Using data collected by the fixed target Fermilab experiment FOCUS, we
measure the branching ratios of the Cabibbo favored decays Ξc+→Σ+K−π+, Ξc+→Σ+Kˉ∗(892)0, and Ξc+→Λ0K−π+π+ relative to Ξc+→Ξ−π+π+ to be
0.91±0.11±0.04, 0.78±0.16±0.06, and 0.28±0.06±0.06,
respectively. We report the first observation of the Cabibbo suppressed decay
Ξc+→Σ+K+K− and we measure the branching ratio relative to
Ξc+→Σ+K−π+ to be 0.16±0.06±0.01. We also set 90%
confidence level upper limits for Ξc+→Σ+ϕ and Ξc+→Ξ∗(1690)0(Σ+K−)K+ relative to Ξc+→Σ+K−π+ to
be 0.12 and 0.05, respectively. We find an indication of the decays Ξc+→Ω−K+π+ and Ξc+→Σ∗(1385)+Kˉ0 and set
90% confidence level upper limits for the branching ratios with respect to
Ξc+→Ξ−π+π+ to be 0.12 and 1.72, respectively. Finally, we
determine the 90% C.L. upper limit for the resonant contribution Ξc+→Ξ∗(1530)0π+ relative to Ξc+→Ξ−π+π+ to be 0.10.Comment: 14 pages, 8 figure