Next-to-leading-logarithmic high-energy factorization in the dense regime

Establish high-energy factorization at next-to-leading-logarithmic accuracy in the dense saturation regime by carrying out the required two-loop operator or observable calculations.

Background

Leading-logarithmic JIMWLK evolution has been established for a broad class of TMD-factorizable processes, but extending the factorization framework to next-to-leading-logarithmic accuracy requires two-loop information. In the dense regime, this entails either calculating a small-x TMD from its operator definition at two loops or calculating a two-loop observable that factorizes onto that TMD.

References

An important challenge for the future is to establish high-energy factorization at next-to-leading logarithmic accuracy.

— Transverse momentum dependent parton distributions at small $x$  (2610.26004 - Caucal et al., 19 Oct 2026) in Section 3.1, paragraph beginning “At a given perturbative order”