Tachyon condensation on fuzzy sphere and noncommutative solitons Original Research Article

We study a brane–antibrane system and a non-BPS D-brane in SU(2) WZW model. We first discuss the tachyon condensation using the vertex operator formalism and find the generation of codimension two D-branes after the condensation. Our result is consistent with the recent interpretation that a D2-brane is a bound state of D0-branes. Then we investigate the world-volume effective theory on a non-BPS D-brane. It becomes a field theory on the “fuzzy sphere” when the level is sent to infinity. The most interesting feature is that there exist the noncommutative tachyonic solitons and we can identify them with D0-branes. We also discuss the brane–antibrane system from the world-volume point of view and comment on the relation to the noncommutative version of the index theorem.