D-branes and Strings as Non-commutative Solitons

Abstract

The non-commutative geometry of a large auxiliary $B$-field simplifies the construction of D-branes as solitons in open string field theory. Similarly, fundamental strings are constructed as localized flux tubes in the string field theory. Tensions are determined exactly using general properties of non-BPS branes, and the non-Abelian structure of gauge fields on coincident D-branes is recovered.