Phys Rev Lett. 2026 Jan 16;136(2):021901. doi: 10.1103/rvgc-sgv7.
ABSTRACT
We propose a novel strategy to systematically isolate the nucleon’s intrinsic nonperturbative three-dimensional structure by employing zero jettiness to suppress initial-state radiation in transverse-momentum-dependent observables. Applying this method to transverse single spin asymmetries (SSAs) in W^{±} and Z^{0} boson production at Relativistic Heavy Ion Collider (RHIC), we demonstrate a substantial enhancement of the asymmetry signal (e.g., by 115% for W^{-} SSA at q_{⊥}=5 GeV). We show that this enhancement yields a substantial net gain in experimental sensitivity-even after accounting for the statistical cost of the veto-facilitating a more definitive test of the predicted Sivers function sign change. We further explore its applicability to spin-dependent measurements at the Electron-Ion Collider. Our analysis is formulated within a joint resummation framework that systematically resums large logarithms associated with both the veto scale and the gauge boson’s transverse momentum.
PMID:41616349 | DOI:10.1103/rvgc-sgv7
