Abstract:We consider an open string stretched between a Y = 0 brane and a Y θ = 0 brane. The latter brane is rotated with respect to the former by an angle θ, and is described by a non-diagonal boundary S-matrix. This system interpolates smoothly between the Y − Y (θ = 0) and the Y −Ȳ (θ = π/2) systems, which are described by diagonal boundary S-matrices. We use integrability to compute the energies of one-particle states at weak coupling up to leading wrapping order (4, 6 loops) as a function of the angle. The results for the diagonal cases exactly match with those obtained previously.