Three types of statistics and the entropy bounds

We investigated the entropy bounds of the three types of statistics: para-Bose, para-Fermi and infinite statistics. We showed that the entropy bounds of the conventional Bose, Fermi statistics and their generalizations to parastatistics obey the $A^{3/4}$ law, while the entropy bound of infinite statistics obeys the area law. This suggests a close relationship between infinite statistics and quantum gravity.Comment: 5 pages, pubished versio

A Note on the Collision of Reissner-Nordstr\"om Gravitational Shock Waves in AdS

We study the collision of two Reissner-Nordstr\"om gravitational shock waves in AdS and show that the charge completely prevents the formation of marginally trapped surfaces of the Penrose type with topology S^(D-2), independently of the energy and the value of the impact parameter. In the case of head-on collisions, a numerical analysis shows that no trapped surfaces with topology S^1 \times S^(D-3) form either.Comment: 13 pages, 6 figures. LaTeX. v2: major change

Scalar dark energy models mimicking Λ\LambdaCDM with arbitrary future evolution

Dark energy models with various scenarios of evolution are considered from the viewpoint of the formalism for the equation of state. It is shown that these models are compatible with current astronomical data. Some of the models presented here evolve arbitrarily close to $\Lambda$CDM up to the present, but diverge in the future into a number of different possible asymptotic states, including asymptotic de-Sitter (pseudo-rip) evolution, little rips with disintegration of bound structures, and various forms of finite-time future singularities. Therefore it is impossible from observational data to determine whether the universe will end in a future singularity or not. We demonstrate that the models under consideration are stable for a long period of time (billions of years) before entering a Little Rip/Pseudo-Rip induced dissolution of bound structures or before entering a soft finite-time future singularity. Finally, the physical consequences of Little Rip, Type II, III and Big Crush singularities are briefly compared.Comment: 15 pages, 1 figure, version to appear in Physics Letters

Generalized planar black holes and the holography of hydrodynamic shear

10.1016/j.nuclphysb.2013.11.013Nuclear Physics B8781186-213NUPB