We study the charmless decays $B\to K_hη$ and $B\to K_hη'$ within the framework of QCD factorization (QCDF) for $K_h= K,K^*,K_0^*(1430)$ and naive factorization for $K_h=K_2^*(1430)$. There are three distinct types of penguin contributions: (i) $b\to sq\bar q\to sη_{q}$, (ii) $b\to ss\bar s\to sη_s$, and (iii) $b\to s q\bar q\to q \bar K_h$, where $η_q=(u\bar u+d\bar d)/\sqrt{2}$ and $η_s=s\bar s$. $B\to K^{(*)}η^{(')}$ decays are dominated by type-II and type-III penguin contributions. The interference, constructive for $Kη'$ and $K^*η$ and destructive for $Kη$ and $K^*η'$, between type-II and type-III diagrams explains the pattern of $Γ(B\to Kη')\ggΓ(B\to Kη)$ and $Γ(B\to K^*η')\llΓ(B\to K^*η)$. Within QCDF, the observed large rate of the $Kη'$ mode can be naturally explained without invoking flavor-singlet contributions or something exotic. The decay pattern for $B\to K_0^*(1430)η^{(')}$ decays depends on whether the scalar meson $K_0^*(1430)$ is an excited state of $κ$ or a lowest-lying $P$-wave $q\bar q$ state. Hence, the experimental measurements of $B\to K_0^*(1430)η^{(')}$ can be used to explore the quark structure of $K_0^*(1430)$. If $K_0^*(1430)$ is a low-lying $q\bar q$ bound state, we find that $K_0^*η$ has a rate slightly larger than $K_0^*η'$ owing to the fact that the $η$-$η'$ mixing angle in the $η_q,η_s$ flavor basis is less than $45^\circ$, in agreement with experiment. Type-III penguin diagram does not contribute to $B\to K_2^*η^{(')}$ under the factorization hypothesis and type-II diagram dominates.
Recent experimental results from CLEO indicate that strong penguin processes are remarkably robust. These results have spurred a variety of theoretical efforts which will be briefly review here. In particular we will discuss exclusive modes, inclusive eta-prime modes, the charm deficit and the implications for CP violation.
We discuss the correlations of charming penguin contributions to $B\toππ$, $πK$ and KK using approximate flavor SU(3) symmetry. Strong constraints are found from the direct CP asymmetries especially in $πK$ modes. We make a global fit to the latest data and find that only a small charming penguin is allowed, and the size of color-suppressed tree amplitude (C) relative to tree amplitudes (T) remains large $C/T\simeq0.6$, which disfavors the possibility of a large charming penguin as an explanation for the $ππ$ puzzle. We show that a small charming penguin can still have sizable effect in the ti…
Electroweak penguin (EWP) amplitudes are studied model-independently in $B$ meson decays to charmless final states consisting of a vector meson ($V$) and a pseudoscalar meson ($P$). A set of SU(3) relations is derived between EWP contributions and tree amplitudes, in the approximation of retaining only the dominant EWP operators $Q_9$ and $Q_{10}$ . Two applications are described for constraining the weak phase $γ$, in $B^{\pm}\to ρ^{\pm} K^0$ and $B^{\pm}\to ρ^0 K^{\pm}$ (or $B^{\pm}\to K^{*\pm}π^0$ and $B^{\pm}\to K^{*0}π^{\pm}$), and in $B^0\to K^{*\pm}π^{\mp}$ and $B^{\pm}\toϕK^{\pm}$. The…
We present estimates of the charming penguin contribution to B => K pi, pi pi,K eta, K eta' decays due to intermediate charmed meson states. We find that this contribution is indeed significant for B => K pi decays, and its inclusion, together with the tree and penguin terms, produces large branching ratios in agreement with data, though the analysis is affected by large theoretical uncertainties. On the other hand, for B => pi pi, K eta, K eta' decays, the effect of the charming penguin contribution is more modest. We also compute CP asymmetries for B => K pi, pi pi decays and we obtain rathe…
A useful inequality is obtained if charmless strange B decays are assumed to be dominated by the gluonic penguin diagram and the tree diagram contribution is small but not negligible. The penguin-tree interference contribution which is linear in the tree amplitude is included but the direct tree contribution which is quadratic is neglected.
We analyze the charmless two-body $B\to VP$ decays in the soft-collinear-effective-theory (SCET), where $V(P)$ denotes a light vector (pseudoscalar) meson. Using the current experimental data, we find two solutions in $χ^2$ fit for the 16 non-perturbative inputs responsible for the 87 $B\to PP$ and $B\to VP$ decay channels in SU(3) symmetry. Chirally enhanced penguins can only change several charming penguins sizably, since they share the same topology. The (S-P)(S+P) annihilation penguins in the perturbative QCD approach have the same topology with charming penguins in SCET, which play an imp…
A useful inequality is obtained if charmless strange B decays are assumed to be dominated by a $ΔI = 0$ transition like that from the gluonic penguin diagram and the contributions of all other diagrams including the tree, electroweak penguin and annihilation diagrams are small but not negligible. The interference contributions which are linear in these other amplitudes are included but the direct contributions which are quadratic are neglected.
We try a global fit of the experimental branching ratios and CP-asymmetries of the charmless $B\to PV$ decays according to QCD factorisation. We find it impossible to reach a satisfactory agreement, the confidence level (CL) of the best fit is smaller than .1 %. The main reason for this failure is the difficulty to accomodate several large experimental branching ratios of the strange channels. Furthermore, experiment was not able to exclude a large direct CP asymmetry in $\bar {B^0}\toρ^+ π^-$, which is predicted very small by QCD factorisation. Trying a fit with QCD factorisation complemented…
We calculate the enhancements to the inclusive charmless decays of b quark, $b \to s g, s q\bar{q}, sgg$, from gluon penguin diagrams induced by the charged and neutral Higgs bosons $(H^{\pm}, h^0, H^0$, and A^0) in the Two-Higgs-Doublet Model with flavor-changing couplings. Within the considered parameter space, the new contributions from charged Higgs boson are dominant. After including the new contributions, the branching ratio $BR(b \to sg)$ (q^2 =0) can be increased form $\sim 0.2%$ in the standard model to 4.4% and 2.6% in the two-Higgs-doublet model for $m_{H^+}=100$ and 200 GeV, respec…
Gluon mediated exclusive hadronic decays of b quarks are studied within the standard model (SM) and the constrained minimally supersymmetric standard model (MSSM). For all allowed regions of the MSSM parameter space (A, tan beta, m_0, m_{1/2}) the penguin magnetic dipole form factor F^R_2 is dominant over the electric dipole and can be larger than the magnetic dipole form factor of the SM. However, overall the SM electric dipole decay amplitude F^L_1 dominates the decay rate. The MSSM penguin contributions to the free quark decay rate approach the 10% level for those regions of parameter space…
We calculate the contributions of penguin diagrams with internal u or c quarks to various inclusive charmless B-decay rates. Further we analyze the influence of the chromomagnetic dipole operator Q_8 on these rates. We find that the rates corresponding to B-bar --> X_{u u-bar s}, B-bar --> X_{d d-bar s}, B-bar --> X_{s s-bar s}, B-bar --> X_{s s-bar d} and B --> X_{d d-bar d} are dominated by the new penguin contributions. The contributions of Q_8 sizably diminish these rates. Despite of an increase of the total charmless decay rate by 36 % the new contributions are not large enough to explain…
The decays of $B$ mesons to a pair of charmless pseudoscalar ($P$) mesons are analyzed within a framework of flavor SU(3). Symmetry breaking is taken into account in tree ($T$) amplitudes through ratios of decay constants; exact SU(3) is assumed elsewhere. Acceptable fits to $B \to ππ$ and $B \to K π$ branching ratios and CP asymmetries are obtained with tree, color-suppressed ($C$), penguin ($P$), and electroweak penguin ($P_{EW}$) amplitudes. Crucial additional terms for describing processes involving $η$ and $η'$ include a large flavor-singlet penguin amplitude ($S$) as proposed earlier and…
In the study of two-body charmless B decays as a mean of looking for direct CP-violation and measuring the CKM mixing parameters in the Standard Model, the short-distance penguin contribution with its absorptive part generated by charm quark loop seems capable of producing sufficient $B \to Kπ$ decays rates, as obtained in factorization and QCD-improved factorization models. However there are also long-distance charming penguin contributions which could give rise to a strong phase due to the rescattering $D^{*}D^{*}_{s} \to Kπ$ etc. In this talk, I would like to discuss recent works on the cha…
We present fits to charmless hadronic B decay data from the BaBar, Belle and Cleo experiments using two theoretical models: (i) the QCD factorization model of Beneke et al. and (ii) QCD factorization complemented with the so-called charming penguins of Ciuchini et al. When we include the data from pseudoscalar-vector decays the results favor the incorporation of the charming penguin terms. We also fit results for the unitarity triangle parameters and the CP-violating asymmetries.
New data from the BaBar, Belle, and CLEO Collaborations on B decays to two-body charmless final states are analyzed, with the following consequences: (1) The penguin amplitude which dominates the decay $B^+ \to π^+ K^{*0}$ has a magnitude similar to that dominating $B^+ \to π^+ K^0$. (2) The decay $B^+ \to π^+ η$, a good candidate for observing direct CP violation, should be detectable at present levels of sensitivity. (3) The decays $B^+ \to η' K^+$ and $B^+ \to ηK^{*+}$ are sufficiently similar in rate to the corresponding decays $B^0 \to η' K^0$ and $B^0 \to ηK^{*0}$, respectively, that one…
We discuss implications of recent experimental data for B decays into two pseudoscalar mesons, with emphasis on those with $η$ and $η'$ in the final states. Applying a U-spin argument, we show that tree and penguin amplitudes, both in $B^+ \to π^+ η$ and in $B^+ \to π^+ η'$, are of comparable magnitudes. Nontrivial relative weak and strong phases between the tree-level amplitudes and penguin-loop amplitudes in the $B^{\pm} \to π^{\pm} η$ modes are extracted. We predict possible values for the averaged branching ratio and CP asymmetry of the $B^{\pm} \to π^{\pm} η'$ modes. We test the assumptio…
The $b \to s$ penguin amplitude affects a number of $B$ meson decays to two pseudoscalar ($P$) mesons in which potential anomalies are being watched carefully, though none has yet reached a statistically compelling level. These include (a) a rate for $B^0 \to K^0 π^0$ which is slightly enhanced with respect to expectations; (b) a time-dependent CP asymmetry parameter $S$ for $B^0 \to K^0 π^0$ which is low in comparison with the expected value of $\sin 2 β\simeq 0.73$, and (c) a similar deviation in the parameter $S$ for $B^0 \to η' K_S$. These and related phenomena involving vector mesons in t…
Charmless B decay modes $B \to ππ, πK$ and $KK$ aresystematically investigated with and without flavor SU(3) symmetry. Independent analyses on $ππ$ and $πK$ modes both favor a large ratio between color-suppressed tree ($C$) and tree ($T)$ diagram, which suggests that they are more likely to originate from long distance effects. The sizes of QCD penguin diagrams extracted individually from $ππ$, $πK$ and $KK$ modes are found to follow a pattern of SU(3) breaking in agreement with the naive factorization estimates. Global fits to these modes are done under various scenarios of SU(3)relations. Th…
Using the QCD factorization approach, we reexamine the two-body hadronic charmless $B$-meson decays to final states involving a pseudoscalar~($P$) and a vector~($V$) meson, with inclusion of the penguin contractions of spectator-scattering amplitudes induced by the $b\to D g^\ast g^\ast$~(where $D=d$ or $s$, and $g^\ast$ denotes an off-shell gluon) transitions, which are of order $α_s^2$. Their impacts on the CP-averaged branching ratios and CP-violating asymmetries are examined. We find that these higher order penguin contraction contributions have significant impacts on some specific decay m…
Based on the low energy effective Hamiltonian with generalized factorization, we calculate the new physics contributions to the branching ratios and CP-violating asymmetries of the two-body charmless hadronic decays $B \to PP, PV$ from the new strong and electroweak penguin diagrams in the TC2 model. The top-pion penguins dominate the new physics corrections, and both new gluonic and electroweak penguins contribute effectively to most decay modes. For tree-dominated decay modes $B \to ππ, ρπ, etc,$ the new physics corrections are less than 10%. For decays $B \to K^{(*)} π$, $K^{(*)} η$, $etc$,…
Branching fractions and CP-violating asymmetries of charmless $\bar B_s\to PP, VP, VV$ decays (P and V denoting pseudoscalar and vector mesons, respectively) are re-examined in the framework of QCD factorization (QCDF). We take into account subleading power corrections to the penguin annihilation topology and to color-suppressed tree amplitudes that are crucial for resolving the CP puzzles and rate deficit problems with penguin-dominated two-body decays and color-suppressed tree-dominated $π^0π^0$ and $ρ^0π^0$ modes in the $B_{u,d}$ sector. Many of the $B_s\to h_1h_2$ decays can be related to …
We provide the analysis of charmless two-body $B\to VP$ decays under the framework of the soft-collinear-effective-theory (SCET), where $V(P)$ denotes a light vector (pseudoscalar) meson. Besides the leading power contributions, some power corrections (chiraly enhanced penguins) are also taken into account. Using the current available $B\to PP$ and $B\to VP$ experimental data on branching fractions and CP asymmetry variables, we find two kinds of solutions in $χ^2$ fit for the 16 non-perturbative inputs which are essential in the 87 $B\to PP$ and $B\to VP$ decay channels. Chiraly enhanced peng…
The space-like penguin contributions to branching ratios and CP asymmetries in charmless decays of $B$ to two pseudoscalar mesons are studied using the next-to-leading order low energy effective Hamiltonian. Both the gluonic penguin and the electroweak penguin diagrams are considered. We find that the effects are significant.
Strangeness-changing decays of $B$ mesons to three-body final states of pions and kaons are studied, assuming that they are dominated by a $ΔI=0$ penguin amplitude with flavor structure $\bar b \to \bar s$. Numerous isospin relations for $B\to Kππ$ and for underlying quasi-two-body decays are compared successfully with experiment, in some cases resolving ambiguities in fitting resonance parameters. The only exception is a somewhat small branching ratio noted in $B^0\to K^{*0}π^0$, interpreted in terms of destructive interference between a penguin amplitude and an enhanced electroweak penguin c…
Latest data on charmless strange vector-pseudoscalar $B^+$ decays now including $B^+\to ρ^+ K^o$ confirm a simple penguin model in which the gluon $G$ in an initial $\bar s u G$ state fragments equally into $u \bar u$, $d \bar d$ and $s \bar s$ and all form factors are equal. A search for possible additional contributions shows only a few signals not obscured by experimental errors whose implications are discussed. The experimental value of $0.25 \pm 0.11$ for the ratio of the branching ratios $BR(B^+ \to K^{*+}η)$ to $BR(B^+\to K^{*+}η')$ confirms the parity selection rule prediction 0.32. La…
We investigate the contributions of neutral Higgs bosons to nonleptonic transition $b \to q \bar{s} s, q=d, s$ under the supersymmetric context. Their effects to decay width and CP violation in corresponding exclusive decays are explored. The anomalous dimension matrices of the operators which have to be incorporated to include the contributions of neutral Higgs bosons are given. We find that when tan$β$ is large (say, 50) and neutral Higgs bosons are not too heavy (say, 100 GeV), contributions of neutral Higgs penguin can dominate electroweak penguin contributions, and for some processes, the…
A model-independent analytical analysis for charmless B decays is presented. It is demonstrated that the CP-averaging branching ratio difference $ΔR = R_c - R_n$ in $B\to πK$ decays with $R_c = 2Br(π^0K^-)/Br(π^-\bar{K}^0)$ and $R_n =Br(π^+K^-)/2Br(π^0\bar{K}^0)$ defines a sensitive quantity for probing new physics as $ΔR$ is dominated by the second order of electroweak penguin contributions. A large discrepancy between experimental data and standard model (SM) prediction $ΔR^{exp}/ΔR^{SM} > 9.0\pm 5.0$ strongly indicates a signal of new physics in the electroweak penguin sector. Within the SM…
We study charmless two-body baryonic B decays in a diagramatic approach. Relations on decay amplitudes are obtained. In general there are more than one tree and more than one penguin amplitudes. The number of independent amplitudes can be reduced in the large m_B limit. It leads to more predictive results. Some prominent modes for experimental searches are pointed out.
The space-like penguin contributions to branching ratios and CP asymmetries in charmless decays of $B_{c}$ to two pseudoscalar mesons are studied using the next-to-leading order low energy effective Hamiltonian and factorization approximation. Both the gluonic penguin and the electroweak penguin diagrams are considered. In addition the annihilation diagram contributions are also taken in account. We find that the space-like penguin effects are significant.
Based upon flavor SU(3) symmetry, we perform global fits to charmless B decays into one pseudoscalar meson and one vector meson in the final states. We consider different symmetry breaking schemes and find that the one implied by na{ï}ve factorization is slightly favored over the exact symmetry case. The $(\barρ,\barη)$ vertex of the unitarity triangle (UT) constrained by our fits is consistent with other methods within errors. We have found large color-suppressed, electroweak penguin and singlet penguin amplitudes when the spectator quark ends up in the final-state vector meson. Nontrivial re…
Under the framework of soft-collinear effective theory, we analyze the charmless $B\to VV$ decays in a global way at leading power in $1/m_b$ and leading order in $α_s$ with $V$ denoting a light vector meson. In the flavor SU(3) symmetry, decay amplitudes for the 28 decay modes are expressed in terms of 8 nonperturbative parameters. With 35 experimental results, we fit these 8 nonperturbative parameters. Annihilation contributions are neglected due to power suppression in the $m_b\to \infty$ limit, so we include in the fit the nonperturbative charm penguins, which will play an important role i…
We address a number of theoretical and phenomenological issues in two-body charmless non-leptonic B decays in the context of a factorization model. A classification of the exclusive decays involving tree and penguin amplitudes is reviewed. The role of QCD anomaly in exclusive decays involving an $η$ or $η'$ is elucidated and comparison is made with the existing data. We argue that the factorization approach accounts for most of the observed two-body B decays.
We use currently available data of nonleptonic charmless 2-body $B\to MM$ decays ($MM = PP, PV, VV$) that are mediated by $b\to (d, s)$ QCD- and QED-penguin operators to study weak annihilation and new-physics effects in the framework of QCD factorization. In particular we introduce one weak annihilation parameter for decays related by ($u \leftrightarrow d$) quark interchange and test this universality assumption. Within the standard model, the data supports this assumption with the only exceptions in the $B\to K π$ system, which exhibits the well-known "$ΔA_{CP}$ puzzle", and some tensions i…
We present fits to charmless strangeless hadronic B decay data for mean branching ratios and CP-violating asymmetries using the QCD factorization model of Beneke et al. Apart from one CP-violating parameter, the model gives a very good representation of 26 measured data. We find the CKM angle alpha = (93.5 +/- 8.4 -1.3) degrees and to be quite stable to plausible "charming penguin" corrections.
The decays of $B$ mesons to a charmless vector ($V$) and pseudoscalar ($P$) meson are analyzed within a framework of flavor SU(3) in which symmetry breaking is taken into account through ratios of decay constants in tree ($T$) amplitudes. The magnitudes and relative phases of tree and penguin amplitudes are extracted from data; the symmetry assumption is tested; and predictions are made for rates and CP asymmetries in as-yet-unseen decay modes. A key assumption for which we perform some tests and suggest others is a relation between penguin amplitudes in which the spectator quark is incorporat…
We present results on the NLO (alpha_s^2) spectator-scattering corrections to the topological penguin amplitudes for charmless hadronic two-body B-decays in QCD factorization. The corrections can be sizable for the colour-suppressed electroweak penguin amplitudes alpha_{4,EW}^p but otherwise are numerically small. Our results explicitly demonstrate factorization at this order. To assess the phenomenological viability of the framework, we consider penguin-to-tree ratios in the penguin-dominated pi K system and find agreement to the expected precision (i.e., a power correction).
The non-$D \bar D$ decays of the $\ppp = ψ(3770)$ resonance are reviewed and possibilities for further measurements are noted. These decays can shed light on S--D mixing, the ``missing'' $ψ' = ψ(3686)$ decays, a possible discrepancy between the total and $D \bar D$ cross sections at the $\ppp$, and rescattering effects contributing to enhanced $b \to s$ penguin amplitudes in $B$ meson decays.
The problem of hadronic input in charmless nonleptonic B decays is discussed. QCD sum rules and their light-cone versions (LCSR) provide an important part of this input, such as the decay constant $f_B$ and $B\to π$ form factor. Employing the LCSR technique, the $B\to ππ$ hadronic matrix elements with emission, penguin and annihilation topologies are calculated, with no evidence for large nonfactorizable effects and/or strong phases.
We calculated the CP averaged branching ratios and CP-violating asymmetries of two-body charmless hadronic Bs->PP,PV decays with the QCDF approach, including the contributions from the chirally enhanced power corrections and weak annihilations. Only several decay modes, such as Bs -> K^(*)K, K^(*{\pm})π^{\mp}, K^{\pm}ρ^{\mp}, η^(')η^('), have large branching ratios, which may be observed in the near future. The penguin-to-tree ratio P_{ππ}/T_{ππ} and a bound on angle $γ$ are given.
The importance of measuring the non-$D \bar D$ decays of the $ψ'' = ψ(3770)$ resonance is discussed. These decays can shed light on a possible discrepancy between the total and $D \bar D$ cross sections at the $ψ''$, and on a proposed mechanism for enhancement of penguin amplitudes in $B$ meson decays through charm--anticharm annihilation. Measurements (including the $ψ''$ line shape) in states of definite G-parity and in inclusive charmless final states such as $η' + X$ are found to be particularly important.
Motivated by the experimental data, we study charmless $B_{u,d,s}\to VT$ ($V$ and $T$ denote light vector and tensor mesons respectively) decays in the perturbative QCD approach. The predictions of branching ratios, polarization fractions and direct CP violations are given in detail. Specifically, within this approach we have calculated the polarization fractions and the branching ratios of $B\to ϕ(K_2^{*-}, \bar K_2^{*0})$ which agree well with the observed experimental data, however the branching ratios of $B\to ω(K_2^{*-}, \bar K_2^{*0})$ are hard to be explained, where the polarization fra…
Based on the low-energy effective Hamiltonian with the generalized factorization, we calculate the new physics contributions to the branching ratios of the two-body charmless hadronic decays of $B_u$ and $B_d$ mesons induced by the new gluonic and electroweak charged-Higgs penguin diagrams in the general two-Higgs doublet models (models I, II and III). Within the considered parameter space, we find that: (a) the new physics effects from new gluonic penguin diagrams strongly dominate over those from the new $γ$- and $Z^0$- penguin diagrams; (b) in models I and II, new physics contributions to m…
Charmless B->PP decays are studied using flavor SU(3) symmetry. Amplitude with charming penguin topology is considered for two cases: with zero and with arbitrary strong phase. Two sets of data (an older and the most recent one) are used in the fits, so that the stability of the fits is tested. It is shown that within the present uncertainties in the data the parameters of the fit may be significantly modified, especially the gamma angle. The fits indicate the strong phase of the charming penguin amplitude to be around $\pm 20^{o}$.
Based on the most recent data in charmless B decays including the very recently reported large direct CP violations, it is shown that the weak phase gamma can well be extracted without two-fold ambiguity even only from two decay modes pi^+pi^- and pi^+K^-, and its value is remarkably consistent with the global standard model fit at a compatible accuracy. A fit to all the pi pi, pi K data favor both large electroweak penguin and color-suppressed tree amplitude with large strong phases. It is demonstrated that the inclusion of small SU(3)symmetry breaking effects of strong phases and the inelast…
Isospin structure of gluon mediated or strong penguin is significantly altered when the full electroweak corrections are included. This has the consequence that some previous analyses which relied on a simple isospin structure in charmless $B$ decays become inapplicable. We present the general Hamiltonian in next-to-leading order QCD, and illustrate our conclusion quantitatively for $B\rightarrow ππ$ and $B\rightarrow Kπ$ decays in the factorization approximation. Some remarks on CP asymmetries in $B$ decays are also made.
Charmless hadronic decays of B mesons to a vector meson (V) and a tensor meson (T) are analyzed in the frameworks of both flavor SU(3) symmetry and generalized factorization. We also make comments on B decays to two tensor mesons in the final states. Certain ways to test validity of the generalized factorization are proposed, using $B \to VT$ decays. We calculate the branching ratios and CP asymmetries using the full effective Hamiltonian including all the penguin operators and the form factors obtained in the non-relativistic quark model of Isgur, Scora, Grinstein and Wise.
Using a theoretical framework based on the next-to-leading order QCD-improved effective Hamiltonian and a factorization Ansatz for the hadronic matrix elements of the four-quark operators, we reassess branching fractions in two-body non-leptonic decays $B \to PP, PV, VV$, involving the lowest lying light pseudoscalar $(P)$ and vector $(V)$ mesons in the standard model. Using the sensitivity of the decay rates on the effective number of colors, $N_c$, as a criterion of theoretical predictivity, we classify all the current-current (tree) and penguin transitions in five different classes. The rec…
Within the framework of QCD factorization (QCDF), we consider two different types of power correction effects in order to resolve the CP puzzles and rate deficit problems with penguin-dominated two-body decays of B mesons and color-suppressed tree-dominated $π^0π^0$ and $ρ^0π^0$ modes: penguin annihilation and soft corrections to the color-suppressed tree amplitude. We emphasize that the electroweak penguin solution to the $B\to Kπ$ CP puzzle via New Physics is irrelevant for solving the CP and rate puzzles related to tree-dominated decays. While some channels e.g. $K^-π^+,K^-ρ^0,π^+π^-,ρ^\pmπ…
Two-body charmless nonleptonic decays of the B_s meson are studied within the framework of generalized factorization in which factorization is applied to the tree level matrix elements while the effective Wilson coefficients are $μ$ and renormalization scheme independent, and nonfactorizable effects are parametrized in terms of N_c(LL) and N_c(LR), the effective numbers of colors arising from (V-A)(V-A) and (V-A)(V+A) four-quark operators, respectively. Branching ratios of $B_s\to PP,PV,VV$ decays are calculated as a function of N_c(LR) with two different considerations for N_c(LL). We find th…
The presence of additional strong phase from power corrections and other chirally enhanced terms makes it more difficult to predict direct CP asymmetries in two-body charmless B decays. In this talk, I would like to report on a recent work on QCD Factorisation and Power Corrections in Charmless B Decays. Using the measured branching ratios for $B\to \rm PV$, it is shown that power corrections in charmless B decays are probably large, at least for penguin dominated $\rm PV$ channels. Since the tree-penguin interference responsible for direct CP asymmetries in two-body charmless B decays are rel…
Toward the goal of extracting the weak angle alpha, the decay B^0/B^0-bar to a_0^{+/-}pi^{-/+} was recently measured. The decay B^0 to a_0^+pi^- is not only forbidden in the factorization limit of the tree interaction, but also strongly suppressed for the penguin interaction if short-distance QCD dominates. This makes extraction of alpha very difficult from a^{+/-}π^{-/+}. We examine the simlar factorization-suppressed decays, in particular, B^0\to b_1^+pi^-. The prospect of obtaining alpha is even less promising with b_1^{+/-}pi^{-/+}. To probe how well the short-distance dominance works, we …
Nonfactorizable effects in hadronic charmless B -> PP, VP decays can be parametrized in terms of the effective number of colors N_c in the effective parameters $a_i^{eff}$ that are linear combinations of Wilson coefficients. It is shown that N_c(V+A) in the penguin amplitudes induced by the (V-A)(V+A) four-quark operators is different from N_c(V-A) in the decay amplitudes arising from the (V-A)(V-A) operators. Central values of the branching ratios of $B^\pm\toωπ^\pm$ and $B\toππ$ decays favor $N_c(V-A)\approx 2$, in accordance with the nonfactorizable effect observed in $B\to D^{(*)}π(ρ)$. Me…
The computation of direct CP asymmetries in charmless B decays at next-to-next-to-leading order (NNLO) in QCD is of interest to ascertain the short-distance contribution. Here we compute the two-loop penguin contractions of the current-current operators Q_{1,2} and provide a first estimate of NNLO CP asymmetries in penguin-dominated b -> s transitions.
Two-body charmless hadronic B decays involving a tensor meson in the final state are studied within the framework of QCD factorization (QCDF). Due to the G-parity of the tensor meson, both the chiral-even and chiral-odd two-parton light-cone distribution amplitudes of the tensor meson are antisymmetric under the interchange of momentum fractions of the quark and anti-quark in the SU(3) limit. Our main results are: (i) In the naive factorization approach, the decays such as $B^-\to \bar K_2^{*0}π^-$ and $\bar B^0\to K_2^{*-}π^+$ with a tensor meson emitted are prohibited owing to the fact that …
Exclusive charmless B decays to $η'$ and $η$ are studied in the standard effective Hamiltonian approach. The effective coefficients that take into account nonfactorizable effects in external and internal W-emission amplitudes are fixed by experiment. Factorization is applied to the matrix elements of QCD, electroweak penguin operators and next-to-leading corrections to penguin Wilson coefficients, which are renormalization-scheme dependent, are included, but the resultant amplitude is renormalization-scheme and -scale independent. We show that the unexpectedly large branching ratio of $B^\pm\t…
The decays of $B$ mesons to charmless final states consisting of a vector meson ($V$) and a pseudoscalar meson ($P$) are analyzed within flavor SU(3). Predictions are compared with new data from the CLEO Collaboration. Dominant contributions to amplitudes and subdominant interfering terms are identified. Evidence is found for a specific penguin amplitude (contributing, for example, to $B^+ \to ρ^+ K^0$) at a level much higher than that implied by most explicit models. The validity of the conclusion $\cos γ< 0$, obtained through other analyses of $B \to VP$ decays, is examined here from a less …
The question of whether the anomalously large $B \to Kη' $ and $B \to Kη' X $ (inclusive) branching ratios are consistent with the standard model or a sign of new physics is still open and in the experimental court. The nature of the extra hadron $X$ in $B \to Kη' X $ is completely unknown. Directions for investigation and analysis of inclusive data are suggested as well as for comparable inclusive data on $B \to KηX $. New data confirming the prediction $BR(K^\pm ρ^o) = BR(K^\pm ω)$ support flavor-topology $B \to VP$ sum rules based on the OZI rule and emphasize the sharp contrast with the fa…
