34,937 research outputs found

    Gauge invariant fluctuations of the metric during inflation from new scalar-tensor Weyl-Integrable gravity model

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    We investigate gauge invariant scalar fluctuations of the metric during inflation in a non-perturbative formalism in the framework of a recently introduced scalar-tensor theory of gravity formulated on a Weyl-Integrable geometry. We found that the Weyl scalar field can play the role of the inflaton field in this theory. As an application we study the case of a power law inflation. In this case the quasi-scale invariance of the spectrum for scalar fluctuations of the metric is achieved for determined values of the ω\omega parameter of the scalar-tensor theory. In our formalism the physical inflaton field has a geometrical origin.Comment: 9 pages, no figures. This is a revised version accepted for publication in Physical Review

    Integral relations and the adiabatic expansion method for 1+2 reactions above the breakup threshold: Helium trimers with soft-core potentials

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    The integral relations formalism introduced in \cite{bar09,rom11}, and designed to describe 1+NN reactions, is extended here to collision energies above the threshold for the target breakup. These two relations are completely general, and in this work they are used together with the adiabatic expansion method for the description of 1+2 reactions. The neutron-deuteron breakup, for which benchmark calculations are available, is taken as a test of the method. The s-wave collision between the 4^4He atom and 4^4He2_2 dimer above the breakup threshold and the possibility of using soft-core two-body potentials plus a short-range three-body force will be investigated. Comparisons to previous calculations for the three-body recombination and collision dissociation rates will be shown.Comment: To be published in Physical Review
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