The impact of prescriptions in phenomenological extractions of transverse momentum dependent distributions

Abstract We investigate the impact of phenomenological prescriptions in the Collins–Soper–Sterman (CSS) approach for global extractions of Transverse Momentum Distributions (TMDs). We show that fits to low-energy Drell–Yan data with different choices of $$b_*$$ b ∗ prescription yield equally good agreement with data and similar TMDs at small partonic transverse momentum. In contrast, sizable differences emerge at intermediate transverse momentum region, significantly affecting the predictions for high-energy Drell–Yan processes. Our results demonstrate that the $$b_*$$ b ∗ prescription represents an intrinsic source of theoretical uncertainty in the CSS approach, introducing systematic effects that influence TMD extractions and their interpretation. At the same time, our analysis emphasizes the interplay between data at different energy scales in assessing the effect of phenomenological prescriptions in TMD fits adopting the CSS framework.