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Measurement of transverse single-spin asymmetries for di-jet production in proton-proton collisions at s**(1/2) = 200-GeV

The collaboration
Phys.Rev.Lett. 99 (2007) 142003, 2007.

Abstract
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). We discuss theoretical attempts to reconcile the new results with the sizable transverse spin effects seen in SIDIS and forward hadron production in pp collisions.

• #### Figure 3c

Data from Figure 3

10.17182/hepdata.102938.v1/t1

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated...

• #### Figure 3d

Data from Figure 3

10.17182/hepdata.102938.v1/t2

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated...

• #### Figure 3e

Data from Figure 3

10.17182/hepdata.102938.v1/t3

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated...

• #### Figure 3f

Data from Figure 3

10.17182/hepdata.102938.v1/t4

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated...