We search for new charmless decays of neutral b-hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 1 fb-1 of integrated luminosity, we report the first observation of the B0s->K-pi+ decay, with a significance of 8.2 sigma, and measure BR(B0s->K-pi+)= (5.0+-0.7(stat)+-0.8(syst))*10^{-6}. We also report the first observation of charmless b-baryon decays in the channels Lambda_b -> p pi and Lambda_b -> pK with significances of 6.0 sigma and 11.5 sigma respectively, and we measure BR(Lambda_b->p pi-) = (3.5+-0.6(stat)+-0.9(syst))*10^{-6} and BR(Lambda_b->p K-) = (5.6+-0.8(stat)+-1.5(syst))*10^{-6}. No evidence is found for the decays B0->K+K- and B0s -> pi+pi-, and we set an improved upper limit BR(B0s -> pi+pi-) < 1.2*10^{-6}$ at the 90% confidence level. All quoted branching fractions are measured using BR(B0->K+pi-)$ as a reference.
A way of circumventing the gauge and infrared problems with effective Wilson coefficients is shown. Implications of experimentally measured charmless $B$ decays are discussed.
We report measurements of direct CP-violating asymmetries in charmless decays of neutral bottom hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 1 fb-1 of integrated luminosity, we obtain the first measurements of direct CP violation in bottom strange mesons, A_CP(BsKpi) = +0.39 +- 0.15 stat +- 0.08 syst, and bottom baryons, A_CP(Lb->ppi) = +0.03 +- 0.17 stat +- 0.05 syst and A_CP(Lb->pK) = +0.37 +- 0.17 +- 0.03 syst. In addition, we measure CP violation in Bd-->Kpi decays with 3.5sigma significance, A_CP(B->…
We perform a model dependent fit to recent data on charmless hadronic B decays and determine $γ$, the phase of $V^*_{ub}$. We find $γ= 114^{+25}_{-21}$ degrees, which disfavors the often quoted $γ\sim 60^\circ$ at the two standard deviation level. We also fit for the form factors $F_0^{Bπ}$ and $A_0^{Bρ}$, and the strange-quark mass. They are consistent with theoretical expectations, although $m_s$ is somewhat low. Such agreement and the good $χ^2$ for the fit may be interpreted as a confirmation of the adequacy of our model assumptions.
We give an overview of the experimental measurements and the theoretical understanding of the branching fractions and CP-violating asymmetries of charmless B-meson decays. Most experimetal results are from the BABAR and Belle experiments during the past decade. The global features of these experimental results are typically well described by the QCD-motivated theories such as QCD factorization, pQCD and soft-collinear effective theory. The agreement between theory and experiment is generally satisfactory, though there remain some unsolved puzzles that pose a great challenge to both theorists a…
Flavor SU(3) analysis of heavy meson ($B$ and $D$) hadronic charmless decays can be formulated in two different ways. One is to construct the SU(3) irreducible representation amplitude (IRA) by decomposing effective Hamiltonian according to the SU(3) transformation properties. The other is to use the topological diagrams (TDA). These two methods should give equivalent physical results in the SU(3) limit. Using $B \to PP$ decays as an example, we point out that previous analyses in the literature using these two methods do not match consistently in several ways, in particular a few SU(3) indepe…
Two-body charmless hadronic decays of $B$ mesons are important for determining Standard Model parameters and for detecting the presence of new physics. We present recent results from the Belle experiment on the charmless hadronic decays $B\rightarrow ηπ^0$ and $B\rightarrow π^0 π^0$.
We present recent results on time integrated and time dependent CP violation for charmless hadronic B decays using BABAR detector at the PEP-II B-factory.
We present recent results on charmless hadronic B decays using data collected by the BaBar detector at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. We report measurements of branching fractions and charge asymmetries in several charmless two-body, three-body, and quasi-two-body decay modes. We also report measurements of polarization in charmless B decays to exclusive final states with two vector mesons.
We present measurements of branching fraction, polarization and charge asymmetry in charmless hadronic B decays with eta, eta', omega, and b_1 in the final state. All the results use the final BABAR dataset.
We report recent measurements of branching fractions and charge asymmetries of charmless hadronic B decays using the data collected with the BABAR detector at the PEP-II asymmetric energy e+e- collider.
We present preliminary measurements of the branching fractions for charmless hadronic decays of B mesons into two-body final states with kaons, pions and a phi resonance. The measurements are based on a data sample of approximately 23 million B-anti-B pairs collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC.
We present experimental measurements of branching fraction and longitudinal polarization fraction in charmless hadronic B decays into vector, axial vector and tensor final states with the final dataset of \babar . Measurements of such kind of decays are a powerful tool both to test the Standard Model and search possible sources of new physics.
We search for new charmless decays of neutral $b$--hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 1 fb$^{-1}$ of integrated luminosity, we report the first observation of the \BsKpi decay, with a significance of $8.2σ$, and measure $\BR(\BsKpi) = (5.0 \pm 0.7\stat \pm 0.8\syst)\times 10^{-6}$. We also report the first observation of charmless $b$--baryon decays in the channels \Lbppi and \LbpK with significances of $6.0σ$ and $11.5σ$ respectively, and we measure $\BR(\Lbppi) = (3.5 \pm 0.6\stat \pm 0.9\syst…
We search for CP violating asymmetries in five charmless hadronic B meson decays using the full CLEO II and CLEO II.V data samples totalling 9.7 million BBbar events. The resulting Acp measurements have a precision that varies from +-0.12 to +-0.25 (absolute) depending on mode. No significant nonzero asymmetry is observed in any mode but 90% CL limits are strong and rule out some estimates of Acp.
We present CDF results on the branching fractions and time-integrated direct CP asymmetries for Bd, Bs and Lb decay modes into pairs of charmless charged hadrons (pions, kaons and protons). The data-set for these measurements amounts to 1fb^{-1} of pbar-p collisions at a center of mass energy 1.96TeV. We report on the first observation of the Bs->Kpi, Lb-ppi and Lb->pK decay modes and on the measurement of their branching fractions and direct CP asymmetries.
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…
Recently Belle collaboration reported new measurements for the branching fractions with the first observing two processes of $\mathcal{B}(Ξ_c^0\toΛK^0_S)$, $\mathcal{B}(Ξ_c^0\toΣ^0 K^0_S)$ and updating data for $\mathcal{B}(Ξ_c^0\toΣ^+ K^-)$. Combined with other known data on charmless two body decays of anti-triplet charmed baryons, a lot of information can be derived with the assistance of $SU(3)$ flavour symmetry. Using $SU(3)$ relations between different decay modes, we can give some predictions based on the new measurements which can be tested with the high luminosity experiments in the f…
Based on the assumption of two-quark structure of the scalar $K_0^*(1430)$, the CP-averaged branching ratios(BRs) and CP-violating asymmetries of charmless hadronic $B_q(q=u,d,s,c) \to \kst \kstb$ decays are studied in the standard model(SM) by employing the perturbative QCD(pQCD) factorization approach. Our predictions are the following: (1) the CP-averaged BRs for $B_{q} \to \kst \kstb$ decays in both scenarios vary in the range of $10^{-6} \sim 10^{-4}$ in the SM; (2) the magnitudes of $\acp^{\rm dir}(B_u \to {\kst}^+ {\kstb}^0)$ and $\acp^{\rm dir}(B_{d,s} \to {\kst}^+ {\kst}^-)$ in Scenar…
We report results from five analyses based on data taken with the BABAR detector at the PEP-II asymmetric e+e- collider. Included are branching fraction measurements for many B-meson decays involving eta, eta', omega, phi or a0 mesons and the final state Kspi+pi-, and a full angular analysis of the decay B->phiK*0.
The CLEO collaboration has studied two-body charmless hadronic decays of $B$ mesons into final states containing two pseudo-scalar mesons, or a pseudo-scalar and a vector meson. We summarize and discuss results presented during the winter/spring 1999 conference season, and provide a brief outlook towards future attractions to come. In particular, CLEO presented preliminary results on the decays $B^\pm \to π^\pmρ^0$ ($Br(B^\pm \to π^\pmρ^0) = (1.5 \pm 0.5 \pm 0.4)\times 10^{-5}$), $B\to π^\pmρ^\mp$ ($Br(B\to π^\pmρ^\mp)=(3.5^{+1.1}_{-1.0}\pm 0.5)\times 10^{-5}$), $B\to π^\pm K^{\star\mp}$ ($Br(…
We present several searches for charmless hadronic two-body and three-body decays of B mesons from electron-positron annihilation data collected by the BABAR detector near the Upsilon(4S) resonance. We report the preliminary branching fractions BR(B0 --> pi+pi-) = (4.1 +/- 1.0 +/- 0.7) x 10^-6, BR(B0 --> K+pi-) = (16.7 +/- 1.6 +/- 1.3) x 10^-6, BR(B0 --> rho-/+ pi+/-) = (49 +/- 13 +6 -5) x 10^-6, BR(B+ --> eta' K+) = (62 +/- 18 +/- 8) x 10^-6, and present upper limits for nine other decays.
I present recent results of measurements of branching fractions and CP-violating asymmetries in B0, Bs, and Lambda_B two-body charmless decays at the upgraded Collider Detector at the Fermilab Tevatron. Measurements of rates of flavor-changing neutral current B0, Bs -->mu+mu- and B+/B0/Bs --> mu+mu- K+/K*0/phi decays are also reported. The results are extracted from samples corresponding to time-intergrated luminosities ranging from 0.78 to 1 fb-1.
We present final measurements of thirteen charmless hadronic B decay modes from the CLEO experiment. The decay modes include the ten pipi, Kpi, and KKbar final states and new limits on dibaryonic final states, ppbar, pLambdabar, and LambdaLambdabar, as well as a new determination of the ratio BR(B-> DK)/BR(B-> Dpi). The results are based on the full CLEO II and CLEO III data samples totalling 15.3 fb-1 at the Upsilon(4S), and supercede previously published results.
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.
We report results of searches for charmless hadronic B meson decays to pseudoscalar(pi^+-,K^+-,Pi^0 or Ks^0)-vector(Rho, K* or Omega) final states. Using 9.7 million BBbar pairs collected with the CLEO detector, we report first observation of B^- --> Pi^-Rho^0, B^0 --> Pi^+-Rho^-+ and B^- --> Pi^-Omega, which are expected to be dominated by hadronic b --> u transitions. The measured branching fractions are (10.4+3.3-3.4+-2.1)x10^-6, (27.6+8.4-7.4+-4.2)x10^-6 and (11.3+3.3-2.9+-1.4)x10^-6, respectively. Branching fraction upper limits are set for all the other decay modes investigated.
Status of nonfactorizable effects in hadronic charmless B decays is reviewed. Implications of new CLEO measurements on $B^0\toπ^+π^-$ and $B\toη' K$ are discussed. Nonfactorizable effects due to color ocet 4-quark operators are calculated using renormalization group improved QCD sum rules. The resultant B-meson lifetime ratio $τ(B^-)/τ(B_d)$ agrees with experiment.
LHCb has a rich programme studying hadronic B-decays and is already showing that with early data it can produce precision measurements which improve on current world averages. The preliminary results presented include the new world's best measurements of the Acp(Bd -> K+ pi-) = -0.088 +/- 0.011 (stat) +/- 0.008 (syst) and tau(Bs -> K+ K-) = 1.440 +/- 0.096 (stat) +/- 0.010 (syst) ps. These were obtained using the full 2010 data sample containing 37 pb-1 and also 320 pb-1 of the 2011 data. The first observation of CP violation in Bs -> pi+ K- is also presented.
We report on preliminary measurements of branching fractions, charge-parity-violating asymmetries, and longitudinal polarization fractions in charmless bottom-meson decays from the Belle~II experiment. We use samples of electron-positron collisions collected in 2019 and 2020 at the $Υ(4S)$ resonance, corresponding to integrated luminosities of up to 62.8 ${\rm fb^{-1}}$. The results are compatible with known values, indicating good understanding of early detector performance.
Within the framework of perturbative QCD factorization, we investigate the nonfactorizable contributions to these factorization-forbidden Quasi-two-body decays $B_{(s)}\rightarrow hχ_{c0}\rightarrow hπ^+π^-(K^+K^-)$ with $ h=π, K$. We compare our predicted branching ratios for the $B_{(s)}\rightarrow Kχ_{c0}\rightarrow Kπ^+π^-(K^+K^-)$ decay with available experiment data as well as predictions by other theoretical studies. The branching ratios of these decays are consistent with data and other theoretical predictions. In the Cabibbo-suppressed decays $B_{(s)}\rightarrow hχ_{c0}\rightarrow hπ^…
Based on a sample of approximately 500,000 hadronic Z0 decays accumulated between 1993 and 1998, the SLD experiment has set limits on 24 fully charged two-body and quasi two-body exclusive charmless hadronic decays of B+, B0, and B0_s mesons. The precise tracking capabilities of the SLD detector provided for the efficient reduction of combinatoric backgrounds, yielding the most precise available limits for ten of these modes.
We search for CP-violating asymmetries (Acp) in the B meson decays to K+- pi-+, K+- pi0, Ks pi+-, K+- eta', and omega pi+-. Using 9.66 million Upsilon(4S) decays collected with the CLEO detector, the statistical precision on Acp is in the range of \pm 0.12 to \pm 0.25 depending on decay mode. While CP-violating asymmetries of up to \pm 0.5 are possible within the Standard Model, the measured asymmetries are consistent with zero in all five decay modes studied.
We search for direct CP violation in charmless hadronic B decays observed in a sample of about 22.7 million $B\bar{B}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy $e^+e^-$ collider. We measure the following charge asymmetries: ${\cal A}_{CP} (B^{\pm}\toη^\prime K^{\pm}) = -0.11\pm 0.11\pm 0.02$, ${\cal A}_{CP} (B^{\pm}\toωπ^{\pm}) = -0.01^{+0.29}_{-0.31}\pm 0.03$, ${\cal A}_{CP} (B^{\pm}\toϕK^{\pm}) = -0.05\pm 0.20\pm 0.03$, ${\cal A}_{CP} (B^{\pm}\toϕK^{*\pm}) = -0.43^{+0.36}_{-0.30}\pm 0.06$, and ${\cal A}_{CP} (B^{0}\toϕK^{*0}) = 0.00\pm 0.27\pm 0.03$.
Using 22.7M BBbar events collected with the BABAR detector at SLAC, we present preliminary measurements of the branching fractions for charmless hadronic decays of B mesons into two-body, quasi two-body and three-body final states with pions, kaons, and rho and a0 resonances. In the search for exclusive $B^0 \to π^+π^-π^0$, we measure ${\cal B}(B^0 \to ρ^{\pm}(770)π^{\mp})=(28.9\pm5.4\pm4.3) \times 10^{-6}$, together with the relative asymmetry ${\cal A}_{\rm phys} = -0.04 \pm 0.18 \pm 0.02$. We also set the upper limits on $B^0 \to ρ^0(770)π^0$, non-resonant $B^0 \to π^+π^-π^0$, $B^0 \to a_0^…
We have studied charmless hadronic decays of B mesons into two-body final states with kaons and pions. We present preliminary results based on 9.66 million $B\bar{B}$ pairs collected with the CLEO detector. We have made the first observation of the decay $B \to π^+π^-$, with the branching fraction of $Br(B \to π^+ π^-) = (4.7^{+1.8}_{-1.5} \pm 0.6) \times 10^{-6}$. We have also observed for the first time the decay $B \to K^0π^0$ with the branching fraction of $Br(B \to K^0 π^0) = (14.8^{+5.9+2.4}_{-5.1-3.3}) \times 10^{-6}$, thus completing the set of four $Kπ$ branching fraction measurements…
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.
he CDF experiment at the Fermilab Tevatron p-pbar collider pioneered the exploration of charmless b-hadron decays in hadron collisions. This provided a unique, rich and highly successful program of measurements that is currently reaching its full maturity. I report here results on two-body decays and the new analysis of B0s-->phiphi decays in a event sample corresponding to 2.9 fb-1.
We report the results of a study of two-body B meson decays to the complete set of K pi, pi pi, and K K final states. The study is performed on a data sample of 31.7 +/- 0.3 million B B-bar events recorded on the Upsilon(4S) resonance by the Belle experiment at KEKB. We observe significant signals in all K pi final states and in the pi+ pi- and pi+ pi0 final states. We set limits on the pi0 pi0 and K K final states. A search is performed for partial-rate asymmetries between conjugate states for flavor-specific final states.
We study constraints on the CP violating phase $γ$ in the Kobayashi-Maskawa model using available experimental data. We first follow the conventional method to up date the constraint on $γ$ by performing a $χ^2$ analysis using data from $|ε_K|$, $Δm_{B_{d,s}}$ and $|V_{ub}/V_{cb}|$. We also include the recent information on $\sin2β$ in the analysis. We obtain the best fit for $γ$ to be $66^\circ$ and the 95% C.L. allowed range to be $42^\circ \sim 87^\circ$. We then develop a method to carry out a $χ^2$ analysis based on SU(3) symmetry using data from $B\to ππ$ and $B\to K π$. We also discuss …
We present results of searches for B-meson decays to charmless final states that include a K*, rho, omega, or phi meson accompanied by a second meson. Using the entire data sample of 9.7 million BBbar pairs collected with the CLEO II and CLEO II.V detectors, we observe a signal for the decay B+ -> omega pi+, and measure a branching fraction of B(B+ -> omega pi+) = (11.3^{+3.3}_{-2.9} \pm 1.5) \times 10^{-6}. We also see evidence for the decay B0 -> omega K0, and set limits for the decays B0 -> rho0 pi0 and B0 -> K*0 pi0. In addition to these new results, we also summarize previous CLEO results…
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…
We have searched for two-body charmless hadronic decays of $B$ mesons. Final states include $ππ$, $K π$, and $KK$ with both charged and neutral kaons and pions; $πρ$, $K ρ$, and $K^*π$; and $Kϕ$, $ K^*ϕ$, and $ϕϕ$. The data used in this analysis consist of 2.6~million $B\bar{B}$~pairs produced at the $Υ(4S)$ taken with the CLEO-II detector at the Cornell Electron Storage Ring (CESR). We measure the branching fraction of the sum of $B^0 \rightarrow π^+π^-$ and $B^0 \rightarrow K^+π^-$ to be $(1.8^{+0.6+0.2}_{-0.5-0.3}\pm0.2) \times 10^{-5}$. In addition, we place upper limits on individual bran…
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 …
We present a search for B decays to a charged scalar meson a0+ and a pi0 where the a0+ decays to an eta meson and a pi+. The analysis was performed on a data sample consisting of 383x10-6 BBbar pairs collected with the Babar detector at the PEP-II asymmetric-energy B Factory at SLAC. We find no significant signal and set an upper limit on the product branching fraction BF[(B+ -> a0+ pi0) x (a0+ -> eta pi+)] of 1.4x10-6 at the 90% confidence level.
We present preliminary results of several searches for rare charmless hadronic decays of the B meson using data collected by the BABAR detector at the Stanford Linear Accelerator Center's PEP-II storage ring. We search for the decays h^+h^-, h^+h^-h^+, h^+h^-pi^0, X^0h^+, and X^0 K_S^0, where h = pi or K, and X^0 = eta^prime or omega. In a sample of 8.8 million B-anti-B decays we measure the branching fractions: BF(B^0 --> pi^+pi^-) = (9.3^{+2.6}_{-2.3}^{+1.2}_{-1.4}) x 10^{-6}, BF(B^0 --> K^+pi^-) = (12.5^{+3.0}_{-2.6}^{+1.3}_{-1.7}) x 10^{-6}, BF(B^0 --> rho^-pi^+) = (49 +/- 13^{+6}_{-5}) x …
We report results of a study of charmless B meson decays to three-body KPiPi, KKPi and KKK final states. Measurements of branching fractions for B decays to K+0Pi+Pi-, K+K+K-, K0K+K-, KsKsK+ and KsKsKs final states are presented. The decays B0=>K0K+K-, B+=>KsKsK+ and B0=>KsKsKs are observed for the first time. We also report evidence for B+=>K+K-Pi+ decay. For the three-body final states K0K+K-, KsKsPi+, K+K+Pi- and K-Pi+Pi+ 90% confidence level upper limits are reported. Finally, we discuss the possibility of using the three-body B0=>KsK+K- decay for CP violation studies. The results are obta…
Implications of recent CLEO measurements of hadronic charmless B decays are discussed. (i) Employing the Bauer-Stech-Wirbel (BSW) model for form factors as a benchmark, the $B\toπ^+π^-$ data indicate that the form factor $F_0^{Bπ}(0)$ is smaller than that predicted by the BSW model, whereas the data of $B\toωπ, K^*η$ imply that the form factors $A_0^{Bω}(0), A_0^{BK^*}(0)$ are greater than the BSW model's values. (ii) The tree-dominated modes $B\toπ^+π^-, ρ^0π^\pm, ωπ^\pm$ imply that the effective number of colors N_c(LL) for (V-A)(V-A) operators is preferred to be smaller, while the current l…
Two-body charmless nonleptonic decays of B_u and B_d mesons are studied within the framework of generalized factorization in which the effective Wilson coefficients $c^{eff}_i$ are renormalization-scale and -scheme independent while factorization is applied to the tree-level hadronic matrix elements. Contrary to previous studies, our $c_i^{eff}$ do not suffer from gauge and infrared problems. 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. Tree and penguin transi…
In this work, we calculate the branching ratios (BRs) and the polarization fractions of sixty two charmless two-body $B_c$ meson decays into final states involving one vector and one axial-vector meson ($VA$) or two axial-vector mesons($AA$) within the framework of perturbative QCD (pQCD) approach systematically, where $A$ is either a $^3P_1$ or $^1P_1$ axial-vector meson. All considered decay channels can only occur through the annihilation topologies in the standard model. Based on the perturbative calculations and phenomenological analysis, we find the following results: (i) the CP-averaged…
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-…
We study 20 charmless hadronic $B \to f_1 P$ decays in the perturbative QCD(pQCD) formalism with $f_1$ representing axial-vector mesons $f_1(1285)$ and $f_1(1420)$ that result from a mixing of quark-flavor $f_{1q}$ and $f_{1s}$ states with the angle $ϕ_{f_1}$. The estimations of branching ratios and CP asymmetries of the considered $B \to f_1 P$ decays are presented in the pQCD approach with $ϕ_{f_1} \sim 24^\circ$ from recently measured $B_{d/s} \to J/ψf_1(1285)$ decays. It is found that (a) the tree(penguin) dominant $B^+ \to f_1 π^+(K^+)$ decays with large branching ratios[${\cal O}(10^{-6}…
Rare charmless hadronic B decays are a good testing ground for QCD. In this paper we describe a selection of new measurements made by the BABAR and BELLE collaborations.
Preliminary results from the BABAR experiment on charmless B decays to charged pions or kaons, and the measurement of the B -> J/psi K* decay amplitudes are presented. The data sample, collected at the asymmetric-energy B-factory PEP-II at SLAC, comprises a total number of 22.7 million Y(4S) decays, corresponding to an integrated on-resonance luminosity of approximately 21 fb-1. We measure the following CP-averaged branching fractions: BR(B -> pi+pi-) = (4.1 +- 1.0(stat) +- 0.7(sys))xE-6 BR(B -> K+pi-) = (16.7 +- 1.6(stat) +1.2-1.7(sys))xE-6 and an upper limit of BR(B -> K+K-) < 2.5xE-6, at 90…
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…
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…
The LHCb experiment has measured CP violation (CPV) across the Dalitz plot of charmless decays of B+ mesons to 3 charged tracks, namely in Kππ, KKK, πππ and πKK final states, with strikingly large CPV that vary strongly with Dalitz variables. Identifying these processes with b -> sqq(bar), sss(bar) and b -> dqq(bar), dss(bar), where q = u, d, then the "sum rule" that requires two-loop absorptive parts by unitarity works well for inclusive b -> s CPV, but less well for inclusive b -> d case. We elucidate the situation, and argue that the 30 year old unitarity/CPT argument is valid to this day, …
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…
