Measurement of the branching fraction of the doubly Cabibbo-suppressed decay D-0 -> K+pi(-)pi(0) and search for D-0 -> K+pi(-)pi(0)pi(0)

Using 2.93 fb(-1) of e(+)e(-) collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we present a measurement of the branching fraction of the doubly Cabibbo-suppressed (DCS) decay D-0 -> K+pi(-)pi(0) and a search for the DCS decay D-0 -> K+pi(-)pi(0)pi(0). The branching fraction of D-0 -> K+pi(-)pi(0) is determined to be [3.13(-0.56)(+0.60)(stat) +/- 0.15(syst)] x 10(-4). No signal is observed for D-0 -> K+pi(-)pi(0)pi(0), and an upper limit of 3.6 x 10(-4) is set on the branching fraction at the 90% CL. We combine these results with the world-average branching fractions of their counterpart Cabibbo-favored decays to determine the ratios of the DCS over the Cabibbo-favored branching fractions, B(D-0 -> K+pi(-)pi(0))/B(D-0 -> K-pi(+)pi(0)) = (0.22 +/- 0.04)% and B(D-0 -> K+pi(-)pi(0)pi(0))/B(D-0 -> K-pi(+)pi(0)pi(0)) < 0.40% at the 90% CL which correspond to (0.75 +/- 0.14) tan(4)theta(C) and 1.37 x tan(4)theta(C), respectively, where theta(C) is the Cabibbo mixing angle.