346 research outputs found

    Aspects of radiative K^+_e3 decays

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    We re-investigate the radiative charged kaon decay K+- --> pi0 e+- nu_e gamma in chiral perturbation theory, merging the chiral expansion with Low's theorem. We thoroughly analyze the precision of the predicted branching ratio relative to the non-radiative decay channel. Structure dependent terms and their impact on differential decay distributions are investigated in detail, and the possibility to see effects of the chiral anomaly in this decay channel is emphasized.Comment: 15 pages, 6 figure

    High-throughput avian molecular sexing by SYBR green-based real-time PCR combined with melting curve analysis

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    <p>Abstract</p> <p>Background</p> <p>Combination of <it>CHD </it>(chromo-helicase-DNA binding protein)-specific polymerase chain reaction (PCR) with electrophoresis (PCR/electrophoresis) is the most common avian molecular sexing technique but it is lab-intensive and gel-required. Gender determination often fails when the difference in length between the PCR products of <it>CHD-Z </it>and <it>CHD-W </it>genes is too short to be resolved.</p> <p>Results</p> <p>Here, we are the first to introduce a PCR-melting curve analysis (PCR/MCA) to identify the gender of birds by genomic DNA, which is gel-free, quick, and inexpensive. <it>Spilornis cheela hoya </it>(<it>S. c. hoya</it>) and <it>Pycnonotus sinensis </it>(<it>P. sinensis</it>) were used to illustrate this novel molecular sexing technique. The difference in the length of <it>CHD </it>genes in <it>S. c. hoya </it>and <it>P. sinensis </it>is 13-, and 52-bp, respectively. Using Griffiths' P2/P8 primers, molecular sexing failed both in PCR/electrophoresis of <it>S. c. hoya </it>and in PCR/MCA of <it>S. c. hoya </it>and <it>P. sinensis</it>. In contrast, we redesigned sex-specific primers to yield 185- and 112-bp PCR products for the <it>CHD-Z </it>and <it>CHD-W </it>genes of <it>S. c. hoya</it>, respectively, using PCR/MCA. Using this specific primer set, at least 13 samples of <it>S. c. hoya </it>were examined simultaneously and the Tm peaks of <it>CHD-Z </it>and <it>CHD-W </it>PCR products were distinguished.</p> <p>Conclusion</p> <p>In this study, we introduced a high-throughput avian molecular sexing technique and successfully applied it to two species. This new method holds a great potential for use in high throughput sexing of other avian species, as well.</p

    Understanding the newly observed Y(4008) by Belle

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    Very recently a new enhancement around 4.05 GeV was observed by Belle experiment. In this short note, we discuss some possible assignments for this enhancement, i.e. ψ(3S)\psi(3S) and DDˉD^*\bar{D}^* molecular state. In these two assignments, Y(4008) can decay into J/ψπ0π0J/\psi\pi^0\pi^0 with comparable branching ratio with that of Y(4008)J/ψπ+πY(4008)\to J/\psi\pi^+\pi^-. Thus one suggests high energy experimentalists to look for Y(4008) in J/ψπ0π0J/\psi\pi^0\pi^0 channel. Furthermore one proposes further experiments to search missing channel DDˉD\bar{D}, DDˉ+h.c.D\bar{D}^*+h.c. and especially χcJπ+ππ0\chi_{cJ}\pi^+\pi^-\pi^0 and ηcπ+ππ0\eta_c\pi^+\pi^-\pi^0, which will be helpful to distinguish ψ(3S)\psi(3S) and DDˉD^*\bar{D}^* molecular state assignments for this new enhancement.Comment: 4 pages, 5 figures. Typos correcte

    Harmful Algal Blooms in Chinese Coastal Waters Will Persist Due to Perturbed Nutrient Ratios

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    The three large marine ecosystems (LMEs) bordering China (Yellow Sea/Bohai Sea, East China Sea, and South China Sea) have received excess nitrogen (N) and phosphorus (P) in the past decades with detrimental consequences for ecosystem functioning, such as increased productivity, loss of biodiversity, and proliferation of harmful algal blooms (HABs). N loading increased much faster than that of P. Here, we show that HABs in the three LMEs started to proliferate after the N:P molar ratio exceeded the threshold value of 25 in the 1980s. The mismatch of N and P inputs is not only related to differences in loads but also inherent to the differences in their biogeochemical cycles which more efficiently filter P than N in land- and waterscapes. Future Shared Socioeconomic Pathways show that high N:P ratios will persist for decades to come, even worsening in a future oriented toward sustainability, and indicate that HABs may be a persisting problem in China’s coastal waters. While efforts in agricultural systems are governed by the agronomic crop requirements and are not easy to manage with respect to N:P ratios, the separate collection of urine in urban and rural areas could contribute to decreases in both total nutrient loads and N:P ratios

    Polluted lake restoration to promote sustainability in the Yangtze River Basin, China

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    China has sought to address water pollution in the last decade by introducing a wide range of laws and regulations (Table S1), which led to nationwide water quality improvement. However, recent quantitative assessment of progress toward Sustainable Development Goals (SDGs) in China suggests that some SDGs underpinning goals for water pollution and biodiversity have not been met. Specifically, tests on water quality improvement in lakes have had contradictory results, leading to confusion about water quality improvement in China

    Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm

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    The PHENIX experiement has measured the electron-positron pair mass spectrum from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions from light meson decays to e^+e^- pairs have been determined based on measurements of hadron production cross sections by PHENIX. They account for nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair yield remaining after subtracting these contributions is dominated by semileptonic decays of charmed hadrons correlated through flavor conservation. Using the spectral shape predicted by PYTHIA, we estimate the charm production cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which is consistent with QCD calculations and measurements of single leptons by PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables. Submitted to Physics Letters B. v2 fixes technical errors in matching authors to institutions. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Heavy quarkonium: progress, puzzles, and opportunities

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    A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the BB-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

    Global Search for New Physics with 2.0/fb at CDF

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    Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication
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