paper

Holographic glueball structure

arXiv:0711.1179 · doi:10.1103/PhysRevD.78.025001

Abstract

We derive and systematically analyze scalar glueball correlation functions in both the hard-wall and dilaton soft-wall approximations to holographic QCD. The dynamical content of the holographic correlators is uncovered by examining their spectral density and by relating them to the operator product expansion, a dilatational low-energy theorem and a recently suggested two-dimensional power correction associated with the short-distance behavior of the heavy-quark potential. This approach provides holographic estimates for the three lowest-dimensional gluon condensates or alternatively their Wilson coefficients, the two leading moments of the instanton size distribution in the QCD vacuum and an effective UV gluon mass. A remarkable complementarity between the nonperturbative physics of the hard- and soft-wall correlators emerges, and their ability to describe detailed QCD results can be assessed quantitatively. We further provide the first holographic estimates for the decay constants of the 0++ glueball and its excitations. The hard-wall background turns out to encode more of the relevant QCD physics, and its prediction f ~ 0.8-0.9 GeV for the phenomenologically important ground state decay constant agrees inside errors with recent QCD sum rule and lattice results.

25 pages, discussion extended to match the published version (up to stylistic details), results and conclusions unchanged

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