Within perturbative QCD approach based on $k_T$ factorization, we analyze the scalar mesons $f_0(980)$ and $f_0(1500)$ productions in $B$ decays. By identifying $f_0(980)$ as the composition of $\overline{s}s$ and $\overline{n}n=(\overline{u}u+\overline{d}d)/\sqrt{2}$, we calculate the exclusive decays $B\to f_0(980)K$. We find that the nonfactorization $f_0$-emission diagrams can give larger contribution to the branching ratio, than the previous PQCD calculation. Our new results can explain the current experimental data well. Under the assumption of quarkonium dominance, we study the branching ratio of decays $B\to f_0(1500)K$. The results show that in the two-quark picture of $f_0$ meson the contribution from $\overline{s}s$ component is at the similar size as that from the $\overline{n}n$ component. Comparing the data, our results show the preference of $f_0(1500)$ as a member of the ground state of scalar $\overline{q}q$ nonet. Similar results can also apply to $f_0(1370)$ and $f_0(1710)$, if these mesons are dominated by the quarkonium content. With more experimental data in the future, these studies will help us understand the intrinsic characters of these scalar mesons.

• Received 12 September 2006

DOI:https://doi.org/10.1103/PhysRevD.74.114010