. This is the first measurement of ๐CP in ๐ต 0 → ๐พ 0๐ 0 conducted at Belle II relying on a time-dependent analysis.
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