A noncommutative M-theory five-brane

We investigate, in a certain decoupling limit, the effect of having a const ant C-field on the M-theory five-brane using an open membrane probe. We def ine an open membrane metric for the five-brane that remains non-degenerate in the limit. The canonical quantisation of the open membrane boundary lead s to a noncommutative loop space which is a functional analogue of the nonc ommutative geometry that occurs for D-branes. (C) 2000 Elsevier Science B.V . All rights reserved.