Measurement of branching fractions for D meson decaying into ϕ meson and a pseudoscalar meson

Abstract The four decay modes D 0 → ϕ π 0 , D 0 → ϕ η , D + → ϕ π + , and D + → ϕ K + are studied by using a data sample taken at the centre-of-mass energy s = 3.773 GeV with the BESIII detector, corresponding to an integrated luminosity of 2.93 fb−1. The branching fractions of the first three decay modes are measured to be B ( D 0 → ϕ π 0 ) = ( 1.168 ± 0.028 ± 0.028 ) × 10 − 3 , B ( D 0 → ϕ η ) = ( 1.81 ± 0.46 ± 0.06 ) × 10 − 4 , and B ( D + → ϕ π + ) = ( 5.70 ± 0.05 ± 0.13 ) × 10 − 3 , respectively, where the first uncertainties are statistical and the second are systematic. In addition, the upper limit of the branching fraction for D + → ϕ K + is given to be 2.1 × 10 − 5 at the 90% confidence level. The ratio of B ( D 0 → ϕ π 0 ) to B ( D + → ϕ π + ) is calculated to be ( 20.49 ± 0.50 ± 0.45 ) % , which is consistent with the theoretical prediction based on isospin symmetry between these two decay modes.