Abstract
The zero-bias conductance peak (ZBCP) in the normal metal-d-wave super-conductor planar junction is investigated using a generalized method of image. We show that the broken reflection symmetry relative to the junction interface is essential for the emergence of ZBCP. The number of localized modes along the interface is shown to be identical to the number of zeros in the bulk Green's function. The formulation is also applicable to other particle-hole pairing states, thus provides a unified view for the ZBCP in various systems.