Table 1: Summary of available perturbative calculations of quark TMD distributions and their leading matching at small-b.

Name Function Leading matching function Twist of leading matching Maximum known order of coef. function Ref. Mix with gluon

unpolarizedtw-2 NNLO ()[4, 5] yes
Sivers tw-3 NLO ()[614]yes

helicitytw-2 NLO ()[6, 1517]yes
worm-gear T, , tw-2/3 LO ()[18]  [6] yes
transversity tw-2 NNLO()[19] no
Boer-Mulders tw-3 LO ()[6] no
worm-gear L, tw-2/3 LO ()[18]  [6] no
pretzelosity tw-4

The calculation is done in the momentum space. The result is given for the moments of distribution.
The pretzelosity can in principle be a twist-2 observable; however its twist-2 matching coefficient has been found to be zero up to NNLO [19]. Therefore one can conjecture that pretzelosity is actually a twist-4 observable. Some arguments in favor of this can also be found in [20].
The quark Sivers function at NLO has a long story [813]. A complete calculation is now available in [14].