1,760 research outputs found

    Heavy mesons in the Quark Model

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    Since the discovery of the J/ψJ/\psi, the quark model was very successful in describing the spectrum and properties of heavy mesons including only qqˉq\bar q components. However since 2003, with the discovery of the X(3872)X(3872), many states that can not be accommodated on the naive quark model have been discovered, and they made unavoidable to include higher Fock components on the heavy meson states. We will give an overview of the success of the quark model for heavy mesons and point some of the states that are likely to be more complicated structures such as meson-meson molecules.Comment: Contribution to the Proceedings of the 15th International Workshop on Meson Physics - MESON201

    Puzzles in quarkonium hadronic transitions with two pion emission

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    The anomalously large rates of some hadronic transitions from quarkonium are studied using QCD multipole expansion (QCDME) in the framework of a constituent quark model which has been successful in describing hadronic phenomenology. The hybrid intermediate states needed in the QCDME method are calculated in a natural extension of our constituent quark model based on the Quark Confining String (QCS) scheme. Some of the anomalies are explained due to the presence of an hybrid state with a mass near the mass of the decaying resonance whereas other are justified by the presence of molecular components in the wave function. Some unexpected results are pointed out.Comment: Conference proceedings of the XI Quark Confinement and the Hadron Spectrum (CONFINEMENT XI). Saint Petersburg (Russia) from 8 to 12 September 201

    The X(3872) and other possible XYZXYZ molecular states

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    We perform a coupled channel calculation of the DD∗DD^* and ccˉc\bar c sectors in the framework of a constituent quark model. The interaction for the DD∗DD^* states is obtained using the Resonant Group Method (RGM) and the underlying quark interaction model. The coupling with the two quark system is performed using the 3P0^3 P_0 model. The X(3872) is found as a molecular state with a sizable ccˉc\bar c component. A comparison with Belle and BaBar data has been done, finding a good agreement. Other possible molecular molecular states are discussed.Comment: 5 pages, 5 figures, Proceedings to the Hadron 2009 - XIII International Conference on Hadron Spectroscopy, Florida State University (USA

    La exclusión métodica del tiempo en metafísica

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    El límite mental es descrito como la plenitud formal del tiempo en atención a su carácter de condición antecedente en relación con la esencia inteligible. El conocimiento metafísico incluye una exclusión metódica que confina el tiempo en la posición de tema en orden a su abandono. El abandono de la plenitud formal del tiempo advierte el ser. Como condición antecedente del objeto pensado, el límite queda atrás de la acción práctica y es en ella traspasado

    La superación del tiempo (III)

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    Se estudian los sentidos en los que cabe entender el comiendo, deteniendo la atención en el comienzo del pensar (distinto del ser) como articulación presencial del tiempo. Este trabajo continúa el estudio sobre el tema del tiempo en la filosofía de Polo comenzado en La superación del tiempo {Studia Poliana, 2003, n° 5, 75-102 y 2005, n° 7, 41-74)

    Nonleptonic B→D(∗)DsJ(∗)B \to D^{(*)}D_{sJ}^{(*)} decays and the nature of the orbitally excited charmed-strange mesons

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    The Belle Collaboration has recently reported a study of the decays B→Ds1(2536)+Dˉ(∗)B \to D_{s1}(2536)^{+}\bar{D}^{(\ast)} and has given also estimates of relevant ratios between branching fractions of decays B→D(∗)DsJ(∗)B \to D^{(\ast)}D_{sJ}^{(\ast)} providing important information to check the structure of the Ds0∗(2317)D_{s0}^{\ast}(2317), Ds1(2460)D_{s1}(2460) and Ds1(2536)D_{s1}(2536) mesons. The disagreement between experimental data and Heavy Quark Symmetry has been used as an indication that Ds0∗(2317)D_{s0}^{\ast}(2317) and Ds1(2460)D_{s1}(2460) mesons could have a more complex structure than the canonical csˉc\bar{s} one. We analyze these ratios within the framework of a constituent quark model, which allows us to incorporate the effects given by finite cc-quark mass corrections. Our findings are that while the Ds1(2460)D_{s1}(2460) meson could have a sizable non-qqˉq\bar{q} component, the Ds0∗(2317)D_{s0}^{\ast}(2317) and Ds1(2536)D_{s1}(2536) mesons seem to be well described by a pure qqˉq\bar{q} structure.Comment: 13 pages, 1 figur

    Recomendações técnicas para o cultivo de melancia (Citrullus lanatus [Thumb.] Matsumura & Nakai) no Amapá.

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    Introdução; Botanica; Cultivares; Clima e época de plantio; Solo; Adubação; Preparo da terra; Preparo de mudas; Transplante; Crescimento e desenvolvimento; Tratos culturais; Doenças; Rotação de culturas; Colheita; Armazenamento; Mercado; Coeficientes técnicos; Bibliografia consultada.bitstream/item/97840/1/CPAF-AP-1999-Recomendacoes-melancia.pd

    Los sentidos del tiempo en Hegel.

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    l. Estudio del tiempo en la filosofía de Hegel, de acuerdo con la interpretación de Polo. Se distinguen dos sentidos hegeüanos del tiempo, y se expone el modo del tránsito dialéctico desde el uno hasta el otro. El primero es el tiempo entendido como la pura forma vacía del devenir, el segundo es el tiempo del espíritu, la pura variaáón negativa que se expresa en términos modales como posibilidad enter
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