We present measurements of time-dependent CP violation parameters in B0 --> K0 PI0, B0 --> Ks Pi+ Pi- and B0 --> Ks K+ K- decays. The latter two are extracted using time-dependent Dalitz plot analyses. These results are obtained from a large data sample that contains 657 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
Penguin transitions play a key role in the search of New Physics hints in the heavy flavor sector. During the last decade CDF has been exploring this opportunity with a rich study of two--body charmless decays of neutral B mesons into charged final--state particles. After briefly introducing the aspects of this physics peculiar to the hadron collision environment, I report on two interesting results: the first polarization measurement of the B^0_s --> phi phi decay and the update of the B^0(_s) --> h^+h'^- decays analysis.
Charmless $B$ decays are dominated by contributions from the short distance amplitudes from tree level and penguin loop-level amplitudes. The Tree contribution presents a weak phase $γ$. The relationship between these two amplitudes can generated a CP asymmetry depending from the relative amount among them in a particular decay. In multi-body charmless $B$ decays, these relative contribution can change along the phase space, given a non isotropic distribution of CP asymmetries in the Dalitz plot. Two recent LHCb analyses involving charmless multi-body B decays are discussed: the obsevation of …
We report on preliminary measurements of time-dependent CP-violation asymmetries in charmless neutral B meson decays to K+K-K0 (including resonant decays phiK0 and f0K0), eta'K0, pi0K0s, K0sK0sK0s, K0sK0s, rho0K0s, omegaK0s. The results are obtained from a data sample of up to 347 million BBbar pairs produced by e+e- annihilation at the Y(4S) resonance collected with the BaBar detector at the PEP-2 asymmetric-energy B-meson Factory at SLAC.
We present a preliminary measurement of the branching fraction for B to rho e nu and of the CKM matrix element |Vub| using approximately 55 million B Bbar meson pairs collected with the BABAR detector. Using isospin relations for several modes we find BF(B0 to rho- e+ nu) = (3.39+-0.44+-0.52+-0.60)x10^(-4) and |Vub| = (3.69+-0.23+-0.27+0.40-0.59)x10^(-3). The quoted errors are statistical, systematic, and theoretical, respectively. These results are obtained by using five different form-factor calculations.
We report recent results from the BABAR experiment on semileptonic charmless B-meson decays and electroweak penguin processes. Semileptonic charmless decays are used to determine |Vub| and the exclusive modes considered here also begin to constrain QCD-lattice form factor calculations. Radiative penguin decays are both sensitive to physics beyond the Standard Model and can be used to extract Heavy Quark parameters related to the b-quark mass and its motion inside the hadron.
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…
The BABAR experiment has completed its first year of data-taking during which 21 $fb^{-1}$ of data were accumulated. We present preliminary results on two types of charmless B decays based on this data sample. The first, $B^0 \to K^{*0}γ$, is a so-called electromagnetic penguin. And the second, $B^0 \to h^+h^{'-}$, where $h^{(')}$ can be either a pion or kaon, can come from either penguin diagrams or Cabibbo suppressed tree diagrams.
We report measurements of charmless hadronic B^0 decays into the pi+pi-K+pi+ final state. The analysis uses a sample of 657x10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at the Y(4S) resonance. The decay B^0 -> rho0 Kpi is observed for the first time; the significance is 5.0sigma and the corresponding partial branching fraction for M_Kpi in (0.75,1.20) GeV/c^2 is [2.8 +- 0.5(stat) +-0.5(syst)] x 10^{-6}. We also obtain the first evidence for B^0 -> f0Kpi with 3.5sigma significance and for B^0 -> pi+pi-K*0 with 4.5sigma significance. For the two-…
Knowing the mass of the b-quark is essential to the study of the structure and decays of B mesons as well as to future tests of the Higgs mechanism of mass generation. We present recent preliminary measurements of the b-quark mass and related nonperturbative parameters from moments of kinematic distributions in charmed and charmless semileptonic and radiative penguin B decays. Their determination from charmless semileptonic B decays is the first measurement in this mode. The data were collected by the BABAR detector at the PEP-II asymmetric-energy e+e- -collider at the Stanford Linear Accelera…
Utilizing all the experimental measured charmless $B \to PP$, $PV$ decay modes, where $P(V)$ denotes a light pseudoscalar (vector) meson, we extract the CKM angle $γ$ by global fit. All the unknown hadronic parameters are fitted with $γ$ together from experimental data, so as to make the approach least model dependent. The different contributions for various decay modes are classified by topological weak Feynman diagram amplitudes, which are to be determined by the global fit. To improve the precision of this approach, we consider flavor SU(3) breaking effects of topological diagram amplitudes…
Charmless hadronic $B$ decays are a good testing ground for the Standard Model (SM) of Particle Physics. The dominant amplitudes are CKM suppressed tree diagrams and/or $ b\to s$ or $b\to d$ loop ("penguin") diagrams. Non-SM particle could appear in the loop, and hence these decays are sensitive to search for New Physics (NP). Some of the recent measurements of two-body charmless hadronic $B$ decays from Belle and their prospects at Belle II are discussed.
This article summarises measurements of time-dependent CP asymmetries in decays of neutral B mesons to charmonium, open-charm and gluonic penguin-dominated charmless final states. Unless otherwise stated, these measurements are based on a sample of approximately 230 million Y(4S) to BBbar decays collected by the BABAR detector at the PEP-II asymmetric-energy B-factory.
The study of charmless b-hadron decays provides information for testing the CKM picture of CP violation in the Standard Model. In addition, as they can proceed through loop diagrams, they are also sensitive to physics beyond the Standard Model. A review of recent results from LHCb on charmless b-hadron decays is presented.
Summary of CKM 2023 working group 5: Direct CP violation (DCPV) including $ϕ_{3}/γ$ from $B\to DK$, DCPV effects, branching fractions and polarisation in charmless $B_{(s)}$ decays
本文总结了CKM2023研讨会工作组5的活动，涵盖了利用$B\ o DK$测量$ϕ_{3}/γ$、在无粲$B$及$b$重子衰变中寻找$CP$破坏、强子$B$到粲衰变分支比测量以及三体非轻子$B$衰变理论的新结果。
In this paper we present first LHCb results on charmless charged two- and three-body $B$ meson decays. In particular, using the first picobarn of integrated luminosity, LHCb observed the $B^{0}\rightarrow K^{+}π^{-}$ and $B^{+}\rightarrow K^{+}π^{+}π^{-}$ decays. Such decays provide an interesting way to determine the angle $γ$ of the Unitary Triangle, thanks to the possible presence of New Physics in the penguin loops.
The weak phase $γ$ is extracted from three-body charmless decays of $B$ mesons following a method proposed by Bhattacharya, Imbeault \& London. The result is obtained by combining the BABAR amplitude analyses for the processes $B^0 \rightarrow K^+ π^0 π^-$, $B^0 \rightarrow K_S^0 π^+ π^-$, $B^0 \rightarrow K_S^0 K_S^0 K_S^0$, $B^0 \rightarrow K^+ K_S^0 K^-$ and $B^+ \rightarrow K^+ π^+ π^-$, under the assumption of $α_{\rm{SU(3)}}$ flavour symmetry. Six possible solutions are found. One solution is compatible with the Standard Model while the others are not. It is also found that, when average…
We report recent measurements of the CKM angle alpha using data collected by the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. In addition to improved constraints on alpha from the decays B+ -> rho+ rho0, we also present preliminary results of neutral and charged B meson decays to K_1(1270) pi and K_1(1400) pi and its impact on the estimate for the CKM angle alpha based on time-dependent analysis of CP-violating asymmetries in B0 -> a_1(1260) pi. Moreover we report the first observation of the decay B -> a_1(1260)+ a_1(1260)-; this mo…
There has been much progress in measurements of charmless hadronic B decays during 1997. Building on the previous indications from CLEO and LEP, CLEO now has clear signals in five exclusive final states: K^+π^, K^0π^+, etapr K^+, etapr K^0, and omega K^+. The branching fractions for the etapr K modes are several times larger than the others. A similar strikingly large signal has been seen in the inclusive decay, B->etapr X_S. All of these signals would appear to be dominated by hadronic penguin processes. (Invited talk presented at the Seventh International Symposium On Heavy Flavor Physics, S…
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…
We present a review of the measurements of the CKM angle beta (phi_1) by the BaBar and Belle experiments at the asymmetric-energy e+e- B Factories PEP-II and KEKB. The angle beta (phi_1) is measured by time-dependent CP analyses of neutral B meson decays in a Upsilon(4S)->BBbar system, where one B meson is fully reconstructed in a final state that can be accessed to by both B0 and B0bar, usually a CP eigenstate. This angle has been measured at a high precision through B0-> (ccbar)K0 channels. We also review another tree-dominated decay B0-> D(*)0 h0 (h0 = pi0, eta^{'}, omega); tree decays with…
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 Belle experiment has measured branching fractions and CP asymmetries for the charmless decays B0->pi+pi- and B0->rho+-pi-+. From these measurements, constraints upon the CKM angle phi_2 can be obtained. These constraints indicate that phi_2 is around 100 degrees.
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…
We present preliminary measurements of branching fractions and CP-asymmetry parameters in two- and three-body charmless hadronic B decays. The available data sample consists of 227 million Upsilon(4S) B decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We establish the observation of the decays B --> pi0 pi0 and B0 --> K0K0bar and constrain the CKM angle alpha with a full SU(2) isospin analysis in the B --> pi pi system and with a B0 --> pi+ pi- pi0 time-dependent Dalitz plot analysis.
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.
We present preliminary results from a search for inclusive charmless B->KX decays. These decays occur dominantly via one-loop b->s penguin transitions, and can provide useful information about these processes. Using a sample of 288.5/fb collected with the BABAR detector at the PEP-II asymmetric-energy e+e- B Factory at SLAC, we search for high-energy kaons recoiling against fully reconstructed B decays. We measure the partial branching fractions for kaons with momentum p*(K)>2.34GeV in the B rest frame, and obtain (in units of 10^-6): B(B->K+X, p*>2.34GeV) = 196^{+37}_{-34}(stat.)^{+31}_{-30}(…
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.
The following is an overview of the current status of charmless semileptonic B decays and the extraction of the CKM matrix element $|V_{ub}|$ by the Belle and BaBaR collaborations.
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 …
Recent branching fraction and asymmetry results of Electroweak Penguin B decays from BaBar, Belle and CLEO experiments are reviewed. While these branching fractions are consistent with the Standard Model expectations and are being used to extract heavy quark model parameters and CKM matrix elements, the asymmetry results are just becoming sensitive to observe any new physics effects.
The Belle and BaBar experiments have measured branching fractions and CP asymmetries in the charmless decay modes B0->pi+pi-, B0->rho+pi-/rho-pi+, and B0->rho+rho-. From these measurements, constraints upon the CKM angle phi_2 can be obtained. These constraints consistently indicate that phi_2 is around 100 degrees.
Various new measurements in charmless $B_{u,d,s}\to PP$ modes, where $P$ is a low lying pseudoscalar meson, are reported by Belle and LHCb. These include the rates of $B^0\toπ^0π^0$, $ηπ^0$, $B_s\toη'η'$, $B^0\to K^+K^-$ and $B^0_s\toπ^+π^-$ decays. Some of these modes are highly suppressed and are among the rarest $B$ decays. Direct CP asymmetries on various modes are constantly updated. It is well known that direct CP asymmetries and rates of suppressed modes are sensitive to final state interaction (FSI). As new measurements are reported and more data will be collected, it is interesting an…
Charmless B hadrons decays offer rich opportunities to test the Standard Model. CP violation in charmless charged two-body and three-body B decays provides ways to measure the CKM angle $γ$ and to search for New Physics. Also, vector-vector final states provide additional interesting observables. Hereby, we present the latest LHCb results on hadronic charmless B decays putting emphasis on the direct CP violation measurements.
We present the partial branching fraction for inclusive charmless semileptonic B decays and the corresponding value of the CKM matrix element |Vub|, using a multivariate analysis method to access ~90% of the B -> Xu l nu phase space. This approach dramatically reduces the theoretical uncertainties from the b-quark mass and non-perturbative QCD compared to all previous inclusive measurements. The results are based on a sample of 657 million B -Bbar pairs collected with the Belle detector. We find that Delta BR(B -> Xu l nu; p^*B_l>1.0 GeV/c=1.963 x (1 +/- 0.088(stat.) +/- 0.081(sys.)) x 10^-3. …
Penguin, or loop, decays of B mesons induce effective flavor-changing neutral currents, which are forbidden at tree level in the Standard Model. These decays give special insight into the CKM matrix and are sensitive to non-standard model effects. In this review, we give a historical and theoretical introduction to penguins and a description of the various types of penguin processes: electromagnetic, electroweak, and gluonic. We review the experimental searches for penguin decays, including the measurements of the electromagnetic penguins b -> s gamma and B -> K* gamma and gluonic penguins B -…
Radiative penguin decays provide an indirect probe for physics beyond the Standard Model and contribute to the determination of the CKM matrix elements. Copious quantities of B mesons produced at the B-Factories permit precision measurements of radiative penguin decays. We review the experimental status of the radiative penguin processes b --> s(d) gamma.
We study the radiative charmless $B_{(s)}\to V(A)γ$ decays in perturbative QCD (pQCD) approach to the leading order in $α_s$ (here $V$ and $A$ denotes vector mesons and two kinds of axial-vector mesons: $^3P_1$ and $^1P_1$ states, respectively.). Our predictions of branching ratios are consistent with the current available experimental data. We update all $B_{(s)}\to V$ form factors and give the predictions for $B\to A$ form factors using the recent hadronic inputs. In addition to the dominant factorizable spectator diagrams, which is form factor like, we also calculate the so-called ``power s…
We present measurements related to the CKM angle beta from BABAR based on 82 or ~115 fb-1 data samples collected at the PEP-II e+e- asymmetric B Factory collider. A new method allowing to measure the sign of cos(2.beta) with B0->J/Psi"K*0" events is explained and related results reported. Recent CP measurements in the penguin dominated modes B0->phi K0,B0->K+K-K0s, B0->pi0 K0s and B0->f0(980) K0s are presented.
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…
Within the factorization-assisted topological-amplitude approach, we studied the 33 charmless $B_{(s)} \to VV$ decays, where $V$ stands for a light vector meson. According to the flavor flows, the amplitude of each process can be decomposed into 8 different topologies. In contrast to the conventional flavor diagrammatic approach, we further factorize each topological amplitude into decay constant, form factors and unknown universal parameters. By $χ^2$ fitting 46 experimental observables, we extracted 10 theoretical parameters with $χ^2$ per degree of freedom around 2. Using the fitted paramet…
We present the first evidence of the decay mode $B_s \to ϕϕ$ and a measurement of partial width and direct CP asymmetry for the $B^+ \to ϕK^+$ decay using $180 pb^{-1}$ of data collected by the CDFII experiment at the Fermilab Tevatron collider. We measure: $BR (\phiphi) = (1.4 \pm 0.6(stat.) \pm 0.2(syst.) \pm 0.5(\BR)) \cdot 10^{-5}$, where the last error is due to the uncertainty on the $B_s \to J/ψϕ$ branching ratio used as normalization, $BR (ϕk) = (7.2 \pm 1.3(stat.) \pm 0.7(syst.)) \cdot 10^{-6}$ and $\ACP(phi k) = -0.07 \pm 0.17 (stat.) \ase{0.06}{0.05} (syst.)$. We also briefly discus…
In the heavy quark limit, both vector mesons in the charmless B -> VV decay should have zero helicity and the corresponding amplitude is proportional to the form factor difference $(A_1-A_2)$. The first observed charmless $B\to VV$ mode, $B\toϕK^*$, indicates that the form factors $A_1(q^2)$ and $A_2(q^2)$ cannot be very similar at low $q^2$ as shown in some form-factor models. The approach of QCD-improved factorization implies that the nonfactorizable correction to each partial-wave or helicity amplitude is not the same; the effective parameters $a_i$ vary for different helicity amplitudes. T…
Non-leptonic $B$ decays into charmless final states offer an important laboratory to study CP violation and the dynamics of strong interactions. Particularly interesting are $B^0_s\to K^-K^+$ and $B^0_d\toπ^-π^+$ decays, which are related by the $U$-spin symmetry of strong interactions, and allow for the extraction of CP-violating phases and tests of the Standard Model. The theoretical precision is limited by $U$-spin-breaking corrections and innovative methods are needed in view of the impressive future experimental precision expected in the era of Belle II and the LHCb upgrade. We have recen…
We report a measurement of the inclusive charmless semileptonic branching fraction of B mesons in a sample of 89 million BBbar events recorded with the BABAR detector at the Y(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. The number of signal events is extracted from the hadronic mass distribution and is used to determine the ratio of branching fractions BR(B->Xulnu)/BR(B->Xlnu) = (2.06 +/-0.25(stat) +/-0.23(syst) +/-0.36(theo)) x 10^{-2}. Using the measured branching fraction for inclus…
We search for the decay B0 -> rho0 rho0 in a data sample of about 227 million Upsilon(4S)-> BBbar decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find no significant signal and set an upper limit of 1.1*10^-6 at 90% CL on the branching fraction. As a result, the uncertainty due to penguin contributions on the CKM unitarity angle alpha measured in B -> rho rho decays is 11 degrees at 68% CL.
We study the rates and direct CP violations of two-body baryonic $\bar B_{u,d,s}\to {{\rm\bf B}\overline{\rm\bf B}}'$ and $B^-_c\to{{\rm\bf B}\overline{\rm\bf B}}'$ decays, where the final state baryons include low-lying octet and decuplet baryons. We incorporate topological amplitude formalism and the factorization approach. Asymptotic relations at large $m_b$ are used to simplify decay amplitudes. Using the most up-to-date data on $\bar B^0\to p\bar p$ and $B^-\toΛ\bar p$ decay rates as inputs, rates and direct CP violations of $\bar B_{u,d,s}\to {{\rm\bf B}\overline{\rm\bf B}}'$ decays are …
Hadronic $B$ decays without a charm quark constitute a powerful probe to search for physics beyond the standard model as well as to provide constraints on $CP$ violation parameters. We report final measurements from Belle of the branching fractions and $CP$ asymmetries for the decays $B^{0} \rightarrow π^{0} π^{0}$ and $B^{\pm} \rightarrow K^{+} K^{-} π^{\pm}$. The $B^{0} \rightarrow π^{0} π^{0}$ measurements enable us to improve constraints on the angle $ϕ_{2}$ of the CKM unitarity triangle. For $B^{\pm} \rightarrow K^{+} K^{-} π^{\pm}$ we measure $CP$ asymmetry as a function of the invariant…
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 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…
Charmless semileptonic decays, ${\bar{B}} \to X_u \ell \barν$, are studied in a sample of 232 million $B\bar{B}$ decays recorded with the BaBar detector, in events where the decay of the second $B$ meson is fully reconstructed. Inclusive charmless decays are selected in kinematic regions where the dominant background from semileptonic B decays to charm is reduced by requirements on the hadronic mass $M_X$ and the momentum transfer $q^2$. The partial branching fraction for ${\bar{B}} \to X_u \ell \barν$ decays for $M_X<1.7$ GeV/c^2 and $q^2>8$ Gev^2/c^4 is measured to be $Δ{\cal{B}}({\bar{B}} \…
With the experimental evidences of $\overline B {}^0\to p \overline{p}$ and $B^-\toΛ\overline p$ decays, it is now possible to extract both tree and penguin amplitudes of the charmless two-body baryonic $B$ decays for the first time. The extracted penguin-tree ratio agrees with the expectation. Using the topological amplitude approach with the experimental results on $\overline B {}^0\to p \overline{p}$ and $B^-\toΛ\bar p$ decay rates as input, predictions on all other $\overline B_q\to {\cal B} \overline {\cal B}$, ${\cal B} \overline {\cal D}$, ${\cal D} \overline {\cal B}$ and ${\cal D} \ov…
Two-body charmless hadronic $B_c$ decays involving a light $1^3\!P_2$-tensor($T$) meson are investigated for the first time within the framework of perturbative QCD(pQCD) at leading order, in which the other meson is the lightest pseudoscalar($P$) or vector($V$) state. The concerned processes can only occur through the pure weak annihilation topology in the standard model. We predict the CP-averaged branching ratios and polarization fractions of those considered decays in Cabibbo-Kobayashi-Maskawa(CKM) favored and suppressed modes. Phenomenologically, several modes$-$such as the $B_c \to K_2^*…
In this paper, we perform a global analysis of $B \to PP$ and $PV$ decays with the QCD factorization approach. It is encouraging to observe that the predictions of QCD factorization are in good agreement with experiment. The best fit $γ$ is around $79^\circ$. The penguin-to-tree ratio $|P_{ππ}/T_{ππ}|$ of $π^+ π^-$ decays is preferred to be larger than 0.3. We also show the confidence levels for some interesting channels: $B^0 \to π^0 π^0$, $K^+ K^-$ and $B^+ \to ωπ^+$, $ωK^+$. For $B \to πK^\ast$ decays, they are expected to have smaller branching ratios with more precise measurements.
We search for the decays B0->rho0rho0, B0->rho0f0, and B0->f0f0 in a sample of about 348 million Upsilon(4S)->BBbar decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find evidence for B0->rho0rho0 with 3.0 sigma significance and measure the branching fraction B = (1.16 +0.37-0.36 +-0.27) 10^{-6} and longitudinal polarization fraction f_L = 0.86 +0.11-0.13 +-0.05. As a consequence, the uncertainty on the CKM unitarity angle alpha due to penguin contributions in B->rhorho decays is estimated to be 18 degrees at 1 sigma level. We also set upper lim…
The QCD factorization (QCDF) method usually contains infrared divergences which introduce large model dependence to its predictions on charmless B decays. The amplitudes of charmless B decays can be decomposed into "tree" and "penguin" parts which are conventionally defined, not from the topology of the dominant diagrams, but through their associated CKM factors V_{ub}^* V_{uq} and V_{tb}^* V_{tq}, respectively, with q=d,s. We find that for B_{d,s} \to π^+ K^- decays, the "tree" amplitude can be well estimated in QCDF with small errors, as the endpoint singularities have been canceled to a lar…
A method based on flavour SU(3) is proposed for identifying and extracting New Physics (NP) amplitudes in charmless $ΔS=1$ $B_s$ decays using time-dependent CP asymmetries in these decays and in flavour SU(3) related $ΔS=0$ decays. For illustration, we assume a hierarchy, $\sim 1: λ: λ^2$ ($λ=0.2$), between a dominant $ΔS=1$ penguin amplitude, a NP amplitude and a Standard Model amplitude with weak phase $γ$. An uncertainty from SU(3) breaking corrections, reduced by using ratios of hadronic amplitudes, is further suppressed by a factor $λ$. We discuss examples for pairs of decays into two neu…
