The unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix has been well established by both direct and indirect measurements without any evidence of discrepancy. The CKM weak phase $α$ is directly measured using an isospin analysis in $B\rightarrow ππ$ and $B\to ρρ$ assuming that electroweak penguin contributions are ignorable. However, electroweak penguins are sensitive to NP, hence, it is important to experimentally estimate their effects. We determine the size of both electroweak penguin and isospin amplitudes, directly from $B\rightarrow ππ$ and $B\to ρρ$ experimental data, using in addition the indirectly measured value of $α$. We find that electroweak penguin contribution are indeed small and agree with SM expectations within $1σ$. We also find that there is a mild enhancement of the $ΔI=\tfrac{1}{2}$ transition amplitude.
In our subgroup, we focused on penguin physics from various different angles. Our discussions included: (1) A method to extract one of the angles of the unitarity triangle $ϕ_2$; (2) Methods to extract $ϕ_3$ from $B\to Kπ$ decays; (3) Effects of non-minimal SUSY on B and K decays; (4) Understnding large branching ratios for $B\to η'+K(K^*)$ decays; (5) New calculation for hadronic matrix elements which are needed to compute $ε'/ε$.
We derive constraints for $B\to VV$ modes ($V= vector meson) that allow aquantitative assessment of the contributions from electroweak penguins (EWP) and/or new physics. Interplay of direct CP with oscillation studies then leads to the extraction of the angles alpha and gamma, using B--> K* omega rho and B--> rho omega (phi) respectively, if by using our constraint equations it can be experimentally demonstrated that color-suppressed EWP are small.
We reanalyze the decay $B_d\toπ^+π^-$ without assuming dominance of QCD penguins with internal top-quark exchanges. In that case the weak phase of the $\bar b \to\bar d$ QCD penguin amplitude is not related in a simple way to the CKM angle $β$. Nevertheless it is still possible to extract the CKM angle $α$ in a transparent and almost model-independent way from the time-dependent CP-violating asymmetry of the transition $B_d\toπ^+π^-$. Aside from that CP asymmetry this approach needs as an input only amplitudes of decays with branching ratios of order $10^{-5}$ and will thus be well within reac…
Using the $SU(3)$ flavour symmetry of strong interactions, we propose strategies for extracting both the CKM-angle $γ$ and the $\bar b\to\bar uu\bar s$ tree-level amplitude $T'$. We present also an approximate approach using the branching ratios for the modes $B^+\toπ^+ K^0$, $B^0_d\toπ^- K^+$, $\bar B^0_d\toπ^+ K^-$ and $B^+\toπ^+π^0$ which should be rather promising from the experimental point of view. The quantities $γ$ and $T'$ determined this way may well be used as an input to control electroweak penguins in nonleptonic $B$-decays as has been discussed in previous work. Following these l…
We show that the presence of intrinsic charm in the hadrons' light-cone wave functions, even at a few percent level, provides new, competitive decay mechanisms for B decays which are nominally CKM-suppressed. For example, the weak decays of the B-meson to two-body exclusive states consisting of strange plus light hadrons, such as B\toπK, are expected to be dominated by penguin contributions since the tree-level b\to s u\bar u decay is CKM suppressed. However, higher Fock states in the B wave function containing charm quark pairs can mediate the decay via a CKM-favored b\to s c\bar c tree-level…
We use the perturbative QCD methods of Lepage and Brodsky to calculate the rate for B-bar_s -> rho K_s, with an eye toward the CP violating unitarity triangle angle gamma. We show that, although the penguins are large, there are regions of the allowed parameter space of the Cabibbo-Kobayashi-Maskawa mixing matrix wherein gamma is measurable in the sense that penguins change the value of sin(2gamma) one would extract from the attendant time dependent asymmetry measurement by less than 29 per cent, so that a 3sigma measurement of sin(2gamma) as being different from 0 is allowed by the correspond…
We study the influence of penguin (especially, electroweak penguin) effects on some methods of measuring the angles $α$, $β$, and $γ$ in the CKM unitarity triangle. We use next-to-leading order effective Hamiltonian, and present numerical estimates based on the factorization approximation. We find that some techniques suggested in the literature, especially for $α$ determination, are not workable in light of the electroweak penguin effects. Nevertheless, there are methods that would work for each angle determination. For angle $β$ we consider $B \rightarrow D^{+} D^{-}$ mode and estimate the p…
We present strategies for determining electroweak penguins from experimental data. Using the CKM-angle $γ$ as one of our central inputs and making some reasonable approximations, we show that the $\bar b\to\bar s$ electroweak penguin amplitude can be determined in a two-step procedure involving i) BR$(B^+\toπ^0K^+)$, BR$(B^-\toπ^0K^-)$, BR$(B^+\toπ^+K^0)$ and ii) either BR$(B^0_d\toπ^-K^+)$, BR$(\bar B^0_d\toπ^+K^-)$ or $\acp(t)$ of the mode $B_s\to K^+K^-$. The determination employing the $B\toπK$ transitions is not affected by $SU(3)$-breaking effects. Relating the $\bar b\to\bar s$ electrow…
Motivated by recent CLEO measurements of $B\toπK$ modes, we investigate their implications for the CKM angle $γ$ and a consistent description of these decays within the Standard Model. Interestingly it turns out that already the measurement of the combined branching ratios $B^\pm\toπ^\pm K$ and $B_d\toπ^\mp K^\pm$ allows to derive stringent constraints on $γ$ which are complementary to the presently allowed range for that angle. This range, arising from the usual fits of the unitarity triangle, is typically symmetric around $γ= 90^\circ$, while our method can in principle exclude a range of th…
The decays $B_d\toπ^+π^-$ and $B_s\to K^+K^-$ provide an interesting strategy to extract the CKM angle $γ$ at ``second-generation'' $B$-physics experiments of the LHC era. A variant for ``first-generation'' experiments can be obtained, if $B_s\to K^+K^-$ is replaced by $B_d\toπ^\mp K^\pm$. We show that the most recent experimental results for the CP-averaged $B_d\toπ^+π^-$ and $B_d\toπ^\mp K^\pm$ branching ratios imply a rather restricted range for the corresponding penguin parameters, and upper bounds on the direct CP asymmetries $A_{CP}^{dir}(B_d\toπ^+π^-)$ and $A_{CP}^{dir}(B_d\toπ^\mp K^\p…
A general parametrization of the $B^+\toπ^+ K^0$ and $B_d^0\toπ^- K^+$ decay amplitudes is presented. It relies only on the isospin symmetry of strong interactions and the phase structure of the Standard Model and involves no approximations. In particular, this parametrization takes into account both rescattering and electroweak penguin effects, which limit the theoretical accuracy of bounds on $γ$ arising from the combined $B^\pm\toπ^\pm K$, $B_d\toπ^\mp K^\pm$ branching ratios. Generalized bounds making also use of the CP asymmetry in the latter decay are derived, and their sensitivity to po…
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…
We present a method of determining the CKM-angle $α$ by performing simultaneous measurements of the mixing-induced CP asymmetries of the decays $B_d\toπ^+π^-$ and $B_d\to K^0\bar K^0$. The accuracy of our approach is limited by $SU(3)$-breaking effects originating from $\bar b\to \bar ds\bar s$ QCD-penguin diagrams. Using plausible power-counting arguments we show that these uncertainties are expected to be of the same order as those arising through electroweak penguins in the standard Gronau-London-method in which $α$ is extracted by means of isospin relations among $B\toππ$ decay amplitudes.…
We introduce the Working Group 2 proceedings contributions from the 2nd workshop on the CKM Unitarity Triangle and note their connection to the proceedings of the first workshop. The topic of WG2 was the determination of the CKM matrix elements Vtd and Vts from B-Bbar mixing, radiative penguin B to X{s/d} gamma decays and rare (semi)leptonic decays such as B to Xs l+ l-.
Rare $B$, $D$ and $K$ decays provide interesting probes of the Standard Model (SM), with a potential sensitivity to New Physics (NP) higher than other, more common, decays. Their experimental measurement is challenging, and their theoretical interpretation requires a precise knowledge of QCD at low energies, in the non-perturbative (hadronic) regime. The various $b$, $c$, $s$ decays provide different types of tests of the Standard Model, which can be performed in different experimental settings and which may exhibit correlated deviations in models of New Physics.
The time-dependent angular distributions of certain $B_{d,s}$ decays into final states that are admixtures of CP-even and CP-odd configurations provide valuable information about CKM phases and hadronic parameters. We present the general formalism to accomplish this task, taking also into account penguin contributions, and illustrate it by considering a few specific decay modes. We give particular emphasis to the decay $B_d\to J/ψρ^0$, which can be combined with $B_s\to J/ψϕ$ to extract the $B^0_d - \bar{B^0_d}$ mixing phase and - if penguin effects in the former mode should be sizeable - also…
The decays $B^\pm\to π^\pm K$ and $B_d\to π^\mp K^\pm$ were observed by the CLEO collaboration last year; they may play an important role to probe the angle $γ$ of the unitarity triangle of the CKM matrix. After a general parametrization of their decay amplitudes within the Standard Model, strategies to constrain and determine the CKM angle $γ$ with the help of the corresponding CP-conserving and CP-violating observables are briefly reviewed. The theoretical accuracy of these methods is limited by certain rescattering and electroweak penguin effects. It is emphasized that the rescattering proc…
In the presence of penguin contributions, the indirect CP asymmetry in B^0(t) --> pi^+ pi^- measures sin 2alpha_{eff}, where alpha_{eff} deviates from the true value of the CKM phase alpha by an amount theta, i.e. alpha_{eff} = alpha + theta. Using the measured value of direct CP asymmetry in B^0(t) --> pi^+ pi^-, we derive new bound on |2 theta|.
In the recent literature, constraints on the CKM angle $γ$ arising from the branching ratios for $B^\pm\toπ^\pm K$ and $B_d\toπ^\mp K^\pm$ decays received a lot of attention. An important theoretical limitation of the accuracy of these bounds is due to rescattering effects, such as $B^+\to\{π^0K^+\}\toπ^+K^0$. We point out that these processes are related to penguin topologies with internal up quark exchanges and derive SU(2) isospin relations among the $B^+\toπ^+K^0$ and $B_d^0\toπ^-K^+$ decay amplitudes by defining ``tree'' and ``penguin'' amplitudes in a proper way, allowing the derivation …
The phenomenon of CP violation in the B system and strategies for extracting CKM phases are reviewed. We focus both on general aspects and on some recent developments including CP-violating asymmetries in B_d decays, the B_s system in light of a possible width difference $ΔΓ_s$, charged B decays, and SU(3) relations among certain transition amplitudes. In order to describe the relevant non-leptonic B decays, low energy effective Hamiltonians calculated beyond the leading logarithmic approximation are used. Special emphasis is given to the role of electroweak penguin operators in such transitio…
We report on recent progress in studying two aspects of $B$ physics, in which penguin amplitudes play an important role: (1) Bounds on penguin pollution in $B^0(t) \to π^+π^-$ constraining CKM parameters, and a lower bound on $B^0 \to π^0π^0$ improving precision in $\sin 2α$. (2) A suggestion for measuring the photon polarization in electroweak penguin decay, $B \to K_1(1400)γ$, providing a precision test of the Standard Model and a probe for new physics.
The determination of the angle $γ$ of the unitarity triangle of the CKM matrix is regarded as a challenge for future $B$-physics experiments. In this context, the decays $B^\pm\to π^\pm K$ and $B_d\toπ^\mp K^\pm$, which were observed by the CLEO collaboration last year, received a lot of interest in the literature. After a general parametrization of their decay amplitudes, strategies to constrain and determine the CKM angle $γ$ with the help of the corresponding observables are reviewed. The theoretical accuracy of these methods is limited by certain rescattering and electroweak penguin effect…
We discuss the usefulness of the CP violating semi-leptonic asymmetry a_{SL} not only as a signal of new physics, but also as a tool in constraining the CKM parameters. We show that this technique could yield useful results in the first years of running at the B factories. We present the analysis graphically in terms of M_{12}, the dispersive part of the B-Bbar mixing amplitude. This is complementary to the usual unitarity triangle representation and often allows a cleaner interpretation of the data.
Penguin effects in the CP asymmetries of $B^0_d\rightarrow π^+π^-$ , $\bd\rightarrowρ^{\pm}π^{\mp}$ and $\bd\rightarrow a^{\pm}_1 π^{\mp}$ are studied as function of the CKM unitarity triangle $α$. Despite a fairly small penguin amplitude, it leads to quite sizable uncertainties in the determination of $\sin(2α)$ from all but very large asymmetries. This effect is maximal for vanishing final state interaction phases, for which it can cause, for instance, an asymmetry of 40\%\ if $α=π/2$.
A major goal in B physics is measuring the CP-violating asymmetry in the decay $B^0 \rightarrow π^+ π^-$. In order to determine one of the phase angles in the CKM matrix from this decay it is necessary to determine the influence of the penguin amplitude. Here we show how, using $SU(3)$ symmetry, the penguin effect can be approximately determined from the ratio of the decay rates of $B^0 \rightarrow K^+ π^-$ and $B^0 \rightarrow π^+ π^-$.
Determinations of the CKM phase $γ$ from weak nonleptonic $B$ decays are affected by electroweak (EW) penguins and rescattering effects. In this talk it is explained how the EW penguin effects can be controlled with the help of SU(3) symmetry, by relating them to tree-level amplitudes. The impact of the final-state interactions on the determination of $γ$ from $B^+\to Kπ$ decays is studied numerically, showing that they can be important. A few alternative methods are discussed which use additional decays to eliminate their effects.
We discuss a method for extracting CP phases from pairs of B decays which are related by flavor SU(3). One decay (B0 -> M1 M2) receives a significant bbar -> dbar penguin contribution. The second (B' -> M1' M2') has a significant bbar -> sbar penguin contribution, but is dominated by a single amplitude. CP phase information is obtained using the fact that the B' -> M1' M2' amplitude is related by SU(3) to a piece of the B0 -> M1 M2 amplitude. The leading-order SU(3)-breaking effect (~25%) responsible for the main theoretical error can be removed. For some decay pairs, it can be written in term…
A brief review of CP violation in the $B$-meson system and of strategies to determine the angles $α$, $β$ and $γ$ of the unitarity triangle of the CKM matrix is given. Both general aspects and some recent developments are discussed, including a critical look at the ``benchmark'' modes, CP violation in penguin decays, $B_s$ decays in the light of the width difference $ΔΓ_s$, charged $B$ decays, and strategies to probe the CKM angle $γ$ with $B\toπK$ modes.
The influence of strong and electroweak penguin amplitudes in $B/ \bar B \rightarrow π^+π^-$ is investigated in connection with the determination of the unitarity triangle angle $α$ of the CKM matrix. A relation between the observable asymmetry, the angle $α$, and the penguin amplitude is established. A model calculation of the penguin amplitude shows that the CP asymmetry in $B^{0}\rightarrow π^{+}π^{-}$ decays is only mildly influenced by the penguin amplitudes. Experimental limits on pure penguin and penguin dominated processes are consistent with the model. This information also suggests i…
The availability of data on $B_s$ decays to strange quasi-two-body final states, either with or without charmonium opens new possibilities for understanding different contributions of weak diagrams and in particular the relative contributions of tree and penguin diagrams. Corresponding $B_d$ and $B_s$ decays to charge conjugate final states are equal in the SU(3) symmetry limit and the dominant SU(3) breaking mechanism is given by ratios of CKM matrix elements. Final State Interactions effects should be small, because strong interactions conserve $C$ and should tend to cancel in ratios between…
Measurements of the combined branching ratios for $B^\pm \to π^\pm K$ and $B_d \to π^\mp K^\pm$ allow interesting constraints on the CKM angle $γ$, the ratio $r \equiv |T'|/|P'|$ of the current-current and penguin operator contributions to $B_d \to π^\mp K^\pm$, and the CP asymmetry in that decay. Present CLEO results for these branching ratios indicate where problems with consistency of the Standard Model may arise in the future. In this paper we discuss scenarios of new physics in these decays and investigate their implications for the above constraints.
In this time of transition to a new generation of quark flavor experiments we review both the theoretical and the experimental progress on the determination of unitarity triangle angles from penguin-dominated B decays. This summarizes the activities of the Working Group VI at the CKM2010 workshop.
We present results of a unitary triangle fit based on the scan method. This frequentist approach employs Gaussian uncertainties for experimental quantities, but makes no arbitrary assumptions about the distribution of theoretical errors. Instead, we perform a large number of fits, scanning over regions of plausible theory errors for each quantity, and retain those fits meeting a specific confidence level criterion, thereby constraining the $\bar ρ- \bar η$ plane using the standard input measurements (CKM matrix elements, $\sin2 β, B^0_{d,s}$ mixing, $ε_K$) as well as branching fraction and \CP…
We calculate CP-violating rates and asymmetry parameters in charged and neutral $B\to ππ, πK$ and $\bar K K$ decays arising from the interference of tree and penguin (strong and electroweak) amplitudes with different strong and CKM phases. The perturbative strong (electroweak) phases develop at order $α_s$ ($α_{em}$) from absorptive parts of one-loop matrix elements of the next-to-leading (leading) logarithm corrected effective Hamiltonian. The BSW model is used to estimate the hadronic matrix elements. Based on this model, we find that the effect of strong phases and penguins is substantial i…
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 also give rise to a strong phase due to the rescattering $D^{*}D^{*} \to Kπ$ . In this talk, I would like to discuss \cite{Isola} a recent work on t…
We present a Scan Method analysis of the allowed region of the rho bar - eta bar plane using the latest input measurements of the CKM matrix elements, sin 2 beta, B0(s,d) mixing, epsilon(K), alpha and gamma. In this approach, we make no assumptions as to the distribution of theory uncertainties; rather, we scan over the range of plausible theoretical uncertainties and determine confidence level contours in the rho bar eta bar plane. We determine alpha from branching fraction and CP asymmetry measurements of B decays to all light pseudoscalar-pseudoscalar, pesudoscalar-vector, vector-vector and…
We discuss the determination of the CKM angles gamma and alpha using recent data from non-leptonic B decays together with flavour symmetries. Penguin effects are controlled by means of the CP-averaged branching ratio B_d \to π^\pm K^\mp. The information from A_{CP}(B_d \to J/ΨK_S) (two solutions for phi_d), Rb and gamma allow us to determine beta, even in presence of New Physics not affecting Delta B=1 amplitudes. In this context we address the question of to what extent there is still space for New Physics.
We discuss a method to extract the CKM $γ$ angle combining Dalitz plot analysis of $B^{\pm} \to K^{\pm} π^+ π^-$ and untagged $B^0$, $\bar B^0 \to K_s π^+ π^-$. The method also allows obtaining the ratio and phase difference between the {\it tree} and {\it penguin} contributions from $B^0$ and $\bar B^0 \to K^{*\pm} π^{\mp} $ decays and direct CP asymmetry between $B^0$ and $\bar{B^0}$. From Monte Carlo studies of 100K events for the neutral mesons, we show the possibility of measuring $γ$ with a precision of $\sim 5^o$.
Several new strategies to extract CKM phases, including a determination of $γ$ from $B_{s(d)}\to J/ψK_S$ decays and a general approach, which makes use of the angular distributions of certain $B_{d,s}$ modes, such as $B_d\to J/ψρ^0$ and $B_s\to J/ψϕ$, are discussed. Special emphasis is put on a simultaneous determination of $β$ and $γ$ with the help of the decays $B_d\to π^+ π^-$ and $B_s\to K^+ K^-$, which relies only on the $U$-spin flavour symmetry of strong interactions and is not affected by any penguin or final-state-interaction effects.
The subject of CP violation in B decays is reviewed in the Standard Model (SM) and beyond the SM. The present explanation of CP violation in terms of phases in the Cabibbo-Kobayashi-Maskawa (CKM) matrix can be tested through a variety of CP asymmtries in neutral and charged B decays. SM constraints on the CKM phases are violated by new mechanisms of CP nonconservation beyond CKM. Different mechanisms can be distinguished by combining measurements of CP asymmetries with rate measurements of so-called penguin B decays.
We present a method to measure the CKM phase $α$ and the tree and penguin (strong and electroweak) amplitudes in $B \rightarrow ππ$ decays, based on isospin consideration and the weak assumption that all tree amplitudes have a common strong phase and all penguin amplitudes have a different common phase. The method needs only the time-independent measurements of the relevant decay rates in $B \rightarrow ππ$. We also propose a method to experimentally examine the validity of the assumption that all penguin amplitudes have the same strong phases, and to extract detailed informations about the ha…
Using perturbative QCD, the contribution at the leading twist, leading $α_s$ level, of charm and up quark loops to the decays $B \rightarrow K^* γ$ and $B \rightarrow ργ$ is presented. In the case of $B \rightarrow ργ$, the relative importance of these contributions depend upon the unknown CKM matrix elements $V_{bu}$ and $V_{td}$. Assuming that the ratio $r = V_{bc}V^*_{cd}/V_{bt}V^*_{td}$ is bounded between $-2.25 \le r \le -.5$ as is suggested by the Particle Data Group, the error in extracting $ |V_{td}/V_{ts}| $ by these decays is estimated.
We analyze the impact of the forthcoming CP-violating observables in the $B_s\to K^+ K^-$ system, combined with the precise measurement of $\sin2β$ , in the extraction of the CKM matrix. Computing the penguin parameters $(r, θ)$ within QCD factorization yields a precise determination of $(\barρ, \barη)$, reflected by a weak dependence on $θ$, which is shown to be a second order effect. Using the SU(3)-flavour symmetry argument and the current $B$-factories data provided by the $B_d \to π^+ π^-$ modes, we complement the $B_s \to K^+ K^-$ CP-violating observables in a variety of ways, in particu…
We present the current wisdom regarding the measurement of the CP-violating phases of the CKM unitarity triangle in $B$-meson decays. After an introduction to the SM picture of CP violation, we review direct and indirect CP violation, the role of penguins and isospin analysis, and $B\to DK$ decays. We also discuss recent work on how to use SU(3) flavor symmetry, along with some dynamical approximations, to get at the CKM weak phases. Through time-independent $B$-decay measurements alone, we show that it is possible to extract all information: the weak phases, the incalculable strong phase shif…
We calculate direct CP-violating observables in charged $B\to VV$ decays arising from the interference of amplitudes with different strong and CKM phases. The perturbative strong phases develop at order $α_s$ from absorptive parts of one-loop matrix elements of the next-to-leading logarithm corrected effective Hamiltonian. CPT constraints are maintained. Based on this model, we find that partial rate asymmetries between charge conjugate $B^{\pm}$ decays can be as high as 15-30\% for certain channels with branching ratios in the $10^{-6}$ range. The small values of the coefficients of angular c…
The recently observed direct CP violation in $B_d \to K^+ π^-$ has raised suggestions of possible new physics. A robust test of the standard model vs. new physics is its prediction of equal direct CP violation in $B_s \to K^- π^+$ decay. CPT invariance requires the observed CP violation to arise from the interference between the dominant penguin amplitude and another amplitude with a different weak phase and a different strong phase. The penguin contribution to $B_d \to K^+ π^-$ is known to be reduced by a CKM factor in $B_s \to K^- π^+$. Thus the two branching ratios are very different and a …
We present a general parametrization of $B^\pm\toπ^\pm K, π^0K^\pm$ and $B_d\toπ^0 K, π^\mp K^\pm$ decays, taking into account both electroweak penguin and rescattering effects. This formalism allows -- among other things -- an improved implementation of the strategies that were recently proposed by Neubert and Rosner to probe the CKM angle $γ$ with the help of $B^\pm\toπ^\pm K, π^0K^\pm$ decays. In particular, it allows us to investigate the sensitivity of the extracted value of $γ$ to the basic assumptions of their approach. We find that certain SU(3)-breaking effects may have an important i…
We provide Standard Model expectations for the rare radiative decays B->K^* gamma, B->rho gamma and B-> omega gamma, and the electroweak penguin decays B->K^* l^+ l^- and B->rho l^+ l^- at the next-to-leading order (NLO), extending our previous results to b->d transitions. We consider branching fractions, isospin asymmetries and direct CP asymmetries. For the electroweak penguin decays, the lepton-invariant mass spectrum and forward-backward asymmetry is also included. Radiative and electroweak penguin transitions in b->d are mainly interesting in the search for new flavour-changing neutral cu…
The Bc -> BP,BV decays are studied with the QCD factorization approach (where P and V denote pseudoscalar and vector mesons, respectively). Considering the contributions of both current-current and penguin operators, the amplitudes of branching ratios are estimated at the leading approximation. We find that the contributions of the penguin operators are very small due to the serious suppression by the CKM elements. The most promising decay modes are Bc -> Bs Pi, Bs rho, which might be easily detected at hadron colliders.
We investigate the time-evolutions of angular distributions for $B_s$ decays into final states that are admixtures of CP-even and CP-odd configurations. A sizable lifetime difference between the $B_s$ mass eigenstates allows a probe of CP violation in time-dependent untagged angular distributions. Interference effects between different final state configurations of $B_s\to D^{*+}_s D^{*-}_s$, $J/ψϕ$ determine the Wolfenstein parameter $η$ from untagged data samples, or -- if one uses $|V_{ub}|/|V_{cb}|$ as an additional input -- the notoriously difficult to measure CKM angle $γ$. Another deter…
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…
Long-distance contributions of operators of the effective non-leptonic weak Hamiltonian containing charmed currents have been recently studied. Penguin-like contractions of these operators, denoted as charming penguins, have been shown to be relevant for several B decays into two pseudoscalar mesons. In particular, they are expected to give large enhancements to processes which would be otherwise Cabibbo suppressed. Their contributions easily lead to values of BR(B^+ \to K^0 π^+) and BR(B_d \to K^+ π^-) of about 1 \times 10^{-5}, as recently found by the CLEO collaboration. In this paper, we s…
We calculate direct CP-violating rate asymmetries in charged $B\to PP$ and $B\to VP$ decays arising from the interference of amplitudes with different strong and CKM phases. The perturbative strong phases develop at order $α_s$ from absorptive parts of one-loop matrix elements of the next-to-leading logarithm corrected effective Hamiltonian. CPT constraints are maintained. Based on this model, we find that partial rate asymmetries between charge conjugate $B^{\pm}$ decays can be as high as 20\% for certain channels with branching ratios in the $10^{-6}$ range. Because the $c\bar{c}$ threshold …
I review the many ways of obtaining information about the CKM matrix through CP violation in the $B$ system. I include direct and indirect CP violation, the role of penguins and isospin analysis, tagging, and $B\to DK$ decays. I also discuss recent developments showing how to use $SU(3)$ flavor symmetry, along with some dynamical approximations, to extract from $B$ decays to $ππ$, $πK$ and $K\kbar$ the weak CKM phases, the strong phase shifts, and the sizes of the various contributing diagrams. Finally, I briefly show what can be learned from an exact treatment of the CKM matrix. (Talk given a…
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…
We constrain the parameters of a representative new physics model with possible dark matter (DM) signature from a global CKM fit analysis. The model has neutral quark current interactions mediated by a scalar, impacting the semileptonic and purely leptonic meson decays at one-loop. We take this opportunity to update the fit results for the Wolfenstein parameters and the CKM elements with and without a contribution from the new model using several other updated inputs. Alongside, we have analyzed and included in the CKM fit the $B\to D^*\ellν_{\ell}$ decay. The newly available inputs on the rel…
CP violation in $B$ decays is reviewed in the Standard Model (SM) and beyond the SM. The present explanation of CP violation in terms of a phase in the Cabibbo-Kobayashi-Maskawa (CKM) matrix can be tested through a variety of CP asymmetries in neutral and charged $B$ decays. Usually, new mechanisms of CP nonconservation enter via $B-\bar{B}$ mixing and violate SM constraints on the CKM parameters in a few characteristic ways. Different models can be partially distinguished by penguin-dominated $B$ decay rate measurements. In radiative decays, large mixing-induced asymmetries may occur due to n…
We compute for the first time the long-distance penguin contribution to the double radiative $B$-meson decays due to the purely hadronic operators acting with the electromagnetic current in the background soft-gluon field from first field-theoretical principles by introducing a novel subleading $B$-meson distribution amplitude. The numerically dominant penguin amplitude arises from the soft-gluon radiation off the light up-quark loop rather than the counterpart charm-loop effect on account of the peculiar analytical behaviour of the short-distance hard-collinear function. Importantly the long-…
Using the experimental result on b\to sγand theoretical result on b\to sg, a four -generation SM is analysed to constrain the rephasing-invariant combinations of the CKM matrix and masses of the fourth generation quarks.
