2,083 research outputs found

    Extended HQEFT Lagrangian and currents

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    From the tree-level heavy quark effective Lagrangian keeping particle-antiparticle mixed sectors we derive the vector current coupling to a hard gluonic field allowing for heavy quark-antiquark pair annihilation and creation.Comment: Talk given at 4th International Conference on Hyperons, Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 2000. LaTeX, 4 pages, 1 EPS figur

    Bottomonium spectroscopy with mixing of eta_b states and a light CP-odd Higgs

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    The mass of the eta_b(1S), measured recently by BABAR, is significantly lower than expected from QCD predictions for the Upsilon(1S) - eta_b(1S) hyperfine splitting. We suggest that the observed eta_b(1S) mass is shifted downwards due to a mixing with a CP-odd Higgs scalar A with a mass m_A in the range 9.4 - 10.5 GeV compatible with LEP, CLEO and BABAR constraints. We determine the resulting predictions for the spectrum of the eta_b(nS) - A system and the branching ratios into tau^+ tau^- as functions of m_A.Comment: 4 pages, 4 figures, submitted to PRL, misprint correcte

    Dynamical Systems from Uniform Completions

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    Let (X,U)\left(X,\mathcal{U}\right) be a compact uniform space, ∑\sum the set of natural numbers or the integers, φ  :  X  ⟶  X\varphi\;:\; X\;\longrightarrow\; X a continuous function or a homeomorphism. Given the dynamical system (X,φ,∑)\left(X,\varphi,\sum\right), an extension (K,φ,^∑)\left(K,\widehat{\varphi,}\sum\right), can be constructed by letting K be the uniform completion of (X,V)\left(X,\mathcal{V}\right), where V\mathcal{V} is a totally bounded uniformity fi{}ner than U\mathcal{U}. If Df_{f} means for the set {x ϵ X ∣ f :(X,U)⟶C  is  discontinuous  at  x}, \left\{ x\:\epsilon\: X\:\mid\: f\::(X,\mathcal{U})\longrightarrow\mathbb{C}\; is\; discontinuous\; at\; x\right\} , we prove that, if C(K) contains a dense subset E which contains no characteristic functions of singletons and such that, for each fϵEf\epsilon E , there exists a fi{}nite subset F of Df_{f} with Df\FD_{f}\backslash F discrete (in (X,U)\left(X,\mathcal{U}\right)), then (K,φ,^∑)\left(K,\widehat{\varphi,}\sum\right) inherits the properties of minimality and topological transitivity from (X,φ,∑)\left(X,\varphi,\sum\right). Several open questions are posed

    A heavy quark effective field lagrangian keeping particle and antiparticle mixed sectors

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    We derive a tree-level heavy quark effective Lagrangian keeping particle-antiparticle mixed sectors allowing for heavy quark-antiquark pair annihilation and creation. However, when removing the unwanted degrees of freedom from the effective Lagrangian one has to be careful in using the classical equations of motion obeyed by the effective fields in order to get a convergent expansion on the reciprocal of the heavy quark mass. Then the application of the effective theory to such hard processes should be sensible for special kinematic regimes as for example heavy quark pair production near threshold.Comment: LaTeX, 14 pages, 1 EPS figure

    Power scaling rules for charmonia production and HQEFT

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    We discuss the power scaling rules along the lines of a complete Heavy Quark Effective Field Theory (HQEFT) for the description of heavy quarkonium production through a color-octet mechanism. To this end, we firstly derive a tree-level heavy quark effective Lagrangian keeping both particle-antiparticle mixed sectors allowing for heavy quark-antiquark pair annihilation and creation, but describing only low-energy modes around the heavy quark mass. Then we show the consistency of using HQEFT fields in constructing four-fermion local operators a la NRQCD, to be identified with standard color-octet matrix elements. We analyze some numerical values extracted from charmonia production by different authors and their hierarchy in the light of HQEFT.Comment: LaTeX, 19 pages, 3 EPS figure

    Virus satellites drive viral evolution and ecology

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    Virus satellites are widespread subcellular entities, present both in eukaryotic and in prokaryotic cells. Their modus vivendi involves parasitism of the life cycle of their inducing helper viruses, which assures their transmission to a new host. However, the evolutionary and ecological implications of satellites on helper viruses remain unclear. Here, using staphylococcal pathogenicity islands (SaPIs) as a model of virus satellites, we experimentally show that helper viruses rapidly evolve resistance to their virus satellites, preventing SaPI proliferation, and SaPIs in turn can readily evolve to overcome phage resistance. Genomic analyses of both these experimentally evolved strains as well as naturally occurring bacteriophages suggest that the SaPIs drive the coexistence of multiple alleles of the phage-coded SaPI inducing genes, as well as sometimes selecting for the absence of the SaPI depressing genes. We report similar (accidental) evolution of resistance to SaPIs in laboratory phages used for Staphylococcus aureus typing and also obtain the same qualitative results in both experimental evolution and phylogenetic studies of Enterococcus faecalis phages and their satellites viruses. In summary, our results suggest that helper and satellite viruses undergo rapid coevolution, which is likely to play a key role in the evolution and ecology of the viruses as well as their prokaryotic hosts
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