2,906 research outputs found

    A precise new KLOE measurement of Fπ2|F_\pi|^2 with ISR events and determination of ππ\pi\pi contribution to aμa_\mu for 0.592<Mππ<0.9750.592 < M_{\pi\pi} < 0.975 GeV

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    The KLOE experiment at the DAΦ\PhiNE ϕ\phi-factory has performed a new precise measurement of the pion form factor using Initial State Radiation events, with photons emitted at small polar angle. Results based on an integrated luminosity of 240 pb1^{-1} and extraction of the ππ\pi\pi contribution to aμa_\mu in the mass range 0.35<Mππ2<0.950.35< M^2_{\pi\pi}<0.95 GeV2^2 are presented. The new value of aμππa^{\pi\pi}_\mu has smaller (30%) statistical and systematic error and is consistent with the KLOE published value (confirming the current disagreement between the standard model prediction for aμa_\mu and the measured value).Comment: 5 pages, proceedings for the CIPANP 2009 conferenc

    Form factor in K+ --> pi+ pi0 gamma: interference versus direct emission

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    We analyze the effect of a form factor in the magnetic contribution to K+ --> pi+ pi0 gamma. We emphasize how this can show up experimentally: in particular we try to explore the difference between a possible interference contribution and a form factor in the magnetic part. The form factor used for K+ --> pi+ pi0 gamma is analogous to the one for KL --> pi+ pi- gamma, experimentally well established.Comment: 9 pages revtex, 10 eps figures; improved presentation of theoretical and experimental status; refs. adde

    Vector meson decays from the Extended Chiral Quark Model

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    We derive the the effective lagrangian that describes the interactions among vector, axial-vector mesons and pseudoscalars starting from the extended chiral quark model (ECQM). The results for the low-energy constants of this effective lagrangian have a parametric resemblance with existing predictions based on the Nambu-Jona-Lasinio model (except for some overall signs that we correct), but are numerically different. Therefore a precise measurement of these decay constants can shed some light on the way chiral symmetry breaking is modelled in QCD. Although most of the constants are poorly measured, comparison with phenomenology allows us to determine one of the parameters of the ECQM that could not be fully determined in previous analyses.Comment: 7 pages, revtex

    Precision Measurement of KS Meson Lifetime with the KLOE detector

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    Using a large sample of pure, slow, short lived K0 mesons collected with KLOE detector at DaFne, we have measured the KS lifetime. From a fit to the proper time distribution we find tau = (89.562 +- 0.029_stat +- 0.043_syst) ps. This is the most precise measurement today in good agreement with the world average derived from previous measurements. We observe no dependence of the lifetime on the direction of the Ks.Comment: 5 pages, 7 figure

    Study of isospin violating ϕ\phi excitation in e+eωπ0e^+e^- \to \omega\pi^0

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    We study the reaction e+eωπ0e^+ e^-\to \omega\pi^0 in the vicinity of ϕ\phi mass region. The isospin-violating ϕ\phi excitation is accounted for by two major mechanisms. One is electromagnetic (EM) transition and the other is strong isospin violations. For the latter, we consider contributions from the intermediate hadronic meson loops and ϕ\phi-ρ0\rho^0 mixing as the major mechanisms via the tt and s-channel transitions, respectively. By fitting the recent KLOE data, we succeed in constraining the model parameters and extracting the ϕωπ0\phi\to\omega\pi^0 branching ratio. It shows that the branching ratio is sensitive to the ϕ\phi excitation line shape and background contributions. Some crucial insights into the correlation between isospin violation and Okubo-Zweig-Iizuka (OZI) rule evading transitions are also learned.Comment: Revised version to appear in J. Phys.

    Reanalysis of pion pion phase shifts from K -> pi pi decays

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    We re-investigate the impact of isospin violation for extracting the s-wave pion pion scattering phase shift difference delta_0(M_K) - delta_2(M_K) from K -> pi pi decays. Compared to our previous analysis in 2003, more precise experimental data and improved knowledge of low-energy constants are used. In addition, we employ a more robust data-driven method to obtain the phase shift difference delta_0(M_K) - delta_2(M_K) = (52.5 \pm 0.8_{exp} \pm 2.8_{theor}) degrees.Comment: 8 page

    Comparative analysis of the SOL plasma in DEMO using EDGE2D/EIRENE and TECXY codes

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    In this contribution a benchmark of the 2D edge codes TECXY and EDGE2D-EIRENE is presented. A conventional DEMO scenario is considered by assuming a simplified geometry, with the target plates perpendicular to the separatrix, and a pure Deuterium plasma. Despite the different models adopted in the two codes, mainly related to the description of the neutral dynamics and to the different boundary conditions, the results show a good match both in terms of power load profiles on the outer target and predicted trends for global quantities. A scan in density and in diffusion coefficients is performed in order to identify the characteristic conditions and the different regimes of the SOL. Comparable values and similar dependency of the global quantities as a function of the power decay length is also observed. Keywords: EDGE2D, EIRENE, TECXY, DEMO, Diverto

    The effect of estrogen and tamoxifen on hepatocyte proliferation in Vivo and in Vitro

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    We have previously shown that changes in estrogen‐hepatocyte interaction occur during liver regeneration. Following 70% hepatectomy, estrogen levels in the blood were elevated, the number of estrogen receptors in the liver was increased and there was an active translocation of estrogen receptors from the cytosol to the nucleus. The injection of tamoxifen, an estrogen antagonist, inhibits hepatocyte proliferation following partial hepatectomy. The administration of 1 μg tamoxifen per gm body weight at zero time or 6 hr after the operation resulted in a significant inhibition both of DNA synthesis and of the number of cells in mitosis. Injections of tamoxifen 12 hr or later after the operation had no effect. Concomitant injections of equimolar amounts of estrogen abolished the inhibition by tamoxifen. The effects of estrogen and tamoxifen were also tested on hepatocytes in primary culture. Estrogens in the presence of 5% normal rat serum stimulated hepatocyte DNA synthesis as determined by [3H]thymidine incorporation and the labeling index, whereas epidermal growth factor‐induced DNA synthesis in the absence of normal rat serum was strongly inhibited. Tamoxifen, in contrast, inhibited DNA synthesis of hepatocytes in the presence of 5% normal rat serum and reversed the stimulatory effect of estrogen in the same system. Attempts to elucidate the mechanism of tamoxifen inhibition in vitro indicated that one effect of tamoxifen is to prevent the amiloride‐sensitive Na+ influx necessary to initiate hepatocyte proliferation. Copyright © 1989 American Association for the Study of Liver Disease
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