@article{d0a5e9f93b7145ffb953c2d555c2d332,
title = "Vacuum state in de Sitter spacetime with static charts",
abstract = "We study the free massive scalar field in de Sitter spacetime with static charts. In particular, we find positive-frequency modes for the Bunch-Davies vacuum state natural to the static charts as superpositions of the well-known positive-frequency modes in the conformally-flat chart. We discuss in detail how these modes are defined globally in the two static charts and the region in their future. The global structure of these solutions leads to the well-known description of the Bunch-Davies vacuum state as an entangled state. Our results are expected to be useful not only for studying the thermal properties in the vacuum fluctuations in de Sitter spacetime but also for understanding the nonlocal properties of the vacuum state.",
author = "Atsushi Higuchi and Kazuhiro Yamamoto",
note = "Funding Information: This work was supported by MEXT/JSPS KAKENHI Grants No. 15H05895, No. 17K05444, and No. 17H06359 (K. Y.). We thank K. Ueda, Y. Nambu, J. Soda, S. Kanno, S. Iso, S.-Y. Lin, T. Markkanen, and M. Sasaki for useful discussions related to the topic in the present paper. K. Y. is grateful for the warm hospitality of the Mathematics Department of the University of York, where part of this work was carried out. Funding Information: This work was supported by MEXT/JSPS KAKENHI Grants No.15H05895, No. 17K05444, and No. 17H06359 (K.Y.). We thank K. Ueda, Y. Nambu, J. Soda, S. Kanno, S. Iso, S.-Y. Lin, T. Markkanen, and M. Sasaki for useful discussions related to the topic in the present paper. K.Y. is grateful for the warm hospitality of the Mathematics Department of the University of York, where part of this work was carried out. Publisher Copyright: {\textcopyright} 2018 American Physical Society.",
year = "2018",
month = sep,
day = "25",
doi = "10.1103/PhysRevD.98.065014",
language = "English",
volume = "98",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Physical Society",
number = "6",
}