661 research outputs found

    BRST Formulation of 4-Monopoles

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    A supersymmetric gauge invariant action is constructed over any 4-dimensional Riemannian manifold describing Witten's theory of 4-monopoles. The topological supersymmetric algebra closes off-shell. The multiplets include the auxiliary fields and the Wess-Zumino fields in an unusual way, arising naturally from BRST gauge fixing. A new canonical approach over Riemann manifolds is followed, using a Morse function as an euclidean time and taking into account the BRST boundary conditions that come from the BFV formulation. This allows a construction of the effective action starting from gauge principles.Comment: 18 pages, Amste

    A new measurement of antineutrino oscillation with the full detector configuration at Daya Bay

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    We report a new measurement of electron antineutrino disappearance using the fully-constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×\times105^5 GWth_{\rm th}-ton-days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six 241^{241}Am-13^{13}C radioactive calibration sources reduced the background by a factor of two for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin22θ13\sin^{2}2\theta_{13} and Δmee2|\Delta m^2_{ee}| were halved as a result of these improvements. Analysis of the relative antineutrino rates and energy spectra between detectors gave sin22θ13=0.084±0.005\sin^{2}2\theta_{13} = 0.084\pm0.005 and Δmee2=(2.42±0.11)×103|\Delta m^{2}_{ee}|= (2.42\pm0.11) \times 10^{-3} eV2^2 in the three-neutrino framework.Comment: Updated to match final published versio

    Detection of Bioactive Exometabolites Produced by the Filamentous Marine Cyanobacterium Geitlerinema sp.

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    Marine cyanobacteria are noted for their ability to excrete metabolites with biotic properties. This paper focuses on such exometabolites obtained from the culture of the marine filamentous cyanobacterium Geitlerinema sp. strain, their purification and subsequent analyses. By this means the recoveries of the active compounds, a prerequisite for properly determining their concentration, are quantified here for the first time. We demonstrate a new procedure using Amberlite XAD-1180 resin in combination with the eluent isopropanol for extraction of the culture media and gas chromatography as simplified chemical analysis. This procedure reduced necessary bacteria cultivation time (from 150 to 21 days) at low volumes of culture media (300 mL) required for identification of two selected bioactive compounds: 4,4′-dihydroxybiphenyl and harmane

    New measurement of θ13\theta_{13} via neutron capture on hydrogen at Daya Bay

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    This article reports an improved independent measurement of neutrino mixing angle θ13\theta_{13} at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β\beta-decays with the emitted neutron captured by hydrogen, yielding a data-set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced 9^9Li and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin22θ13=0.071±0.011\sin^22\theta_{13} = 0.071 \pm 0.011 in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported.Comment: 26 pages, 23 figure

    Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

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    The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GWth_{\textrm{th}} reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective 239^{239}Pu fission fractions, F239F_{239}, from 0.25 to 0.35, Daya Bay measures an average IBD yield, σˉf\bar{\sigma}_f, of (5.90±0.13)×1043(5.90 \pm 0.13) \times 10^{-43} cm2^2/fission and a fuel-dependent variation in the IBD yield, dσf/dF239d\sigma_f/dF_{239}, of (1.86±0.18)×1043(-1.86 \pm 0.18) \times 10^{-43} cm2^2/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the 239^{239}Pu fission fraction at 10 standard deviations. The variation in IBD yield was found to be energy-dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1σ\sigma. This discrepancy indicates that an overall deficit in measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes 235^{235}U, 239^{239}Pu, 238^{238}U, and 241^{241}Pu. Based on measured IBD yield variations, yields of (6.17±0.17)(6.17 \pm 0.17) and (4.27±0.26)×1043(4.27 \pm 0.26) \times 10^{-43} cm2^2/fission have been determined for the two dominant fission parent isotopes 235^{235}U and 239^{239}Pu. A 7.8% discrepancy between the observed and predicted 235^{235}U yield suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.Comment: 7 pages, 5 figure

    Improved Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay

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    A new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9~GWth_{\mathrm{th}} nuclear reactors and detected by eight antineutrino detectors deployed in two near (560~m and 600~m flux-weighted baselines) and one far (1640~m flux-weighted baseline) underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD) candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946±0.0200.946\pm0.020 (0.992±0.0210.992\pm0.021) for the Huber+Mueller (ILL+Vogel) model. A 2.9~σ\sigma deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4-6~MeV was found in the measured spectrum, with a local significance of 4.4~σ\sigma. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.Comment: version published in Chinese Physics

    Towards a Proof Theory of G\"odel Modal Logics

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    Analytic proof calculi are introduced for box and diamond fragments of basic modal fuzzy logics that combine the Kripke semantics of modal logic K with the many-valued semantics of G\"odel logic. The calculi are used to establish completeness and complexity results for these fragments
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