Browsing by Author "Poireau, V."
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Item Amplitude Analysis and Measurement of the Time-Dependent CP Asymmetry of B⁰→K_S⁰K_S⁰K_S⁰ Decays(American Physical Society, 2012-03-27) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D. A.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We present the first results on the Dalitz-plot structure and improved measurements of the time-dependent CP-violation parameters of the process B⁰→K_S⁰K_S⁰K_S⁰ obtained using 468×10⁶ BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The Dalitz-plot structure is probed by a time-integrated amplitude analysis that does not distinguish between B⁰ and B̅⁰ decays. We measure the total inclusive branching fraction ℬ(B⁰→K_S⁰K_S⁰K_S⁰)=(6.19 ± 0.48 ± 0.15 ± 0.12)×10⁻⁶, where the first uncertainty is statistical, the second is systematic, and the third represents the Dalitz-plot signal model dependence. We also observe evidence for the intermediate resonant states ʄ₀(980), ʄ₀(1710), and ʄ₂(2010). Their respective product branching fractions are measured to be (2.70_{-1.19}^{+1.25} ± 0.36 ± 1.17)×10⁻⁶, (0.50_{-0.24}^{+0.46 ± 0.04 ± 0.10)×10⁻⁶, and (0.54_{-0.20}^{+0.21} ± 0.03 ± 0.52)×10⁻⁶. Additionally, we determine the mixing-induced CP-violation parameters to be S = -0.94_{-0.21}^{+0.24 ± 0.06 and C = -0.17 ± 0.18 ± 0.04, where the first uncertainty is statistical and the second is systematic. These values are in agreement with the standard model expectation. For the first time, we report evidence of CP violation in B⁰→K_S⁰K_S⁰K_S⁰ decays; CP conservation is excluded at 3.8 standard deviations including systematic uncertainties.Item Branching Fraction and Form-Factor Shape Measurements of Exclusive Charmless Semileptonic B Decays, and Determination of |V_{ub}|(American Physical Society, 2012-11-05) Lees, J. P.; Poireau, V.; Tisserand, V.; Tico, J. Garra; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 0000-0003-0867-2189 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We report the results of a study of the exclusive charmless semileptonic decays, B0→π -+ν, B+ → π0⁺ν, B +→ω +ν, B +→η +ν, and B +→η ′+ν (=e or μ) undertaken with approximately 462×106 BB̄ pairs collected at the Υ(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of q2, the square of the momentum transferred to the lepton-neutrino pair, for B0→π - +ν, B +→π0 +ν, B +→ω +ν, and B +→η +ν. From these distributions, we extract the form-factor shapes f +(q2) and the total branching fractions B(B0→π -+ν)=(1.45±0.04 stat±0.06 syst)×10 -4 (combined π - and π0 decay channels assuming isospin symmetry), B(B +→ω +ν)=(1.19±0.16 stat±0.09 syst)×10 -4 and B(B +→η +ν)=(0.38±0.05 stat±0.05 syst)×10 -4. We also measure B(B +→η ′+ν)=(0.24±0. 08 stat±0.03 syst)×10 -4. We obtain values for the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V ub| by direct comparison with three different QCD calculations in restricted q2 ranges of B→π +ν decays. From a simultaneous fit to the experimental data over the full q2 range and the FNAL/MILC lattice QCD predictions, we obtain |V ub|=(3.25±0.31)×10 -3, where the error is the combined experimental and theoretical uncertainty. © 2012 American Physical Society.Item Branching fraction of τ-→π-Ks0Ks0(π0)ν τ decays(American Physical Society, 2012-11-26) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We present a study of τ -→π -KS0KS0(π0) ν τ and τ -→K -KS0KS0(π0) ν τ decays using a data set of 430 million tau lepton pairs, corresponding to an integrated luminosity of 468 fb(-1), collected with the BABAR detector at the PEP-II asymmetric energy e(+)e(-) storage rings. We measure branching fractions of (2.31 +/- 0.04 +/- 0.08) x 10(-4) and (1.60 +/- 0.20 +/- 0.22) x 10(-5) for the τ -→π -KS0KS0ν τ and τ -→π -KS0KS0π0ν τ decays, respectively. We find no evidence for τ -→K -KS0KS0ν τ and τ -→K -KS0KS0π0ν τ decays and place upper limits on the branching fractions of 6.3 x 10(-7) and 4.0 x 10(-7) at the 90% confidence level.Item Cross Sections for the Reactions e⁺e⁻ → K⁺ K⁻ π⁺π⁻, K⁺ K⁻ π⁰π⁰, and K⁺ K⁻K⁺ K⁻ Measured Using Initial-State Radiation Events(Amer Physical Soc, 2012-07-26) Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 56366505900 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We study the processes e⁺e⁻ → K⁺ K⁻ π⁺π⁻γ, K⁺ K⁻ π⁰π⁰γ, and K⁺ K⁻ K⁺ K⁻ γ, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb⁻¹ of BABAR data. The invariant mass of the hadronic final state defines the e⁺e⁻ center-of-mass energy, so that the K⁺ K⁻ π⁺π⁻γ data can be compared with direct measurements of the e⁺e⁻ → K⁺ K⁻ π⁺π⁻ reaction. No direct measurements exist for the e⁺e⁻→ K ⁺K ⁻ π⁰π⁰ or e⁺e⁻ → K⁺ K⁻K⁺ K⁻ - reactions, and we present an update of our previous result based on a data sample that is twice as large. Studying the structure of these events, we find contributions from a number of intermediate states and extract their cross sections. In particular, we perform a more detailed study of the e⁺e⁻ → φ(1020)ππγ reaction and confirm the presence of the Y(2175) resonance in the φ(1020)f⁰(980) and K⁺ K⁻ f⁰ (980) modes. In the charmonium region, we observe the J/ψ in all three final states and in several intermediate states, as well as the ψ(2S) in some modes, and measure the corresponding products of branching fraction and electron width.Item Evidence for an excess of B̄ → D^(*)_τ⁻ ν̅_τ decays(Amer Physical Soc, 2012-09-06) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 56366505900 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.Based on the full BABAR data sample, we report improved measurements of the ratios R(D^( *) = ℬ(B̄→D^( *)τ -ν {̄τ}) / ℬ(B̄→D^( *)ℓe̅ν ̅ℓ), where ℓ is either e or μ. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D*) = 0.440 ± 0.058 ± 0.042 and R(D*) = 0.332 ± 0.024 ± 0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, our results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model.Item Measurement of Branching Fractions and Rate Asymmetries in the Rare Decays B → K^{(*)}ℓ⁺ℓ⁻(American Physical Society, 2012-08-24) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 0000-0003-0867-2189 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.In a sample of 471 x 106 BB̅ events collected with the BABAR detector at the PEP-II e⁺e⁻ collider we study the rare decays B → K^{(*)}ℓ⁺ℓ⁻, where ℓ⁺ℓ⁻ is either e⁺e⁻ or μ⁺μ⁻. We report results on partial branching fractions and isospin asymmetries in seven bins of dilepton mass-squared. We further present CP and lepton-flavor asymmetries for dilepton masses below and above the J/ψ resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.Item Measurement of the Semileptonic Branching Fraction of the B_s Meson(American Physical Society, 2012-01-03) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D. A.; Izen, Joseph M.; Lou, Xinchou; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BABAR detector in the center-of-mass energy region above the Υ(4S) resonance. We use the inclusive yield of mesons and the yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of center-of-mass energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be ℬ(B_s → ℓνX) = 9.5_{-2.0}^{+2.5}(stat)_{-1.9}^{+1.1}(syst)%, where ℓ indicates the average of e and μ.Item Measurement of ℬ(B → Χ_sγ), the B → Χ_sγ Photon Energy Spectrum, and the Direct CP Asymmetry in B → Χ_{s+d}γ Decays.(American Physical Society, 2012-12-28) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 0000-0003-0867-2189 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.The photon spectrum in B → X{s}γ decay, where X{s} is any strange hadronic state, is studied using a data sample of (382.8 ± 4.2) x 10⁶ e⁺e⁻ → Υ(4S) → BB̅ events collected by the BABAR experiment at the PEP-II collider. The spectrum is used to measure the branching fraction ℬ(B → X{s}γ) = (3. 21 ± 0.15 ± 0.29 ± 0.08) x 10⁻⁴ and the first, second, and third moments E{γ} = 2.267 ± 0. 019 ± 0.032 ± 0.003 GeV, <(E{γ}) -- )² = 0.0484 ± 0.0053 ± 0.0077 ± 0.0005 GeV², and <(E{γ}) -- )³ = -0.0048 ± 0.0011 ± 0.0011± 0.0004 GeV3, for the range E{γ} > 1.8 GeV, where E{γ} is the photon energy in the B-meson rest frame. Results are also presented for narrower E{γ} ranges. In addition, the direct CP asymmetry A{CP}(B → X{s+d}γ) is measured to be 0.057 ± 0.063. The spectrum itself is also unfolded to the B-meson rest frame; that is the frame in which theoretical predictions for its shape are made.Item Observation and Study of the Baryonic B-Meson Decays B→D^{(*)}pp̅ (π)(π)(American Physical Society, 2012-05-30) Del Amo Sanchez, P.; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We present results for B-meson decay modes involving a charm meson, protons, and pions using 455×10⁶ BB̄ pairs recorded by the BaBar detector at the SLAC PEP-II asymmetric-energy e⁺e⁻ collider. The branching fractions are measured for the following ten decays: B̅⁰→D⁰pp̄, B̅⁰→D*⁰pp̄, B̅⁰→D⁺pp̄π⁻, B̅⁰→D*⁺pp̄π⁻, B⁻→D⁰pp̄π⁻, B⁻→D*⁰ pp̄π⁻, B̅⁰→D⁰pp̄→D0pp̄π⁻π⁺, B̅⁰→D*⁰pp̄π⁻π⁺, B⁻→D*⁺pp̅π⁻, B⁻→D⁰pp̄π⁻, B⁻→D*⁰pp̄π⁻, B̅⁰→D⁰pp̄π⁻π⁺, B̅⁰→D*⁰pp̄π⁻π⁺, B⁻→D⁺pp̄π⁻π⁻, and B⁻→D*⁺pp̄π⁻π⁻. The four B⁻ and the two five-body B̅⁰ modes are observed for the first time. The four-body modes are enhanced compared to the three- and the five-body modes. In the three-body modes, the M(pp̄) and M(D^{(*)⁰}p) invariant-mass distributions show enhancements near threshold values. In the four-body mode B̅⁰→D⁺pp̄π⁻, the M(pπ⁻) distribution shows a narrow structure of unknown origin near 1.5 GeV/c². The distributions for the five-body modes, in contrast to the others, are similar to the expectations from uniform phase-space predictions.Item Observation of Time-Reversal Violation in the B⁰ Meson System(American Physical Society, 2012-11-19) Lees, J. P.; Poireau, V.; Tisserand, V.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B⁰ or B̄⁰), and J/ψK_L⁰ or cc̄K_S⁰ final states (referred to as B₊ or B₋), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B̅⁰ → B₋ and B₋ → B̅⁰, as a function of the time difference between the two B decays. Using 468 × 10⁶ BB̄ pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS_T⁺ = -1.37 ± 0.14(stat) ± 0.06(syst) and ΔS_T⁻ = 1.17 ± 0.18(stat) ± 0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.Item Precise Measurement of the e⁺e⁻ → π⁺π⁻ (γ) Cross Section with the Initial-State Radiation Method at BABAR(American Physical Society, 2012-08-28) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.A precise measurement of the cross section of the process e⁺e⁻ → π⁺π⁻ (γ) 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⁻ → μ⁺μ⁻ (γ) γ_{ISR}, which is found to agree with the next-to-leading-order QED prediction to within 1.1%. The cross section for the process e⁺e⁻ → π⁺π⁻ (γ) is obtained with a systematic uncertainty of 0.5% in the dominant ρ resonance region. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured π π cross section from threshold to 1.8 GeV is (514.1 ± 2.2(stat) ± 3.1(syst))×10⁻¹⁰.Item Precision Measurement of the B→X_sγ Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry A_{CP}(B→X_{s+d}γ)(American Physical Society, 2012-11-09) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B→X_sγ plus B→X_dγ, is studied using a data sample of (382.8 ± 4.2)×10⁶Υ(4S) →BB̄ decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction ℬ(B→X_sγ)=(3. 21 ± 0.33) ×10⁻⁴ for E_γ > 1.8 GeV and the direct CP asymmetry A_{CP} (B→X_{s+d}γ)=0. 057 ± 0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.Item Search for B̄→Λ_c⁺Xℓ⁻ν̅_ℓ decays in Events with a Fully Reconstructed B Meson(American Physical Society, 2012-01-12) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D. A.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We present a search for semileptonic B decays to the charmed baryon Λc+ based on 420fb -1 of data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e +e - storage rings. By fully reconstructing the recoiling B in a hadronic decay mode, we reduce non-B backgrounds and determine the flavor of the signal B. We statistically correct the flavor for the effect of the B0 mixing. We obtain a 90% confidence level upper limit of B(B̄→Λc+X -ν ̄)/B(B̄→Λc+X)<3.5%. © 2012 American Physical Society.Item Search for CP Violation in the Decay τ⁻ → π⁻ K_S⁰(0π⁰)ν_τ(American Physical Society, 2012-02-13) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D. A.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We report a search for CP violation in the decay τ⁻ → π⁻ K_S⁰ (0π⁰)ν_τ using a data set of 437×106 τ-lepton pairs, corresponding to an integrated luminosity of 476 fb⁻¹, collected with the BABAR detector at the PEP-II asymmetric-energy e⁺e⁻ storage rings. The CP-violating decay-rate asymmetry is determined to be (-0.36 ± 0.23 ± 0.11)% approximately 2.8 standard deviations from the standard model prediction of (0.36 ± 0.01)%.Item Search for Lepton-Number Violating Processes in B⁺ → h⁻ l⁺ l⁺ Decays(Amer Physical Soc, 2012-04-19) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 0000-0003-0867-2189 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We have searched for the lepton-number violating processes B +→h -- +- + with h -=K -/π - and - +=e +/μ +, using a sample of 471±3 million BB̄ events collected with the BABAR detector at the PEP-II e +e - collider at the SLAC National Accelerator Laboratory. We find no evidence for these decays and place 90%-confidence-level upper limits on their branching fractions B(B +→π -e +e +)<2.3×10 -8, B(B +→K -e +e +)<3.0×10 -8, B(B +→π -μ +μ +)<10. 7×10 -8, and B(B +→K -μ +μ +)<6.7×10 -8. © 2012 American Physical Society.Item Search for Resonances Decaying to η_c π+ π- in Two-Photon Interactions(American Physical Society, 2012-11-06) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 0000-0003-0867-2189 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We report a study of the process γγ→X→η cπ +π -, where X stands for one of the resonances χ c2(1P), η c(2S), X(3872), X(3915), or χ c2(2P). The analysis is performed with a data sample of 473.9fb -1 collected with the BABAR detector at the PEP-II asymmetric-energy electron-positron collider. We do not observe a significant signal for any channel, and calculate 90% confidence-level upper limits on the products of branching fractions and two-photon widths Γ X→γγB(X→η cπ +π -): 15.7eV for χ c2(1P), 133eV for η c(2S), 11.1eV for X(3872) (assuming it to be a spin-2 state), 16eV for X(3915) (assuming it to be a spin-2 state), and 18eV for χ c2(2P). We also report upper limits on the ratios of branching fractions B(η c(2S) →η cπ +π -)/B(η c(2S) →KS0K +π -)<10.0 and B(χ c2(1P) →η cπ +π -) /B(χ c2(1P)→KS0K +π -)<32.9 at the 90%confidence level. © 2012 American Physical Society.Item Search for the Decay D⁰ → γγ and Measurement of the Branching Fraction for D⁰ → π⁰π⁰(American Physical Society, 2012-05-18) Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We search for the rare decay of the D⁰ meson to two photons, D⁰ → γγ, and present a measurement of the branching fraction for a D⁰ meson decaying to two neutral pions, B(D⁰ → π⁰π⁰). The data sample analyzed corresponds to an integrated luminosity of 470.5 fb⁻¹ collected by the BABAR detector at the PEP-II asymmetric-energy e⁺e⁻ collider at SLAC. We place an upper limit on the branching fraction, B(D⁰ → γγ) < 2.2 × 10⁻⁶ at 90% confidence level. This limit improves on the existing limit by an order of magnitude. We also find B(D⁰→π⁰π⁰) = (8.4 ± 0.1 ± 0.4 ± 0.3) × 10⁻⁴.Item Search for the Decay Modes B^± → h^± τℓ(American Physical Society, 2012-07-16) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Milanes, D. A.; Palano, A.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We present a search for the lepton flavor violating decay modes B^± → h^± τ ℓ (h=K, π, ℓ = e, μ) using the BABAR data sample, which corresponds to 472 × 10⁶ BB̄ pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and ℓ candidates, we are able to fully determine the τ four-momentum. The resulting τ candidate mass is our main discriminant against combinatorial background. We see no evidence for B ^± → h^± τ ℓ decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10⁻⁵.Item Search for the Decay Modes D⁰ → e⁺e⁻, D⁰ → μ⁺μ⁻, and D⁰ → e^{±} μ^{∓}(Amer Physical Soc, 2012-08-01) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 0000-0003-0867-2189 (Lou, X); 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We present searches for the rare decay modes D0→e +e -, D0→μ +μ -, and D0→e ±μ ∓ in continuum e +e -→cc̄ events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468fb -1. These decays are highly Glashow-Iliopoulos-Maiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D0→μ +μ - channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman-Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D0→e +e -)<1. 7×10 -7, B(D0→μ +μ -) within 0.6, 8.1]×10 -7, and B(D0→e ±μ ∓)<3.3×10 -7. © 2012 American Physical Society.Item Search for the Z₁(4050)⁺ and Z₂(4250)⁺ States in B̅⁰→ χ_{c1}K⁻ π⁺ and B⁺ → χ_{c1}K_s⁰ π⁺(American Physical Society, 2012-03-16) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D. A.; Izen, Joseph M.; Lou, Xinchou; BaBar Collaboration; 250674117 (Izen, JM); 250674117 (Izen, JM); Lou, Xinchou; Izen, Joseph M.We search for the Z₁(4050)⁺ and Z₂(4250)⁺ states, reported by the Belle Collaboration, decaying to χ_{c1}π⁺ in the decays B̅⁰ → χ_{c1}K⁻ π⁺ and B⁺ → χ_{c1}K_S⁰ π⁺ where χ_{c1} → J/ψγ. The data were collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e⁺e⁻ collider operating at center-of-mass energy 10.58 GeV, and correspond to an integrated luminosity of 429 fb⁻¹. In this analysis, we model the background-subtracted, efficiency-corrected χ_{c1}π⁺ mass distribution using the Kπ mass distribution and the corresponding normalized Kπ Legendre-polynomial moments, and then test the need for the inclusion of resonant structures in the description of the χ_{c1}π⁺ mass distribution. No evidence is found for the Z₁(4050)⁺ and Z₂(4250)⁺ resonances, and 90% confidence level upper limits on the branching fractions are reported for the corresponding B-meson decay modes.