D-branes in asymmetrically gauged WZW models and axial-vector duality

Abstract

We construct D-branes in a left-right asymmetrically gauged WZW model, with the gauge subgroup embedded differently on the left and the right of the group element. The symmetry-preserving boundary conditions for the group-valued field g are described, and the corresponding action is found. When the subgroup H= U(1), we can implement T-duality on the axially gauged WZW action; an orbifold of the vectorially gauged theory is produced. For the parafermion SU(2)/ U(1) coset model, a σ-model is obtained with vanishing gauge field on D-branes. We show that a boundary condition surviving from the SU(2) parent theory characterizes D-branes in the parafermion theory, determining the shape of A-branes. The gauge field on B-branes is obtained from the boundary condition for A-branes, by the orbifold construction and T-duality. These gauge fields stabilize the B-branes.