The doubly Cabibbo-suppressed decay $D^+\to K^+ π^- π^+$

Abstract

We report the observation of the doubly Cabibbo-suppressed decay $D^+\to K^+ π^- π^+$ in data from Fermilab charm hadroproduction experiment E791. With a signal of 59 \pm 13 events we measured the ratio of the branching fraction for this mode to that of the Cabibbo-favored decay $D^+\to K^- π^+ π^+$ to be $B(D^+ \to K^+ π^- π^+) / B(D^+ \to K^- π^+ π^+) = (7.7 \pm 1.7 \pm 0.8) \times 10^{-3}$. A Dalitz plot analysis was performed to search for resonant structures.