U-Spin Symmetry in Doubly Cabibbo-Suppressed Charmed Meson Decays

Abstract

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 $D^0-\text{od}$ 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.

Comments: Two references updated, to appear in Phys. Lett. B