Updated analysis of D→PP,VP , and VV decays: Implications for <…

An updated analysis of the two-body D→PP,VP, and VV decays within the framework of the topological diagram approach is performed. A global fit to the Cabibbo-favored (CF) modes in the VP sector gives many solutions with similarly small local minima in χ2. The solution degeneracy is lifted once we use them to predict for the singly-Cabibbo-suppressed modes. Topological amplitudes are extracted for the η−η′ mixing angles ϕ=40.4° and 43.5°. The KS0−KL0 asymmetries in D→KS,L0M decays denoted by R(D,M) are studied. While the predicted R(D0,P) for P=π0,η and η′ agree with experiment, the calculated R(D+,π+), R(Ds+,K+), R(D0,ω), and R(D0,ϕ) deviate from the data. We conjecture that the relative phase between the topological amplitudes (C+A) and (T+C) should be slightly smaller than 90° in order to explain the first two discrepancies and that additional singlet contributions due to the SU(3)-singlet nature of ω and ϕ are needed to account for the last two. For doubly-Cabibbo-suppressed (DCS) D→VP decays, their topological amplitudes (double primed) cannot be all the same as the corresponding ones in the CF modes. The assumption of EV,P′′=EV,P for the W-exchange amplitude leads to some inconsistencies with the experiment. Through the measured relative phases between CF and DCS channels, the relations of EV,P′′ with EV,P are determined. Long-distance contributions to the D0−D¯0 mixing parameter y are evaluated in the exclusive approach. In particular, we focus on D→PP and VP decays where y can be reliably estimated. We conclude that yPP∼(0.110±0.011)% and the lower bound on yVP is (0.220±0.071)%. It is thus conceivable that at least half of the mixing parameter y can be accounted for by the two-body PP and VP modes. The main uncertainties arise from the yet-to-be-measured DCS channels and their phases relative to the CF ones. Published by the American Physical Society 2024