Speaker
Description
We use the background field formalism to calculate NLO corrections to a quark transverse momentum dependent parton distribution function (TMD) in the projectile light-cone gauge, i.e. $A^+=0$ for a left-moving target.
We calculate the full result using two different ways, corresponding to different prescriptions for handling the light-cone singularity: the Mandelstam–Leibbrandt and a family of prescriptions including principal value, retarded, and advanced prescriptions.
From the one-loop renormalization of the quark TMD, we obtain the Collins-Soper-Sterman (CSS) evolution equations. Remarkably, different prescriptions for the light-cone gauge will yield very different results for individual diagrams, but ultimately lead to the same final result.
The calculation is a continuation of similar work in the target light-cone gauge [1].
The projectile light-cone gauge is widely used in calculations within the gluon saturation regime. Our work therefore opens a way to understanding the connections between the TMD and Colour Glass Condensate (CGC) approaches within the same framework.
[1] T. Altinoluk, G. Beuf, J. Jalilian-Marian, arXiv:2505.20467 [hep-ph]
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