1,334 research outputs found

    Direct CP violation in K->3pi decays induced by SUSY chromomagnetic penguins

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    An analysis of the CP violating asymmetry in K±(3π)±K^\pm \to (3\pi)^\pm decays in the Standard Model and, by means of the mass insertion approximation, in a wide class of possible supersymmetric extensions, is presented. We find that the natural order of magnitude for this asymmetry is \cO(10^{-5}) in both cases. Within supersymmetric models effects as large as \cO(10^{-4}) are possible, but only in a restricted range of the relevant parameters.Comment: Latex, 11 pages, 1 figur

    First Crystal Structure for a Gold Carbene-Protein Adduct

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    The X-ray structure of the adduct formed in the reaction between the gold N-heterocyclic carbene compound Au(NHC)Cl (with NHC = 1-butyl-3-methyl-imidazole-2-ylidene) and the model protein thaumatin is reported here. The structure reveals binding of Au(NHC)(+) fragments to distinct protein sites. Notably, binding of the gold compound occurs at lysine side chains and at the N-terminal tail; the metal binds the protein after releasing Cl- ligand, but retaining NHC fragment

    Multiple isoform recovery (MIR)-PCR: a simple method for the isolation of related mRNA isoforms

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    We present a rapid and efficient method for the detection of related transcripts with different expression levels. This approach combines the rapid amplification of cDNA ends (RACE) method with a cDNA subtractive technique. The strategy is based on successive subtractions of prevalent isoforms resulting in enrichment of less expressed transcripts. For each subtraction, a biotinylated primer specific for the prevalent isoform is hybridized on the total cDNA and the hybrid is retained on a streptavidin affinity column. The unbound cDNA serves as a template for subsequent isoform identification. To illustrate its application we describe the isolation of three new actin cDNA isoforms in the freshwater planarian Dugesia (S) polychro

    Supersymmetric contributions to direct CP violation in K -> pi pi gamma decays

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    We analyze the supersymmetric contributions to direct-CP-violating observables in KππγK \to \pi\pi\gamma decays induced by gluino-mediated magnetic-penguin operators. We find that \epsp_{+-\gamma} and the differential width asymmetry of K±π±π0γK^\pm \to \pi^\pm \pi^0 \gamma decays could be substantially enhanced with respect to their Standard Model values, especially in the scenario where \epsp/\eps is dominated by supersymmetric contributions. These observables could therefore provide a useful tool to search for New Physics effects in ΔS=1|\Delta S|=1 transitions, complementary to \epsp/\eps and rare decays.Comment: 14 pages, Latex. Numerical error in Eq.(36) corrected, conclusions unchanged; version to appear in Phys. Lett.

    GRANULATION TISSUE AS A CONTRACTILE ORGAN : A STUDY OF STRUCTURE AND FUNCTION

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    Contracting granulation tissues contain fibroblasts that develop characteristics typical of smooth muscle: (a) They contain an extensive cytoplasmic fibrillar system. (b) They show immunofluorescent labeling of their cytoplasm with human anti-smooth muscle serum. (c) The nuclei show complicated folds and indentations, indicative of cellular contraction. (d) There are cell-to-cell and cell-to-stroma attachments. (e) It is possible to extract similar quantities of actomyosin (having the same adenosine triphosphatase activity) from granulation tissue and from pregnant rat uterus. (f) Strips of granulation tissue, when tested pharmacologically in vitro, behave similarly to smooth muscle. All these data support the view that, under certain conditions, fibroblasts can differentiate into a cell type structurally and functionally similar to smooth muscle and that this cell, the "myo-fibroblast," plays an important role in connective tissue contraction

    Vector-meson contributions do not explain the rate and spectrum in K_L -> pi0 gamma gamma

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    We analyze the recent NA48 data for the reaction K_L -> pi0 gamma gamma with and without the assumption of vector meson dominance (VMD). We find that the data is well described by a three-parameter expression inspired by O(p^6) chiral perturbation theory. We also find that it is impossible to fit the shape of the decay distribution and the overall rate simultaneously if one imposes the VMD constraints on the three parameters. We comment on the different fits and their implications for the CP-conserving component of the decay K_L -> pi0 e+ e-.Comment: Version accepted for publication on Phys. Rev. D. 19 pages, LaTeX, 8 figures, uses epsf.st

    Beyond MFV in family symmetry theories of fermion masses

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    Minimal Flavour Violation (MFV) postulates that the only source of flavour changing neutral currents and CP violation, as in the Standard Model, is the CKM matrix. However it does not address the origin of fermion masses and mixing and models that do usually have a structure that goes well beyond the MFV framework. In this paper we compare the MFV predictions with those obtained in models based on spontaneously broken (horizontal) family symmetries, both Abelian and non-Abelian. The generic suppression of flavour changing processes in these models turns out to be weaker than in the MFV hypothesis. Despite this, in the supersymmetric case, the suppression may still be consistent with a solution to the hierarchy problem, with masses of superpartners below 1 TeV. A comparison of FCNC and CP violation in processes involving a variety of different family quantum numbers should be able to distinguish between various family symmetry models and models satisfying the MFV hypothesis.Comment: 34 pages, no figure

    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 Σ+pμ+μ\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 K0Kˉ0K^0-\bar{K}^0 mixing are automatically satisfied once the constraints from kaon decays are satisfied.Comment: 18 pages, 7 figure

    Connections between epsilon'/epsilon and Rare Kaon Decays in Supersymmetry

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    We analyze the rare kaon decays KLπ0ννˉK_L \to \pi^0 \nu \bar \nu, K+π+ννˉK^+ \to \pi^+ \nu \bar \nu, KLπ0e+eK_L \to \pi^0 e^+ e^- and KLμ+μK_L \to \mu^+ \mu^- in conjunction with the CP violating ratio ϵ/ϵ\epsilon'/\epsilon in a general class of supersymmetric models in which ZZ- and magnetic-penguin contributions can be substantially larger than in the Standard Model. We point out that radiative effects relate the double left-right mass insertion to the single left-left one, and that the phenomenological constraints on the latter reflect into a stringent bound on the supersymmetric contribution to the ZZ penguin. Using this bound, and those coming from recent data on ϵ/ϵ\epsilon'/\epsilon we find {\rm BR}(K_L \to \pi^0 \nu \bar \nu)\lsim 1.2\cdot 10^{-10}, {\rm BR}(K^+ \to \pi^+ \nu \bar \nu)\lsim 1.7\cdot 10^{-10}, {\rm BR}(K_L \to \pi^0 e^+ e^-)_{\rm dir}\lsim 2.0\cdot 10^{-11}, assuming the usual determination of the CKM parameters and neglecting the possibility of cancellations among different supersymmetric effects in ϵ/ϵ\epsilon'/\epsilon. Larger values are possible, in principle, but rather unlikely. We stress the importance of a measurement of these three branching ratios, together with improved data and improved theory of ϵ/ϵ\epsilon'/\epsilon, in order to shed light on the realization of various supersymmetric scenarios. We reemphasize that the most natural enhancement of ϵ/ϵ\epsilon'/\epsilon, within supersymmetric models, comes from chromomagnetic penguins and show that in this case sizable enhancements of BR(KLπ0e+e)dirBR(K_L \to \pi^0 e^+ e^-)_{\rm dir} can also be expected.Comment: 40 pages, 5 figure

    Grand Unification of Quark and Lepton FCNCs

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    In the context of Supersymmetric Grand Unified theories with soft breaking terms arising at the Planck scale, it is generally possible to link flavor changing neutral current and CP violating processes occurring in the leptonic and hadronic sectors. We study the correlation between flavor changing squark and slepton mass insertions in models \`a la SU(5). We show that the constraints coming from lepton flavor violation exhibit a strong impact on CP-violating B decays.Comment: 4 pages, 1 figur
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