Observation of the cabibbo-suppressed decay Ξ+c→pK- π+

Abstract

We report the first observation of the Cabibbo-suppressed charm baryon decay Ξ+c→pK- π+. We observe 150±22±5 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600GeV/c Σ- beam. The branching fractions of the decay relative to the Cabibbo-favored Ξ+c→Σ+K-π+ and Ξ+c→Ξ-π+π+ are measured to be B(Ξ+c→pK-π+)/B(Ξ+c→Σ+K-π+)=0.22±0.06±0.03 and B(Ξ+c→pK-π+)/B(Ξ+c→Ξ-π+π+)=0.20±0.04±0.02, respectively. © 2000 The American Physical Society.