  We consider the effect of including a non-minimal coupling between a $U(1)$
vector gauge field and the graviton Regge trajectory in holographic QCD models.
This coupling describes the QCD interaction between the quark bilinear
electromagnetic current and the Pomeron. We test this new coupling against DIS
data at low Bjorken $x$ and obtain an excellent fit with a chi squared of 1.1
over a very large kinematical range in the photon virtuality $Q^2<400 \ {\rm
GeV}^2$ and for $x<10^{-2}$. The scale of the new dimension full coupling,
which arises from integrating higher spin fields, is of order $6\ {\rm GeV}$.
This value matches precisely the expectations from effective field theory,
which indicate that such corrections are controlled by the mass gap between the
spin two and spin four glueballs that are described holographically by the
graviton and spin four field in the graviton Regge trajectory, respectively
