B→Kη,Kη′ Decays

The nonet symmetry scheme seems to describe rather well the masses and η–η′ mixing angle of the ground state pseudo-scalar mesons and is thus expected to be also a good approximation for the matrix elements of the pseudo-scalar density operators which play an important role in charmless two-body B decays with η or η′ in the final state. In this talk, I would like to report on a recent work on the B−→K−η,K−η′ decay using nonet symmetry for the matrix elements of pseudo-scalar density operators. We find that the branching ratio B→PP, with an η meson in the final state agrees well with data, while those with an η′ meson are underestimated by 20–30%. This could be considered as a more or less successful prediction for QCDF, considering the theoretical uncertainties involved. This could also indicate that an additional power-suppressed terms could bring the branching ratio close to experiment, as with the B→K∗π and B→K∗η decay for which the measured branching ratios are much bigger than the QCDF predictions.