862 research outputs found

    Phenomenological research on professsional knowledge and educational relationship building

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    Following Dewey’s (1997) and Schwab’s (2013) ideas, Clandinin & Connelly (1992) developed their notion of teacher as curriculum maker, it means, the “teacher not so much as a maker of curriculum but as a part of it and to imagine a place for contexts, culture (Dewey´s notion of interaction), and temporality (both past and future contained in Dewey´s notion of continuity)” (p.365). In this way, teachers are not seen as implementers of curricular plans but as part of the curriculum making process. In other words, they understand that students create their curriculum in their experience at school when they interact with teachers and the environment. Therefore, the educational relationship creates the framework where learning can take place and students can build knowledge (Atkinson, 2015); it means, relationships generate meeting places that allow the making and reshaping of curriculum. If teaching takes place in the relationship, it means recognition (and acceptance) of the other person, of the otherness. It supposes trying to come into relation with the other, and it implies also acceptance of the uncertainty that otherness has. Therefore, education Is not about the implementation of an education programme in order to achieve (pre)determined results. It is not about intervention on students, but it is an experience of relationship where each one constructs their own story (Molina, Blanco & Arbiol, 2016). In short, curriculum is made through experiences that are lived in relation and, therefore, we could say that education is an act of relationship (Piussi, 2006). In this way, education does not require that teachers have the most appropriate knowledge and programme for every situation; the educational experience is unpredictable and ineffable, we cannot anticipate or face it completely (Van Manen, 2015). Thus, teaching requires becoming aware of how we build relationships and how we see the other person (Contreras, 2002).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Meson-Baryon s-wave Resonances with Strangeness -3

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    Starting from a consistent SU(6) extension of the Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian (Phys. Rev. D74 (2006) 034025), we study the s-wave meson-baryon resonances in the strangeness S=-3 and negative parity sector. Those resonances are generated by solving the Bethe-Salpeter equation with the WT interaction used as kernel. The considered mesons are those of the 35-SU(6)-plet, which includes the pseudoscalar (PS) octet of pions and the vector (V) nonet of the rho meson. For baryons we consider the 56-SU(6)-plet, made of the 1/2+ octet of the nucleon and the 3/2+ decuplet of the Delta. Quantum numbers I(J^P)=0(3/2^-) are suggested for the experimental resonances Omega*(2250)- and Omega*(2380)-. Among other, resonances with I=1 are found, with minimal quark content sss\bar{l}l', being s the strange quark and l, l' any of the the light up or down quarks. A clear signal for such a pentaquark would be a baryonic resonance with strangeness -3 and electric charge of -2 or 0, in proton charge units. We suggest looking for K- Xi- resonances with masses around 2100 and 2240 MeV in the sector 1(1/2^-), and for pi Omega- and K- Xi*- resonances with masses around 2260 MeV in the sector 1(3/2^-).Comment: 3 pages, 1 Postscript figure, 7 table

    Large Nc Weinberg-Tomozawa interaction and negative parity s--wave baryon resonances

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    It is shown that in the 70 and 700 SU(6) irreducible spaces, the SU(6) extension of the Weinberg-Tomozawa (WT) s-wave meson-baryon interaction incorporating vector mesons ({\it hep-ph/0505233}) scales as O(Nc0){\cal O}(N_c^0), instead of the well known O(Nc1){\cal O}(N_c^{-1}) behavior for its SU(3) counterpart. However, the WT interaction behaves as order O(Nc1){\cal O}(N_c^{-1}) within the 56 and 1134 meson-baryon spaces. Explicit expressions for the WT couplings (eigenvalues) in the irreducible SU(2NFN_F) spaces, for arbitrary NFN_F and NcN_c, are given. This extended interaction is used as a kernel of the Bethe-Salpeter equation, to study the large NcN_c scaling of masses and widths of the lowest--lying negative parity s-wave baryon resonances. Analytical expressions are found in the NcN_c\to \infty limit, from which it can be deduced that resonance widths and excitation energies (MRM)(M_R-M) behave as order O(Nc0){\cal O} (N^0_c), in agreement with model independent arguments, and moreover they fall in the 70-plet, as expected in constituent quark models for an orbital excitation. For the 56 and 1134 spaces, excitation energies and widths grow O(Nc1/2){\cal O} (N_c^{1/2}) indicating that such resonances do not survive in the large NcN_c limit. The relation of this latter NcN_c behavior with the existence of exotic components in these resonances is discussed. The interaction comes out repulsive in the 700.Comment: 21 pages, 3 figures, requires wick.sty and young.sty. Subsection added. Conclusions revised. To appear in Physical Review

    Non-localities and Fermi motion corrections in KK^- atoms

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    We evaluate the p-wave KNK^-N amplitudes from the chiral Lagrangians and from there construct the p-wave part of the KK^- nucleus optical potential plus a small s-wave part induced from the elementary p-wave amplitude and the nuclear Fermi motion. Simultaneously, the momentum and energy dependence of the s-wave optical potential, previously developed, are taken into account and shown to generate a small p-wave correction to the optical potential. All the corrections considered are small compared to the leading s-wave potential, and lead to changes in the shifts and widths which are smaller than the experimental errors. A thorough study of the threshold region and low densities is conducted, revealing mathematical problems for which a physical solution is given.Comment: revised version, 28 pages, Latex, 8 postscript figures. Submitted to Nucl. Phys.

    D mesic nuclei

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    The energies and widths of several D^0 meson bound states for different nuclei are obtained using a D-meson selfenergy in the nuclear medium, which is evaluated in a selfconsistent manner using techniques of unitarized coupled-channel theory. The kernel of the meson-baryon interaction is based on a model that treats heavy pseudoscalar and heavy vector mesons on equal footing, as required by heavy quark symmetry. We find D^0 bound states in all studied nuclei, from 12C up to 208Pb. The inclusion of vector mesons is the keystone for obtaining an attractive D-nucleus interaction that leads to the existence of D^0-nucleus bound states, as compared to previous studies based on SU(4) flavor symmetry. In some cases, the half widths are smaller than the separation of the levels, what makes possible their experimental observation by means of a nuclear reaction. This can be of particular interest for the future PANDA@FAIR physics program. We also find a D^+ bound state in 12C, but it is too broad and will have a significant overlap with the energies of the continuum.Comment: 13 pages, 6 figures, 2 table

    Chiral Symmetry and s-wave Low-Lying Meson-Baryon Resonances

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    The ss-wave meson-baryon scattering is analyzed for the isospin-strangeness I=1/2,S=0I=1/2, S=0 and I=0,S=1I=0,S=-1 sectors, in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry. For both sectors, four channels have been considered: πN\pi N, ηN\eta N, KΛK \Lambda, KΣK \Sigma and πΣ\pi \Sigma, KˉN\bar K N, ηΛ\eta \Lambda, KΞK \Xi, respectively. The needed two particle irreducible matrix amplitudes are taken from lowest order Chiral Perturbation Theory in a relativistic formalism. There appear undetermined low energy constants, as a consequence of the renormalization of the amplitudes, which are obtained from fits to the available data: elastic πN\pi N phase-shifts, πpηn\pi^- p \to \eta n and πpK0Λ\pi^- p \to K^0 \Lambda cross sections and to πΣπΣ\pi\Sigma\to\pi\Sigma mass-spectrum, the elastic KˉNKˉN\bar K N \to \bar K N and KˉNπΣ \bar K N\to \pi \Sigma tt--matrices and to the KpηΛ K^- p \to \eta \Lambda cross section data. The position and residues of the complex poles in the second Riemann sheet of the scattering amplitude determine masses, widths and branching ratios of the S11S_{11}- NN(1535) and N-N(1650) and S01S_{01}- Λ\Lambda(1405) and Λ-\Lambda(1670) resonances, in reasonable agreement with experiment. A good overall description of data, from threshold up to around 2 GeV is achieved despite the fact that three-body channels have not been explicitly included.Comment: 5 Pages, 2 figures, invited contribution to Focus Session on Nature of Threshold N*, to be published in Proceedings of Nstar 2002, Pittsburgh, USA, October 9-12, 2002 (World Scientific

    Charmed hadrons in nuclear medium

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    We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner. We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions. We discuss the implications of the in-medium properties of open-charm mesons on the Ds0(2317)D_{s0}(2317) and the predicted X(3700) scalar resonances.Comment: 4 pages, 5 figures, invited parallel talk in the 5th International Conference on Quarks and Nuclear Physics (QNP09), Beijing, September 21-26, 200
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