Update: September 30, 2012

It was pointed out to me that I labeled the figures in terms of θ_jet. This is a mistake. These figures should be labeled in terms of η_jet.

In previous updates (Sivers and Collins) I looked at asymmetries for a single run 12046105. In this update I look at Collins and Sivers asymmetries for the currently available jet trees. These runs are described as Set-1.

Again, I have not implemented many track cuts; but I have changed a few since last time. The Sivers cuts have not changed. For the Collins asymmetries I have tried to restrict myself to pions utilizing the same -1 < n_σ(π) < 2 range as the Run-6 Preliminary result. Note, I do not restrict myself to pions for the Sivers asymmetries. I simply look at the jets regardless of the hadrons inside.

Cuts and Kinematics

Figure 1

As I mentioned before, there is also TOF information available; however, at this point, I have not attempted to use it. For the full run, this may be advantageous. To ensure that φ_h is well-determined, I have implemented a cut of ΔR > 0.1.

Figure 2

Finally, I have calculated asymmetries in j_T for two ranges of z: 0.1 < z < 0.8 and 0.4 < z < 0.8. As Carl points out, smaller z gets bogged down by stuff at the low end of the fragmentation chain, while higher z gets close to exclusive production and heavy trigger bias.

Figure 3

One issue that remains is binning. These triggers push the j_T reach much lower than Run-6, and I don't have much statistics at higher j_T. So, the binning I'm using is probably not practical. The same is probably true for z. I also note that some hot spots appear in the track η-φ scatter plot. So, I probably need to revisit the QA a bit.

Figure 4

Asymmetries

Asymmetries, again, are shown before correcting for polarization. Note the axis is labeled "P_beam×A_N."

Figure 5: Sivers Asymmetry as a Function of p_{T, jet}

Triggers
Comparison of Hemispheres and xF

As in every other measurement, I don't see any sign of a sizable Sivers asymmetry at mid rapidity. Thankfully, I also see no sign of an asymmetry for x_F < 0. The stories appear consistent between the two hemispheres.

Figure 6: Collins Asymmetry as a Function of z

Triggers
charge > 0	charge < 0
Comparison of Hemispheres and xF
charge > 0	charge < 0

It is still difficult to draw too many conclusions, here. There is a bit of a tease in the "All Trigger" plots, but I'm not ready to make any declarations.

Figure 7: Collins Asymmetry as a Function of j_T (0.1 < z < 0.8)

Triggers
charge > 0	charge < 0
Comparison of Hemispheres and xF
charge > 0	charge < 0

Again, the binning appears fairly ridiculous. It does seem like the points on "All Triggers" π⁺ lie systematically above the axis. The story is not quite as clear for π^-. Probably, it is worth rebinning these figures to see if the case is more clear.

Figure 8: Collins Asymmetry as a Function of j_T (0.4 < z < 0.8)

Triggers
charge > 0	charge < 0
Comparison of Hemispheres and xF
charge > 0	charge < 0

Statistics are pretty limited in the 0.4 < z < 0.8 case, so it's tough to conclude too much. Again, rebinning the histograms is worthwhile.