5 pages, 3 figures; To appear in the proceedings of the 2009 Europhysics Conference on High Energy Physics, July 16-22, 2009, Krakow, Poland. v2: added ref. [17]. v3: accepted version
The large data sample being recorded with the Belle detector at the Y(5S) energy provides a unique opportunity to study the poorly-known Bs0 meson. Three analyses, using a sample of 23.6 /fb, are presented. We report the first observation of the three dominant exclusive Bs0 decays, Bs0 -> Ds*- pi+, Bs0 -> Ds- rho+ and Bs0 -> Ds*- rho+, the first observation of the CP-eigenstate decay Bs0 -> J/psi eta, and the results from a study of the charmless Bs0 -> K+K-, Bs0 -> K+pi-, Bs0 -> pi+pi- and Bs0 -> K0 K0bar decays.
We overview recent measurements in B -> rho rho decays which are based on data samples collected at the PEP-II and KEKB asymmetric-energy e+e- colliders with the BABAR and Belle detectors. Special emphasis is given to the determination of the CP-violating coefficients A and S from an analysis of B -> rho+ rho- decays. The values of A and S, branching fractions, and longitudinal polarization fractions of B -> rho rho decays are used to constrain the Cabibbo-Kobayashi-Maskawa phase alpha/phi2 using an isospin analysis; the solution consistent with the standard model is 71 deg. < alpha < 113 deg.…
We present measurements of time-dependent asymmetries in decays of neutral B mesons to the final states B0 -> rho+ pi-. Measurements are based on a 140 fb-1 data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
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.
We report on a search for the exclusive two-body charmless hadronic B meson decays B-> eta' rho, B-> eta' K*, B-> eta' phi, B-> eta' omega and B->eta' eta('). The results are obtained from a data sample containing 535 x 10^6 BBbar pairs that were collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We find no significant signals and report upper limits in the range 0.5-6.5 x 10^{-6} for all of the above decays.
We present a time-dependent analysis of CP violation in B0 -> rho pi decays based on a 140 1/fb data sample collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We fully reconstruct one neutral B meson in the rho+-pi-+ final state and identify the flavor of the accompanying B meson from its decay products. We obtain the charge asymmetry ACP = -0.16+-0.10(stat)+-0.02(syst). An unbinned maximum likelihood fit to the proper-time distributions yields C = 0.25+-0.17(stat)+0.02-0.06(syst), DC = 0.38+-0.18(stat)+0.02-0.04(syst), S = -0.28+-0.23(stat)+0…
Using the data sample of 10.5 fb-1 collected by the Belle detector, we searched for two-body charmless decays involving vector mesons. The clear signal signature of B+ -> phi K+ is seen and its branching fraction is measured to be (1.39+.32-.30 +- 0.2) X 10-5. The evidence for B+ -> rho pi+, B0 -> rho- pi+ and B+ -> phi K*+ is reported and their branching fractions are determined. No significant signals are observed for B0 -> phi K0S, -> phi K*0, -> rho- K+, B+ -> rho K+, -> omega pi+ and -> omega K+ only the 90% C.L. upper limits are given.
We search for dimuon decays of a low mass particle in the decays B0->K*0 X and B0->rho X using a data sample of 657x10^6 B Bbar events collected with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider. We find no evidence for such a particle in the mass range from 212 MeV/c2 to 300 MeV/c2, and set upper limits on its branching fractions. In particular, we search for a particle with a mass of 214.3 MeV/c2 reported by the HyperCP experiment, and obtain upper limits on the products B(B0->K*0 X)xB(X->mu^+ mu^-) < 2.26 (2.27)x10^-8 and B(B0->rho0 X)xB(X->mu^+ mu^-) < 1.73 (1.73)x10^-…
We present the results of a time-dependent Dalitz plot analysis of B0 -> pi+ pi- pi0 decays based on a 414fb^-1 data sample that contains 449MBB pairs collected on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. The direct CP violating parameters of B0 -> rho+-pi-+ decay mode are measured to be A_rhopi^+- = +0.22 +- 0.08(stat.) +- 0.05(syst.) and A_rhopi^-+ = +0.08 +- 0.17(stat.) +- 0.12(syst.). We also measure the CP violating parameters of the decay mode B0 -> rho0pi0 as A_rho0pi0 = -0.45 +- 0.35(stat.) +- 0.32(syst.) and S_rho0pi0 = +0.15 +- 0.…
We present a search for the rare decays B -> h(*) nu nubar, where h(*) stands for a light meson. A data sample of 535 million BBbar pairs collected with the Belle detector at the KEKB e+e- collider is used. Signal candidates are required to have an accompanying B meson fully reconstructed in a hadronic mode and signal-side particles consistent with a single h(*) meson. No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level. The limits on B0 -> K*0 nu nubar and B+ -> K+ nu nubar decays are more stringent than the previous constraints, while …
We report the first observation of the charmless vector-vector decay process B+ ->rho+ rho0. The measurement uses a 78 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric e+e- collider operating at the Upsilon(4S) resonance. We obtain a branching fraction of Br(B+ ->rho+ rho0)=(31.7+-7.1(stat.)+3.8-6.7(sys.))*10^{-6}. An analysis of the rho helicity-angle distributions gives a longitudinal polarization of Gamma_{L}/Gamma=(94.8+-10.6(stat.)+-2.1(sys.))%.
We present the first evidence of the decay B0 --> rho0 pi0, using 140fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e+e- collider. We detect a signal with a significance of 3.5 standard deviations, and measure the branching fraction to be Br(B0 ->- rho0 pi0) = (5.1 +/- 1.6(stat) +/- 0.9(syst))*10^-6.
We report an observation of the decay B0 -> D*- tau+ nu and a search for the rare decays B -> h(*) nu nubar\ove, where h(*) stands for a light meson. A data sample of 535 million BBbar pairs collected with the Belle detector at the KEKB e+e- collider is used. We find a signal with a significance of 5.2 standard deviations on B0 -> D*- tau+ nu and measure the branching fraction to be 2.02 +0.40/-0.37 (stat.) +- 0.37 (syst.)%. No significant signal is observed for B -> h(*) nu nubar decays and we set upper limits on the branching fractions at 90% confidence level. The limits on B0 -> K*0 nu nuba…
The large data sample recorded with the Belle detector at the Y(5S) energy provides a unique opportunity to study the poorly-known Bs0 meson. Several analyses, made with a data sample representing an integrated luminosity of 23.6 /fb, are presented. We report the study of the large-signal Bs0 -> Ds(*)- h+ (h+ = pi+ or rho+) decays including the first observations of Bs0 -> Ds*- pi+ and Bs0 -> Ds(*)- rho+. In addition, several results on CP-eigenstate Bs0 decays are described. These include the study of the Bs0 -> J/psi eta(') and Bs0 -> J/psi f0(980) decays, the charmless Bs0 -> K+ K-, Bs0 -> …
Recent BABAR and Belle results on rare B decays involving photons or lepton pairs are reviewed. New preliminary limits from both experiments for B-->rho gamma and B-->omega gamma, and from BABAR for B --> K nu nu and B --> tau nu are presented. Also summarized from the past year are Belle measurements of B-->Xs l+l- and B0-->K2(1430) gamma, preliminary BABAR measurements of B-->Xs gamma, and preliminary results from BABAR and Belle on B-->K(*)l+l-. No significant deviations from Standard Model predictions have yet been found.
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.
We report on a study of the branching fractions for the exclusive charmless semileptonic B decay modes B to pi+ l nu, B to pi0 l nu, B to rho+ l nu, B to rho0 l nu and B to omega l nu, using events tagged by fully reconstructing one of the B mesons in a hadronic decay mode. The obtained branching fractions are B(B to pi+ l nu) = (1.12 +- 0.18 +- 0.05) x 1E-4, B(B to pi0 l nu) = (0.66 +- 0.12 +- 0.03) x 1E-4, B(B to rho+ l nu) = (2.56 +- 0.46 +- 0.12) x 1E-4, B(B to rho0 l nu) = (1.80 +- 0.23 +- 0.07) x 1E-4 and B(B to omega l nu) = (1.19 +- 0.32 +- 0.05) x 1E-4, where the first error in each c…
We present a measurement of the CP-violating asymmetry in rho+rho- decays using 535 million BBbar pairs collected with the Belle detector at the KEKB e+e- collider. We measure CP-violating coefficients A = 0.16 +- 0.21(stat) +- 0.07 (syst) and S = 0.19 +- 0.30(stat) +- 0.07 (syst}. These values are used to determine the unitarity triangle angle phi_2 using an isospin analysis; the solution consistent with Standard Model lies in the range 53 < phi_2 < 114 deg. at 90 C.L.
It is experimentally observed that ratios of branching fractions for semitauonic and semileptonic $B$ decays, known as the $R(D^{(*)})$, are higher than Standard Model (SM) predictions. The $B \to \bar{D}^{(*)} τ^{+} ν_τ$ decays, except for the branching fractions, offer also other observables, in particular, angular observables may determine spin structure of a potential New Physics (NP) providing some clues to explain the $R(D^{(*)})$ puzzle. In this review, polarization measurements in $B \to \bar{D}^{*} τ^{+} ν_τ$ decays at Belle are presented and prospects for measurements of characterist…
Studies of semileptonic $B_s$ decays by the Belle, Babar and D0 experiments are reported. In particular measurements of inclusive semileptonic $B_s$ decays by Belle and Babar and the exclusive excited charm mode $B_s \to D_{s1} μν$ from D0 are presented. An outlook on further semileptonic $B_s$ measurements with $Υ(5S)$ data at Belle and Belle II is also given.
We present a study of the radiative decays of X(3872) at Belle. In the χ_{c1}γfinal state, we got the first evidence of a new particle at 3823 MeV$/c^2$.
We report on the first Belle II measurements of branching fractions and CP-violating charge asymmetries in charmless $B$ decays. We use 34.6 fb$^{-1}$ from electron-positron collisions collected in 2019 and 2020 at the $Υ(4S)$ resonance. The results are compatible with known values and show performance already comparable with Belle.
With ~10fb$^{-1}$ data from Belle, the results of b to c and u decays have been represented here. Several decay modes have been studied, which include charmonium, semileptonic decay and Cabibbo-suppressed decays mode. The preliminary results and the measurements of KM matrix elements will also be presented here.
A review of recent results concerning decays of charmed mesons, charmed baryons and $τ$ leptons for the Belle and BaBar Experiments is given. The review was presented at the 43$^{rd}$ Rencontres de Moriond (QCD and High Energy Interactions), LaThuile, March 8-15, 2008.
In this review we report the recent results of open charm decays and spectroscopy using the data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider.
Belle II is an upcoming experiment at the next generation SuperKEKB e+e- collider. It will record about 50 ab-1 of data mostly at the Y(4S) resonance. The high statistics will allow precision measurements for rare decays, which can be then compared with the Standard Model predictions in order to search indirectly for new physics. We present the prospects for rare decay studies at Belle II.
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 report recent observations of baryonic B decays with charmless and charmed baryons in the final state. We show the angular distributions of the di-baryon low-mass enhancements in the charmless three-body baryonic B decays andthe branching fractions of B decays with two charmed baryons or charmonium in the final states. We also report the observation of the decay $η_c \to Λ\barΛ$ at Belle.
We review recent results of the BABAR and BELLE Collaborations on the the alpha and gamma angles of the unitary triangle, on the B to K pi pi Dalitz-plot analyses, and on the searches for baryonic B decays and for B to DD decays.
We report study of B+- to J/psi eta K+- decays at Belle. In this analysis we search for X(3872) as well as other narrow resonances in the J/psi eta final state.
Recent measurements of branching fractions and CP-violating partial-rate asymmetries for rare hadronic B-meson decays by the asymmetric-energy B-factory experiments, Belle and BaBar, are reviewed.
Results on a number of rare hadronic B decays are presented. A data sample of $29.1 {\rm fb}^{-1}$ accumulated using the Belle detector at the KEKB asymmetric $e^+e^-$ collider operating at the $Υ(4S)$ resonance is used.
We summarise the most recent results of the Belle experiment about flavour changing neutral current (FCNC) radiative and (semi-) leptonic B decays. In particular, we report about the first observation of the decays B->K*l+l-, B->phi K gamma, the inclusive B->Xs l+l-$. We also report about searches for B->l+l- decay and for CP asymmetries in B->K*gamma.
We report the recent results of charmed baryon decays, based on the data collected by the Belle experiment at the KEKB collider. This includes the observation of the doubly Cabibbo-suppressed decay $Λ_c^+\toπ^-K^+p$, search for the decay $Λ_c^+\toϕp π^0$, and the branching fraction measurement of $Λ_c^+\toπ^+K^-pπ^0$.
The results on charmless B meson decays to three-body Khh final states, where h stands for the charged or neutral pion or kaon are presented. The data sample used in this analysis consists of 43 1/fb on-resonance data collected with the Belle detector operating at the KEKB collider.
We present recent results for radiative and electroweak penguin decays of $B$ me son at Belle. Measurements of differential branching fraction, isospin asymmetr y, $K^*$ polarization, and forward-backward asymmetry as functions of $q^2$ for $B \to K^{(*)}ll$ decays are reported. For the results of the radiative process, we report measurements of branching fractions for inclusive $B\to X_s γ$ and the exclusive $B\to K η' γ$ modes.
A study of CP violation in $B\to J/ψK^*(K_S^0π^0)$ decays by time dependent angular analysis is discussed. Status of time independent analyses for other $B\to VV$ decays is also reported. The data used for the analyses are taken with the Belle detector at KEK.
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.
$CP$ violation and branching fraction measurements in $D$ decays are interesting topics as any difference with respect to the Standard Model prediction would be an indication of new physics. With the large data sample collected by the Belle detector, which sits at the interaction point of KEKB asymmetric $e^{+} e^{-}$ collider in Japan, we present the results of searches for $CP$ violation in $D^{0}\rightarrow Vγ~(V = ϕ, \overline{K}^{*0}, ρ^{0})$ decay and the rare $D$ decay $D^{0}\rightarrow γγ$.
We review recent experimental results on Bd and Bs mesons decays by the BaBar and Belle experiments. These include measurements of the color-suppressed decays B0bar to D(*)0h0, h0=pi0, eta, etaprime, omega, observation of the baryonic decay B0bar to Lambdac+ Lambdabar K-, measurements of the charmless decays B to eta h, h=K, pi, B to Kpi and observation of CP eigenstates in the Bs decays: B0s to J/psi f0(980), B0s to J/psi f0(1370) and B0s to J/psi eta. The theoretical implications of these results will be considered.
We report a measurement of the CP violation parameters in b->c anti-c d decays. Mixing-induced CP violation involving this transition is studied using a sample of B0->J/psi pi0, D*+D*- and D*+-D-+ decays with a data set accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. CP violation parameters are extracted from a fit to the distributions of time intervals between two B0 meson decay vertexes.
Recent results obtained using the data sample of 23.6 fb^-1 collected on the Y(5S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider are discussed. Measurements of several B_s^0 decay branching fractions are reported. Studies of the Y(5S) decays to the channels with B^+ and B^0 mesons or bottomonium states are discussed.
We report on recent results on charmless hadronic and radiative rare $B_s^0$ decays, based on the data collected by the Belle experiment at the KEKB $e^+e^-$ collider. These include the studies of $B_s^0\rightarrow K^0\bar{K^0}$, $B_s^0\rightarrowϕγ$ and $B_s^0\rightarrowγγ$.
The Belle experiment, running at the KEKB e^+ e^- asymmetric energy collider during the first decade of the century, has recorded 770 fb^-1 of data at the Upsilon(4S) resonance. A combination of recent Belle results obtained with this sample is used to perform a measurement of the CKM angle gamma. We use B^+- -> DK^+- and B^+- -> D^*K^+- decays where the D meson decays into K_S^0pi+pi-, Kpi, KK, pipi, K_S^0 pi^0 and K_S^0 eta final states and D^* decays into Dpi^0 and Dgamma. Belle obtains the most precise gamma measurement to date, gamma = (68^{+15}_{-14}) degree.
The CKM angle $ϕ_3$ is less precisely known than the angle $ϕ_1$ and the only one that is accessible with tree-level decays in a theoretically clean way. The key method to measure $ϕ_3$ is through the interference between $B^+\to D^0 K^+$ and $B^+ \to \bar D^0 K^+$ decays which occurs if the final state of the charm-meson decay is accessible to both the $D^0$ and $\bar D^0$ mesons. To achieve the best sensitivity, a large variety of $D$ and $B$ decay modes is required, which is possible at Belle experiment as almost any final state can be reconstructed including those with photons. The results…
We have searched for the lepton-flavor-violating decay tau -> e gamma using a data sample of 86.7/fb collected with the Belle detector at the KEKB asymmetric e^+ e^- collider. No evidence for a signal is obtained, and we set an upper limit for the branching fraction Br(tau -> e gamma) < 3.9 x 10^-7 at the 90% C.L.
The $b\to s(d)$ quark-level transitions are flavor-changing neutral current processes, which are not allowed at tree level in the standard model. These processes are very rare and constitute a potential probe for new physics. Belle II at SuperKEKB is a substantial upgrade of the Belle experiment. It aims to collect 50 ab$^{-1}$ of data with a design peak luminosity of $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ that is 40 times more than its predecessor. It has been recording data since 2019 and during these early days of the experiment, efforts are being made to detect early signals of the above deca…
The Belle and Babar experiments have measured the branching fractions for B+ -> tau+ nu and Ds+ -> mu+ nu decays. From these measurements one can extract the B+ and Ds+ decay constants, which can be compared to lattice QCD calculations. For the Ds+ decay constant, there is currently a 2.1 sigma difference between the calculated value and the measured value.
We report results on the Dalitz analysis of three-body charmless B+=>K+pi+pi-, B0=>K0pi+pi- and B+=>K+K+K- decays including searches for direct CP violation in the B+=>K+pi+pi- mode. Branching fractions for a number of quasi-two-body intermediate states are reported. We also observe evidence with 3.9 sigma significance for a large direct CP violation in B+-=>rho(770)0K+- channel. This is the first evidence for CP violation in a charged meson decay. The results are obtained using a Dalitz analysis technique with a large data sample of BBbar pairs collected with the Belle detector operating at t…
