Intrinsic non-commutativity of closed string theory

Laurent Freidel, Robert G. Leigh, Djordje Minic

Research output: Contribution to journalArticlepeer-review


We show that the proper interpretation of the cocycle operators appearing in the physical vertex operators of compactified strings is that the closed string target is noncommutative. We track down the appearance of this non-commutativity to the Polyakov action of the flat closed string in the presence of translational monodromies (i.e., windings). In view of the unexpected nature of this result, we present detailed calculations from a variety of points of view, including a careful understanding of the consequences of mutual locality in the vertex operator algebra, as well as a detailed analysis of the symplectic structure of the Polyakov string. We also underscore why this non-commutativity was not emphasized previously in the existing literature. This non-commutativity can be thought of as a central extension of the zero-mode operator algebra, an effect set by the string length scale — it is present even in trivial backgrounds. Clearly, this result indicates that the α → 0 limit is more subtle than usually assumed.

Original languageEnglish (US)
Article number60
JournalJournal of High Energy Physics
Issue number9
StatePublished - Sep 1 2017


  • Conformal Field Theory
  • Non-Commutative Geometry
  • String Duality

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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