We analyse various $U(1)_{EM}$ form factors of mesons at strong coupling in an $mathcal{N}=2$ flavored version of $mathcal{N}=4$ $SYM$ which becomes conformal in the UV. The quark mass breaks the conformal symmetry in the IR and generates a mass gap.
In the appropriate limit, the gravity dual is described in terms of probe $D7$-branes in $AdS_5times S^5$. By studying the $D7$ fluctuations we find the suitable terms in a meson effective theory which allow us to compute the desired form factors, namely the $gammapirho$ and $gamma f_0rho$ transition form factors. At large $q^2$ we find perfect agreement with the naive parton model counting, which is a consequence of the conformal nature of both QCD and our model in the UV. By using the same tools, we can compute the $gamma^*gamma^*pi$ form factor. However this channel is more subtle and comparisons to the QCD result are more involved.
A warped resolved conifold background of type IIB theory, constructed in hep-th/0701064, is dual to the supersymmetric $SU(N)times SU(N)$ gauge theory with a vacuum expectation value (VEV) for one of the bifundamental chiral superfields. This VEV bre
aks both the superconformal invariance and the baryonic symmetry. The absolute value of the VEV controls the resolution parameter of the conifold. In this paper we study the phase of the VEV, which corresponds to the Goldstone boson of the broken symmetry. We explicitly construct the linearized perturbation of the 4-form R-R potential that contains the Goldstone boson. On general grounds, the theory should contain global strings which create a monodromy of the pseudoscalar Goldstone boson field. We identify these strings with the $D3$-branes wrapping the two-cycle at the tip of the warped resolved conifold.
