Six-dimensional tensionless strings in the large N limit Original Research Article

When N five-branes of M-theory coincide the world-volume theory contains tensionless strings, according to Stromingerʹs construction. This suggests a large N limit of tensionless string theories. For the small E8 instanton theories, the definition would be a large instanton number. An adiabatic argument suggests that in the large N limit an effective extra uncompactified dimension might be observed. We also propose “surface equations”, which are an analog of the Makeenko-Migdal loop equations, and might describe correlators in the tensionless string theories. In these equations, the anti-self-dual 2-forms of 6D and the tensionless strings enter on an equal footing. Addition of strings with CFTs on their world-sheet is analogous to addition of matter in 4D QCD.