Abstract
We have analyzed of data collected at the resonance by the Belle experiment using the KEKB asymmetric-energy collider to search for the decay . We observe no signal and report an upper limit on the branching fraction of 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