Browsing by Author "Milanes, D. A."
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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 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 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 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 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.Item Study of B̅ → X_u ℓν̅ decays in BB̅ events tagged by a fully reconstructed B-meson decay and determination of |V_{ub}|(American Physical Society, 2012-08-07) Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D. A.; 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 measurements of partial branching fractions for inclusive charmless semileptonic B decays B̄→X ulν̄ and the determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V ub|. The analysis is based on a sample of 467×106 Υ(4S)→BB̄ decays recorded with the BABAR detector at the PEP-II e +e - storage rings. We select events in which the decay of one of the B mesons is fully reconstructed and an electron or a muon signals the semileptonic decay of the other B meson. We measure partial branching fractions ΔB in several restricted regions of phase space and determine the CKM element |V ub| based on different QCD predictions. For decays with a charged lepton momentum pl*>1.0GeV in the B meson rest frame, we obtain ΔB=(1.80±0.13 stat±0.15 sys±0.02 theo)×10 -3 from a fit to the two-dimensional M X-q2 distribution. Here, M X refers to the invariant mass of the final state hadron X and q2 is the invariant mass squared of the charged lepton and neutrino. From this measurement we extract |V ub|=(4.33±0.24 exp±0.15 theo) ×10 -3 as the arithmetic average of four results obtained from four different QCD predictions of the partial rate. We separately determine partial branching fractions for B ̄0 and B - decays and derive a limit on the isospin breaking in B̄→X ulν̄ decays. .Item Study of CP Violation in Dalitz-Plot Analyses of B⁰→K⁺K⁻K_S⁰, B⁺→K⁺K⁻K⁺, and B⁺→K_S⁰ K_S⁰K⁺(American Physical Society, 2012-06-22) 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 perform amplitude analyses of the decays B⁰→K⁺K⁻K_S⁰, B⁺→K⁺K⁻K⁺, and B⁺→K_S⁰K_S⁰K⁺, and measure CP-violating parameters and partial branching fractions. The results are based on a data sample of approximately 470 × 10⁶ BB̄ decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the SLAC National Accelerator Laboratory. For B⁺→K⁺K⁻K⁺, we find a direct CP asymmetry in B⁺→φ(1020)K₊ of A_{CP}=(12.8±4.4±1.3)%, which differs from zero by 2.8σ. For B⁰→K⁺K⁻K_S⁰, we measure the CP-violating phase β_{eff}(φ(1020)K_S⁰)=(21±6±2)°. For B⁺→K_S⁰K_S⁰K⁺→K_S⁰K_S⁰K⁺, we measure an overall direct CP asymmetry of A _{CP}=(4_{-5}^{+4} ± 2)%. We also perform an angular-moment analysis of the three channels and determine that the ʄχ(1500) state can be described well by the sum of the resonances ʄ₀(1500), ʄ′₂(1525), and ʄ₀(1710).