44 research outputs found

    Effect of gluon-exchange pair-currents on the ratio G(E(P))/G(M(P))

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    The effect of one-gluon-exchange (OGE) pair-currents on the ratio ÎĽpGEp/GMp\mu_p G_E^p/G_M^p for the proton is investigated within a nonrelativistic constituent quark model (CQM) starting from SU(6)Ă—O(3)SU(6) \times O(3) nucleon wave functions, but with relativistic corrections. We found that the OGE pair-currents are important to reproduce well the ratio ÎĽpGEp/GMp\mu_p G_E^p/G_M^p. With the assumption that the OGE pair-currents are the driving mechanism for the violation of the scaling law we give a prediction for the ratio ÎĽnGEn/GMn\mu_n G_E^n/G_M^n of the neutron.Comment: 5 pages, 4 figure

    Design and analysis of cross vaults along history

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    The history of cross vaults began almost 2,000 years ago with a widespread use during the Middle Ages and Renaissance, becoming nowadays one of the most diffused and fascinating structural typologies of the European building cultural heritage. However, conversely to the undeniable excellence achieved by the ancient masons, the structural behavior of these elements is still at the center of the scientific debate. In this regard, with the aim of reviewing the knowledge on this subject as a concise and valuable support for researchers involved in conservation of historical buildings, with a focus on design rules and structural analysis, the present study firstly introduces the cross vaults from a historical perspective, by describing the evolution of the main geometrical shapes together with basic practical rules used to size them. Then, the article deals with the subsequent advancements in structural analysis methods of vaults, until the development of modern limit analysis.This work was partially carried out under the program "Dipartimento di Protezione Civile - Consorzio RELUIS", signed on 2013-12-27.info:eu-repo/semantics/publishedVersio
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