paper

Noether symmetries and duality transformations in cosmology

arXiv:1602.08914 · doi:10.1142/S0217732316501832

Abstract

We discuss the relation between Noether (point) symmetries and discrete symmetries for a class of minisuperspace cosmological models. We show that when a Noether symmetry exists for the gravitational Lagrangian then there exists a coordinate system in which a reversal symmetry exists. Moreover as far as concerns the scale-factor duality symmetry of the dilaton field, we show that it is related to the existence of a Noether symmetry for the field equations, and the reversal symmetry in the normal coordinates of the symmetry vector becomes scale-factor duality symmetry in the original coordinates. In particular the same point symmetry as also the same reversal symmetry exists for the Brans-Dicke- scalar field with linear potential while now the discrete symmetry in the original coordinates of the system depends on the Brans-Dicke parameter and it is a scale-factor duality when . Furthermore, in the context of the O'Hanlon theory for -gravity, it is possible to show how a duality transformation in the minisuperspace can be used to relate different gravitational models.

12 pages; discussion improved; to appear in MPLA

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