74,164 research outputs found

    Comparing pion production models to MiniBooNE data

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    Predictions for neutrino-induced charged- and neutral-current single pion production on CH_2 from theoretical models and Monte Carlo event generators are compared with the cross section measurements from the MiniBooNE experiment.Comment: Presented at the Eigth International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt12

    Nature of the Gravitational Field and its Legitimate Energy-Momentum Tensor

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    In this paper we show how a gravitational field generated by a given energy-momentum distribution (for all realistic cases) can be represented by distinct geometrical structures (Lorentzian, teleparallel and non null nonmetricity spacetimes) or that we even can dispense all those geometrical structures and simply represent the gravitational field as a field, in the Faraday's sense, living in Minkowski spacetime. The explicit Lagrangian density for this theory is given and the field equations (which are a set of four Maxwell's like equations) are shown to be equivalent to Einstein's equations. We also analyze if the teleparallel formulation can give a mathematical meaning to "Einstein's most happy thought", i.e. the equivalence principle. Moreover we discuss the Hamiltonian formalism for for our theory and its relation to one of the possibles concepts for energy of the gravitational field which emerges from it and the concept of ADM energy. One of the main results of the paper is the identification in our theory of a legitimate energy-mometum tensor for the gravitational field expressible through a really nice formula.Comment: paper presented at the IX International Conference on Clifford Algebras and their Applications in Mathematical Physics (ICC9), Weimar, July 15-20, 2011. This version corrects some misprints of the version appearing in Rep. Math. Phys. 69, 265-279 (2012

    Spiralling dynamics near heteroclinic networks

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    There are few explicit examples in the literature of vector fields exhibiting complex dynamics that may be proved analytically. We construct explicitly a {two parameter family of vector fields} on the three-dimensional sphere \EU^3, whose flow has a spiralling attractor containing the following: two hyperbolic equilibria, heteroclinic trajectories connecting them {transversely} and a non-trivial hyperbolic, invariant and transitive set. The spiralling set unfolds a heteroclinic network between two symmetric saddle-foci and contains a sequence of topological horseshoes semiconjugate to full shifts over an alphabet with more and more symbols, {coexisting with Newhouse phenonema}. The vector field is the restriction to \EU^3 of a polynomial vector field in \RR^4. In this article, we also identify global bifurcations that induce chaotic dynamics of different types.Comment: change in one figur

    Numerical model to account for the influence of infill masonry on the RC structures behaviour

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    It is a common misconception considers that masonry infill walls in structural RC buildings can only increase the overall lateral load capacity, and, therefore, must always be considered beneficial to seismic performance. Recent earthquakes have showed numerous examples of severe damages or collapses of buildings caused by structural response modification induced by the non-structural masonry partitions. From a state-of-the-art review of the available numerical models for the representation of the infill masonry behaviour in structural response, it was proposed an upgraded model. The proposed model is inspired on the equivalent bi-diagonal compression strut model, and considers the non-linear behaviour of the infill masonry subjected to cyclic loads. The model was implemented and calibrated in a non-linear dynamic computer code, VISUALANL. In this paper, it is presented the proposed model and the results of the calibration analyses are briefly introduced and discussed
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