Semi-inclusive B Decays and Direct CP Violation in QCD Factorization

Abstract

We have systematically investigated the semi-inclusive B decays B->MX, which are manifestations of the quark decay b->Mq, within the framework of 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 $\alpha$ and $\gamma$ of the unitarity triangle. The nonfactorizable effects, such as vertex-type and penguin-type corrections to the two-body b decay and hard spectator corrections to the 3-body decay are calculable in the heavy quark limit. QCD factorization is applicable when the emitted meson is a light meson or a charmonium. We discuss the issue of the CPT constraint on partial rate asymmetries. 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 $({\pi }^0,{\rho }^0,\omega )X_{\bar{s}}$. The nonfactorizable hard spectator interactions in the 3-body decay, though phase-space suppressed, are extremely important for the tree-dominated modes $({\pi }^0,{\rho }^0,\omega )X_{\bar{s}},\varphi X$, $J{X}_s,JX$ and the penguin-dominated mode $\omega X_{s\bar{s}}$. In fact, they are dominated by the hard spectator corrections. Our result for $\mathcal{B}(B\to J/\psi X_s)$ is in agreement with experiment. The semi-inclusive decay modes: $B_s^0\to ({\pi }^0,{\rho }^0,\omega )X_{\bar{s}}$, ${\rho }^0{X}_{s\bar{s}}$, $B^0\to (K^{-}X,K^{\ast -}X)$ and $B^{-}\to (K^0{X}_s,K^{\ast 0}{X}_s)$ are the most promising ones in searching for direct CP violation. In fact, they have branching ratios of order $10^{-6}-10^{-4}$ and CP rate asymmetries of order $(10-40)$.

28 pages

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Cited by in corpus (8)

• Direct CP Violation in $B\to {\pi }^{+}{\pi }^{-}\pi$: Determination of $\alpha$ without discrete ambiguity
• Direct CP Violation, Branching Ratios and Form Factors $B\to \pi$, $B\to K$ in $B$ Decays
• Probing electroweak physics using B -> XM decays in the endpoint region
• Enhanced direct CP violation in $B^{\pm ,0}\to {\pi }^{+}{\pi }^{-}{K}^{\pm ,0}$
• Semi-inclusive hadronic B decays in the endpoint region
• Semi-inclusive Decay $B\to \varphi X_s$: Rate and Momentum Spectrum of $\varphi$
• A study of semi-inclusive charmless $B\to \pi X$ decays
• Semi-inclusive hadronic B decays as null tests of the Standard Model