paper

Evidence for Q-Dependent Nuclear Transverse-Momentum Redistribution Beyond Broadening from AI-driven analysis of p-Cu Drell-Yan

arXiv:2605.05425

Abstract

We extract a target-side Cu transverse-momentum profile from fixed-target $p$ --Cu Drell--Yan data by holding a momentum-space proton reference fixed and training only an asymmetric Cu kernel in the small- $q_{T}$ region. In the supported window, $0.15 \leq x_{C u} \leq 0.46$ and $7.5 \leq Q_{M} \leq 15.75$ GeV, the nuclear modification is not a universal width increase. It appears as $Q$ -dependent redistribution: an $O (1 GeV)$ shoulder and compensating probability flow between shoulder and resolved-tail regions, beyond one-parameter broadening.