Nucleon Tomography with Zero Jettiness.

Area of Science:

• High Energy Physics
• Quantum Chromodynamics
• Particle Physics

Background:

• Probing the nucleon's internal structure is crucial for understanding quantum chromodynamics.
• Transverse-momentum-dependent (TMD) observables are sensitive to the nucleon's three-dimensional structure.
• Initial-state radiation complicates the extraction of TMD information from experimental data.

Purpose of the Study:

• To develop a novel strategy for isolating the nucleon's intrinsic nonperturbative three-dimensional structure.
• To enhance the measurement of transverse single spin asymmetries (SSAs) in W and Z boson production.
• To facilitate a more definitive test of the predicted sign change of the Sivers function.

Main Methods:

• Employing zero jettiness as a veto to suppress initial-state radiation in TMD observables.
• Applying the method to W^{±} and Z^{0} boson production at the Relativistic Heavy Ion Collider (RHIC).
• Formulating the analysis within a joint resummation framework to handle large logarithms.

Main Results:

• Demonstrated a substantial enhancement of the asymmetry signal, e.g., 115% for W^{-} SSA at q_{⊥}=5 GeV.
• Showed a significant net gain in experimental sensitivity, even after accounting for statistical costs.
• Confirmed the method's potential for more definitive tests of the Sivers function sign change.

Conclusions:

• The proposed zero jettiness strategy effectively isolates nonperturbative nucleon structure.
• This method significantly improves sensitivity for spin-dependent measurements at RHIC and the future Electron-Ion Collider (EIC).
• The approach provides a powerful tool for advancing our understanding of the nucleon's internal dynamics.