paper

On the Couplings of Vector Mesons in AdS/QCD

arXiv:hep-th/0409118 · doi:10.1088/1126-6708/2006/04/003

Abstract

We address, in the AdS/CFT context, the issue of the universality of the couplings of the rho meson to other hadrons. Exploring some models, we find that generically the rho-dominance prediction f_ρg_{ρH H}=m_ρ^2 does not hold, and that g_{ρH H} is not independent of the hadron H. However, we prove that, in any model within the AdS/QCD context, there are two limiting regimes where the g_{ρH H}, along with the couplings of all excited vector mesons as well, become H-independent: (1) when H is created by an operator of large dimension, and (2) when H is a highly-excited hadron. We also find a sector of a particular model where universality for the rho coupling is exact. Still, in none of these cases need it be true that f_ρg_ρ=m_ρ^2, although we find empirically that the relation does hold approximately (up to a factor of order two) within the models we have studied.

28 pages, 3 figures. ver 2: Comments about the commutability of two universal limits in the D3/D7 case corrected. Typos corrected. ver 3: Substantive revisions of certain calculations, with improved conventions, correction of typos, clarifications, new formulas, new figures; no changes in essential results or conclusions

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