  The high energy (Regge) limit provides a playground for understanding all
loop structures of scattering amplitudes, and plays an important role in the
description of many phenomenologically relevant cross-sections. While well
understood in the planar limit, the structure of non-planar corrections
introduces many fascinating complexities, for which a general organizing
principle is still lacking. We study the structure of multi-reggeon exchanges
in the context of the effective field theory for forward scattering, and derive
their factorization into collinear operators (impact factors) and soft
operators. We derive the structure of the renormalization group consistency
equations in the effective theory, showing how the anomalous dimensions of the
soft operators are related to those of the collinear operators, allowing us to
derive renormalization group equations in the Regge limit purely from a
collinear perspective. The rigidity of the consistency equations provides
considerable insight into the all orders organization of Regge amplitudes in
the effective theory, as well as its relation to other approaches. Along the
way we derive a number of technical results that improve the understanding of
the effective theory. We illustrate this collinear perspective by re-deriving
all the standard BFKL equations for two-Glauber exchange from purely collinear
calculations, and we show that this perspective provides a number of conceptual
and computational advantages as compared to the standard view from soft or
Glauber physics. We anticipate that this formulation in terms of collinear
operators will enable a better understanding of the relation between BFKL and
DGLAP in gauge theories, and facilitate the analysis of renormalization group
evolution equations describing Reggeization beyond next-to-leading order.
