1,341 research outputs found
Direct CP violation in K->3pi decays induced by SUSY chromomagnetic penguins
An analysis of the CP violating asymmetry in 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
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
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
We analyze the supersymmetric contributions to direct-CP-violating
observables in decays induced by gluino-mediated
magnetic-penguin operators. We find that \epsp_{+-\gamma} and the
differential width asymmetry of 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 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
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
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
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^-
The observation of three events for the decay
with a dimuon invariant mass of MeV 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 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
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
We analyze the rare kaon decays , , and in conjunction
with the CP violating ratio in a general class of
supersymmetric models in which - 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 penguin. Using
this bound, and those coming from recent data on 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 . 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 , in order to shed light on the realization of various
supersymmetric scenarios. We reemphasize that the most natural enhancement of
, within supersymmetric models, comes from chromomagnetic
penguins and show that in this case sizable enhancements of can also be expected.Comment: 40 pages, 5 figure
Grand Unification of Quark and Lepton FCNCs
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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