Measurement of Transverse Single-Spin Asymmetries for Di-Jet Production in Proton-Proton Collisions at $\sqrt{s} = 200$ GeV

Understand

We report the first measurement of the opening angle distribution between pairs of jets produced in high-energy collisions of transversely polarized protons.

• The measurement probes (Sivers) correlations between the transverse spin orientation of a proton and the transverse momentum directions of its partons.
• With both beams polarized, the wide pseudorapidity ($-1 \leq \eta \leq +2$) coverage for jets permits separation of Sivers functions for the valence and sea regions.
• The resulting asymmetries are all consistent with zero and considerably smaller than Sivers effects observed in semi-inclusive deep inelastic scattering (SIDIS).