Electromagnetic form factors from the fifth dimension

Abstract

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 $Ad{S}_5\times S^5$. 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 $\gamma \pi \rho$ and $\gamma f_0\rho$ 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 ${\gamma }^{\ast }{\gamma }^{\ast }\pi$ form factor. However this channel is more subtle and comparisons to the QCD result are more involved.

34 pages, 6 figures, pdflatex. References and clarifications added

References in corpus (5)

• Light-Front Dynamics and AdS/QCD Correspondence: Gravitational Form Factors of Composite Hadrons
• Gravitational Form Factors in the Axial Sector from an AdS/QCD Model
• Anomalous Form Factor of the Neutral Pion in Extended AdS/QCD Model with Chern-Simons Term
• Deep inelastic structure functions from supergravity at small x
• The supergravity dual of 3d supersymmetric gauge theories with unquenched flavors

Cited by in corpus (1)

• Light-Front Dynamics and AdS/QCD Correspondence: Gravitational Form Factors of Composite Hadrons