Abstract
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.
Original language | English (US) |
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Pages (from-to) | 1649-1679 |
Number of pages | 31 |
Journal | Journal of High Energy Physics |
Volume | 8 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 2004 |
Keywords
- Bosonic Strings
- Discrete and Finite Symmetries
- Renormalization Regularization and Renormalons
ASJC Scopus subject areas
- Nuclear and High Energy Physics