We have analyzed $121.4{\mathrm{fb}}^{-1}$ of data collected at the $\mathrm{\Upsilon }(5S)$ resonance by the Belle experiment using the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider to search for the decay $B_s^0\to J/\psi {\pi }^0$. We observe no signal and report an upper limit on the branching fraction $\mathcal{B}(B_s^0\to J/\psi {\pi }^0)$ of $1.21\times {10}^{-5}$ at 90% confidence level. This result is the most stringent, improving the previous bound by 2 orders of magnitude.

• Received 23 November 2023
• Accepted 17 January 2024

DOI:https://doi.org/10.1103/PhysRevD.109.032007

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Published by the American Physical Society