D0-D̄0 mixing parameter y in the factorization-assisted topological-amplitude approach**Supported by National Natural Science Foundation of China (11347027, 11505083, 11375208, 11521505, 1162113100, 11235005, U1732101), Ministry of Science and Technology of R.O.C. (MOST-104-2112-M-001-037-MY3) and DFG Forschergruppe FOR 1873 “Quark Flavour Physics and Effective Field Theories”

Abstract

We calculate the mixing parameter y in the factorization-assisted topological-amplitude (FAT) approach, considering contributions from , PV, and VV modes, where P (V) stands for a pseudoscalar (vector) meson. The and PV decay amplitudes are extracted in the FAT approach, and the decay amplitudes with final states in the longitudinal polarization are estimated via the parameter set for . It is found that the VV contribution to y, being of order of 10−4, is negligible, and that the PP and PV contributions amount only up to , a prediction more precise than those previously obtained in the literature, and much lower than the experimental data . We conclude that D0 meson decays into other two-body and multi-particle final states are relevant to the evaluation of y, so it is difficult to understand it fully in an exclusive approach.