2,448 research outputs found

    Zc(3900)Z_c(3900): Confronting theory and lattice simulations

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    We consider a recent TT-matrix analysis by Albaladejo {\it et al.}, [Phys.\ Lett.\ B {\bf 755}, 337 (2016)] which accounts for the J/ψπJ/\psi\pi and DDˉD^\ast\bar{D} coupled--channels dynamics, and that successfully describes the experimental information concerning the recently discovered Zc(3900)±Z_c(3900)^\pm. Within such scheme, the data can be similarly well described in two different scenarios, where the Zc(3900)Z_c(3900) is either a resonance or a virtual state. To shed light into the nature of this state, we apply this formalism in a finite box with the aim of comparing with recent Lattice QCD (LQCD) simulations. We see that the energy levels obtained for both scenarios agree well with those obtained in the single-volume LQCD simulation reported in Prelovsek {\it et al.} [Phys.\ Rev.\ D {\bf 91}, 014504 (2015)], making thus difficult to disentangle between both possibilities. We also study the volume dependence of the energy levels obtained with our formalism, and suggest that LQCD simulations performed at several volumes could help in discerning the actual nature of the intriguing Zc(3900)Z_c(3900) state

    Heavy-to-light scalar form factors from Muskhelishvili-Omn\`es dispersion relations

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    By solving the Muskhelishvili-Omn\`es integral equations, the scalar form factors of the semileptonic heavy meson decays DπˉνD\to\pi \bar \ell \nu_\ell, DKˉˉνD\to \bar{K} \bar \ell \nu_\ell, Bˉπνˉ\bar{B}\to \pi \ell \bar\nu_\ell and BˉsKνˉ\bar{B}_s\to K \ell \bar\nu_\ell are simultaneously studied. As input, we employ unitarized heavy meson-Goldstone boson chiral coupled-channel amplitudes for the energy regions not far from thresholds, while, at high energies, adequate asymptotic conditions are imposed. The scalar form factors are expressed in terms of Omn\`es matrices multiplied by vector polynomials, which contain some undetermined dispersive subtraction constants. We make use of heavy quark and chiral symmetries to constrain these constants, which are fitted to lattice QCD results both in the charm and the bottom sectors, and in this latter sector to the light-cone sum rule predictions close to q2=0q^2=0 as well. We find a good simultaneous description of the scalar form factors for the four semileptonic decay reactions. From this combined fit, and taking advantage that scalar and vector form factors are equal at q2=0q^2=0, we obtain Vcd=0.244±0.022|V_{cd}|=0.244\pm 0.022, Vcs=0.945±0.041|V_{cs}|=0.945\pm 0.041 and Vub=(4.3±0.7)×103|V_{ub}|=(4.3\pm 0.7)\times10^{-3} for the involved Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. In addition, we predict the following vector form factors at q2=0q^2=0: f+Dη(0)=0.01±0.05|f_+^{D\to\eta}(0)|=0.01\pm 0.05, f+DsK(0)=0.50±0.08|f_+^{D_s\to K}(0)|=0.50 \pm 0.08, f+Dsη(0)=0.73±0.03|f_+^{D_s\to\eta}(0)|=0.73\pm 0.03 and f+Bˉη(0)=0.82±0.08|f_+^{\bar{B}\to\eta}(0)|=0.82 \pm 0.08, which might serve as alternatives to determine the CKM elements when experimental measurements of the corresponding differential decay rates become available. Finally, we predict the different form factors above the q2q^2-regions accessible in the semileptonic decays, up to moderate energies amenable to be described using the unitarized coupled-channel chiral approach.Comment: includes further discussions and references; matches the accepted versio

    Lowest-lying even-parity Bˉs{\bar{B}}_s B ¯ s mesons: heavy-quark spin-flavor symmetry, chiral dynamics, and constituent quark-model bare masses

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    The discovery of the Ds0(2317)D^*_{s0}(2317) and Ds1(2460)D_{s1}(2460) resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between QqˉQ{\bar{q}} and (Qqˉ)(qqˉ)(Q{\bar{q}})(q{\bar{q}}) Fock components. In contrast to the csˉc{\bar{s}} sector, there is no experimental evidence of JP=0+,1+J^P=0^+,1^+ bottom–strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the Ds0(2317)D_{s0}^*(2317) and Ds1(2460)D_{s1}(2460) states are analyzed within a heavy meson chiral unitary scheme. As a novelty, the coupling between the constituent quark-model P-wave Bˉs{\bar{B}}_s scalar and axial mesons and the Bˉ()K{\bar{B}}^{(*)}K channels is incorporated employing an effective interaction, consistent with heavy-quark spin symmetry, constrained by the lattice energy levels

    Anomalous Nuclear Quantum Effects in Ice

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    One striking anomaly of water ice has been largely neglected and never explained. Replacing hydrogen (1^1H) by deuterium (2^2H) causes ice to expand, whereas the "normal" isotope effect is volume contraction with increased mass. Furthermore, the anomaly increases with temperature TT, even though a normal isotope shift should decrease with TT and vanish when TT is high enough to use classical nuclear motions. In this study, we show that these effects are very well described by {\it ab initio} density functional theory. Our theoretical modeling explains these anomalies, and allows us to predict and to experimentally confirm a counter effect, namely that replacement of 16^{16}O by 18^{18}O causes a normal lattice contraction.Comment: 5 pages, 3 figure

    The 2011 submarine volcanic eruption in El Hierro (Canary Islands)

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    Forty years after the Teneguía Volcano (La Palma, 1971), a submarine eruption took place off the town of La Restinga, south of El Hierro, the smallest and youngest island of the Canarian Archipelago. Precursors allowed an early detection of the event and its approximate location, suggesting it was submarine. Uncertainties derived from insufficient scientific information available to the authorities during the eruption, leading to disproportionate civil protection measures, which had an impact on the island's economy-based primarily on tourism-while residents experienced extra fear and distress. © 2012 Blackwell Publishing Ltd, The Geologists' Association & The Geological Society of London.Peer Reviewe

    The 2011 submarine volcanic eruption in El Hierro (Canary Islands)

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    Forty years after the Teneguía Volcano (La Palma, 1971), a submarine eruption took place off the town of La Restinga, south of El Hierro, the smallest and youngest island of the Canarian Archipelago. Precursors allowed an early detection of the event and its approximate location, suggesting it was submarine. Uncertainties derived from insufficient scientific information available to the authorities during the eruption, leading to disproportionate civil protection measures, which had an impact on the island's economy-based primarily on tourism-while residents experienced extra fear and distress. © 2012 Blackwell Publishing Ltd, The Geologists' Association & The Geological Society of London.Peer Reviewe

    3849_REDITS. Red Interuniversitaria para la didáctica en Trabajo Social

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    El presente trabajo se enmarca en el seno del Programa de Redes-ICE de investigación en docencia universitaria del Vicerrectorado de Calidad e Innovación Educativa-Instituto de Ciencias de la Educación de la Universidad de Alicante (convocatoria 2016-17), “Ref.: 3849 REDITS”. Como primera estrategia partimos de la revisión de la literatura especializada recogiendo lo que venimos trabajando sobre competencias en Trabajo Social y promoción del trabajo colaborativo, e incorporando los aspectos relativos a la supervisión, estableciendo la diferencia entre la supervisión educativa y la supervisión profesional. Se realizó una revisión de la producción desarrollada por REDITS, a efectos de ir procurando no solo la homologación de criterios sino la construcción de estrategias de trabajo a partir de los resultados de las supervisiones. La segunda estrategia consistió en el seguimiento de experiencias puntuales de docencia en las que la red constituye un espacio de construcción de alternativas a partir de poner en común casos de cada universidad buscando puntos de convergencia y alternativas de trabajo. Se trabajó particularmente aspectos relativos a la educación inclusiva en el ámbito universitario. Como tercera estrategia se realizo un grupo de discusión de profesorado y se pasaron evaluaciones abiertas al alumnado sobre los tipos de supervisión en el proceso de enseñanza aprendizaje
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