Strings in time-dependent orbifolds

Hong Liu, Gregory Moore, Nathan Seiberg

Research output: Contribution to journalArticlepeer-review

133 Scopus citations


We continue and extend our earlier investigation "Strings in a Time-Dependent Orbifold" (hep-th/0204168). We formulate conditions for an orbifold to be amenable to perturbative string analysis and classify the low dimensional orbifolds satisfying these conditions. We analyze the tree and torus amplitudes of some of these orbifolds. The tree amplitudes exhibit a new kind of infrared divergences which are a result of some ultraviolet effects. These UV enhanced IR divergences can be interpreted as due to back reaction of the geometry. We argue that for this reason the three dimensional parabolic orbifold is not amenable to perturbation theory. Similarly, the smooth four dimensional null-brane tensored with sufficiently few noncompact dimensions also appears problematic. However, when the number of noncompact dimensions is sufficiently large perturbation theory in these time dependent backgrounds seems consistent.

Original languageEnglish (US)
Pages (from-to)623-649
Number of pages27
JournalJournal of High Energy Physics
Issue number10
StatePublished - Oct 1 2002

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


  • Bosonic Strings
  • Conformal Field Models in String Theory
  • Superstrings and Heterotic Strings


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