  In JHEP 11 (2022) 169, we performed the first complete computation of the
back-to-back inclusive di-jet cross-section in Deeply Inelastic Scattering
(DIS) at small $x_{\rm Bj}$ to next-to-leading order (NLO) in the Color Glass
Condensate effective field theory (CGC EFT). We demonstrate here that for
di-jets with relative transverse momentum $P_\perp$ and transverse momentum
imbalance $q_\perp$, to leading power in $q_\perp/P_\perp$, the cross-section
for longitudinally polarized photons can be fully factorized into the product
of a perturbative impact factor and the nonperturbative Weizs\"{a}cker-Williams
(WW) transverse momentum dependent (TMD) gluon distribution to NLO accuracy.
The impact factor can further be expressed as the product of a universal soft
factor which resums Sudakov double and single logs in $P_\perp/q_\perp$ and a
coefficient function given by a remarkably compact analytic expression. We show
that in the CGC EFT the WW TMD satisfies a kinematically constrained JIMWLK
renormalization group evolution in rapidity. This factorization formula is
valid to all orders in $Q_s/q_\perp$ for $q_\perp, Q_s \ll P_\perp$, where
$Q_s$ is the semi-hard saturation scale that grows with rapidity.
