Measurement of the branching fraction of decay at Belle

Using of data collected with the Belle detector operating at the KEKB asymmetric-energy collider, we present a measurement of the branching fraction of the singly Cabibbo-suppressed decay . A clear signal is observed for with a statistical significance of 9.1 standard deviations, and we measure the ratio of branching fractions , from which we infer the branching fraction . The first quoted uncertainty is statistical, the second systematic, and the third from the reference mode . © 2021 Published by the American Physical Society