An exact solution of BPS domain wall junction

An exact solution of domain wall junction is obtained in a four-dimensional N = 1 supersymmetric U(1) x U(1)' gauge theory with three pairs of chiral superfields which is motivated by the N = 2 SU(2) gauge theory with one flavor perturbed by an adjoint scalar mass. The solution allows us to evaluate various quantities including a new central charge I, associated with the junction besides Z(k) which appears already in domain walls. We find that the new central charge Y-k gives a negative contribution to the mass of the domain wall junction whereas the central charge Z(k) gives a dominant positive contribution. One has to be cautious to identify the central charge Y-k alone as the mass of the junction. (C) 1999 Published by Elsevier Science B.V. All rights reserved.