The impact of prescriptions in phenomenological extractions of Transverse Momentum Dependent distributions

TL;DR

This paper examines how different phenomenological prescriptions within the CSS framework affect the extraction of TMDs, revealing that the choice of $b_*$ prescription introduces significant theoretical uncertainties, especially at intermediate and high transverse momenta.

Contribution

It demonstrates that the $b_*$ prescription causes systematic uncertainties in TMD extractions, highlighting the importance of prescription choice in phenomenological analyses.

Findings

Fits to low-energy data are insensitive to $b_*$ choices.

Differences in TMDs become significant at intermediate transverse momentum.

The $b_*$ prescription is a key source of theoretical uncertainty.

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 $b_*$ 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 $b_*$ 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.