Four-point functions and kaon decays in a minimal AdS/QCD model
Thomas Hambye, Babiker Hassanain, John March-Russell, Martin Schvellinger
Abstract
We study the predictions of holographic QCD for various observable four-point quark flavour current-current correlators. The dual 5-dimensional bulk theory we consider is a
SU(3
)
L
×SU(3
)
R
Yang Mills theory in a slice of
Ad
S
5
spacetime with boundaries. Particular UV and IR boundary conditions encode the spontaneous breaking of the dual 4D global chiral symmetry down to the
SU(3
)
V
subgroup. We explain in detail how to calculate the 4D four-point quark flavour current-current correlators using the 5D holographic theory, including interactions. We use these results to investigate predictions of holographic QCD for the
ΔI=1/2
rule for kaon decays and the
B
K
parameter. The results agree well in comparison with experimental data, with an accuracy of 25% or better. The holographic theory automatically includes the contributions of the meson resonances to the four-point correlators. The correlators agree well in the low-momentum and high-momentum limit, in comparison with chiral perturbation theory and perturbative QCD results, respectively.