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arXiv · 1309.3402

Unitarity and singular backgrounds

Nikos Brouzakis·Mariano Quiros
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Abstract

We compute the graviton Kaluza-Klein spectrum on a gravity-dilaton background with a naked singularity for all possible boundary conditions at the singularity which are consistent with unitary evolution. We apply methods from non-relativistic quantum mechanics with singular Schr\"{o}dinger potentials. In general the spectrum contains a tachyon, a sign of instability. Only for a particular boundary condition at the singularity is the spectrum free of tachyons. In this case the lowest-lying graviton mode is massless. We argue that this result will also hold for other backgrounds with similar geometry near the curvature singularity. We complete our study with a brief discussion on radion perturbations and the Higgs mechanism on this singular background.

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Nikos Brouzakis, Mariano Quiros. 2013-09-13. Unitarity and singular backgrounds. https://doi.org/10.1103/physrevd.88.096007

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