Measurement of the branching ratio of the decay ${\Xi }^0\to {\Sigma }^{+}{\mu }^{-}{\bar{\nu }}_{\mu }$

Abstract

From the 2002 data taking with a neutral kaon beam extracted from the CERN-SPS, the NA48/1 experiment observed 97 ${\Xi }^0\to {\Sigma }^{+}{\mu }^{-}{\bar{\nu }}_{\mu }$ candidates with a background contamination of $30.8\pm 4.2$ events. From this sample, the BR(${\Xi }^0\to {\Sigma }^{+}{\mu }^{-}{\bar{\nu }}_{\mu }$) is measured to be $(2.17\pm 0.32_{\mathrm{stat}}\pm 0.17_{\mathrm{syst}})\times 10^{-6}$.