  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.
