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arXiv · hep-th/0310123

Troubles with Spacetime Noncommutative Theories: Tachyons or S-branes?

Dongsu Bak·Seok Kim
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Abstract

We find Lorentzian solutions of spacetime noncommutative gauge theories that are localized exponentially in space and time. Together with time translational invariance of the theories, we argue that perurbative S matrix formulation of such theories is problematic in the sense that the S matrix based on free in and out states misses the spacetime localized degrees. We show that, in 3+1 dimensions, the problem disappears for the cases where the noncommutativity becomes purely spatial by an appropriate Lorentz transformation or the noncommutativity is lightlike with its electric and magnetic parts orthogonal to each other.

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Dongsu Bak, Seok Kim. 2004-05-19. Troubles with Spacetime Noncommutative Theories: Tachyons or S-branes?. https://doi.org/10.1088/1126-6708%2F2004%2F05%2F053

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