TY - JOUR
T1 - The taming of closed time-like curves
AU - Biswas, Rahul
AU - Keski-Vakkuri, Esko
AU - Leigh, Robert G.
AU - Nowling, Sean
AU - Sharpe, Eric
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2004/1/1
Y1 - 2004/1/1
N2 - We consider a ℝ1,d/ℤ2 orbifold, where ℤ2 acts by time and space reversal, also known as the embedding space of the elliptic de Sitter space. The background has two potentially dangerous problems: time-nonorientability and the existence of closed time-like curves. We first show that closed causal curves disappear after a proper definition of the time function. We then consider the one-loop vacuum expectation value of the stress tensor. A naive QFT analysis yields a divergent result. We then analyze the stress tensor in bosonic string theory, and find the same result as if the target space would be just the Minkowski space ℝ1,d, suggesting a zero result for the superstring. This leads us to propose a proper reformulation of QFT, and recalculate the stress tensor. We find almost the same result as in Minkowski space, except for a potential divergence at the initial time slice of the orbifold, analogous to a spacelike Big Bang singularity. Finally, we argue that it is possible to define local S-matrices, even if the spacetime is globally time-nonorientable.
AB - We consider a ℝ1,d/ℤ2 orbifold, where ℤ2 acts by time and space reversal, also known as the embedding space of the elliptic de Sitter space. The background has two potentially dangerous problems: time-nonorientability and the existence of closed time-like curves. We first show that closed causal curves disappear after a proper definition of the time function. We then consider the one-loop vacuum expectation value of the stress tensor. A naive QFT analysis yields a divergent result. We then analyze the stress tensor in bosonic string theory, and find the same result as if the target space would be just the Minkowski space ℝ1,d, suggesting a zero result for the superstring. This leads us to propose a proper reformulation of QFT, and recalculate the stress tensor. We find almost the same result as in Minkowski space, except for a potential divergence at the initial time slice of the orbifold, analogous to a spacelike Big Bang singularity. Finally, we argue that it is possible to define local S-matrices, even if the spacetime is globally time-nonorientable.
KW - Bosonic Strings
KW - Discrete and Finite Symmetries
KW - Renormalization Regularization and Renormalons
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U2 - 10.1088/1126-6708/2004/01/064
DO - 10.1088/1126-6708/2004/01/064
M3 - Article
AN - SCOPUS:23144466916
VL - 8
SP - 1649
EP - 1679
JO - Journal of High Energy Physics
JF - Journal of High Energy Physics
SN - 1126-6708
IS - 1
ER -