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A conformally coupled massive scalar field in the de Sitter expanding universe with the mass term treated as a perturbation

Lee, Yen Cheong (2009) A conformally coupled massive scalar field in the de Sitter expanding universe with the mass term treated as a perturbation. Classical and Quantum Gravity, 26 (13). pp. 1-14. ISSN 0264-9381; 1361-6382

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Official URL: http://iopscience.iop.org/0264-9381/

Abstract

We study conformally-coupled massive scalar field theory with the mass term treated as a perturbation in the expanding half of de Sitter spacetime as a toy model for comparing various perturbative formalisms. We point out that the in-out perturbation theory breaks down due to infrared divergences coming from the infinite future. We then clarify the relation between the free-theory vacuum and the true vacuum using the Bogolubov transformation and show that the discrepancy between the free-theory out-vacuum and the true vacuum causes apparent pair creation of free-theory particles and makes the in-out two-point function differ from the true two-point function. We also identify the infinite Bogolubov coefficients as the cause of infrared divergences. We then examine two alternative approaches: the Euclidean and in-in formalisms. We verify that there are no infrared divergences in perturbation theory with the mass term treated as a perturbation in either of these approaches and that the two-point function of massive scalar field is reproduced correctly by these methods.

Item Type:Article
Impact Factor:3.098
Subjects:Q Science > QC Physics
ID Code:7532
Deposited By: Dr. Yen Cheong Lee
Deposited On:12 Mar 2012 00:14
Last Modified:19 Jan 2017 08:25

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