874 research outputs found
Evidence for the Baryonic Decay [bar over B][superscript 0] → D[superscript 0]Λ[bar over Λ]
No full textEvidence is presented for the baryonic B meson decay [bar over B][superscript 0] → D[superscript 0]Λ[bar over Λ] based on a data sample of 471 × 10[superscript 6] B[bar over B] pairs collected with the BABAR detector at the PEP-II asymmetric e[superscript +]e[superscript −] collider located at the SLAC National Accelerator Laboratory. The branching fraction is determined to be B([bar over B][superscript 0] → D[superscript 0]Λ[bar over Λ]) = (9.8[+2.9 over −2.6] ± 1.9) × 10[superscript −6], corresponding to a significance of 3.4 standard deviations including additive systematic uncertainties. A search for the related baryonic B meson decay [bar over B][superscript 0] → D[superscript 0]Σ[superscript 0][bar over Λ] with Σ[superscript 0] → Λγ is performed and an upper limit B([bar over B][superscript 0] → D[superscript 0]Σ[superscript 0][bar over Λ] + [bar over B][superscript 0] → D[superscript 0]Λ[bar over Σ][superscript 0]) < 3.1 × 10[superscript −5] is determined at 90% confidence level.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Evidence of B[superscript +]→τ[superscript +]ν decays with hadronic B tags
No full textWe present a search for the decay B[superscript +]→τ[superscript +]ν using 467.8×10[superscript 6] BB̅ pairs collected at the Υ(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. We select a sample of events with one completely reconstructed B[superscript -] in the hadronic decay mode (B[superscript -]→D[superscript (*)0]X[superscript -] and B[superscript -]→J/ψX[superscript -]). We examine the rest of the event to search for a B[superscript +]→τ[superscript +]ν decay. We identify the τ[superscript +] lepton in the following modes: τ[superscript +]→e[superscript +]νν̅ , τ[superscript +]→μ[superscript +]νν̅ , τ[superscript +]→π[superscript +]ν̅ and τ[superscript +]→ρ[superscript +]ν̅ . We find an excess of events with respect to the expected background, which excludes the null signal hypothesis at the level of 3.8σ (including systematic uncertainties) and corresponds to a branching fraction value of B(B[superscript +]→τ[superscript +]ν)=(1.83[+0.53 over -0.49](stat)±0.24(syst))×10[superscript -4].United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Search for b→u transitions in B±→[K∓π±π0]DK± decays
No full textWe present a study of the decays B[superscript ±]→DK[superscript ±] with D mesons reconstructed in the K[superscript +]π[superscript -]π[superscript 0] or K[superscript -]π[superscript +]π[superscript 0] final states, where D indicates a D[superscript 0] or a D̅[superscript 0] meson. Using a sample of 474×10[superscript 6] BB̅ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e[superscript +]e[superscript -] collider at SLAC, we measure the ratios R[superscript ±]≡Γ(B[superscript ±]→[K[superscript ∓]π[superscript ±π]0][subscript D]K[superscript ±])/Γ(B[superscript ±]→[K[superscript ±]π[superscript ∓]π[superscript 0]][subscript D]K[superscript ±]). We obtain R[superscript +]=(5[subscript -10][superscript +12](stat)-4[superscript +2](syst))×10[superscript -3] and R-=(12[subscript -10][[superscript +12](stat)[subscript -5][[superscript +3](syst))×10[superscript -3], from which we extract the upper limits at 90% probability: R[superscript +]<23×10[superscript -3] and R[superscript -]<29×10[superscript -3]. Using these measurements, we obtain an upper limit for the ratio r[subscript B] of the magnitudes of the b→u and b→c amplitudes r[subscript B]<0.13 at 90% probability.United States. Dept. of EnergyNational Science Foundation (U.S.)Natural Sciences and Engineering Research Council of Canada (NSERC)France. Commissariat à l'énergie atomiqueInstitut national de physique nucléaire et de physique des particulesGermany. Federal Ministry of Education and Research (BMBF)Deutsche Forschungsgemeinschaft (DFG)Istituto nazionale di fisica nucleare (INFN)Foundation for Fundamental Research on Matter (Netherlands)Research Council of NorwayMinistry of Education and Science of the Russian FederationSpain. Ministerio de Ciencia e Innovacio´n (MICINN)Science and Technology Facilities Council (Great Britain)Marie Curie International FellowshipAlfred P. Sloan Foundatio
Measurement of CP-violating asymmetries in B[superscript 0]→(ρπ)[superscript 0] decays using a time-dependent Dalitz plot analysis
No full textWe present results for a time-dependent Dalitz plot measurement of CP-violating asymmetries in the mode B[superscript 0]→π[superscript +]π[superscript -]π[superscript 0]. The data set is derived from the complete sample of 471×10[superscript 6] BB̅ meson pairs collected with the BABAR detector at the PEP-II asymmetric-energy e[superscript +]e[superscript -] collider at the SLAC National Accelerator Laboratory operating on the Υ(4S) resonance. We extract parameters describing the time-dependent B[superscript 0]→ρπ decay probabilities and CP asymmetries, including C=0.016±0.059±0.036, ΔC=0.234±0.061±0.048, S=0.053±0.081±0.034, and ΔS=0.054±0.082±0.039, where the uncertainties are statistical and systematic, respectively. We perform a two-dimensional likelihood scan of the direct CP-violation asymmetry parameters for B[superscript 0]→ρ[superscript ±]π[superscript ∓] decays, finding the change in χ[superscript 2] between the minimum and the origin (corresponding to no direct CP violation) to be Δχ[superscript 2]=6.42. We present information on the CP-violating parameter α in a likelihood scan that incorporates B[superscript ±]→ρπ measurements. To aid in the interpretation of our results, statistical robustness studies are performed to assess the reliability with which the true values of the physics parameters can be extracted. Significantly, these studies indicate that α cannot be reliably extracted with our current sample size, though the other physics parameters are robustly extracted.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Search for a light Higgs boson decaying to two gluons or ss̅ in the radiative decays of Υ(1S)
No full textWe search for the decay Υ(1S)→γA[superscript 0], A[superscript 0]→gg or ss̅ , where A[superscript 0] is the pseudoscalar light Higgs boson predicted by the next-to-minimal supersymmetric Standard Model. We use a sample of (17.6±0.3)×10[superscript 6] Υ(1S) mesons produced in the BABAR experiment via e[superscript +]e[superscript -]→Υ(2S)→π[superscript +]π[superscript -]Υ(1S). We see no significant signal and set 90%-confidence-level upper limits on the product branching fraction B(Υ(1S)→γA[superscript 0])·B(A[superscript 0]→gg or ss̅) ranging from 10[superscript -6] to 10[superscript -2] for A[superscript 0] masses in the range 0.5–9.0 GeV/c[superscript 2].United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Search for lepton-number violating B[superscript +] → X[superscript −]ℓ[superscript +]ℓ[superscript ′+] decays
No full textWe report on a search for eleven lepton-number violating processes B[superscript +] → X[superscript −]ℓ[superscript +]ℓ[superscript '+] with X[superscript −] = K[superscript −], π[superscript −], ρ[superscript −], K[superscript *−], or D[superscript −] and ℓ[superscript +]/ℓ[superscript '+] = e[superscript +] or μ[superscript +], using a sample of 471±3 million B[¯ over B] events collected with the BABAR detector at the PEP-II e[superscript +]e[superscript −] collider at the SLAC National Accelerator Laboratory. We find no evidence for any of these modes and place 90% confidence level upper limits on their branching fractions in the range (1.5–26)×10[superscript −7].United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Dalitz plot analysis of B-→D+π-π-
No full textWe report on a Dalitz plot analysis of B-→D+π-π- decays, based on a sample of about 383×106 Υ(4S)→BB̅ decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We find the total branching fraction of the three-body decay: B(B-→D+π-π-)=(1.08±0.03±0.05)×10-3. We observe the established D2*0 and confirm the existence of D0*0 in their decays to D+π-, where the D2*0 and D0*0 are the 2+ and 0+cu̅ P-wave states, respectively. We measure the masses and widths of D2*0 and D0*0 to be: mD2*0=(2460.4±1.2±1.2±1.9) MeV/c2, ΓD2*0=(41.8±2.5±2.1±2.0) MeV, mD0*0=(2297±8±5±19) MeV/c2, and ΓD0*0=(273±12±17±45) MeV. The stated errors reflect the statistical and systematic uncertainties, and the uncertainty related to the assumed composition of signal events and the theoretical model.Science and Technology Facilities Council, United KingdomMEC (Spain)Ministry of Education and Science of the Russian FederationNorges forskningsrådFOM of the NetherlandsIstituto Nazionale di Fisica Nucleare of ItalyDeutsche ForschungsgemeinschaftBundesministerium für Bildung und Forschung, GermanyInstitut National de Physique Nucleaire et Physique des Particules/CNRSCommissariat à l'Energie Atomique (France)Natural Sciences and Engineering Research Council of CanadaNational Science FoundationUnited States Department of Energ
Study of the reaction e[superscript +]e[superscript -]→J/ψπ[superscript +]π[superscript -] via initial-state radiation at BABAR
No full textWe study the process e[superscript +]e[superscript -]→J/ψπ[superscript +]π[superscript -] with initial-state-radiation events produced at the PEP-II asymmetric-energy collider. The data were recorded with the BABAR detector at center-of-mass energies 10.58 and 10.54 GeV, and correspond to an integrated luminosity of 454 fb[superscript -1]. We investigate the J/ψπ[superscript +]π[superscript -] mass distribution in the region from 3.5 to 5.5 GeV/c[superscript 2]. Below 3.7 GeV/c[superscript 2] the ψ(2S) signal dominates, and above 4 GeV/c[superscript 2] there is a significant peak due to the Y(4260). A fit to the data in the range 3.74–5.50 GeV/c[superscript 2] yields a mass value 4245±5(stat)±4(syst) MeV/c[superscript 2] and a width value 114[subscript -15][superscript +16](stat)±7(syst) MeV for this state. We do not confirm the report from the Belle Collaboration of a broad structure at 4.01 GeV/c[superscript 2]. In addition, we investigate the π[superscript +]π[superscript -] system which results from Y(4260) decay.United States. Dept. of EnergyNational Science Foundation (U.S.
Study of the decay B̅[superscript 0]→Λ[+ over c]p̅π[superscript +]π[superscript -] and its intermediate states
No full textWe study the decay B̅[superscript 0]→Λ[+ over c]p̅π[superscript +]π[superscript -], reconstructing the Λ[+ over c] baryon in the pK[superscript -]π[superscript +] mode, using a data sample of 467×10[superscript 6] BB̅ pairs collected with the BABAR detector at the PEP-II storage rings at SLAC. We measure branching fractions for decays with intermediate Σ[subscript c] baryons to be B[B̅[superscript 0]→Σ[subscript c](2455)[superscript ++]p̅π[superscript -]]=(21.3±1.0±1.0±5.5)×10[superscript -5], B[B̅[superscript 0]→Σ[subscript c](2520)[superscript ++]p̅ π[superscript -]]=(11.5±1.0±0.5±3.0)×10[superscript -5], B[B̅[superscript 0]→Σ[subscript c](2455)[superscript 0]p̅ π[superscript +]]=(9.1±0.7±0.4±2.4)×10[superscript -5], and B[B̅[superscript 0]→Σ[subscript c](2520)[superscript 0]p̅π[superscript +]]=(2.2±0.7±0.1±0.6)×10[superscript -5], where the uncertainties are statistical, systematic, and due to the uncertainty on the Λ[+ over c]→pK[superscript -]π[superscript +] branching fraction, respectively. For decays without Σ[subscript c](2455) or Σ[subscript c](2520) resonances, we measure B[B̅[superscript 0]→Λ[+ over c]p̅π[superscript +]π[superscript -]][subscript non-Σc]= (79±4±4±20)×10[superscript -5]. The total branching fraction is determined to be B[B̅[superscript 0]→Λ[+ over c]p̅π[superscript +]π[superscript -]][subscript total]=(123±5±7±32)×10[superscript -5]. We examine multibody mass combinations in the resonant three-particle Σ[subscript c]p̅ π final states and in the four-particle Λ[+ over c]p̅π[superscript +]π[superscript -] final state, and observe different characteristics for the p̅ π combination in neutral versus doubly charged Σ[subscript c] decays.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
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