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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik

MP 12: Quantenfeldtheorie und Kosmologie

MP 12.2: Vortrag

Donnerstag, 12. März 2009, 16:20–16:40, M010

The new ekpyrotic ghost — Renata Kallosh², •Jin U Kang^1,3, Andrei Linde², and Viatcheslav Mukhanov¹ — ¹Arnold-Sommerfeld-Center for Theoretical Physics, Department of Physics, Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, D-80333 Munich Germany — ²Department of Physics, Stanford University, Stanford, CA 94305, USA — ³Department of Physics, Kim Il Sung University, Pyongyang, DPR. Korea

The new ekpyrotic scenario attempts to solve the singularity problem by involving violation of the null energy condition in a model which combines the ekpyrotic/cyclic scenario with the ghost condensate theory and the curvaton mechanism of production of adiabatic perturbations of metric. The Lagrangian of this theory, as well as of the ghost condensate model, contains a term with higher derivatives, which was added to the theory to stabilize its vacuum state. We found that this term may affect the dynamics of the cosmological evolution. Moreover, after a proper quantization, this term results in the existence of a new ghost field with negative energy, which leads to a catastrophic vacuum instability. We explain why one cannot treat this dangerous term as a correction valid only at small energies and momenta below some UV cut-off, and demonstrate the problems arising when one attempts to construct a UV completion of this theory.