Small-x computation of the gluon g1T TMD

Compute the gluon g_{1T} TMD at small x, including its first nonvanishing sub-eikonal contribution and high-energy behavior.

Background

Several polarized gluon TMDs have been derived at sub-eikonal accuracy, but the small-x operator and evolution of g_{1T} remain unavailable. Its expected sub-eikonal suppression makes it part of the unresolved spin-dependent sector.

References

To our knowledge, the remaining TMD $g_{1T}$, which is also expected to be at least subeikonal, has not yet been computed at small $x$.

— Transverse momentum dependent parton distributions at small $x$  (2610.26004 - Caucal et al., 19 Oct 2026) in Section 4.1, paragraph beginning “The TMD h1L”