Brane Bulk Couplings and Condensation from REA Fusion

The physical meaning of the Reflection Equation Algebras of hep-th/0107265 and hep-th/0203110 is elucidated in the context of Wess--Zumino--Witten D-brane geometry, as determined by couplings of closed-string modes to the D-brane. Particular emphasis is laid on the role of algebraic fusion of the matrix generators of the Reflection Equation Algebras. The fusion is shown to induce transitions among D-brane configurations admitting an interpretation in terms of RG-driven condensation phenomena.