  The high-energy evolution of Wilson line operators, which at leading order is
described by the Balitsky-JIMWLK equations, receives large radiative
corrections enhanced by single and double collinear logarithms at
next-to-leading order and beyond. We propose a method for resumming such
logarithmic corrections to all orders, at the level of the Langevin formulation
of the JIMWLK equation. The ensuing, collinearly-improved Langevin equation
features generalized Wilson line operators, which depend not only upon rapidity
(the logarithm of the longitudinal momentum), but also upon the transverse size
of the color neutral projectile to which the Wilson lines belong. This
additional scale dependence is built up during the evolution, via the condition
that the successive emissions of soft gluons be ordered in time. The presence
of this transverse scale in the Langevin equation furthermore allows for the
resummation of the one-loop running coupling corrections.
