https://doi.org/10.1140/epjc/s10052-008-0642-2
Regular Article - Theoretical Physics
Couplings of the rho meson in a holographic dual of QCD with Regge trajectories
1
Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui, 230026, P.R. China
2
Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, Beijing, 100049, P.R. China
* e-mail: zuof@mail.ihep.ac.cn
Received:
5
January
2008
Revised:
10
May
2008
Published online:
27
June
2008
The couplings gρHH of the ρ meson with a scalar meson H are calculated in a holographic dual of QCD in which the Regge trajectories for the mesons are manifest. In contrast to the conclusion in general AdS/QCD models, the resulting couplings grow linearly with the quantum number of excited H; thus they are far from universal. This non-universality seems to result from the disappearance of an explicit cutoff in the holographic dimension in this model. Correspondingly, the ρ-dominance for the electromagnetic form factors of H does not hold any more, even in an apparent sign-alternating manner. With these couplings at hand, the asymptotic behavior of the form factors can easily be calculated. The form factor exhibits the 1/Q(2Δ-2) behavior, which is in accordance with the scaling behavior of the fixed-angle scattering amplitude based on the AdS/CFT correspondence. It is also pointed out that the asymptotic behavior can be matched to the results of perturbative QCD, if the conformal dimension Δ of the operator is replaced by the combination τ+L of the meson.
© Springer-Verlag , 2008
