We explore tensor mesons in AdS/QCD focusing on $f_2(1270)$, the lightest spin-2 resonance in QCD. We find that the $f_2$ mass and the partial width $\Gamma (f_2\to \gamma \gamma )$ are in very good agreement with data. In fact, the dimensionless ratio of these two quantities comes out to be within the current experimental bound. The result for this ratio depends only on $N_c$ and $N_f$, and the quark and glueball content of the operator responsible for the $f_2$; more importantly, it does not depend on chiral symmetry breaking and so it is both independent of much of the arbitrariness of AdS/QCD and completely out of reach of chiral perturbation theory. For comparison, we also explore $f_2\to \pi \pi$, which, because of its sensitivity to the UV corrections, has much more uncertainty. We also calculate the masses of the higher spin resonances on the Regge trajectory of the $f_2$, and find they compare favorably with experiment.

• Received 12 December 2005

DOI:https://doi.org/10.1103/PhysRevD.74.086004