Cosmic Acceleration and Anisotropic models with Magnetic field

Plane symmetric cosmological models are investigated with or without any dark energy components in the field equations. Keeping an eye on the recent observational constraints concerning the accelerating phase of expansion of the universe, the role of magnetic field is assessed. In the absence of dark energy components, magnetic field can favour an accelerating model even if we take a linear relationship between the directional Hubble parameters. In presence of dark energy components in the form of a time varying cosmological constant, the influence of magnetic field is found to be limited.Comment: 19 pages, 3 figures, submitted to EPJ plu

On the Uniqueness of Supersymmetric Attractors

In this paper we discuss the uniqueness of supersymmetric attractors in four dimensional N=2 supergravity theories coupled to n vector multiplets. We prove that for a given charge configuration the supersymmetry preserving axion free attractors are unique. We generalise the analysis to axionic attractors and state the conditions for uniqueness explicitly. We consider the example of a two-parameter model and find all solutions to the supersymmetric attractor equations and discuss their uniqueness.Comment: 12 pages, Late