%0 Journal Article %T U-Spin Symmetry in Doubly Cabibbo-Suppressed Charmed Meson Decays %A Michael Gronau %A Jonathan L. Rosner %J Physics %D 2000 %I arXiv %R 10.1016/S0370-2693(01)00080-6 %X We prove a U-spin amplitude triangle relation among doubly Cabibbo-suppressed (DCS) charmed meson decays, $D^0\to K^+\pi^-, D^0 \to K^0\pi^0$ and $D^+_s \to K^0 K^+$, congruent to an isospin relation among corresponding Cabibbo-favored (CF) decays. U-spin breaking in relative phases between CF and DCS amplitudes affects time-dependent studies of $D^0-\od$ mixing. Comparison of final state phase patterns in DCS and CF amplitude triangles, which can shed some light on these phases, is carried out in a phenomenological framework incorporating resonance contributions. %U http://arxiv.org/abs/hep-ph/0010237v4