On the (Non)Hadamard Property of the SJ State in a \(1+1\)D Causal Diamond

The Sorkin-Johnston (SJ) state is a candidate physical vacuum state for a scalar field in a generic curved spacetime. It has the attractive feature that it is covariantly and uniquely defined in any globally hyperbolic spacetime, often reflecting the underlying symmetries if there are any. A potenti...

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Bibliographic Details
Published inarXiv.org
Main Authors Yifeng Rocky Zhu, Yazdi, Yasaman K
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 15.12.2023
Subjects
Diamonds
Entanglement
Relativity
Scalars
Set theory
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Summary:The Sorkin-Johnston (SJ) state is a candidate physical vacuum state for a scalar field in a generic curved spacetime. It has the attractive feature that it is covariantly and uniquely defined in any globally hyperbolic spacetime, often reflecting the underlying symmetries if there are any. A potential drawback of the SJ state is that it does not always satisfy the Hadamard condition. In this work, we study the extent to which the SJ state in a \(1+1\)D causal diamond is Hadamard, finding that it is not Hadamard at the boundary. We then study the softened SJ state, which is a slight modification of the original state to make it Hadamard. We use the softened SJ state to investigate whether some peculiar features of entanglement entropy in causal set theory may be linked to its non-Hadamard nature.
ISSN:2331-8422
DOI:10.48550/arxiv.2212.10592