Erratum: QCD sum rules study of the JPC=1−−J^{PC}=1^{--} charmonium YY mesons

We correct a mistake in the analytical expression given in Nucl. Phys. {\bf A} 815, 53 (2009) [arXiv:0804.4817] for the $D_{s0}\bar{D}_s^*$ and $D_{0}\bar{D}^*$ molecular currents. As a consequence, the mass obtained for the $D_{0}\bar{D}^*$ molecular current: $m_{D_{0}\bar{D}^*}=(4.96\pm 0.11)$ GeV is no longer compatible with the experimental mass of the meson Y(4260).Comment: 1 pag

Production of the Y(4260) State in B Meson Decay

We calculate the branching ratio for the production of the meson $Y(4260)$ in the decay $B^- \to Y(4260)K^-$. We use QCD sum rules approach and we consider the $Y(4260)$ to be a mixture between charmonium and exotic tetraquark, $[\bar{c}\bar{q}][qc]$, states with $J^{PC}=1^{--}$. Using the value of the mixing angle determined previously as: $\theta=(53.0\pm0.5)^\circ$, we get the branching ratio $\mathcal{B}(B\to Y(4260)K)=(1.34\pm0.47)\times10^{-6}$, which allows us to estimate an interval on the branching fraction $3.0 \times 10^{-8} < {\mathcal B}_{_Y} < 1.8 \times 10^{-6}$ in agreement with the experimental upper limit reported by Babar Collaboration.Comment: 5 pages, 2 figures, 1 table. arXiv admin note: text overlap with arXiv:1105.134

Comment on ``Casimir force in compact non-commutative extra dimensions and radius stabilization''

We call attention to a series of mistakes in a paper by S. Nam [JHEP 10 (2000) 044, hep-th/0008083].Comment: 6 pages, LaTeX, uses JHEP.cl

Y(4260) as a mixed charmonium-tetraquark state

Using the QCD sum rule approach we study the Y(4260) state assuming that it can be described by a mixed charmonium-tetraquark current with $J^{PC}=1^{--}$ quantum numbers. For the mixing angle around $\theta \approx (53.0\pm 0.5)^{0}$, we obtain a value for the mass which is in good agreement with the experimental mass of the Y(4260). However, for the decay width we find the value \Ga_Y \approx (1.0\pm 0.2) MeV which is not compatible with the experimental value \Ga \approx (88\pm 23) MeV. Therefore, we conclude that, although we can explain the mass of the Y(4260), this state cannot be described as a mixed charmonium-tetraquark state since, with this assumption, we can not explain its decay width.Comment: 9 pages, 6 figure

A Neural Network Gravitational Arc Finder based on the Mediatrix filamentation Method

Automated arc detection methods are needed to scan the ongoing and next-generation wide-field imaging surveys, which are expected to contain thousands of strong lensing systems. Arc finders are also required for a quantitative comparison between predictions and observations of arc abundance. Several algorithms have been proposed to this end, but machine learning methods have remained as a relatively unexplored step in the arc finding process. In this work we introduce a new arc finder based on pattern recognition, which uses a set of morphological measurements derived from the Mediatrix Filamentation Method as entries to an Artificial Neural Network (ANN). We show a full example of the application of the arc finder, first training and validating the ANN on simulated arcs and then applying the code on four Hubble Space Telescope (HST) images of strong lensing systems. The simulated arcs use simple prescriptions for the lens and the source, while mimicking HST observational conditions. We also consider a sample of objects from HST images with no arcs in the training of the ANN classification. We use the training and validation process to determine a suitable set of ANN configurations, including the combination of inputs from the Mediatrix method, so as to maximize the completeness while keeping the false positives low. In the simulations the method was able to achieve a completeness of about 90% with respect to the arcs that are input to the ANN after a preselection. However, this completeness drops to $\sim$ 70% on the HST images. The false detections are of the order of 3% of the objects detected in these images. The combination of Mediatrix measurements with an ANN is a promising tool for the pattern recognition phase of arc finding. More realistic simulations and a larger set of real systems are needed for a better training and assessment of the efficiency of the method.Comment: Updated to match published versio

On invariants of almost symplectic connections

We study the irreducible decomposition under Sp(2n, R) of the space of torsion tensors of almost symplectic connections. Then a description of all symplectic quadratic invariants of torsion-like tensors is given. When applied to a manifold M with an almost symplectic structure, these instruments give preliminary insight for finding a preferred linear almost symplectic connection on M . We rediscover Ph. Tondeur's Theorem on almost symplectic connections. Properties of torsion of the vectorial kind are deduced

Detection of Exotic Massive Hadrons in Ultra High Energy Cosmic Ray Telescopes

We investigate the detection of exotic massive strongly interacting hadrons (uhecrons) in ultra high energy cosmic ray telescopes. The conclusion is that experiments such as the Pierre Auger Observatory have the potential to detect these particles. It is shown that uhecron showers have clear distinctive features when compared to proton and nuclear showers. The simulation of uhecron air showers, and its detection and reconstruction by fluorescence telescopes is described. We determine basic cuts in observables that will separate uhecrons from the cosmic ray bulk, assuming this is composed by protons. If these are composed by heavier nucleus the separation will be much improved. We also discuss photon induced showers. The complementarity between uhecron detection in accelerator experiments is discussed.Comment: 9 page 9 figure

Coleção de cultivares acidófilas de mandioca do CPATU.

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