Study of Cabibbo suppressed decays of the Ds+ charmed-strange meson involving a KS0

Abstract We study the decay of D s + mesons into final states involving a K S 0 and report the discovery of Cabibbo suppressed decay modes D s + → K S 0 π − π + π + ( 179 ± 36 events) and D s + → K S 0 π + ( 113 ± 26 events). The branching fraction ratios for the new modes are Γ ( D s + → K S 0 π − π + π + ) Γ ( D s + → K S 0 K − π + π + ) = 0.18 ± 0.04 ± 0.05 and Γ ( D s + → K S 0 π + ) Γ ( D s + → K S 0 K + ) = 0.104 ± 0.024 ± 0.014 .