Asymptotic constraints on QCD correlators and holographic models

Abstract

We study the high-energy asymptotics of two bottom-up holographic models of QCD motivated by the AdS/CFT correspondence. In particular we compute the transition form factors of the lowest lying pseudoscalar mesons and an infinite tower of axial vector mesons and their contributions to the hadronic light-by-light scattering tensor. The results obtained are compared to high-energy expressions of real QCD, which are obtained via the operator product expansion, results on Goldstone bosons, and the chiral anomaly that appears when the axial currents are coupled to external fields. The results from the holographic side qualitatively reproduce the QCD results for one model (HW2) and qualitatively in the case of another model (HW1). In particular it is shown that two constraints on the hadronic light-by-light scattering tensor can only be fulfilled when including an infinite number of axial vector resonances and a finite amount of resonances cannot produce the right fall off behaviour.