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Entanglement and entropy operator for strings in pp-wave time dependent background

A. L. Gadelha·Dafni Z. Marchioro·Daniel L. Nedel
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Abstract

In this letter new aspects of string theory propagating in a pp-wave time dependent background with a null singularity are explored. It is shown the appearance of a 2d entanglement entropy dynamically generated by the background. For asymptotically flat observers, the vacuum close to the singularity is unitarily inequivalent to the vacuum at $τ= -\infty$ and it is shown that the 2d entanglement entropy diverges close to this point. As a consequence, the positive time region is inaccessible for observers in $τ=-\infty$. For a stationary measure, the vacuum at finite time is seen by those observers as a thermal state and the information loss is encoded as a heat bath of string states.

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A. L. Gadelha, Dafni Z. Marchioro, Daniel L. Nedel. 2006-06-21. Entanglement and entropy operator for strings in pp-wave time dependent background. https://doi.org/10.1016/j.physletb.2006.06.044

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