We report the first observation of two Cabibbo-suppressed decay modes, Ξc+ → Σ+ π- π+ and Ξc+ → Σ- π+ π+. We observe 59 ± 14 over a background of 87, and 22 ± 8 over a background of 13 events, respectively, for the signals. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV / cΣ- beam. The branching ratios of the decays relative to the Cabibbo-favored Ξc+ → Ξ- π+ π+ are measured to be B (Ξc+ → Σ+ π- π+) / B (Ξc+ → Ξ- π+ π+) = 0.48 ± 0.20, and B (Ξc+ → Σ- π+ π+) / B (Ξc+ → Ξ- π+ π+) = 0.18 ± 0.09, respectively. We also report branching ratios for the same decay modes of the Λc+ relative to Λc+ → p K- π+.
|Number of pages||6|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - 4 Sep 2008|