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Unexorcized ghost in DGP brane world

Keisuke Izumi·Kazuya Koyama·Takahiro Tanaka
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Abstract

The braneworld model of Dvali-Gabadadze-Porrati realizes the self-accelerating universe. However, it is known that this cosmological solution contains a spin-2 ghost. We study the possibility of avoiding the appearance of the ghost by slightly modifying the model, introducing the second brane. First we consider a simple model without stabilization of the separation of the brane. By changing the separation between the branes, we find we can erase the spin-2 ghost. However, this can be done only at the expense of the appearance of a spin-0 ghost instead. We discuss why these two different types of ghosts are correlated. Then, we examine a model with stabilization of the brane separation. Even in this case, we find that the correlation between spin-0 and spin-2 ghosts remains. As a result we find we cannot avoid the appearance of ghost by two-branes model.

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Keisuke Izumi, Kazuya Koyama, Takahiro Tanaka. 2007-02-22. Unexorcized ghost in DGP brane world. https://doi.org/10.1088/1126-6708%2F2007%2F04%2F053

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