In my previous update I showed a first look at Sivers asymmetries. Here, I show a first look at Collins asymmetries. For this brief look I have not implemented many track cuts. Eventually, I will probably need to set limits on j_T and z, as well as an appropriate range of n_σ(π) among other cuts.

I show the asymmetries as functions of z and j_T. The binning is substantially different from the 2006 preliminary result. This will probably need to be revisited. Also, I have not selected "leading" charged-particles. I simply loop over all tracks within the trigger-matched jets. In this case, I believe this is the more desirable approach. I have not attempted to evaluate leak-through asymmetries at this early stage.

Figure 1: Collins Asymmetry as a Function of z

charge > 0	charge < 0

Figure 2: Collins Asymmetry as a Function of j_T

charge > 0	charge < 0

 As expected, there is no clear signal from a single run, especially, given the lack of track cuts. However, sufficient statistics are available to begin tuning cuts for larger data samples.

 It is also useful at this point to examine some track summary figures. These may inform appropriate cuts down the road.

Figure 3: Track Angle and Kinematic Coverage

There appears to be some structure in φ_S. My guess is this is from trigger patches, but perhaps my intuition is off. In any case, far more of the phase space is illuminated than in my dissertation.

Figure 4: Track ID

At some point it will be instructive to evaluate the asymmetries for various track ID cuts. The headline measurement will likely be pions. The 2006 preliminary result selected pions by taking -1 < n_σ(π) < 2. It's not clear to me this range is most appropriate for 2011. Additionally, there is TOF information which was not available in 2006, though, I suspect this corresponds mostly to low-p_T tracks.