A. J. Schwartz
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.
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We report recent measurements of the CKM angle phi_1/beta using large data samples collected by the Belle and BaBar experiments at the e^+ e^- asymmetric-energy colliders.
I report on recent measurements from the Belle and BaBar collaborations on the decay of the B-meson to hadronic final states without a charm quark.
We report recent measurements of the Unitarity triangle angles phi_1 and phi_2 using large data samples collected with Belle and BaBar detectors at e+e- asymmetric-energy colliders.
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.
Results are presented from the CLEO, BaBar and Belle collaborations on searches for lepton-number-violating B decays.
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.
The $B$-factories provide rich opportunities to search for new phenomena, in $B$, charm, and tau decays. Presented here is a selection of recent results from Belle and Babar.
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.
BaBar and Belle have recently revived the interest in charmonium spectroscopy, discovering many unexpected resonances. In this review, I'll focus mostly on the states found in B decays and double $\ccbar$. A better understanding of their production mechanism can help to discriminate among models, confirm tentative $J^{PC}$ assignments, and clarify the overall picture.
We present a short review on the recent progresses that have been made in meson spectroscopy. We discuss the experimental discoveries made at the BaBar and Belle experiments, as well as the possible interpretations of the new resonances.
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.
There are several exciting results for the hadronic B decays of Belle and BaBar recently. My report focuses on the ratios of branching fractions and $CP$ asymmetry for $B \to hh$ decays at Belle and BaBar where $h$ denotes $π$ or $K$. The observations of $B^+ \to K^+ \bar{K}{}^0$, $B^0 \to K^0 \bar{K}{}^0$ are published both by Belle and BaBar and shown here. We also report the observation of $B^+ \to ρ^+ K^0$ and search of $B^+ \to \bar{K}{}^{* 0} K^+$, $B^0 \to ρ^0 ρ^0$, $B^0 \to a_0^- π^+$ and $B^0 \to a_0^- K^+$ at BaBar. Finally, we will show the results of amplitude analysis of the decay…
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.
Belle and BaBar experiments at the KEKB and PEP-II B-factories provide also an excellent environment for spectroscopy studies. In this report we present recent results in the field of charmonium spectroscopy, focusing on new charmonium-like states observed in B decays, and on $J^{PC}=1^{--}$ resonances created in $e^+ e^-$ annihilation through the photon radiative return.
Recent results obtained using the data sample collected on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider and the Babar detector at the PEP-II asymmetric-energy e^+ e^- collider are discussed. Measurements of several charmless and charmed baryonic B decay branching fractions are reported, and some behaviors and mechanisms are discussed.
We report measurements of the CKM angles beta/phi_1 and alpha/phi_2 done by the BABAR and Belle experiments. Both experiments have collected large data samples, corresponding to a total of more than 1 billion of BBbar pairs, at the e^+e^- asymmetric-energy colliders PEP-II (SLAC) and KEK-B (KEK), respectively.
Recent results on the search for new physics at BaBar and Belle B-factories are presented. The search for a light Higgs boson produced in the decay of different Y resonances is shown. In addition, recent measurements aimed to discover invisible final states produced by new physics mechanisms beyond the standard model are presented.
The principal goal of the B-factories is to test the CKM paradigm through measurements that overconstrain the shape of the so-called Unitarity Triangle. The sides of the triangle are evaluated through absolute values of several elements of the CKM matrix, so achieving high precision on these is an important aspect of the B-factory program. Recent results from Belle and Babar are presented.
The BELLE detector has already accumulated e^+ e^- collision data at the KEKB-collider corresponding to 600 fb^-1. BaBar has accumulated data of approximately 390 fb^-1 at PEP-II. Both are running on asymmetric energy e^+ e^- colliders at the Upsilon(4S) energy. The paper selects important results from both experiments with the emphasis on CP violation in B meson decays and its implications for the Unitarity Triangle.
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.
Evidence from the \babar, Belle and CDF experiments for the phenomenon of \dzdzb\ oscillations is reviewed. A summary is made of the current understanding of the parameters defining the mixing of mass eigenstates that give rise to the oscillations. Results of searches for CP violation induced by mixing, are given, and estimates for the precision of measurements that can be expected in future experiments are made.
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.
I will review the latest developments in determining the CP-violating phases of the CKM matrix elements from measurements by the BaBar and BELLE experiments at the high-luminosity B factories (PEP-II and KEKB). The emphasis will be on the angle gamma/phi_3 of the Unitarity Triangle, which is the relative phase arg(-V_ud V_ub^*/V_cd V_cb^*), or the CP-violating phase of the b to u transition in the commonly used Wolfenstein convention.
We report on measurements of branching fractions for several hadronic tau decays to final states with kaons, which can be used to determine the strange quark mass and the element |V_us| of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are obtained from data collected with the BaBar and Belle detectors at the PEP-II and KEKB asymmetric-energy e+e- colliders at SLAC and KEK, respectively, both operating at center-of-mass energies near the Y(4S) resonance.
Spectroscopy results for Belle and BaBar are reported. A particular focus is put on new results of the X(3872) state with its radiative decays to $J$/$ψ$$γ$ and $ψ'$$γ$, its decay into $J$/$ψ$3$π$ and the search for production in radiative Upsilon decays. Another focus is $L$=2 mesons, in particlar a possible $D$-wave assignment to the X(3872) and the confirmation of an Upsilon $D$-wave state.
A brief review of experimental results on charmonium and charmonium-like hadron spectroscopy at B-factories is presented. A special focus is put on recent results of eta_c and eta_c(2S) study, X(3872) radiative decays, omega J/psi final state study and search for charmonium production in radiative Upsilon 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.…
A summary of the results of several recent studies of charm mixing is presented. A number of different methods were used, including the measurement of lifetime ratios for final states of different CP, time dependence of wrong-sign hadronic decays, fits to time-dependent Dalitz plots, and searches for wrong-sign semi-leptonic decays. Taken together, they suggest mixing is of order 1%. The status of searches for indirect CP violation is also reported.
Recent results from BaBar and Belle experiments on $B \bar B$ mixing and $\sin 2ϕ_1$ are presented. Accuracy of $Δm_d$ measurements has reached 1.2%. Higher order effects within the Standard Model or possible new physics effect that might appear in the $B \bar B$ mixing through non-zero $ΔΓ/Γ$, CP violation, or $CPT$ violation have been explored. The BaBar and Belle results on $\sin 2ϕ_1$ from the $b \to c \bar{c} s$ modes are in good agreement with each other and a combined result with an accuracy of 8% is in good agreement with a global CKM fit. A simple average of the $\sin 2ϕ_1$ values tha…
After nine years of operation the BABAR experiment at the B factory PEPII (Standford Linear Accelerator Center) stopped data taking in April 2008. The last three month of data taking were devoted to e+e- collisions at center of mass energies of the Upsilon(2S), Upsilon(3S) and to an energy scan above the Upsilon(4S). Besides the observation of the bottomonium ground state eta_b, the center of mass energy dependent e+e- -> b bbar cross section was measured in the energy range from 10.54 to 11.20 GeV. BELLE observed an enhancement in the production cross section for e+e- -> Upsilon(nS) pi+ pi- -…
A combined fit is performed to the BaBar and Belle measurements of the $\EE \to ϕπ^+ π^-$ and $ϕ\fzero$ cross sections for center-of-mass energy between threshold and 3.0 GeV. The resonance parameters of the $ϕ(1680)$ and Y(2175) are determined. The mass is $(1681^{+10}_{-12})$ MeV/$c^2$ and the width is $(221^{+34}_{-24})$ MeV/$c^2$ for the $ϕ(1680)$, and the mass is $(2117^{+59}_{-49})$ MeV/$c^2$ and the width is $(164^{+69}_{-80})$ MeV/$c^2$ for the Y(2175). These information will shed light on the understanding of the nature of the excited $ϕ$ and $Y$ states observed in $\EE$ annihilation.
We report recent results on CP violation measurements from the two B-factory experiments, Belle and BaBar.
A brief report of some recent experimental developments concerning the $X$, $Y$ and $Z$ charmoniumlike mesons states and other puzzling states from the BaBar, Belle, BESIII and CDF experiments is presented.
We present results of a new analysis campaign, which combines the final data samples collected by the B factory experiments BABAR and Belle in single physics analyses to achieve a unique sensitivity in time-dependent \CP\ violation measurements. The data samples contain $(471 \pm 3) \times 10^6 ~B \bar B$ pairs recorded by the BABAR detector and $(772 \pm 11) \times 10^6 ~ B \bar B$ pairs recorded by the Belle detector in $e^+e^-$ collisions at the center-of-mass energies corresponding to the mass of the $Υ(4S)$ resonance at the asymmetric-energy $B$ factories PEP-II at SLAC and KEKB at KEK, r…
Recent results in the field of spectroscopy from the BABAR experiment are reported, with particular attention to the new states observed in ISR and $γγ$ interactions using the full BABAR data sample. We confirm the states Y(4260) and Y(4360) with higher precision and for the first time the state Y(4660) is observed. We do not confirm the Y(4008) state reported by Belle. In addition, the analysis of the invariant mass of the $J/ψω$ system produced in $γγ$ interactions is presented in confirmation of the Belle observation of the X(3915) in this process.
We report the recent measurements of $B^0\to J/ψπ^0$ and other CP violation modes based on the data collected by the Belle experiment at the KEKB collider. The CP asymmetry parameters for the decay $B^0\to J/ψπ^0$ have previously been measured by BaBar and Belle experiments, but the results of mixing induced CP asymmetry $[S=-η_f\sin(2ϕ_1)]$ were not in good agreement with each other. Furthermore, the BaBar result lies outside the physically allowed region. Previous Belle measurements were based on $535\times10^6$ $B\bar{B}$ pairs. We updated the measurements using the final Belle data set of …
The BaBar experiment has discovered a narrow state, denoted as D*_{sJ}(2317)+, near 2.32 GeV/c^2 in the D+s pi^0 invariant mass distribution from inclusive $e^{+}e^{-}$ interactions at center-of-mass energies near 10.6 GeV. The same experiment has hinted the presence of a second new state near 2.46 GeV/c^2 in the D+_s pi^0 gamma mass spectrum. These discoveries have triggered CLEO and Belle experiments in their own search for new states coupled to D+_s meson. They have confirmed the existence of the D*_{sJ}(2317)^+ state and established the evidence for the second state denoted as D*_{sJ}(2458…
We confront predictions for hybrid charmonium and other gluonic excitations in the charm region with recently observed structures in the mass range above 3 GeV. The Y(4260), if resonant, is found to agree with expectations for hybrid charmonium. The possibility that other gluonic excitations may be influencing the data in this region is discussed.
A combined fit is performed to the BaBar and Belle measurements of the e+e- to pi+pi-psi(2S) cross sections for center-of-mass energy between threshold and 5.5 GeV. The resonant parameters of the Y(4360) and Y(4660) are determined. The mass is 4355^{+9}_{-10}\pm 9 MeV/c^2 and the width is 103^{+17}_{-15}\pm 11 MeV/c^2 for the Y(4360), and the mass is 4661^{+9}_{-8}\pm 6 MeV/c^2 and the width is 42^{+17}_{-12}\pm 6 MeV/c^2 for the Y(4660). The production of the Y(4260) in pi+pi-psi(2S) mode is found to be at 2σlevel, and B(Y(4260) to pi+pi-psi(2S))Γ_{e+e-} is found to be less than 4.3 eV/c^2 at…
The BaBar and Belle experiments have recently presented evidence for D-Dbar mixing. We explain the following points: (i) The measurements imply width difference $y \sim 0.01$. In the limit of small CP violation, the CP-odd state is longer-lived; (ii) $y\sim0.01$ is consistent with the Standard Model. It suggests that SU(3) breaking from phase space effects is likely to play a major role; (iii) There is no evidence for either large mass splitting or CP violation. Consequently, there is no hint for new physics; (iv) The stronger bounds on the mass splitting and on CP violation imply that, if squ…
Several charmonium-like states above $D\bar{D}$ threshold have been discovered at the Belle and BABAR B-factories. Some of these states are produced via Initial State Radiation (e.g. Y(4260) and Y(4350)), and some are observed in B-meson decays (e.g. X(3872), and Y(3940)). The Belle observations of the enhancements in the $ψ(2S)π^-$ and $χ_{c1}π^-$, i.e. the Z(4430)-, Z_1(4050)-, and Z_2(4250)-, have generated a great deal of interest, because such states must have minimum quark content $(c\bar{c}d\bar{u})$, i.e. these are candidate four-quark state. The BABAR Collaboration does not confirm th…
Results by the BaBar and Belle experiments of the measurements $\sin 2α$, $\sin 2β$ and $\sin (2β+ γ)$ along with the CKM matrix elements $V_{cb}$ and $V_{ub}$ are presented. The BaBar and Belle experiments $b \to sc\bar{c}$ results for $\sin 2β$ are in good agreement with each other, comfortably establishing CP violation within B decays. However, there is a 3.5 standard deviation between this result and $\sin 2β$ measured by the Belle experiment using $B^0 \to ϕK^0_S$ decays. Belle also find evidence for CP violation through time dependent measurements of the decay $B^0 \to π^+ π^-$, whilst a…
Recently, several charmonium-like states above $D\bar{D}$ threshold have been discovered at the BELLE and BABAR $B$-factories. Some of these states are produced via Initial State Radiation ({\it e.g.} Y(4260) and Y(4350)) and some are observed in $B$ meson decays ({\it{e.g.}} X(3872), Y(3940)). The BELLE observation of the enhancement in the $ψ(2S)π^-$, {\it {i.e.}} the $Z(4430)^-$ state, has generated a great deal of interest, because such a state must have minimum quark content ($c\bar{c}d\bar{u}$), so that it would represent the unequivocal manifestation of a four-quark meson state. Here we…
We review recent results from the BABAR and Belle experiments on rare electroweak B-meson decays, with emphasis on those occurring through flavor changing neutral current interactions of the type b -> s l l. The recent results include measurements of the isospin asymmetry and lepton forward-backward asymmetry in B -> K* l+ l- decays from BABAR, a search for B -> pi l+ l- from Belle, and searches for B \to K(*) nu anti-nu from BABAR. We also briefly review the status of B0 -> l+ l- and B+ -> l+ nu searches.
We summarize recent results by the BABAR and Belle Collaborations on the search for CP violation and new physics beyond the Standard Model in several rare B meson decays. The measurements exploit the final BABAR and Belle Upsilon(4S) datasets, which consist of approximately 470 and 772 million BBbar pairs, respectively.
The BaBar and Belle collaborations have recently found evidence for mixing within the D meson system. We present some of the mixing search techniques used by BaBar and their status as of the beginning of the summer 2007. These have culminated in a measurement in the K decay final state of the D that is inconsistent with the no-mixing hypothesis with a significance of 3.9 standard deviations.
The pion-photon transition form factor (TFF) provides strong constraints on the pion distribution amplitude (DA). We perform an analysis of all existing data (CELLO, CLEO, BaBar, Belle) on the pion-photon TFF by means of light-cone pQCD approach in which we include the next-to-leading order correction to the valence-quark contribution and estimate the non-valence-quark contribution by a phenomenological model based on the TFF's limiting behavior at both $Q^2\to 0$ and $Q^2\to\infty$. At present, the pion DA is not definitely determined, it is helpful to have a pion DA model that can mimic all …
A state-of-the-art analysis of the pion-photon transition form factor is presented based on an improved theoretical calculation that includes the effect of a finite virtuality of the quasi-real photon in the method of light-cone sum rules. We carry out a detailed statistical analysis of the existing experimental data using this method and by employing pion distribution amplitudes with up to three Gegenbauer coefficients $a_2, a_4, a_6$. Allowing for an error range in the coefficient $a_6\approx 0$, the theoretical predictions for $γ^*γ\toπ^0$ obtained with nonlocal QCD sum rules are found to b…
We summarize recent results of baryonic B decays from Belle and BaBar. The results from Belle are based on 140 /fb and results from BaBar are based on 81 /fb of data collected at the Upsilon(4S) resonance at KEKB or PEPII respectively. We report the results of two- and three-body baryonic B decays as well as searches for pentaquarks. The three-body baryonic B decays display an enhancement in the low mass region, which is not in agreement with general phase space expectations.
The Belle II experiment is under construction at the KEK laboratory in Japan. Belle II will study e+e- collisions at or near the Upsilon(4S) resonance with the goal of collecting 50 ab-1 of data, which is a large increase over that recorded by the Belle and BaBar experiments. This data will provide a large sample of charm meson decays, and Belle II will have a very active charm physics program. Here we discuss some highlights of this program, focusing on measurements of mixing, CP violation, and leptonic decays.
We report the updated results of direct CP violation measurements from Belle and BaBar for the following modes: B -> h+h-/h+-pi^0, B -> eta(') h+- and B -> K+-pi+-pi-+, where h stands for a charged kaon or pion. The data used in these studies are up to 386 million BBbar pairs for Belle and 232 million BBbar pairs for BaBar. The current significant measurements include: Acp(B -> K+ pi-)=-0.108+/-0.016, Acp(B -> rho0(770) K+)=0.31+0.11-0.10, and Acp(B -> eta K+)=-0.33+/-0.12.
The photon spectrum in B->X_{s,d} γdecay, where X_s(d) is any strange (non-strange) hadronic state, is studied using data samples of $e^+e^- \rightarrow Υ(4S) \to B B-bar decays collected by the Babar and Belle experiments. Here I present the latest measurements of the branching fraction and spectral mo ments from B -> X_s gamma$ decays by Belle and the direct CP asymmetry of B->X_{s+d} gamma measured at Babar. The determination of |V_{td}/V_{ts}|^2$ i also presented.
The Belle II experiment is under construction at the KEK laboratory in Japan. Belle II will study e+e- collisions at or near the Upsilon(4S) resonance with the goal of collecting 50 ab-1 of data, which is a large increase over that recorded by the Belle and BaBar experiments. This data will provide a large sample of charm meson decays. In this report we present the expected sensitivity of Belle II for measuring time-dependent mixing and CP violation in the D0-D0bar system. We focus on measurements of D0-> K+ pi-, D0-> K+ pi- pi0, and D0-> K0_S pi+ pi- decays.
Today the B-factories BaBar and Belle have accumulated largest samples of tau-tau events and are competing to be called tau-factories. Among the problems to be tested and measurements to be done by BaBar and Belle are check of CP and CPT invariance in tau decays, measurement of strange and non-strange spectral functions, extraction of mass of strange quark and |V_us|, searches for lepton flavor violation processes. In this paper, the latest results in tau physics by these two experiments and measurements to be done within next few years are reviewed.
The new data on the $γ^*γ\to π^0$ transition form factor of the Belle Collaboration are analyzed in comparison with those of BaBar (including the older data of CELLO and CLEO) using an approach based on light-cone sum rules. Performing a 2-, and a 3-parametric fit to these data, we found that the Belle and the BaBar data have no overlap at the $1σ$ level. While the Belle data agree with our predictions, the Babar data are in conflict with them.
We report recent measurements of rare charmless B decays performed by BaBar. The results are based on the final BaBar dataset of 424 fb^{-1} collected at the PEP-II $B$-factory based at the SLAC National Accelerator Laboratory.
One of the most intriguing puzzles in hadron spectroscopy are the numerous charmonium-like states observed in the last decade, including charged states that are manifestly exotic. The $BABAR$ and Belle experiments have extensively studied those in B meson decays, initial state radiation processes and two photon reactions. We can question what we have understood after 11 year search in this field, and try to combine results to conclude on what these new unpredicted resonant states are, and how they can be accommodated in the theory. Big effort has been made from theoretical and experimental poi…
We present the results of a simulation study to perform the extraction of 2beta+gamma from B0->D+KsPi- decays through a time-dependent Dalitz analysis of BaBar data.
We present recent results on leptonic 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 searches for the B -> tau nu decay, based on two statistically independent data samples.
In this article we will review recent BABAR measurements of Unitarity Triangle angle beta in B meson decays to charm and charmonium.
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