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 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.
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.
Since 1999, the B-factories collaborations BaBar and Belle have accumulated and studied large samples of tau lepton pairs. We summarize in the following the most interesting recent results.
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.
Recent measurements of hadronic branching fractions of D and Ds mesons, performed by the BaBar and Belle experiments at the asymmetric e+e- B factories colliders PEP II and KEKB, are reviewed.
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.
On behalf of the Babar and Belle collaborations, we report on the measurement of the angle gamma and on the sum of angles 2 beta+gamma of the Unitarity Triangle.
Since 1999, the B-factories collaborations BABAR and Belle have accumulated and studied large samples of tau lepton pairs. The experimental results on Lepton Universality checks and Lepton Flavour Violation searches are reported.
We will present a review of the most interesting results on rare B decays from the B Factories, based on the data collected by the BaBar and Belle detectors at asymmetric $e^+ e^-$ colliders at the center of mass energy of the $Υ(4S)$ resonance.
We review recent measurements of leptonic $D_s$-meson decays performed by Belle and BaBar collaborations. Described measurements enable experimental extraction of the $D_s$-meson decay constant which can be compared with lattice QCD calculations.
Both the B-factories BaBar and Belle have ended data-taking and have mostly completed the data analysis aimed at searching Lepton Flavor Violation in Tau decays. No evidence of LFV in tau decays has been found yet. We review in the following the experimental upper limits that have been set.
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.
In this talk, a wide range of recently published results on rare B decays from BABAR and Belle are covered. The decays of B->XsGamma, B->K(*)l+l-, and lepton-number violation in B decays are measured for new physics searches.
The prospects for measuring the angle gamma with present day B factories are examined. A number of approaches are discussed with reference to recent preliminary measurements based on a data sample of approximately 88 million \BB pairs collected by the BaBar detector at the PEP-II asymmetric B Factory at SLAC.
BABAR and Belle measurements of branching fractions, rate asymmetries and angular observables in the decay modes B \to K(*)l+l- are reviewed and new results from CDF on B \to K(*)μ+μ- branching fractions and angular observables are discussed. A first search for B+ \to K+τ+τ- is presented.
We report measurements of hadronic final states produced in $e^+e^-$ annihilations from the BaBar and Belle experiments. In particular, we present cross sections measured in several different processes, including two-photon physics, Initial-State Radiation, and exclusive hadron productions at center-of-mass energies near 10.58 GeV. Results are compared with theoretical predictions.
Radiative and leptonic decays of B-mesons represent an excellent laboratory for the search for New Physics. I present here recent results on radiative and leptonic decays from the Belle and BABAR collaborations.
In this article, I review the most recent results in radiative penguin decays from the B factories Belle and Babar. Most notably, I will talk about the recent new observations in the decays B -> (rho/omega) gamma, a new analysis technique in b -> s gamma, and first measurements of radiative penguin decays in the B_s meson system. Finally, I will summarize the current status and future prospects of radiative penguin B physics at the B factories.
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.
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 report measurements of time-dependent CP asymmetries related to the CKM angle $β/ϕ_1$, using decays of neutral B mesons to charmonium, open charm and in $b\to s$ loop processes. A preliminary measurement of time-dependent CP asymmetries in $B^0\to ρ^0(770) K^0_S$ decays from the BaBar experiment is given here.
We present a short review of the measurements of the CKM angle gamma performed by the babar experiment. We focus on methods using charged B decays, which give a direct access to gamma and provide the best constraints so far.
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 the proceedings of the lectures given at the 2008 Helmholtz International Summer School Heavy Quark Physics at the Bogoliubov Laboratory of Theoretical Physics in Dubna. In two lectures we present recent results from the existing $B$-factories experiments, Belle and BaBar. The discussed topics include short phenomenological motivation, experimental methods and results on $B$ meson oscillations, selected rare $B$ meson decays (leptonic, $b\to sγ$ and $b\to s\ell^+\ell^-$), mixing and CP violation in the system of $D^0$ mesons, and leptonic decays of $D_s$ mesons.
The recent measurements of the CKM angle gamma by the BABAR experiment are reported. The analyses have been performed using the complete sample of 468 million BBbar pairs collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B factory during the years 1999-2007.
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.
The B factories provide a unique playground for studying the properties of conventional and exotic charmonium states. We present recent results in initial state radiation and two-photon fusion, obtained using the full data set collected by the BaBar experiment. Amongst BaBar 's harvest presented in this talk, the determination of the quantum numbers of the X(3915) resonance, a body of concording evidence pointing to JPC = 1++ for the X(3872), and updates on the family of the Y resonance to the full integrated luminosity.
BABAR results are presented for B -> Xs gamma decays, including branching fraction and photon spectrum measurements from both a fully inclusive analysis and a semi-inclusive analysis that reconstructs 38 distinct final states for Xs.
Since the discovery of the X(3872) in 2003 the B-factory experiments BaBar and Belle have been driving forces in the spectroscopy of new charmonium-like states. In this article the latest results on the decays X(3872) -> D0 D*0bar and X(3872) -> psi gamma, where psi stands for J/psi or psi(2S), are presented and analyses of Z(4430)+ -> psi pi+ and Z(4050/4250)+ -> chi_c1 pi+ are discussed.
Electro-weak penguin and leptonic decays provide an indirect probe for physics beyond the Standard Model and contribute to the determination of Standard Model parameters. Copious quantities of B mesons produced at the B-Factories permit precision measurements of the electro-weak penguin decays and searches for leptonic decays. We review the current experimental status of b -> s(d) gamma, B^0 -> D^{*0} gamma, b -> s l^+ l^- and finally B->tau nu decays at BaBar.
We report on our recent measurements of the Cabibbo-Kobayashi-Maskawa CP-violating phase gamma and of related CP-asymmetries and branching fraction ratios. The measurements have been performed on samples of up to 465 million BBbar pairs collected by the BaBar detector at the SLAC PEP-II asymmetric-energy B factory in the years 1999-2007.
We report on recent measurements, from the BaBar and Belle experiments, of B-meson decays to purely hadronic final states that do not contain charm. The studies are based on large samples of BBbar pairs collected at the Upsilon(4S) or B_s(*)B_s(*) pairs collected at the Upsilon(5S) by the BaBar and Belle detectors at the asymmetric energy e+e- colliders at SLAC and KEK-B, respectively. This paper includes the following results: measurements of branching fractions and charge asymmetries of B meson decays to eta' rho, eta' f0, and eta' K*, where the K* stands for a vector, tensor, or scalar stra…
The most recent determinations of the CKM angle gamma/phi3 by the BABAR Collaboration, using time-integrated observables measured in charged B --> D(*)K(*) decays, are presented.The measurements have been performed on the full sample of 468 million BBbar pairs collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B factory in the years 1999-2007.
We present the combination of the CKM angle gamma measurements performed by the BaBar experiment at the PEP-II e+e- collider at SLAC National Laboratory. The analysis supersedes previous results obtained by collaboration and gives gamma=69+17-16 degrees modulo 180 degrees. The results are inconsistent with the absence of CP violation at a significance of 5.9 standard deviations
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.
We perform a measurement of the tau -> l gamma nu anti-nu (l = e, mu) branching fractions for a minimum photon energy of 10 MeV in the tau rest frame, using 431fb^-1 of e^+e^- collisions collected at the center-of-mass energy of the Upsilon(4S) resonance with the BaBar detector at the PEP-II storage rings. We find B(tau -> mu gamma nu anti-nu ) = (3.69pm0.03pm0.10)x10^-3, and B(tau -> e gamma nu anti-nu ) = (1.847pm0.015pm0.052)x10^-2, where the first quoted error is statistical, and the second is systematic. These results are substantially more precise than previous measurements.
A sample of 23 million B B-bar events collected with the BABAR detector at the PEP-II collider is used in a search for direct CP violation in charmless two-body B decays, quasi two-body B decays, and the radiative penguin decays B to K* gamma. No evidence for direct CP violation is found in the considered modes and 90% confidence level limits are reported. We also present a limit on the branching fraction of the decay B0 to gamma gamma.
The time-dependent CP asymmetries in fully reconstructed B0 --> D(*)pi/rho decays (new preliminary result), and in partially reconstructed B0 --> D(*)pi decays, are measured with the BaBar detector at the PEP-II asymmetric B factory at SLAC, using 232 million Y(4S) -> BB decays. We combine the above results and, using other measurements and theoretical assumptions, we interpret them in terms of the angles of the unitarity triangle describing the Cabibbo-Kobayashi-Maskawa matrix. We find |sin(2beta+gamma)|>0.64(0.42) at 68%(90%) confidence level using a frequentistic approach and |2beta+gamma|=…
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…
Recent BaBar results on rare B decays involving flavour-changing neutral currents or purely leptonic final states are presented. New measurements of the CP asymmetries in B -> K* gamma, B -> K*2(1430) gamma, and b -> s gamma are reported, as well as a new measurement of the B -> K* gamma branching fraction. Also reported are updated limits on B -> mu nu and recent measurements of B -> K* l+ l- and b -> s l+ l-. The data sample comprises 123 10^6 Y4S -> B Bbar decays collected with the BaBar detector at the PEP-II e+e- storage ring.
Some recent $τ$-physics results are presented from the BaBar and Belle experiments at the SLAC and KEK B factories, which produce copious numbers of $τ$-lepton pairs. Measurements of the tau mass and lifetime allow to test lepton universality and CPT invariance, while searches for lepton-flavour violation in tau decays are powerful ways to look for physics beyond the Standard Model. In semihadronic, non-strange tau decays, the vector hadronic final state is particularly important in helping determine the hadronic corrections to the anomalous magnetic moment of the muon, while studies of strang…
We present recent measurements of the CKM angles alpha and gamma using data collected by the BaBar detector at the PEP-II asymmetric-energy e+ e- collider at the Stanford Linear Accelerator Center. In addition to constraints on alpha from the decays B0 -> pi+ pi-, B0 -> rho+ pi- and B0 -> rho+ rho-, we also report the first measurement of time-dependent CP asymmetries in the decay B0 -> a1+(1260) pi-. We present measurements of gamma in B+ -> D(*)0 K+ decays using a Dalitz analysis in the modes D^0 -> Ks pi+ pi- and D^0 -> pi+ pi- pi0.
We present a study for the measurement of of radiative decays, tau -> l gamma nu nu, l=e, mu, and tau -> pi gamma nu using 500 fb-1 of electron-positron annihilations recorded by the BaBar detector at the PEP-II asymmetric B-factory.
A precise measurement of the cross section of the process e+ e- to pi+ pi- (gamma) from threshold to an energy of 3 GeV is obtained with the initial state radiation (ISR) method using 232 fb^-1 of data collected with the BABAR detector at e+ e- center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e+ e- to mu+ mu- gamma (gamma). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the pi pi cross section measured from threshold to 1.8 GeV is (514.1 +-2.2(stat} +-3.1(syst}) x 10^{-10}.
We perform a measurement of the branching fractions for tau -> l gamma nu anti-nu (l= e, mu) decays for a minimum photon energy of 10 MeV in the tau rest frame using 430 fb^-1 of e^+ e^- collisions collected at the center-of-mass energy of the Upsilon(4S) resonance around 10.58GeV with the BaBar detector at the PEP-II storage rings. We find B(tau -> mu gamma nu nu) = (3.69pm0.03pm0.10)x10^-3 and B(tau -> e gamma nu anti-nu) = (1.847pm0.015pm0.052)x10^-2 where the first quoted error is statistical and the second is systematic. These results represent a substantial improvement with respect to ex…
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.
A search for the Z(3930) resonance in gamma gamma production of the DDbar system has been performed using a data sample corresponding to an integrated luminosity of 384 fb^-1 recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DDbar invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8 sigma. We determine mass and width values of (3926.7 +- 2.7 +- 1.1) MeV/c^2 and (21.3 +- 6.8 +- 3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C-…
We present an update on total and partial branching fractions and on CP asymmetries in the semi-inclusive decay B -> Xs l+l-. Further, we summarize our results on branching fractions and CP asymmetries for semi-inclusive and fully-inclusive B -> Xs gamma decays. We present the first result on the CP asymmetry difference of charged and neutral B -> Xs gamma$ decays yielding the first constraint on the ratio of Wilson coefficients Im (C8/C7).
The present experimental status of searches for lepton flavor violating decays of the $τ$ lepton to a lighter mass lepton and a photon or a pseudoscalar meson is presented. The results obtained are from $e^+e^-$ annihilation data collected at a center-of-mass energy near 10.58 GeV by the \babar and the Belle detectors. In order to benefit from larger available datasets, the first $\babar-$Belle combinations of upper limits on the branching fractions of lepton flavor violating $τ$-decays are obtained.
I review the latest results on exotic, lepton flavor violating (LFV) and lepton number violating (LNV) decays of the B, D mesons and the tau leptons, obtained at the two B-factory experiments, Belle and BaBar. Where appropriate, results from other experiments are also described.
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 present measurements of the gamma gamma* --> pi0 transition form factor for the momentum transfer range Q^2=4-40 GeV^2 and the gamma gamma* --> eta_c transition form factor for the range Q^2=2-50 GeV^2. The results of the measurement of the eta_c mass, total and two-photon widths are also presented.
We present the recent BaBar searches for the leptonic decay B+ --> tau+ nu and for the rare decay B --> K(*) nu nubar, using a data sample of about 470 x 10^6 BB pairs. Both searches use a technique in which one B meson is hadronically reconstructed before searching for evidence of the signal decay in the rest of the event. BaBar measures B(B+ --> tau+ nu) = (1.83 ^{+0.53}_{-0.49} +/- 0.24) x 10^{-4}, and preliminary upper limits at 90% confidence level of B(B --> K nu nubar) < 3.2 x 10^{-5} and B(B --> K* nu nubar) < 7.9 x 10^{-5}. We also discuss the expected observations and precision impro…
We report recent results in the search for the rare B meson decays B-->rho gamma and B0-->pi0 pi0. These results are based on 56.4 1/fb collected by the BaBar Collaboration at the SLAC PEP-II e+e- B Factory. We set new 90% confidence level upper limits BR(B0 --> rho0 gamma) < 1.5 x 10^-6, BR(B+ --> rho+ gamma) < 2.8 x 10^-6, and BR(B0 --> pi0 pi0) < 3.4 x 10^-6.
A precise measurement of the cross section for the process e+e- --> K+K-(gamma) from threshold to an energy of 5 GeV is obtained with the initial-state radiation (ISR) method using 232 fb^{-1} of data collected with the BaBar detector at e+e- center-of-mass energies near 10.6 GeV. The measurement uses the effective ISR luminosity determined from the e+e- --> mu+mu-(gamma)gamma_ISR process with the same data set. The corresponding lowest-order contribution to the hadronic vacuum polarization term in the muon magnetic anomaly is found to be a_mu^{KK, LO}=(22.93 +- 0.18_{stat} +- 0.22_{syst}) * 1…
