4,336 research outputs found

    Empirical parameterization of the K+- -> pi+- pi0 pi0 decay Dalitz plot

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    As first observed by the NA48/2 experiment at the CERN SPS, the \p0p0 invariant mass (M00) distribution from \kcnn decay shows a cusp-like anomaly at M00=2m+, where m+ is the charged pion mass. An analysis to extract the pi pi scattering lengths in the isospin I=0 and I=2 states, a0 and a2, respectively, has been recently reported. In the present work the Dalitz plot of this decay is fitted to a new empirical parameterization suitable for practical purposes, such as Monte Carlo simulations of K+- -> pi+- pi0 pi0 decays.Comment: 9 pages, 3 figures

    Improved Determination of the Electroweak Penguin Contribution to epsilon'/epsilon in the Chiral Limit

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    We perform a finite energy sum rule analysis of the flavor ud two-point V-A current correlator, Delta Pi (Q^2). The analysis, which is performed using both the ALEPH and OPAL databases for the V-A spectral function, Delta rho, allows us to extract the dimension six V-A OPE coefficient, a_6, which is related to the matrix element of the electroweak penguin operator, Q_8, by chiral symmetry. The result for a_6 leads directly to the improved (chiral limit) determination epsilon'/epsilon = (- 15.0 +- 2.7) 10^{-4}. Determination of higher dimension OPE contributions also allows us to perform an independent test using a low-scale constrained dispersive analysis, which provides a highly nontrivial consistency check of the results.Comment: 17 pages, 4 figures, Revte

    Contributions from SUSY-FCNC couplings to the interpretation of the HyperCP events for the decay \Sigma^+ \to p \mu^+ \mu^-

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    The observation of three events for the decay ÎŁ+→pÎŒ+Ό−\Sigma^+ \to p \mu^+ \mu^- with a dimuon invariant mass of 214.3±0.5214.3\pm0.5MeV by the HyperCP collaboration imply that a new particle X may be needed to explain the observed dimuon invariant mass distribution. We show that there are regions in the SUSY-FCNC parameter space where the A10A^0_1 in the NMSSM can be used to explain the HyperCP events without contradicting all the existing constraints from the measurements of the kaon decays, and the constraints from the K0−Kˉ0K^0-\bar{K}^0 mixing are automatically satisfied once the constraints from kaon decays are satisfied.Comment: 18 pages, 7 figure

    Search for direct CP-violation in K+- --> pi+-pi0pi0 decays

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    A search for direct CP-violation in K+- --> pi+-pi0pi0 decays based on 47.14 million events has been performed by the NA48/2 experiment at the CERN SPS. The asymmetry in the Dalitz plot linear slopes A_g=(g^+ - g^-)/(g^+ + g^-) is measured to be A_g=(1.8 +- 2.6).10^{-4}. The design of the experiment and the method of analysis provide good control of instrumental charge asymmetries in this measurement. The precision of the result is limited by statistics and is almost one order of magnitude better than that of previous measurements by other experiments.Comment: 14 page

    The s ---> d gamma decay in and beyond the Standard Model

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    The New Physics sensitivity of the s ---> d gamma transition and its accessibility through hadronic processes are thoroughly investigated. Firstly, the Standard Model predictions for the direct CP-violating observables in radiative K decays are systematically improved. Besides, the magnetic contribution to epsilon prime is estimated and found subleading, even in the presence of New Physics, and a new strategy to resolve its electroweak versus QCD penguin fraction is identified. Secondly, the signatures of a series of New Physics scenarios, characterized as model-independently as possible in terms of their underlying dynamics, are investigated by combining the information from all the FCNC transitions in the s ---> d sector.Comment: 54 pages, 14 eps figure

    Observation of the rare decay K_S -> pi^0mu^+mu^-

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    A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1 Collaboration at the CERN SPS accelerator. The data were collected during 2002 with a high-intensity K_S beam. Six events were found with a background expectation of 0.22^+0.18_-0.11 event. Using a vector matrix element and unit form factor, the measured branching ratio is B(K_S -> pi^0mu^+mu^-)=[2.9^+1.5_-1.2(stat)+/-0.2(syst)]x10^{-9}.Comment: 19 pages, 8 figures, 4 tables. To be published in Physics Letters

    Future Directions in the Molecular Breeding of Forage and Turf

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    Key points Molecular breeding of forage and turf plants and their endosymbionts has entered the post-genomic era with a large amount of structural genomics information and genomic resources available for key forage and turf species and relevant model systems. A primary future challenge is the conversion of this information into useful functional knowledge for the development of molecular breeding technologies and products that address a range of high impact outcome scenarios in forage and turf. High-throughput approaches for spatial and temporal analysis, from genome to phenome, and the respective data integration in a systems biology context will be critical for the establishment of stringent gene-function correlations. Translational genomics will permit results obtained using model systems to have major impact on the understanding of the molecular basis of plant processes and direct application to the molecular breeding of forage and turf plants. These developments will be enhanced through applications of transgenesis and functionally-associated genetic markers in forage and turf molecular breeding building on genomic and post-genomic discoveries in these target species

    First observation of the KS->pi0 gamma gamma decay

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    Using the NA48 detector at the CERN SPS, 31 KS->pi0 gamma gamma candidates with an estimated background of 13.7 +- 3.2 events have been observed. This first observation leads to a branching ratio of BR(KS->pi0 gamma gamma) = (4.9 +- 1.6(stat) +- 0.9(syst)) x 10^-8 in agreement with Chiral Perturbation theory predictions.Comment: 10 pages, 4 figures submitted to Phys. Lett.

    First Observation and Measurement of the Decay K+- -> pi+- e+ e- gamma

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    Using the full data set of the NA48/2 experiment, the decay K+- -> pi+- e+ e- gamma is observed for the first time, selecting 120 candidates with 7.3 +- 1.7 estimated background events. With K+- -> pi+- pi0D as normalisation channel, the branching ratio is determined in a model-independent way to be Br(K+- -> pi+- e+ e- gamma, m_eegamma > 260 MeV/c^2) = (1.19 +- 0.12_stat +- 0.04_syst) x 10^-8. This measured value and the spectrum of the e+ e- gamma invariant mass allow a comparison with predictions of Chiral Perturbation Theory.Comment: 13 pages, 3 figures. Accepted for publication in Phys.Lett.
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