We discuss the recombination of brane/anti-brane pairs carrying $D3$ brane charge in $AdS_5 times S^5$. These configurations are dual to co-dimension one defects in the ${cal N}=4$ super-Yang-Mills description. Due to their $D3$ charge, these defects
are actually domain walls in the dual gauge theory, interpolating between vacua of different gauge symmetry. A pair of unjoined defects each carry localized $(2+1)$ dimensional fermions and possess a global $U(N)times U(N)$ flavor symmetry while the recombined brane/anti-brane pairs exhibit only a diagonal U(N). We study the thermodynamics of this flavor-symmetry breaking under the influence of external magnetic field.
