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Stringy Fuzziness as the Custodian of Time-Space Noncommutativity

J. L. F. Barbon·E. Rabinovici
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Abstract

We study aspects of obtaining field theories with noncommuting time-space coordinates as limits of open-string theories in constant electric-field backgrounds. We find that, within the standard closed-string backgrounds, there is an obstruction to decoupling the time-space noncommutativity scale from that of the string fuzziness scale. We speculate that this censorship may be string-theory's way of protecting the causality and unitarity structure. We study the moduli space of the obstruction in terms of the open- and closed-string backgrounds. Cases of both zero and infinite brane tensions as well as zero string couplings are obtained. A decoupling can be achieved formally by considering complex values of the dilaton and inverting the role of space and time in the light cone. This is reminiscent of a black-hole horizon. We study the corresponding supergravity solution in the large-N limit and find that the geometry has a naked singularity at the physical scale of noncommutativity.

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J. L. F. Barbon, E. Rabinovici. 2000-05-22. Stringy Fuzziness as the Custodian of Time-Space Noncommutativity. https://doi.org/10.1016/s0370-2693(00)00735-8

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