1,059 research outputs found

    Spinless Matter in Transposed-Equi-Affine Theory of Gravity

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    We derive and discus the equations of motion for spinless matter: relativistic spinless scalar fields, particles and fluids in the recently proposed by A. Saa model of gravity with covariantly constant volume with respect to the transposed connection in Einstein-Cartan spaces. A new interpretation of this theory as a theory with variable Plank "constant" is suggested. We show that the consistency of the semiclassical limit of the wave equation and classical motion dictates a new definite universal interaction of torsion with massive fields.Comment: 29 pages, latex, no figures. New Section on semiclassical limit of wave equation added; old references rearranged; new references, remarks, comments, and acknowledgments added; typos correcte

    Riemannian and Teleparallel Descriptions of the Scalar Field Gravitational Interaction

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    A comparative study between the metric and the teleparallel descriptions of gravitation is made for the case of a scalar field. In contrast to the current belief that only spin matter could detect the teleparallel geometry, scalar matter being able to feel the metric geometry only, we show that a scalar field is able not only to feel anyone of these geometries, but also to produce torsion. Furthermore, both descriptions are found to be completely equivalent, which means that in fact, besides coupling to curvature, a scalar field couples also to torsion.Comment: Minor corrections made, and a paragraph added to the last section. Version to appear in Gen. Rel. Gra

    Neutron star in presence of torsion-dilaton field

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    We develop the general theory of stars in Saa's model of gravity with propagating torsion and study the basic stationary state of neutron star. Our numerical results show that the torsion force decreases the role of the gravity in the star configuration leading to significant changes in the neutron star masses depending on the equation of state of star matter. The inconsistency of the Saa's model with Roll-Krotkov-Dicke and Braginsky-Panov experiments is discussed.Comment: 29 pages, latex, 24 figures, final version. Added: 1)comments on different possible mass definitions; 2)new sections: a)the inconsistency of the Saa's model with Roll-Krotkov-Dicke and Braginsky-Panov experiments; b)stability analysis via catastrophe theory; 3)new figers added and some figures replaced. 4)new reference

    The Raychaudhuri equations: a brief review

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    We present a brief review on the Raychaudhuri equations. Beginning with a summary of the essential features of the original article by Raychaudhuri and subsequent work of numerous authors, we move on to a discussion of the equations in the context of alternate non--Riemannian spacetimes as well as other theories of gravity, with a special mention on the equations in spacetimes with torsion (Einstein--Cartan--Sciama--Kibble theory). Finally, we give an overview of some recent applications of these equations in General Relativity, Quantum Field Theory, String Theory and the theory of relativisitic membranes. We conclude with a summary and provide our own perspectives on directions of future research.Comment: 35 pages, two figures, to appear in the special issue of Pramana dedicated to the memory of A. K. Raychaudhur

    Two Loop Scalar Self-Mass during Inflation

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    We work in the locally de Sitter background of an inflating universe and consider a massless, minimally coupled scalar with a quartic self-interaction. We use dimensional regularization to compute the fully renormalized scalar self-mass-squared at one and two loop order for a state which is released in Bunch-Davies vacuum at t=0. Although the field strength and coupling constant renormalizations are identical to those of lfat space, the geometry induces a non-zero mass renormalization. The finite part also shows a sort of growing mass that competes with the classical force in eventually turning off this system's super-acceleration.Comment: 31 pages, 5 figures, revtex4, revised for publication with extended list of reference

    Anales de Edafología y Agrobiología Tomo 47 Número 3-4

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    Suelos. Física. Resistencia del suelo y susceptibilidad a la compactación en terrenos a monte sometidos a pastoreo. Por R. Pérez Moreira y F. Diaz-Fierros Viqueira.-- La reserva de agua útil de los suelos de Galicia. l. Relación con la textura y el contenido de materia orgánica. Por A. M. Martinez Cortizas.-- Química Empleo de aminas alifáticas en el estudio de asociaciones haloisita-esmectita en suelos. Por F. J. Aragoneses, J. Casas, y J. L. Martin de Vidales.-- Quelación por EDDHA de micronutrientes en suelos calizos. Ecuación de límite máximo. Por M. Juárez, J. Sánchez-Andréu, L. Pla y J. Jorda.-- Quelación por EDDHA de micronutrientes en suelos calizos. Ecuación de orden "n ".Por J. Sánchez-Andréu, M. Juarez, L. Pla y J. Jordá.-- Génesis, Clasificación y Cartografía Caracterización de un podsol ferro - húmico en el Puerto de la Quesera (Sierra del Ayllón). Por R. Espejo Serrano, F. Guerrero López y A. Saa Requejo.-- Natrixerales en el Baix Segre (Lleida). Por J. Bech i Borrás, J. Garrigo i Reixach y J. R. Torrento i Marselles.-- Aspectos micromorfológicos del horizonte superior en suelos artificiales (Sorribas) de las Islas Canarias. Por A. Rodríguez Rodríguez y J. M. Ontañón Sánchez.-- Fertilidad Influencia de diferentes factores del suelo sobre su contenido en microelementos asimilables: Mn, Fe, Cu y Zn. Por B. C. Ortega, Ma C. Ortega y J. G. de las Heras.--Incidencia de la salinidad del agua de riego en la mineralización del nitrógeno orgánico en suelos calizos del sureste español. Por J. García-Serna, J. Sánchez Andréu, M. Juárez y J. Mataix.-- Biología Vegetal-Fisiología Efectos de la toxicidad del flúor sobre el ciclo biológico en especies herbáceas dicotiledoneas. Por M. Ibarra, F. López Belmonte y Ma A. Diez.-- Efectos de la toxicidad del flúor sobre el ciclo biológico de especies de monocotiledoneas. Por M. Ibarra, F. López-Belmonte y Mª A . Diez.-- Proteasas ácidas en uvas Vitis vinifera (variedad Macabeo). l. Actividad proteásica durante su maduración. Por J. Marín Expósito, C. Miguel Gordillo, J. l. Maynar Mariño y J. L. Mesias Iglesias.-- Agro biología Efectos de enmiendas calcáreas en suelos fijadores de fósforo. Por S. G. Ramos Hernández y N. Aguilera Herrera.-- III. Trabajo Recapitulativo. Una deriva hacia hemiparasftismo de los líquenes epifitos: Análisis fisiológico de las relaciones con sus fitoforos. Por C. VicentePeer reviewed2019-08.- CopyBook.- Libnova.- Biblioteca IC

    Cross section measurement of t-channel single top quark production in pp collisions at root s=13 TeV

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    Coherent J/psi photoproduction in ultra-peripheral PbPb collisions at root s(NN)=2.76 TeV with the CMS experiment

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