1,873 research outputs found

    Results on CP violation and CKM UT angles from Belle and BaBar

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    We report recent results on CP violation measurements from the two B-factory experiments, Belle and BaBar.Comment: 4 pages, 4 figures, appeared in the proceedings of the IX International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2010), June 21-26, 2010, Perugia, Ital

    Assessment of damage caused by Ephestia cautella (Walker) to stored cocoa beans

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    Ephestia cautella is one of the most common storage pests of stored cocoa beans. When left uncontrolled it can cause extensive damage to stored dried cocoa beans. Increased Free Fatty Acid levels (FFA) affect the fat structure and reduce the hardness of cocoa butter. Insects have been found to be a contributory factor to the increased levels of FFA. Inadequate studies have been done exclusively on the influence of E. cautella. The study was to evaluate extent of damage of E. cautella and its impact on the FFA levels, Experiments were conducted under temperature and relative humidity ranges of 27 °C – 36.5 °C and 40 – 85 percent, respectively, in the Insectary building of the Department of Crop and Soil Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana and Quality Control Division of COCOCBOD, Tema, Ghana. Thirty six mini sacks, each containing 400 g of cocoa beans stackes were grouped into four, and placed in a transparent cage measuring 65 cm length × 65 cm width and 75 cm high. Each group had a pile up stack of three, placed side by side, totaling nine mini sacks per group. Twenty newly emerged E. cautella were released into the cage and damaged assessed monthly up to a period of 4 months. The damage caused included significant decrease in weight loss and increase in Free Fatty Acid levels to stored cocoa beans over a period of 4 months. The mean percentage damage to cocoa beans by E. cautella were 10.31 and 29.05 in the first and fourth months, respectively, with corresponding percentage weight losses of 1.21 and 6.53. There were high levels of FFA in damaged beans caused by E. cautella as compared to the controlled beans. The FFA levels in the controlled beans were all below 1 percent, whilst the FFA levels in E. cautella infested beans were above the threshold of 1.75 percent aside month 1. Thus, E. cautella infestation caused increased levels of FFA within stored cocoa beans. There was a strong positive correlation among insect numbers monthly, percentage damage, weight loss and free fatty acid

    Aspects of the biology of Ephestia cautella and Tribolium castaneum on fermented stored cocoa beans

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     Ephestia cautella (Walker) (Lepidotera: Pyralidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) are pests associated with dried fermented stored cocoa beans that cause extensive damage. The biology of these pests on cocoa beans in Ghana has not been well documented, especially on T. castaneum. Due to climate changes and improved/hybrid seedlings being released to farmers, it has become necessary to re-evaluate the biology and damage of these pests on fermented stored cocoa beans. The experiments were conducted in the Insectary laboratory of the Department of Crop and Soil Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. Paired 0-1 day old E. cautella adults were placed in Petri dishes and covered with Kilner jars. The eggs laid daily by each female were carefully transferred onto 15 g cocoa beans in Petri dishes. The egg incubation period was four days, 31 days larval period and the pupal period of seven days. Unmated adult males lived for 12.1 days and females 7.9; mated males lived for 10.9 days and females 5.5. Paired T. castaneum were introduced on 2.0 g broken cocoa beans in Petri dishes. The average incubation period was nine days, 40 days larval period, and pupal period of five days

    The Rules of Human T Cell Fate in vivo.

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    The processes governing lymphocyte fate (division, differentiation, and death), are typically assumed to be independent of cell age. This assumption has been challenged by a series of elegant studies which clearly show that, for murine cells in vitro, lymphocyte fate is age-dependent and that younger cells (i.e., cells which have recently divided) are less likely to divide or die. Here we investigate whether the same rules determine human T cell fate in vivo. We combined data from in vivo stable isotope labeling in healthy humans with stochastic, agent-based mathematical modeling. We show firstly that the choice of model paradigm has a large impact on parameter estimates obtained using stable isotope labeling i.e., different models fitted to the same data can yield very different estimates of T cell lifespan. Secondly, we found no evidence in humans in vivo to support the model in which younger T cells are less likely to divide or die. This age-dependent model never provided the best description of isotope labeling; this was true for naïve and memory, CD4+ and CD8+ T cells. Furthermore, this age-dependent model also failed to predict an independent data set in which the link between division and death was explored using Annexin V and deuterated glucose. In contrast, the age-independent model provided the best description of both naïve and memory T cell dynamics and was also able to predict the independent dataset

    Analysis of the D^+ → K^-π^+e^+ν_e decay channel

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    Using 347.5  fb^(-1) of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244×10^3 signal events for the D^+ → K^-π^+e^+ν_e decay channel are analyzed. This decay mode is dominated by the K̅ ^*(892)^0 contribution. We determine the K̅ ^*(892)^0 parameters: m_(K^*(892)^0)=(895.4±0.2±0.2)  MeV/c^2, Γ_(K^*(892)^0)=(46.5±0.3±0.2)  MeV/c^2, and the Blatt-Weisskopf parameter r_(BW) =2.1±0.5±0.5  (GeV/c)^-1, where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q^2 = 0 (r_V = ^(V(0))/_(A1(0)) = 1.463 ± 0.017 ± 0.031, r_2 = _(A1(0)) ^(A2(0))= 0.801±0.020±0.020) and the value of the axial-vector pole mass parametrizing the q^2 variation of A_1 and A_2: m_A=(2.63±0.10±0.13)  GeV/c^2. The S-wave fraction is equal to (5.79±0.16±0.15)%. Other signal components correspond to fractions below 1%. Using the D^+ → K^-π^+π^+ channel as a normalization, we measure the D^+ semileptonic branching fraction: B(D^+ → K^-π^+e^+ν_e)=(4.00±0.03±0.04±0.09)×10^(-2), where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A_1 at q^2=0: A_1(0)=0.6200±0.0056±0.0065±0.0071. Fixing the P-wave parameters, we measure the phase of the S wave for several values of the Kπ mass. These results confirm those obtained with Kπ production at small momentum transfer in fixed target experiments

    Observation of η_c(1S) and η_c(2S) decays to K^+K^-π^+π^-π^0 in two-photon interactions

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    We study the processes γγ→K_S^0K^±π^∓ and γγ→K^+K^-π^+π-π^0 using a data sample of 519.2fb^(-1) recorded by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at center-of-mass energies near the Υ(nS) (n=2, 3, 4) resonances. We observe the η_c(1S), χ_(c0)(1P) and η_c(2S) resonances produced in two-photon interactions and decaying to K^+K^-π^+π^-π^0, with significances of 18.1, 5.4 and 5.3 standard deviations (including systematic errors), respectively, and report 4.0σ evidence of the χ_(c2)(1P) decay to this final state. We measure the η_c(2S) mass and width in K_S^0K^±π^∓ decays, and obtain the values m(η_c(2S))=3638.5±1.5±0.8  MeV/c^2 and Γ(η_c(2S))=13.4±4.6±3.2  MeV, where the first uncertainty is statistical and the second is systematic. We measure the two-photon width times branching fraction for the reported resonance signals, and search for the χ_(c2)(2P) resonance, but no significant signal is observed

    Evidence for the decay X(3872)→J/ψω

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    We present a study of the decays B^(0,+)→J/ψπ^+π^-π^0K^(0,+), using 467×10^6 BB[overbar] pairs recorded with the BABAR detector. We present evidence for the decay mode X(3872)→J/ψω, with product branching fractions B(B^+→X(3872)K^+)×B(X(3872)→J/ψω)=[0.6±0.2(stat)±0.1(syst)]×10^(-5), and B(B^0→X(3872)K^0)×B(X(3872)→J/ψω)=[0.6±0.3(stat)±0.1(syst)]×10^(-5). A detailed study of the π^+π^-π^0 mass distribution from X(3872) decay favors a negative-parity assignment

    Study of B → πlν and B → ρlν decays and determination of |V_(ub)|

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    We present an analysis of exclusive charmless semileptonic B-meson decays based on 377 × 10^6 BB̅ pairs recorded with the BABAR detector at the Υ(4S) resonance. We select four event samples corresponding to the decay modes B^0 → π^-ℓ^+ν, B^+ → π^0ℓ^+ν, B^0 → ρ^-ℓ^+ν, and B^+ → ρ^0ℓ^+ν and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B → πℓν samples, and similarly the two B → ρℓν samples, and measure the branching fractions B(B^0→π^-ℓ^+ν)=(1.41 ± 0.05 ± 0.07) × 10^(-4) and B(B^0 → ρ^-ℓ^+ν)=(1.75 ± 0.15 ± 0.27) × 10^(-4), where the errors are statistical and systematic. We compare the measured distribution in q^2, the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element |V_(ub)|. Based on the measured partial branching fraction for B → πℓν in the range q^2 < 12  GeV^2 and the most recent QCD light-cone sum-rule calculations, we obtain |V_(ub)|=(3.78 ± 0.13^(+0.55)_(-0.40)) × 10^(-3), where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full q^2 range and the FNAL/MILC lattice QCD results, we obtain |V_(ub)|=(2.95 ± 0.31) × 10^(-3) from B → πℓν, where the error is the combined experimental and theoretical uncertainty

    Study of B → Xγ decays and determination of |V_(td)/V_(ts)|

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    Using a sample of 471×10^6 BB̅[overbar] events collected with the BABAR detector, we study the sum of seven exclusive final states B→X_(s(d))γ, where X_(s(d)) is a strange (nonstrange) hadronic system with a mass of up to 2.0  GeV/c^2. After correcting for unobserved decay modes, we obtain a branching fraction for b→dγ of (9.2±2.0(stat)±2.3(syst))×10^(-6) in this mass range, and a branching fraction for b→sγ of (23.0±0.8(stat)±3.0(syst))×10^(-5) in the same mass range. We find B[script](b→dγ)/B[script](b→sγ)=0.040±0.009(stat)±0.010(syst), from which we determine |V_(td)/V_(ts)|=0.199±0.022(stat)±0.024(syst)±0.002(th)

    Measurements of branching fractions, polarizations, and direct CP-violation asymmetries in B^+ → ρ^0K^(*+) and B^+ → f_0 (980)K^(*+) decays

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    We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B^+→ρ^0K^(*+) and B^+→f_0(980)K^(*+) with a sample of (467±5)×10^6BB̅ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. We observe B+→ρ0K*+ with a significance of 5.3σ and measure the branching fraction B(B^+→ρ^0K^(*+))=(4.6±1.0±0.4)×10^(-6), the longitudinal polarization f_L=0.78±0.12±0.03, and the CP-violation asymmetry A_(CP)=0.31±0.13±0.03. We observe B^+→f_0(980)K^(*+) and measure the branching fraction B(B^+→f_0(980)K^(*+))×B(f_0(980)→π^+π^-)=(4.2±0.6±0.3)×10^(-6) and the CP-violation asymmetry A_(CP)=-0.15±0.12±0.03. The first uncertainty quoted is statistical and the second is systematic
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