Phenomenological Applications of QCD Factorization to Semi-inclusive B Decays

Abstract

We have systematically investigated the semi-inclusive B decays $B\to MX$, which are manifestations of the quark decay $b \to Mq$, within a framework inspired by QCD-improved factorization. These decays are theoretically clean and have distinctive experimental signatures. We focus on a class of these that do not require any form factor information and therefore may be especially suitable for extracting information on the angles $α$ and $γ$ of the unitarity triangle. The strong phase coming from final-state rescattering due to hard gluon exchange between the final states can induce large rate asymmetries for tree-dominated color-suppressed modes $(π^0,ρ^0,ω)X_{\bar s}$. The nonfactorizable hard spectator interactions in the 3-body decay $B\to Mq_1\bar q_2$, though phase-space suppressed, are extremely important for the tree-dominated modes $(π^0,ρ^0,ω)X_{\bar s},~ϕX$, $J X_s,J X$ and the penguin-dominated mode $ωX_{s\bar s}$. Our result for ${\cal B}(B\to J X_s)$ is in agreement with experiment. $B^0_s\to (π^0,ρ^0,ω)X_{\bar s}$, $ρ^0X_{s\bar s}$, $B^0\to(K^-X,K^{*-}X)$ and $B^-\to (K^0X_s,K^{*0}X_s)$ are the most promising ones in searching for direct CP violation: they have branching ratios of order $10^{-6}-10^{-4}$ and CP rate asymmetries of order $(10-40)%$.