37 research outputs found
Angular distributions in the decay B -> K*l(+)l(-)
We use a sample of 384 million BBbar events collected with the Babar detector at the PEP-II e+e- collider to study angular distributions in the rare decays B -> K* l+l-, where l+l- is either e+e- or mu+mu-. For low dilepton invariant masses, m(l+l-)3.2$ GeV/c^2, we measure AFB=0.76 (+0.52,-0.32) +/- 0.07 FL=0.71 (+0.20,-0.22) +/- 0.04.We are grateful for the excellent luminosity and machine
conditions provided by our PEP-II colleagues, and
for the substantial dedicated effort from the computing
organizations that support BABAR. The collaborating
institutions wish to thank SLAC for its support and
kind hospitality. This work is supported by DOE and
NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3
(France), BMBF and DFG (Germany), INFN (Italy),
FOM (The Netherlands), NFR (Norway), MES (Russia),
MEC (Spain), and STFC (United Kingdom). Individuals
have received support from the Marie Curie EIF (European
Union) and the A. P. Sloan Foundation.Peer reviewe
Observation of Tree-Level B Decays with ss̅ Production from Gluon Radiation
We report on our search for decays proceeding via a tree-level b→c quark transition in which a gluon radiates into an ss̅ pair. We present observations of the decays B-→Ds(*)+K-π- and B̅ 0→Ds+KS0π- and evidence for B-→Ds+K-K- and set upper limits on the branching fractions for B̅ 0→Ds*+KS0π- and B-→Ds*+K-K- using 383×10^6 Υ(4S)→BB̅ events collected by the BABAR detector at SLAC. We present evidence that the invariant mass distributions of Ds(*)+K- pairs from B-→Ds(*)+K-π- decays are inconsistent with the phase-space model, suggesting the presence of charm resonances lying below the Ds(*)+K- threshold
Study of the B-→J/ψK-π+π- decay and measurement of the B-→X(3872)K- branching fraction
We study the decay B-→J/ψK-π+π- using 117×106 BB̅ events collected at the Y(4S) resonance with the BABAR detector at the PEP-II e+e- asymmetric-energy storage ring. We measure the branching fractions B (B-→J/ψK-π+π-)=(116±7(stat.)±9(syst.))×10-5 and B (B-→X(3872)K-)× B (X(3872)→J/ψπ+π-)=(1.28±0.41)×10-5 and find the mass of the X(3872) to be 3873.4±1.4 MeV/c2. We search for the hc narrow state in the decay B-→hcK-, hc→J/ψπ+π- and for the decay B-→J/ψD0π-, with D0→K-π+. We set the 90% C.L. limits B(B-→hcK-)×B(hc→J/ψπ+π-)<3.4×10-6 and B(B-→J/ψD0π-)<5.2×10-5
Measurement of CP violation parameters with a Dalitz plot analysis of B-+/- -> D pi+pi(-)pi K-0(+/-)
We report the results of a CP violation analysis of the decay B-+/- -> D pi+pi(-)pi K-0(+/-), where D-pi(+)pi(-)pi(0) indicates a neutral D meson detected in the final state pi(+)pi(-)pi(0), excluding K-S(0)pi(0). The analysis makes use of 324x10(6) e(+)e -> B (B) over bar events recorded by the BABAR experiment at the PEP-II e(+)e(-) storage ring. Analyzing the pi(+)pi(-)pi(0) Dalitz plot distribution and the B-+/- -> D-pi(+)pi(-)pi K-0(+/-) branching fraction and decay rate asymmetry, we find the following one-standard-deviation constraints on the amplitude ratio and on the weak and strong phases: 0.06 pi(+)pi(-)pi(0) decay amplitude
Evidence for X(3872)->psi(2S)gamma in B-+/--> X(3872)K-+/- decays and a study of B -> cc gamma K
In a search for B -> cc gamma K decays with the BABAR detector, where cc> includes J/psi and psi(2S), and K includes K-+/-, K-S(0), and K-*(892), we find evidence for X(3872)-> J/psi gamma and X(3872)->psi(2S)gamma with 3.6 sigma and 3.5 sigma significance, respectively. We measure the product of branching fractions B(B-+/--> X(3872)K-+/-)xB(X(3872)-> J/psi gamma)=[2.8 +/- 0.8(stat)+/- 0.1(syst)]x10(-6) and B(B-+/--> X(3872)K-+/-)xB(X(3872)->psi(2S)gamma)=[9.5 +/- 2.7(stat)+/- 0.6(syst)]x10(-6)
Branching fraction and charge asymmetry measurements in B→J/ψππn decays
We study the decays B-0 -> J/psi pi(+)pi(-) and B+-> J/psi pi(+)pi(0), including intermediate resonances, using a sample of 382x10(6) B (B) over bar pairs recorded by the BABAR detector at the PEP-II e(+)e(-) B factory. We measure the branching fractions B(B-0 -> J/psi rho(0))=(2.7 +/- 0.3 +/- 0.2)x10(-5) and B(B+-> J/psi rho(+))=(5.0 +/- 0.7 +/- 0.3)x10(-5). We also set the following upper limits at the 90% confidence level: B(B-0 -> J/psi pi(+)pi(-) nonresonant) J/psi f(2)) J/psi pi(+)pi(0) nonresonant)< 7.3x10(-6). We measure the charge asymmetry in charged B decays to J/psi rho to be -0.11 +/- 0.12 +/- 0.08
Measurements of the Branching Fractions of , and
8 pages, 2 postscript figures, submitted to Lepton Photon 2007A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using 376 fb^{-1} of data collected at an e^+e^- center-of-mass energy around 10.58 GeV with the BaBar detector at the PEP-II storage rings. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (4-8) x 10^{-8} at 90% confidence level
Measurement of time dependent CP asymmetry parameters in B0 meson decays to ωKS0, η′K0, and π0KS0
We present measurements of the time-dependent CP-violation parameters S and C in the decays B0→ωKS0, B0→η′K0, reconstructed as η′KS0 and η′KL0, and B0→π0KS0. The data sample corresponds to the full BABAR dataset of 467×10^6 BB̅ pairs produced at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. The results are SωKS0=0.55-0.29+0.26±0.02, CωKS0=-0.52-0.20+0.22±0.03, Sη′K0=0.57±0.08±0.02, Cη′K0=-0.08±0.06±0.02, Sπ0KS0=0.55±0.20±0.03, and Cπ0KS0=0.13±0.13±0.03, where the first errors are statistical and the second systematic. These results are consistent with our previous measurements and the world average of sin2β measured in B0→J/ψKS0
Measurement of the B→Xsγ branching fraction and photon energy spectrum using the recoil method
We present a measurement of the branching fraction and photon-energy spectrum for the decay B→Xsγ using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210 fb-1, from which approximately 680 000 BB̅ events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high-energy photon is identified. We measure B(B→Xsγ)=(3.66±0.85stat±0.60syst)×10-4 for photon energies Eγ above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters mb and μπ2. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented
Measurement of the hadronic form factor in D0→K-e+νe decays
The shape of the hadronic form factor f(+)(q(2)) in the decay D-0 -> K(-)e(+)nu(e) has been measured in a model independent analysis and compared with theoretical calculations. We use 75 fb(-1) of data recorded by the BABAR detector at the PEP-II electron-positron collider. The corresponding decay branching fraction, relative to the decay D-0 -> K-pi(+), has also been measured to be R-D=B(D-0 -> K(-)e(+)nu(e)(gamma))/B(D-0 -> K-pi(+)(gamma))=0.927 +/- 0.007 +/- 0.012. From these results, and using the present world average value for B(D-0 -> K-pi(+)), the normalization of the form factor at q(2)=0 is determined to be f(+)(0)=0.727 +/- 0.007 +/- 0.005 +/- 0.007 where the uncertainties are statistical, systematic, and from external inputs, respectively