η(′) productions in semileptonic B decays

Inspired by the new measurements on B−→η(′)ℓν¯ℓ from the BaBar Collaboration, we examine the constraint on the flavor-singlet mechanism, proposed to understand the large branching ratios for B→η′K decays. Based on the mechanism, we study the decays of B¯d,s→η(′)ℓ+ℓ− and find that they are sensitive to the flavor-singlet effects. In particular, we show that the decay branching ratios of B¯d,s→η′ℓ+ℓ− can be as large as O(10−8) and O(10−6), respectively.